./usr/bin/bison 755 0 0 202000 5303476054 12013 0ustar rootwheel dk-̀\ `-:D$4 `PP`[̀rUWVS1ۋ=8}P Ƌ$ ~CfFu=8P @]P H1ۃ=8~9 @=8}E]HÃ9U54=8Pp De[^_U8UPE <t@P/ 8h LÐU=4t54)`=8t58`=<t5<`=@t5@`=Dt5D`=Ht5H`=Lt 5L`ÐU55= tM @ P P ;=0~ = u 8ÐUWVS198~DC9815x95vF$ X~Du4f xG@fCfD뵐=0e[^_UWVS90~W=4}}u}څ~"D^9~f|VfE@U ^9Mv$fff9tE}t 9Mw݃}u>~tvu@FE}tu LƉ4Fe[^_statesUWVS=D~ hM@M4D<)]PsfMfJ f DfJfZ B9sff9r$$DЍe[^_Uj $HDÐUVS50u Pá f@fCf50fs<K50u9sf2f19r=(t ((e[^UWVS1x9v.$ 8C} ffF9wtduC P f@fAfq8Q9sf8f:9r=,t , ,e[^_UWVSQf{{HE@ 9~(uF9}M MA 9~A9|UB 9z]C9|C9CE PEfxfsfFfpf DfHSU~ufTsMfTqM} uU29(u5(wS_ij Efxf@f5DfpM5(+CE P5EfSfBfPHEE1f{~LuF 9}9}ufDMfTyGufLsufL~UUGEC9E|9}uf DufL~3U29(u(teS_Zj yfCf DfK,j IfCf5Dfs(jEf DfH$U$j f5DfsDfCf DfK((DjEf5DfpD$M $e[^_Ujvf DfHf fH $$j If DfHDf@f DfH((%s: memory exhausted USEujP\_Åu5 hd h `_ j؋]UuÐUUUPxt y\PoPU$WVSh\PB\)УT[\TE5u958\]䐐E+`XE0uEE]98u]s`<u}u}4uE}9=8]5h5Xe[^_UWVSuU P=\ȉE9Uw܋Mh9Uv9 :9UwC9]e[^_reduceshiftan errorUWVS M$)ĉeL$MM HPUE=h19X#M)fBA9|C9DÍe[^_gotosUWVSh@P=})Уh@P M)ЉE=}t`MAp|F}TwlP9+=u h3fXNyM MuE5958~>uu=8}fMfE9|5958~(uEf8f:F9588f f Pf }f W=}PX MP==}tn lM=}E𐐐MQAp|8}DwMA9M}tO]]PEȋ}19}EȋM䐐f1f0B9U]}f_Eu9555EE]9~,}<t t 4t_Eu95׃=t5O_]ȉ}t u5_}tu$_e[^_add_lookback_edgeUWVSULPLP19}#]9E tCu9|u h;j<8f}fxe[^_UWVS] ]PKE~/U4 tf9|}fGf9}9|ڋ] ]SESE19u ~VE}}U]}~+]PU}] }fyUEEF9u }t u_19u ~;]]䐐}t f9|]f2f9}EF9u ̓}tu__Ee[^_US5119~!<t t 4#_C9߃=t 5_]UWVS=}DLPU19}[=]á t2UA9]s8 :9r uЉ]F9u19u~' tt QX_مuF9uك=t55_=t 5_e[^_US]  |@P@P=~! Mf9|19~+fu {e[^_tokentermntermtypeguardunionexpectstartleftrightnonassocbinarysemantic_parserpure_parserprecUWVS5DP9PrP轲_tP@26%t30@= <*>{t_S `X$2D9u V_ƈ؈FP9PrP_tP@ `X$u_t5S_5DMt5DMu 5DMu y5DMu Y5DMu 95DMu 5DMu 5DMu 5DMu 5DMu 5DM t5DMuf5DMu H5DM u (5DNt e[^_UVSu] 4 ,SV~;sz蹰7=t ++B5,e[^fatal error: %s "%s", line %d: %s UE=uPhQh `蹲_ P55hQh `蘲_jUSu(u$u uuuuu u8S胻_(Sz4limit of %d exceeded, too many %sUSuhh>R8S-_S$4internal error, %s UuhRh `˱_ 苮_UWVS5h蠷+5huPEEEt@PeE=hPL5)ЉEhPE] $f9}4؋@B|ދ<u}fEM0 9~uڋMufV}43fSl}9}sTu}Et8Suf Vu@P|<u}fEċu9ur}t u>_}t u-_=Et P_}tu_e[^_U塐tP_ #include "%s" extern int yyerror; extern int yycost; extern char * yymsg; extern YYSTYPE yyval; yyguard(n, yyvsp, yylsp) register int n; register YYSTYPE *yyvsp; register YYLTYPE *yylsp; { yyerror = 0; yycost = 0; yymsg = 0; switch (n) { #include "%s" extern YYSTYPE yyval; extern int yychar;yyaction(n, yyvsp, yylsp) register int n; register YYSTYPE *yyvsp; register YYLTYPE *yylsp; { switch (n) { switch (yyn) { #define yyparse %sparse #define yylex %slex #define yyerror %serror #define yylval %slval #define yychar %schar #define yydebug %sdebug U=t5@hT5^_ 5@dV=tUP56_ =5hwV5 _ 5hV5 _ 5hV5 ެ_ 5hV5 Ŭ_ 5hV5 謬_ 5hV5 蓬_Ð } } } U=t(hW5d_hW5Q_ÐhX#ifndef YYDEBUG #define YYDEBUG %d #endif #include "%s" #include #ifndef __STDC__ #define const #endif US=uo5褲_X9XrP_tP @t* Z9ZrPRj_뭐BB뢐=\t%PhDX5 ._ =t5@hpX5 _ hX5 _hX5 _" =$t5$۪_=tZ !] #define YYTRANSLATE(x) ((unsigned)(x) <= %d ? yytranslate[x] : %d) static const char yytranslate[] = { 0 static const short yytranslate[] = { 0%6d }; #define YYTRANSLATE(x) (x) UVS=L585`hY5 螩_=~ h~PhZ5 赦_ h0\5 蠦_f>hhZ5 耦_e[^ static const short yystos[] = { 0UVSh^5 ;_ 95D J9Jrj,R_ B,B ~. J9Jrj R_ B BClpPhZ5 譥_ F95DhZ5 葥_e[^ #if YYDEBUG != 0 static const short yyrline[] = { 0 }; static const char * const yytname[] = { "%s"\%c\n\t\b\%03o }; #endif static const short yyr1[] = { 0 }; static const short yyr2[] = { 0%6d }; UWVSh^5 蓤_ 9=t J9Jrj,Rj_ B,B ~. B9Brj R@_ B BFxPhZ5 _ G9=t} 81h3_5 _ 880҉փ+9=8 B9Brj,R覟_ B,BFK~( J9Jrj R{_ B B1 B9Brj"RS_ B"BF8;"t;\u"Phg_5 _ ; uhk_; uhn_ ;uhq_5 Ӣ_V;~;~~Pht_5 誢_ - J9JrPR萞_ JBFCt ;; B9Br j"RY_ B"BFG9=8hz_5 %_ 9=t| J9Jrj,R_ B,B ~. B9Brj R؝_ B BF@xPhZ5 蝡_ G9=t}@t R蠡_h_5 m_ 9=t J9Jrj,RF_ B,B ~. B9Brj R_ B BF Txx)JRhZ5 ٠_ G9=tu J9Jrj,R軜_ B,B ~' B9Brj R萜_ B Bt QU)HPh_5 K_  tRW_e[^_ #define YYFINAL %d #define YYFLAG %d #define YYNTBASE %d U5hYd5 ӟ_ hhpd5 軟_ 5hd5 袟_UDhPxP]UPBUP'!\=Lt5L(_=t5_=t5_=lt5l_Ut P_=t5詞_=t5蒞_] h7R static const short yydefact[] = {%6dUVS MPjPh4f5 _ j 9D J9Jrj,R辙_ B,B ~. J9Jrj R蔙_ B BFS]PhZ5 Y_ S C9DthZ5 0_=t 59_e[^U}]ċuЍEȹ19~-E}ȅtfuf0u EB9ً=)}ЃEK9]~uEă}tTH19}J=l}܋5uȐ}T_t%uV9~}fG9duEC9|ʡxut& 19}=}ĐDZufFC9|}}}<tu~}E]9]~n5u؍]EE}7u]19~M9EuEȃB9}9}~ uȉu}ĉ}EC9]}~-19~ 9EufB9]}u5u95~*=}Аf:uf9|Ee[^_U WVS119=~f8tGB9 }MQݟEu]4uE19~2f %s %s (rule %d)UWVSUUz }_E9}.M}DO$]f;~ f;3ޡ@p84h}5_ p$9]v(84h}5م_ 9]wڋJ9Jrj.R_0B.B"84h}5艅_ f;Vh}5l_ z9zrj R[_ B BEM9Mz9zr j R&_ B Be[^_ $default accept NO ACTIONS $ go to state %d %-4s shift, and go to state %d %-4s error (nonassociative) $default reduce using rule %d (%s) %-4s go to state %d UWVS}EHExE}u1}9=uh}h5_]{}19}^]f|stMTsl P9 ~=uRh5蚃_ R84h5{_F9u~3z9zrj R`_B B 1E}tr];}19}9]f|St&LS84h5U_ UB9UɅ~&z9zrj R~_ B B]<t9}tD}G@ B84Ph5脂_}t u莚9u~_]f|st*Tsl PR84h)52_F9uŋz9zr j R~_ B Be[^_ Grammar rule %-4d %s -> /* empty */ Terminals, with rules where they appear %s (-1) %s%s (%d) %d%s Nonterminals, with rules where they appear on left:, on right:UxWVS5h;_EU9t @]fv_/13lJÐjunk after `%%' in definition sectionno input grammarunknown character `%c' in declaration sectionunknown character with code 0x%x in declaration sectionU蓲% P9$0\t|ȏ̏ЏO뉐jjjjWo? bVW J>jjj! %=Lph` uh~ PhPhŎÐ#line %d "%s" unterminated stringunterminated comment in `%{' definitionunterminated `%{' definitionUWVS=u55h`5s_EH9HrPo_tP@ S09$LܕPDPJ9JrPRhn_ BBEދJ9JrPR&n_ BBH9HPYn_t u hoJ9JrPRm_BB\urH9HrPm_tP@u ho萾J9JrPRUm_BB uH9HrPm_tP@9J9JXdJ9JrPRl_ BBH9HrP m_tP@*t /)/J9JrPRdl_ BBH9HrPl_tP@1*J9JrPRk_ BBH9HrP)l_tBB*t/J9Jrj/B/ uSJ9Jrj Rck_ B BH9HriPk_u[juh=YJ9JrPRk_ BBH9HrP5k_tP@5hʻJ9JrPRj_ BBH9HrPj_tP@}t*}t4J9Jrj%R.j_ B%BEe[^_symbol %s redefinedtype redeclaration for %sinvalid text in %token or %nterm declarationUWVS115衪Py_%ÃtՃu<0=DPCs5DVv_뗐u{`x9} uph耺`UP}utfhfPhB`x u p /ph+u'u"`fTfPLh螹e[^_multiple %start declarationsinvalid %start declarationU=4t h$>4|t hA`Ðill-formed %type declarationinvalid %type declarationUWt h輸0=DPlq5DWt_5mPv_%tK辫tt (u#͐`x ux ph臸몐h.띐}redefining precedence of %sinvalid text in association declarationmalformatted association declarationUWVS115艧Pu_%c֪ƍV98$DКtttttttttttttttttH0=DPo5DSZs_`fxtph`f fHfMfHxuph`@tZx uX Oph軶;u`f TfHLhhљ2e[^_multiple %union declarations #line %d "%s" typedef unionunterminated commentunmatched close-brace (`}') YYSTYPE; UWVS=t h苵=u!55h51h_h5h_h5 h_=th5g_1H9HP1d_p|J9JrPRc_ BB=t'J9JrPRc_ BB{ t/t#}sH9HrP}c_tP@*t/t5Sir_qJ9JrPRb_ BB=t'J9JrPRb_ BB/H9HrPb_tP@J9JrPR0b_ BB=t'J9JrPRa_ BB ueu h͛*H9HrPa_tP@/J9Jrj/Rha_ B/B=J9Jrj/R4a_B/BH9HrPaa_tP@dGau hOuLh5d_=th5d_蜡Ã;tK5So_=H9HrP`_tP@ve[^_USH9Hr+Pr`_u,H9HrPU`_tP@ tʃ t1>T+CH9HrP `_tP@/~9~D+5Rn_EP`_]invalid $ valueUWVS}}5X] 19}t{u55F9|C@ e[^_ case %d: unmatched right brace ('}')yyval.%s%s:%d: warning: $$ of '%s' has no declared type. yyvsp[%d]%s:%d: warning: $%d of '%s' has no declared type. $%c is invalid@%c is invalidyylsp[%d]unterminated %guard clause; break;}UWVSE=tE 5th5a_ =u55h`5a_J9Jr j{R]_ B{B1H9H0P]_);6/b@$%" t<'{{tO@d}tkWJ9Jrj R\_ B BLJ9Jrj{R\_ B{BEGJ9Jrj}Rf\_ B}B~OhbދJ9JrPR\_ BBH9HPQ\_t u hoJ9JrPR[_BB\urH9HrP[_tP@u ho般J9JrPRM[_BB uH9HrPz[_tP@9J9JlxJ9Jrj/RZ_ B/BH9HrP[_tP@*t /V/J9JrPR`Z_ BBH9HrPZ_tP@ *J9JrPRY_ BBH9HrP%Z_tBB*t/J9Jrj/B/ uSJ9Jrj R_Y_ B BH9HriPY_u[juh͛9YJ9JrPRX_ BBH9HrP1Y_tP@1ɅHH9HrPX_tP@1<5DH9HrPX_tP@>t~ ؈F뿐5DH9HrP`X_tP@$uzh5[_u MAp tVh5[_ B=5MAp55h¡h `m[_  `X$u -5Sf_5EH9HrP|W_tP@u}~uuƋE+E Ph5Z_ tVh5Z_ =|MApu55hh `xZ_MSh5٧H9HrPV_tP@ `X$u-uV5Se_5EH9HrPGV_tP@ShD-E+E PhS5Y_ mh]讦J9JrPRsU_ BB}ut0H9HrPU_tP@} hx5X_{t<=uEH9HrP:U_tP@{uu u; 5Sd_e[^_invalid @-constructunmatched '{'UWVS=tE 5th5AX_ =u55h`5X_J9Jrj{RT_ B{BEH9HNP1T_<H'1"e t@h$+W@w/<{t7/J9Jrj RNS_ B B$J9Jrj{RS_ B{BEދJ9JrPRR_ BBH9HrP!S_P@t u ho责J9JrPRyR_BB\uvH9HrPR_tBBu hoDJ9JrPR R_BB uH9HrP6R_tBB9J9J|J9Jrj/RQ_ B/BH9HrPQ_tP@*t /^/J9JrPRQ_ BBH9HrPQQ_tP@ *J9JrPRP_ BBH9HrPP_tBB*t/J9Jrj/#B/* uSJ9Jrj RP_ B BH9HriPHP_u[juh͛YJ9JrPRO_ BBH9HrPO_tBB1ɅXH9HrPO_tP@1<5DH9HrPiO_tBB>t~ ؈F뿐5DH9HrPO_tP@$h5zR_uuj!ƅtVh5OR_ <=/MAp55h¡h `R_ `X$u -5Sg]_5ǡH9HrP!N_tP@u~uWJƉ+E Ph5wQ_ tVh5_Q_ =pMApW55hh `"Q_CSh5聞H9HrPQM_tP@ `X$u-uR5S6\_5ǡH9HrPL_tP@h莝+E PhS5MP_ ghZJ9JrPRL_ BBH9HrPUL_tP@}Mt\J9JrPRK_BBH9HrPK_tP@}hx5]O_e[^_@%dU5h35DYX_ 5D"@fhfPhill-formed rulegrammar starts with vertical barrule given for %s, which is a token%guard present but %semantic_parser not specifiedtwo actions at end of one rule%s:%d: warning: type clash ('%s' '%s') on default action %s:%d: warning: empty rule for typed nonterminal, and no action invalid inputtoo many symbols (tokens plus nonterminals); maximum %d#ifndef YYSTYPE #define YYSTYPE int #endif symbol %s used, not defined as token, and no rules for it U WVSEt FEEEEu" `M[ƃt h|=tu$u hߙ=4u Ut9j ~RËMKUUt]]MyuAfhfQhMyuqh袙蛌ƃt /=`}S}=`}u}}tutlj QÃ}t U {j QEMj rQÉ{U]Eu&j IQË `KU]uuEEEj QËM]uv `UJeƃ u&=u hѵuu&u/}t hӗuu- }}ttUJ U9J tfz tUz tr Mq S_tuUB u"PMA u"P55h#h `J_5}u-}u'Uz t55h_h `I_uu\ ujjG ujj3 u ; uuR uFh膖t.=8~hh觖=tu hE=u8=u/h5H_=th5H_XtD{u4shh `H_ ,Cf hfKh[u8+he[^_%s: memory exhausted U l9 t|Lt E lP5N_u5 hh `H_ jmtf f PÐUWOt h0=DPM5DW3Q_ tt-u' `x ux phϔ뾐}$tokens %s and %s both assigned number %dthe start symbol %s is undefinedthe start symbol %s is a token extern YYSTYPE %slval; extern YYSTYPE yylval; #define NT%s %d U WVS8@P{L85 8MPZL=8}P?L`EX 8M=}{uf fK2=Ltf{u Ef}f{C9`}`fsFC{M<Cf{Mf`@PtKP=`|‹=`}Аf9~Xt]C9~H=Lt?CPf_=t54>_= t 5 >_e[^UWVSU} P$f;~L95+y}$)u1f;e[^_UWVShyPFCEhyX|"U8:Ky9tڅ}S5 م}K$)5S@X+5uyU}M}$M)} ޅ}s= }څ}Sم}K$)} C9thyPu5 uE=}=t 5;_}=e[^_U,WVS8yPAEt yPgAE+y5uԉم}$)}ԅUԅ}5u܋]ԅ}Mԅ}$M)} 8yX|"U02Ky9t= }5u=}萐څ}Sم}K$)uڅ}Sم}K$)}_@fXf}ffEԉf}f$f)‰ȸuԋ} X$Ef8uf>f}95+UyM܅}$M)ut[fEf}}ffEfEf}}fffEf}f$f}f)ljȸ} u܉Euf>J]ԅ}{}}څ}Sم}K$)} uԉC9t48yPu5% uE5u=t5x8_}== t5 E8_u5 t yPu=t)lj= 98~D5uԉڅ}Sم}K$)}ԅt C98ŋ5h+5 5$9t=}Z5tuЉEf;tTff}ffE܉f}ffEԉf}f$f)‰ȸu} }܉9]e[^_UWVS=~c9t|V= }5@uӅ}Zх}J$)}uufEB9t}=$=h}P;< U)ȉE98~ ‹58uEf9|]98~Y=}u<^}څ}Sم}K$)ut fu}f7EEC9898~^}_2u}|(f/_ F95tbh5/_h5 /_95t@p84Vh5._ p$f;~)84h5._ f;h5}._F95tyh5]._e[^%d rules never reduced %s contains %d useless nonterminal%s and %d useless rule%s. U= t!=t5h2h `-_ 5hJh `-_ =$~P=$uP5$hWh `-_=$~=~Ghph `a-_=~,=uP5hvh `,-_hh `-_h `,_ÐUSM19t1%?A9uЋ]UVSu>tB@8uR2VS?6_؍e[^Uh2\XUWVSu^ǡ\1t)su5_u ttڅu\8j 2á\Cu'CC=Xu X X\؍e[^_UVS1\tt P+_؅uF~փ=\t 5\+_e[^UWVSE P}P><EEMMM9sV]E9Ev23t$U M9s 9Ew9Ewu E}M9Mre[^_UWVS}u VWQF}F>Í 89s u9re[^_GNU Bison version 1.19 UUM :t9uÐB:u1ÐUVS]u U19}  0@9|e[^UWVSu4+0)܉SW0P +4P0P4Pn S0+4PWO+404e[^_POSIXLY_CORRECT--%s: option `%s' is ambiguous %s: option `--%s' doesn't allow an argument %s: option `%c%s' doesn't allow an argument %s: option `%s' requires an argument %s: unrecognized option `--%s' %s: unrecognized option `%c%s' %s: unrecognized option, character code 0%o %s: unrecognized option `-%c' %s: option `-%c' requires an argument U,WVS]=40(U:-u,EDM9+u,E+h"r(_t, ,=(t(8=,490t9t#u  9 4t 0E9}RM 49tU 4>+u~u'M9 }U 4>-uŀ~t 4E9t~M 42EMԨuR490t&9tu . 49 0u 0U4M9 u490t@02 E 4>-u~uat >+u~uR=,u M m]UUE51tM Ex-E}G}U  (U 4>-u ~-t}u >+5(EEEF>t>=uE;tc+(P5(3._ u:+ (M؋;0I9M}u ]EEEE;u}tL}uF=tM 41h5h `H$_0=(H(}FEE>tiUzt F5= E \{-uU20hSrM1]SE 0hh `#_XUzusM9 }U O=tU t2hh `N#_0=(H(?0=(H(}tEMUztJM܋B 1UB }t/ E {-t;+t(PuFuo=tOM {-u5(1hh `q"_$5(]SE 0hh `K"_((E(]SuNj5(>ut}:uC=}~}~~SU 2h SM 1hAh `!_::u>t 5aX>t 5EE9u%=tSU 2h`h `O!_E? E (Ee[^_Ujjjuu uÐUjuuuu uÐUjuuuu uÐUVSdu1҃̀} ى jh0huj9$Xp|djh:jh.jh"jh)jh= jhQj̀򐐋H %t 93D$ځ%9u 9}D$T$t;jh0hujujhjd̀򐐃>L[^_]þ=t.jhephh0hkj>u֐1۸̀[^_]/lib/libc.so.4Jump table 4.1,\,(,b, ,a,,o,,V, . `ibgc./usr/man/man1/bison.1 644 0 0 11563 5303476054 13002 0ustar rootwheel.TH BISON 1 local .SH NAME bison \- GNU Project parser generator (yacc replacement) .SH SYNOPSIS .B bison [ .BI \-b " file-prefix" ] [ .BI \-\-file-prefix= file-prefix ] [ .B \-d ] [ .B \-\-defines ] [ .B \-l ] [ .B \-\-no-lines ] [ .BI \-o " outfile" ] [ .BI \-\-output-file= outfile ] [ .BI \-p " prefix" ] [ .BI \-\-name-prefix= prefix ] [ .B \-t ] [ .B \-\-debug ] [ .B \-v ] [ .B \-\-verbose ] [ .B \-V ] [ .B \-\-version ] [ .B \-y ] [ .B \-\-yacc ] [ .B \-\-fixed-output-files ] file .SH DESCRIPTION .I Bison is a parser generator in the style of .IR yacc (1). It should be upwardly compatible with input files designed for .IR yacc . .PP Input files should follow the .I yacc convention of ending in .BR .y . Unlike .IR yacc , the generated files do not have fixed names, but instead use the prefix of the input file. For instance, a grammar description file named .B parse.y would produce the generated parser in a file named .BR parse.tab.c , instead of .IR yacc 's .BR y.tab.c . .PP This description of the options that can be given to .I bison is adapted from the node .B Invocation in the .B bison.texinfo manual, which should be taken as authoritative. .PP .I Bison supports both traditional single-letter options and mnemonic long option names. Long option names are indicated with .B \-\- instead of .BR \- . Abbreviations for option names are allowed as long as they are unique. When a long option takes an argument, like .BR \-\-file-prefix , connect the option name and the argument with .BR = . .SS OPTIONS .TP .BI \-b " file-prefix" .br .ns .TP .BI \-\-file-prefix= file-prefix Specify a prefix to use for all .I bison output file names. The names are chosen as if the input file were named \fIfile-prefix\fB.c\fR. .TP .B \-d .br .ns .TP .B \-\-defines Write an extra output file containing macro definitions for the token type names defined in the grammar and the semantic value type .BR YYSTYPE , as well as a few .B extern variable declarations. .sp If the parser output file is named \fIname\fB.c\fR then this file is named \fIname\fB.h\fR. .sp This output file is essential if you wish to put the definition of .B yylex in a separate source file, because .B yylex needs to be able to refer to token type codes and the variable .BR yylval . .TP .B \-l .br .ns .TP .B \-\-no-lines Don't put any .B #line preprocessor commands in the parser file. Ordinarily .I bison puts them in the parser file so that the C compiler and debuggers will associate errors with your source file, the grammar file. This option causes them to associate errors with the parser file, treating it an independent source file in its own right. .TP .BI \-o " outfile" .br .ns .TP .BI \-\-output-file= outfile Specify the name .I outfile for the parser file. .sp The other output files' names are constructed from .I outfile as described under the .B \-v and .B \-d switches. .TP .BI \-p " prefix" .br .ns .TP .BI \-\-name-prefix= prefix Rename the external symbols used in the parser so that they start with .I prefix instead of .BR yy . The precise list of symbols renamed is .BR yyparse , .BR yylex , .BR yyerror , .BR yylval , .BR yychar , and .BR yydebug . .sp For example, if you use .BR "\-p c" , the names become .BR cparse , .BR clex , and so on. .TP .B \-t .br .ns .TP .B \-\-debug Output a definition of the macro .B YYDEBUG into the parser file, so that the debugging facilities are compiled. .TP .B \-v .br .ns .TP .B \-\-verbose Write an extra output file containing verbose descriptions of the parser states and what is done for each type of look-ahead token in that state. .sp This file also describes all the conflicts, both those resolved by operator precedence and the unresolved ones. .sp The file's name is made by removing .B .tab.c or .B .c from the parser output file name, and adding .B .output instead. .sp Therefore, if the input file is .BR foo.y , then the parser file is called .B foo.tab.c by default. As a consequence, the verbose output file is called .BR foo.output . .TP .B \-V .br .ns .TP .B \-\-version Print the version number of .IR bison . .TP .B \-y .br .ns .TP .B \-\-yacc .br .ns .TP .B \-\-fixed-output-files Equivalent to .BR "\-o y.tab.c" ; the parser output file is called .BR y.tab.c , and the other outputs are called .B y.output and .BR y.tab.h . The purpose of this switch is to imitate .IR yacc 's output file name conventions. Thus, the following shell script can substitute for .IR yacc : .sp .RS .ft B bison \-y $* .ft R .sp .RE .PP The long-named options can be introduced with `+' as well as `\-\-', for compatibility with previous releases. Eventually support for `+' will be removed, because it is incompatible with the POSIX.2 standard. .SH FILES /usr/local/lib/bison.simple simple parser .br /usr/local/lib/bison.hairy complicated parser .SH SEE ALSO .IR yacc (1) .br The .IR "Bison Reference Manual" , included as the file .B bison.texinfo in the .I bison source distribution. .SH DIAGNOSTICS Self explanatory. ./usr/emacs/info/bison.info 644 0 0 7070 5303476055 14170 0ustar rootwheelThis is Info file bison.info, produced by Makeinfo-1.47 from the input file /home/gd/gnu/bison/bison.texinfo. This file documents the Bison parser generator. Copyright (C) 1988, 1989, 1990 Free Software Foundation, Inc. Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided also that the sections entitled "GNU General Public License" and "Conditions for Using Bison" are included exactly as in the original, and provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one. Permission is granted to copy and distribute translations of this manual into another language, under the above conditions for modified versions, except that the sections entitled "GNU General Public License", "Conditions for Using Bison" and this permission notice may be included in translations approved by the Free Software Foundation instead of in the original English.  Indirect: bison.info-1: 1171 bison.info-2: 50488 bison.info-3: 100199 bison.info-4: 148300  Tag Table: (Indirect) Node: Top1173 Node: Introduction2339 Node: Conditions3506 Node: Copying5379 Node: Concepts24536 Node: Language and Grammar25605 Node: Grammar in Bison30641 Node: Semantic Values32375 Node: Semantic Actions34450 Node: Bison Parser35632 Node: Stages37875 Node: Grammar Layout39097 Node: Examples40353 Node: RPN Calc41516 Node: Rpcalc Decls42699 Node: Rpcalc Rules44218 Node: Rpcalc Input45959 Node: Rpcalc Line47421 Node: Rpcalc Expr48532 Node: Rpcalc Lexer50490 Node: Rpcalc Main52984 Node: Rpcalc Error53362 Node: Rpcalc Gen54340 Node: Rpcalc Compile55452 Node: Infix Calc56327 Node: Simple Error Recovery58989 Node: Multi-function Calc60876 Node: Mfcalc Decl62439 Node: Mfcalc Rules64418 Node: Mfcalc Symtab65797 Node: Exercises72038 Node: Grammar File72544 Node: Grammar Outline73319 Node: C Declarations74080 Node: Bison Declarations74684 Node: Grammar Rules75076 Node: C Code75513 Node: Symbols76416 Node: Rules80045 Node: Recursion81683 Node: Semantics83401 Node: Value Type84491 Node: Multiple Types85121 Node: Actions86063 Node: Action Types88442 Node: Mid-Rule Actions89745 Node: Declarations95296 Node: Token Decl96546 Node: Precedence Decl97845 Node: Union Decl99375 Node: Type Decl100201 Node: Expect Decl100878 Node: Start Decl102402 Node: Pure Decl102781 Node: Decl Summary104021 Node: Multiple Parsers105224 Node: Interface106665 Node: Parser Function107505 Node: Lexical108358 Node: Calling Convention109746 Node: Token Values111068 Node: Token Positions112186 Node: Pure Calling113044 Node: Error Reporting114020 Node: Action Features115740 Node: Algorithm119238 Node: Look-Ahead121508 Node: Shift/Reduce123623 Node: Precedence126032 Node: Why Precedence126688 Node: Using Precedence128563 Node: Precedence Examples129531 Node: How Precedence130233 Node: Contextual Precedence131342 Node: Parser States133114 Node: Reduce/Reduce134351 Node: Mystery Conflicts137549 Node: Stack Overflow140935 Node: Error Recovery142309 Node: Context Dependency147446 Node: Semantic Tokens148302 Node: Lexical Tie-ins151346 Node: Tie-in Recovery152868 Node: Debugging155037 Node: Invocation158309 Node: Bison Options158968 Node: Option Cross Key162427 Node: VMS Invocation163113 Node: Table of Symbols163899 Node: Glossary169480 Node: Index175142  End Tag Table ./usr/emacs/info/bison.info-1 644 0 0 142472 5303476055 14374 0ustar rootwheelThis is Info file bison.info, produced by Makeinfo-1.47 from the input file /home/gd/gnu/bison/bison.texinfo. This file documents the Bison parser generator. Copyright (C) 1988, 1989, 1990 Free Software Foundation, Inc. Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided also that the sections entitled "GNU General Public License" and "Conditions for Using Bison" are included exactly as in the original, and provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one. Permission is granted to copy and distribute translations of this manual into another language, under the above conditions for modified versions, except that the sections entitled "GNU General Public License", "Conditions for Using Bison" and this permission notice may be included in translations approved by the Free Software Foundation instead of in the original English.  File: bison.info, Node: Top, Next: Introduction, Prev: (DIR), Up: (DIR) This manual documents version 1.19 of Bison. * Menu: * Introduction:: * Conditions:: * Copying:: The GNU General Public License says how you can copy and share Bison Tutorial sections: * Concepts:: Basic concepts for understanding Bison. * Examples:: Three simple explained examples of using Bison. Reference sections: * Grammar File:: Writing Bison declarations and rules. * Interface:: C-language interface to the parser function `yyparse'. * Algorithm:: How the Bison parser works at run-time. * Error Recovery:: Writing rules for error recovery. * Context Dependency::What to do if your language syntax is too messy for Bison to handle straightforwardly. * Debugging:: Debugging Bison parsers that parse wrong. * Invocation:: How to run Bison (to produce the parser source file). * Table of Symbols:: All the keywords of the Bison language are explained. * Glossary:: Basic concepts are explained. * Index:: Cross-references to the text.  File: bison.info, Node: Introduction, Next: Conditions, Prev: Top, Up: Top Introduction ************ "Bison" is a general-purpose parser generator that converts a grammar description for an LALR(1) context-free grammar into a C program to parse that grammar. Once you are proficient with Bison, you may use it to develop a wide range of language parsers, from those used in simple desk calculators to complex programming languages. Bison is upward compatible with Yacc: all properly-written Yacc grammars ought to work with Bison with no change. Anyone familiar with Yacc should be able to use Bison with little trouble. You need to be fluent in C programming in order to use Bison or to understand this manual. We begin with tutorial chapters that explain the basic concepts of using Bison and show three explained examples, each building on the last. If you don't know Bison or Yacc, start by reading these chapters. Reference chapters follow which describe specific aspects of Bison in detail. Bison was written primarily by Robert Corbett; Richard Stallman made it Yacc-compatible. This edition corresponds to version 1.19 of Bison.  File: bison.info, Node: Conditions, Next: Copying, Prev: Introduction, Up: Top Conditions for Using Bison ************************** Bison grammars can be used only in programs that are free software. This is in contrast to what happens with the GNU C compiler and the other GNU programming tools. The reason Bison is special is that the output of the Bison utility--the Bison parser file--contains a verbatim copy of a sizable piece of Bison, which is the code for the `yyparse' function. (The actions from your grammar are inserted into this function at one point, but the rest of the function is not changed.) As a result, the Bison parser file is covered by the same copying conditions that cover Bison itself and the rest of the GNU system: any program containing it has to be distributed under the standard GNU copying conditions. Occasionally people who would like to use Bison to develop proprietary programs complain about this. We don't particularly sympathize with their complaints. The purpose of the GNU project is to promote the right to share software and the practice of sharing software; it is a means of changing society. The people who complain are planning to be uncooperative toward the rest of the world; why should they deserve our help in doing so? However, it's possible that a change in these conditions might encourage computer companies to use and distribute the GNU system. If so, then we might decide to change the terms on `yyparse' as a matter of the strategy of promoting the right to share. Such a change would be irrevocable. Since we stand by the copying permissions we have announced, we cannot withdraw them once given. We mustn't make an irrevocable change hastily. We have to wait until there is a complete GNU system and there has been time to learn how this issue affects its reception.  File: bison.info, Node: Copying, Next: Concepts, Prev: Conditions, Up: Top GNU GENERAL PUBLIC LICENSE ************************** Version 2, June 1991 Copyright (C) 1989, 1991 Free Software Foundation, Inc. 675 Mass Ave, Cambridge, MA 02139, USA Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed. Preamble ======== The licenses for most software are designed to take away your freedom to share and change it. By contrast, the GNU General Public License is intended to guarantee your freedom to share and change free software--to make sure the software is free for all its users. This General Public License applies to most of the Free Software Foundation's software and to any other program whose authors commit to using it. (Some other Free Software Foundation software is covered by the GNU Library General Public License instead.) You can apply it to your programs, too. When we speak of free software, we are referring to freedom, not price. Our General Public Licenses are designed to make sure that you have the freedom to distribute copies of free software (and charge for this service if you wish), that you receive source code or can get it if you want it, that you can change the software or use pieces of it in new free programs; and that you know you can do these things. To protect your rights, we need to make restrictions that forbid anyone to deny you these rights or to ask you to surrender the rights. These restrictions translate to certain responsibilities for you if you distribute copies of the software, or if you modify it. For example, if you distribute copies of such a program, whether gratis or for a fee, you must give the recipients all the rights that you have. You must make sure that they, too, receive or can get the source code. And you must show them these terms so they know their rights. We protect your rights with two steps: (1) copyright the software, and (2) offer you this license which gives you legal permission to copy, distribute and/or modify the software. Also, for each author's protection and ours, we want to make certain that everyone understands that there is no warranty for this free software. If the software is modified by someone else and passed on, we want its recipients to know that what they have is not the original, so that any problems introduced by others will not reflect on the original authors' reputations. Finally, any free program is threatened constantly by software patents. We wish to avoid the danger that redistributors of a free program will individually obtain patent licenses, in effect making the program proprietary. To prevent this, we have made it clear that any patent must be licensed for everyone's free use or not licensed at all. The precise terms and conditions for copying, distribution and modification follow. TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION 1. This License applies to any program or other work which contains a notice placed by the copyright holder saying it may be distributed under the terms of this General Public License. The "Program", below, refers to any such program or work, and a "work based on the Program" means either the Program or any derivative work under copyright law: that is to say, a work containing the Program or a portion of it, either verbatim or with modifications and/or translated into another language. (Hereinafter, translation is included without limitation in the term "modification".) Each licensee is addressed as "you". Activities other than copying, distribution and modification are not covered by this License; they are outside its scope. The act of running the Program is not restricted, and the output from the Program is covered only if its contents constitute a work based on the Program (independent of having been made by running the Program). Whether that is true depends on what the Program does. 2. You may copy and distribute verbatim copies of the Program's source code as you receive it, in any medium, provided that you conspicuously and appropriately publish on each copy an appropriate copyright notice and disclaimer of warranty; keep intact all the notices that refer to this License and to the absence of any warranty; and give any other recipients of the Program a copy of this License along with the Program. You may charge a fee for the physical act of transferring a copy, and you may at your option offer warranty protection in exchange for a fee. 3. 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If the modified program normally reads commands interactively when run, you must cause it, when started running for such interactive use in the most ordinary way, to print or display an announcement including an appropriate copyright notice and a notice that there is no warranty (or else, saying that you provide a warranty) and that users may redistribute the program under these conditions, and telling the user how to view a copy of this License. (Exception: if the Program itself is interactive but does not normally print such an announcement, your work based on the Program is not required to print an announcement.) These requirements apply to the modified work as a whole. If identifiable sections of that work are not derived from the Program, and can be reasonably considered independent and separate works in themselves, then this License, and its terms, do not apply to those sections when you distribute them as separate works. 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Accompany it with the complete corresponding machine-readable source code, which must be distributed under the terms of Sections 1 and 2 above on a medium customarily used for software interchange; or, b. Accompany it with a written offer, valid for at least three years, to give any third party, for a charge no more than your cost of physically performing source distribution, a complete machine-readable copy of the corresponding source code, to be distributed under the terms of Sections 1 and 2 above on a medium customarily used for software interchange; or, c. Accompany it with the information you received as to the offer to distribute corresponding source code. (This alternative is allowed only for noncommercial distribution and only if you received the program in object code or executable form with such an offer, in accord with Subsection b above.) The source code for a work means the preferred form of the work for making modifications to it. 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Any attempt otherwise to copy, modify, sublicense or distribute the Program is void, and will automatically terminate your rights under this License. However, parties who have received copies, or rights, from you under this License will not have their licenses terminated so long as such parties remain in full compliance. 6. You are not required to accept this License, since you have not signed it. However, nothing else grants you permission to modify or distribute the Program or its derivative works. These actions are prohibited by law if you do not accept this License. Therefore, by modifying or distributing the Program (or any work based on the Program), you indicate your acceptance of this License to do so, and all its terms and conditions for copying, distributing or modifying the Program or works based on it. 7. 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For example, if a patent license would not permit royalty-free redistribution of the Program by all those who receive copies directly or indirectly through you, then the only way you could satisfy both it and this License would be to refrain entirely from distribution of the Program. If any portion of this section is held invalid or unenforceable under any particular circumstance, the balance of the section is intended to apply and the section as a whole is intended to apply in other circumstances. It is not the purpose of this section to induce you to infringe any patents or other property right claims or to contest validity of any such claims; this section has the sole purpose of protecting the integrity of the free software distribution system, which is implemented by public license practices. Many people have made generous contributions to the wide range of software distributed through that system in reliance on consistent application of that system; it is up to the author/donor to decide if he or she is willing to distribute software through any other system and a licensee cannot impose that choice. This section is intended to make thoroughly clear what is believed to be a consequence of the rest of this License. 9. If the distribution and/or use of the Program is restricted in certain countries either by patents or by copyrighted interfaces, the original copyright holder who places the Program under this License may add an explicit geographical distribution limitation excluding those countries, so that distribution is permitted only in or among countries not thus excluded. In such case, this License incorporates the limitation as if written in the body of this License. 10. The Free Software Foundation may publish revised and/or new versions of the General Public License from time to time. Such new versions will be similar in spirit to the present version, but may differ in detail to address new problems or concerns. Each version is given a distinguishing version number. If the Program specifies a version number of this License which applies to it and "any later version", you have the option of following the terms and conditions either of that version or of any later version published by the Free Software Foundation. If the Program does not specify a version number of this License, you may choose any version ever published by the Free Software Foundation. 11. If you wish to incorporate parts of the Program into other free programs whose distribution conditions are different, write to the author to ask for permission. For software which is copyrighted by the Free Software Foundation, write to the Free Software Foundation; we sometimes make exceptions for this. Our decision will be guided by the two goals of preserving the free status of all derivatives of our free software and of promoting the sharing and reuse of software generally. NO WARRANTY 12. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR OR CORRECTION. 13. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. END OF TERMS AND CONDITIONS How to Apply These Terms to Your New Programs ============================================= If you develop a new program, and you want it to be of the greatest possible use to the public, the best way to achieve this is to make it free software which everyone can redistribute and change under these terms. To do so, attach the following notices to the program. It is safest to attach them to the start of each source file to most effectively convey the exclusion of warranty; and each file should have at least the "copyright" line and a pointer to where the full notice is found. ONE LINE TO GIVE THE PROGRAM'S NAME AND A BRIEF IDEA OF WHAT IT DOES. Copyright (C) 19YY NAME OF AUTHOR This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. Also add information on how to contact you by electronic and paper mail. If the program is interactive, make it output a short notice like this when it starts in an interactive mode: Gnomovision version 69, Copyright (C) 19YY NAME OF AUTHOR Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'. This is free software, and you are welcome to redistribute it under certain conditions; type `show c' for details. The hypothetical commands `show w' and `show c' should show the appropriate parts of the General Public License. Of course, the commands you use may be called something other than `show w' and `show c'; they could even be mouse-clicks or menu items--whatever suits your program. You should also get your employer (if you work as a programmer) or your school, if any, to sign a "copyright disclaimer" for the program, if necessary. Here is a sample; alter the names: Yoyodyne, Inc., hereby disclaims all copyright interest in the program `Gnomovision' (which makes passes at compilers) written by James Hacker. SIGNATURE OF TY COON, 1 April 1989 Ty Coon, President of Vice This General Public License does not permit incorporating your program into proprietary programs. If your program is a subroutine library, you may consider it more useful to permit linking proprietary applications with the library. If this is what you want to do, use the GNU Library General Public License instead of this License.  File: bison.info, Node: Concepts, Next: Examples, Prev: Copying, Up: Top The Concepts of Bison ********************* This chapter introduces many of the basic concepts without which the details of Bison will not make sense. If you do not already know how to use Bison or Yacc, we suggest you start by reading this chapter carefully. * Menu: * Language and Grammar:: Languages and context-free grammars, as mathematical ideas. * Grammar in Bison:: How we represent grammars for Bison's sake. * Semantic Values:: Each token or syntactic grouping can have a semantic value (the value of an integer, the name of an identifier, etc.). * Semantic Actions:: Each rule can have an action containing C code. * Bison Parser:: What are Bison's input and output, how is the output used? * Stages:: Stages in writing and running Bison grammars. * Grammar Layout:: Overall structure of a Bison grammar file.  File: bison.info, Node: Language and Grammar, Next: Grammar in Bison, Prev: Concepts, Up: Concepts Languages and Context-Free Grammars =================================== In order for Bison to parse a language, it must be described by a "context-free grammar". This means that you specify one or more "syntactic groupings" and give rules for constructing them from their parts. For example, in the C language, one kind of grouping is called an `expression'. One rule for making an expression might be, "An expression can be made of a minus sign and another expression". Another would be, "An expression can be an integer". As you can see, rules are often recursive, but there must be at least one rule which leads out of the recursion. The most common formal system for presenting such rules for humans to read is "Backus-Naur Form" or "BNF", which was developed in order to specify the language Algol 60. Any grammar expressed in BNF is a context-free grammar. The input to Bison is essentially machine-readable BNF. Not all context-free languages can be handled by Bison, only those that are LALR(1). In brief, this means that it must be possible to tell how to parse any portion of an input string with just a single token of look-ahead. Strictly speaking, that is a description of an LR(1) grammar, and LALR(1) involves additional restrictions that are hard to explain simply; but it is rare in actual practice to find an LR(1) grammar that fails to be LALR(1). *Note Mysterious Reduce/Reduce Conflicts: Mystery Conflicts, for more information on this. In the formal grammatical rules for a language, each kind of syntactic unit or grouping is named by a "symbol". Those which are built by grouping smaller constructs according to grammatical rules are called "nonterminal symbols"; those which can't be subdivided are called "terminal symbols" or "token types". We call a piece of input corresponding to a single terminal symbol a "token", and a piece corresponding to a single nonterminal symbol a "grouping". We can use the C language as an example of what symbols, terminal and nonterminal, mean. The tokens of C are identifiers, constants (numeric and string), and the various keywords, arithmetic operators and punctuation marks. So the terminal symbols of a grammar for C include `identifier', `number', `string', plus one symbol for each keyword, operator or punctuation mark: `if', `return', `const', `static', `int', `char', `plus-sign', `open-brace', `close-brace', `comma' and many more. (These tokens can be subdivided into characters, but that is a matter of lexicography, not grammar.) Here is a simple C function subdivided into tokens: int /* keyword `int' */ square (x) /* identifier, open-paren, */ /* identifier, close-paren */ int x; /* keyword `int', identifier, semicolon */ { /* open-brace */ return x * x; /* keyword `return', identifier, */ /* asterisk, identifier, semicolon */ } /* close-brace */ The syntactic groupings of C include the expression, the statement, the declaration, and the function definition. These are represented in the grammar of C by nonterminal symbols `expression', `statement', `declaration' and `function definition'. The full grammar uses dozens of additional language constructs, each with its own nonterminal symbol, in order to express the meanings of these four. The example above is a function definition; it contains one declaration, and one statement. In the statement, each `x' is an expression and so is `x * x'. Each nonterminal symbol must have grammatical rules showing how it is made out of simpler constructs. For example, one kind of C statement is the `return' statement; this would be described with a grammar rule which reads informally as follows: A `statement' can be made of a `return' keyword, an `expression' and a `semicolon'. There would be many other rules for `statement', one for each kind of statement in C. One nonterminal symbol must be distinguished as the special one which defines a complete utterance in the language. It is called the "start symbol". In a compiler, this means a complete input program. In the C language, the nonterminal symbol `sequence of definitions and declarations' plays this role. For example, `1 + 2' is a valid C expression--a valid part of a C program--but it is not valid as an *entire* C program. In the context-free grammar of C, this follows from the fact that `expression' is not the start symbol. The Bison parser reads a sequence of tokens as its input, and groups the tokens using the grammar rules. If the input is valid, the end result is that the entire token sequence reduces to a single grouping whose symbol is the grammar's start symbol. If we use a grammar for C, the entire input must be a `sequence of definitions and declarations'. If not, the parser reports a syntax error.  File: bison.info, Node: Grammar in Bison, Next: Semantic Values, Prev: Language and Grammar, Up: Concepts From Formal Rules to Bison Input ================================ A formal grammar is a mathematical construct. To define the language for Bison, you must write a file expressing the grammar in Bison syntax: a "Bison grammar" file. *Note Grammar File::. A nonterminal symbol in the formal grammar is represented in Bison input as an identifier, like an identifier in C. By convention, it should be in lower case, such as `expr', `stmt' or `declaration'. The Bison representation for a terminal symbol is also called a "token type". Token types as well can be represented as C-like identifiers. By convention, these identifiers should be upper case to distinguish them from nonterminals: for example, `INTEGER', `IDENTIFIER', `IF' or `RETURN'. A terminal symbol that stands for a particular keyword in the language should be named after that keyword converted to upper case. The terminal symbol `error' is reserved for error recovery. *Note Symbols::. A terminal symbol can also be represented as a character literal, just like a C character constant. You should do this whenever a token is just a single character (parenthesis, plus-sign, etc.): use that same character in a literal as the terminal symbol for that token. The grammar rules also have an expression in Bison syntax. For example, here is the Bison rule for a C `return' statement. The semicolon in quotes is a literal character token, representing part of the C syntax for the statement; the naked semicolon, and the colon, are Bison punctuation used in every rule. stmt: RETURN expr ';' ; *Note Rules::.  File: bison.info, Node: Semantic Values, Next: Semantic Actions, Prev: Grammar in Bison, Up: Concepts Semantic Values =============== A formal grammar selects tokens only by their classifications: for example, if a rule mentions the terminal symbol `integer constant', it means that *any* integer constant is grammatically valid in that position. The precise value of the constant is irrelevant to how to parse the input: if `x+4' is grammatical then `x+1' or `x+3989' is equally grammatical. But the precise value is very important for what the input means once it is parsed. A compiler is useless if it fails to distinguish between 4, 1 and 3989 as constants in the program! Therefore, each token in a Bison grammar has both a token type and a "semantic value". *Note Semantics::, for details. The token type is a terminal symbol defined in the grammar, such as `INTEGER', `IDENTIFIER' or `',''. It tells everything you need to know to decide where the token may validly appear and how to group it with other tokens. The grammar rules know nothing about tokens except their types. The semantic value has all the rest of the information about the meaning of the token, such as the value of an integer, or the name of an identifier. (A token such as `','' which is just punctuation doesn't need to have any semantic value.) For example, an input token might be classified as token type `INTEGER' and have the semantic value 4. Another input token might have the same token type `INTEGER' but value 3989. When a grammar rule says that `INTEGER' is allowed, either of these tokens is acceptable because each is an `INTEGER'. When the parser accepts the token, it keeps track of the token's semantic value. Each grouping can also have a semantic value as well as its nonterminal symbol. For example, in a calculator, an expression typically has a semantic value that is a number. In a compiler for a programming language, an expression typically has a semantic value that is a tree structure describing the meaning of the expression.  File: bison.info, Node: Semantic Actions, Next: Bison Parser, Prev: Semantic Values, Up: Concepts Semantic Actions ================ In order to be useful, a program must do more than parse input; it must also produce some output based on the input. In a Bison grammar, a grammar rule can have an "action" made up of C statements. Each time the parser recognizes a match for that rule, the action is executed. *Note Actions::. Most of the time, the purpose of an action is to compute the semantic value of the whole construct from the semantic values of its parts. For example, suppose we have a rule which says an expression can be the sum of two expressions. When the parser recognizes such a sum, each of the subexpressions has a semantic value which describes how it was built up. The action for this rule should create a similar sort of value for the newly recognized larger expression. For example, here is a rule that says an expression can be the sum of two subexpressions: expr: expr '+' expr { $$ = $1 + $3; } ; The action says how to produce the semantic value of the sum expression from the values of the two subexpressions.  File: bison.info, Node: Bison Parser, Next: Stages, Prev: Semantic Actions, Up: Concepts Bison Output: the Parser File ============================= When you run Bison, you give it a Bison grammar file as input. The output is a C source file that parses the language described by the grammar. This file is called a "Bison parser". Keep in mind that the Bison utility and the Bison parser are two distinct programs: the Bison utility is a program whose output is the Bison parser that becomes part of your program. The job of the Bison parser is to group tokens into groupings according to the grammar rules--for example, to build identifiers and operators into expressions. As it does this, it runs the actions for the grammar rules it uses. The tokens come from a function called the "lexical analyzer" that you must supply in some fashion (such as by writing it in C). The Bison parser calls the lexical analyzer each time it wants a new token. It doesn't know what is "inside" the tokens (though their semantic values may reflect this). Typically the lexical analyzer makes the tokens by parsing characters of text, but Bison does not depend on this. *Note Lexical::. The Bison parser file is C code which defines a function named `yyparse' which implements that grammar. This function does not make a complete C program: you must supply some additional functions. One is the lexical analyzer. Another is an error-reporting function which the parser calls to report an error. In addition, a complete C program must start with a function called `main'; you have to provide this, and arrange for it to call `yyparse' or the parser will never run. *Note Interface::. Aside from the token type names and the symbols in the actions you write, all variable and function names used in the Bison parser file begin with `yy' or `YY'. This includes interface functions such as the lexical analyzer function `yylex', the error reporting function `yyerror' and the parser function `yyparse' itself. This also includes numerous identifiers used for internal purposes. Therefore, you should avoid using C identifiers starting with `yy' or `YY' in the Bison grammar file except for the ones defined in this manual.  File: bison.info, Node: Stages, Next: Grammar Layout, Prev: Bison Parser, Up: Concepts Stages in Using Bison ===================== The actual language-design process using Bison, from grammar specification to a working compiler or interpreter, has these parts: 1. Formally specify the grammar in a form recognized by Bison (*note Grammar File::.). For each grammatical rule in the language, describe the action that is to be taken when an instance of that rule is recognized. The action is described by a sequence of C statements. 2. Write a lexical analyzer to process input and pass tokens to the parser. The lexical analyzer may be written by hand in C (*note Lexical::.). It could also be produced using Lex, but the use of Lex is not discussed in this manual. 3. Write a controlling function that calls the Bison-produced parser. 4. Write error-reporting routines. To turn this source code as written into a runnable program, you must follow these steps: 1. Run Bison on the grammar to produce the parser. 2. Compile the code output by Bison, as well as any other source files. 3. Link the object files to produce the finished product.  File: bison.info, Node: Grammar Layout, Prev: Stages, Up: Concepts The Overall Layout of a Bison Grammar ===================================== The input file for the Bison utility is a "Bison grammar file". The general form of a Bison grammar file is as follows: %{ C DECLARATIONS %} BISON DECLARATIONS %% GRAMMAR RULES %% ADDITIONAL C CODE The `%%', `%{' and `%}' are punctuation that appears in every Bison grammar file to separate the sections. The C declarations may define types and variables used in the actions. You can also use preprocessor commands to define macros used there, and use `#include' to include header files that do any of these things. The Bison declarations declare the names of the terminal and nonterminal symbols, and may also describe operator precedence and the data types of semantic values of various symbols. The grammar rules define how to construct each nonterminal symbol from its parts. The additional C code can contain any C code you want to use. Often the definition of the lexical analyzer `yylex' goes here, plus subroutines called by the actions in the grammar rules. In a simple program, all the rest of the program can go here.  File: bison.info, Node: Examples, Next: Grammar File, Prev: Concepts, Up: Top Examples ******** Now we show and explain three sample programs written using Bison: a reverse polish notation calculator, an algebraic (infix) notation calculator, and a multi-function calculator. All three have been tested under BSD Unix 4.3; each produces a usable, though limited, interactive desk-top calculator. These examples are simple, but Bison grammars for real programming languages are written the same way. You can copy these examples out of the Info file and into a source file to try them. * Menu: * RPN Calc:: Reverse polish notation calculator; a first example with no operator precedence. * Infix Calc:: Infix (algebraic) notation calculator. Operator precedence is introduced. * Simple Error Recovery:: Continuing after syntax errors. * Multi-function Calc:: Calculator with memory and trig functions. It uses multiple data-types for semantic values. * Exercises:: Ideas for improving the multi-function calculator.  File: bison.info, Node: RPN Calc, Next: Infix Calc, Prev: Examples, Up: Examples Reverse Polish Notation Calculator ================================== The first example is that of a simple double-precision "reverse polish notation" calculator (a calculator using postfix operators). This example provides a good starting point, since operator precedence is not an issue. The second example will illustrate how operator precedence is handled. The source code for this calculator is named `rpcalc.y'. The `.y' extension is a convention used for Bison input files. * Menu: * Decls: Rpcalc Decls. Bison and C declarations for rpcalc. * Rules: Rpcalc Rules. Grammar Rules for rpcalc, with explanation. * Input: Rpcalc Input. Explaining the rules for `input'. * Line: Rpcalc Line. Explaining the rules for `line'. * Expr: Rpcalc Expr. Explaining the rules for `expr'. * Lexer: Rpcalc Lexer. The lexical analyzer. * Main: Rpcalc Main. The controlling function. * Error: Rpcalc Error. The error reporting function. * Gen: Rpcalc Gen. Running Bison on the grammar file. * Comp: Rpcalc Compile. Run the C compiler on the output code.  File: bison.info, Node: Rpcalc Decls, Next: Rpcalc Rules, Prev: RPN calc, Up: RPN calc Declarations for `rpcalc' ------------------------- Here are the C and Bison declarations for the reverse polish notation calculator. As in C, comments are placed between `/*...*/'. /* Reverse polish notation calculator. */ %{ #define YYSTYPE double #include %} %token NUM %% /* Grammar rules and actions follow */ The C declarations section (*note C Declarations::.) contains two preprocessor directives. The `#define' directive defines the macro `YYSTYPE', thus specifying the C data type for semantic values of both tokens and groupings (*note Value Type::.). The Bison parser will use whatever type `YYSTYPE' is defined as; if you don't define it, `int' is the default. Because we specify `double', each token and each expression has an associated value, which is a floating point number. The `#include' directive is used to declare the exponentiation function `pow'. The second section, Bison declarations, provides information to Bison about the token types (*note Bison Declarations::.). Each terminal symbol that is not a single-character literal must be declared here. (Single-character literals normally don't need to be declared.) In this example, all the arithmetic operators are designated by single-character literals, so the only terminal symbol that needs to be declared is `NUM', the token type for numeric constants.  File: bison.info, Node: Rpcalc Rules, Next: Rpcalc Input, Prev: Rpcalc Decls, Up: RPN Calc Grammar Rules for `rpcalc' -------------------------- Here are the grammar rules for the reverse polish notation calculator. input: /* empty */ | input line ; line: '\n' | exp '\n' { printf ("\t%.10g\n", $1); } ; exp: NUM { $$ = $1; } | exp exp '+' { $$ = $1 + $2; } | exp exp '-' { $$ = $1 - $2; } | exp exp '*' { $$ = $1 * $2; } | exp exp '/' { $$ = $1 / $2; } /* Exponentiation */ | exp exp '^' { $$ = pow ($1, $2); } /* Unary minus */ | exp 'n' { $$ = -$1; } ; %% The groupings of the rpcalc "language" defined here are the expression (given the name `exp'), the line of input (`line'), and the complete input transcript (`input'). Each of these nonterminal symbols has several alternate rules, joined by the `|' punctuator which is read as "or". The following sections explain what these rules mean. The semantics of the language is determined by the actions taken when a grouping is recognized. The actions are the C code that appears inside braces. *Note Actions::. You must specify these actions in C, but Bison provides the means for passing semantic values between the rules. In each action, the pseudo-variable `$$' stands for the semantic value for the grouping that the rule is going to construct. Assigning a value to `$$' is the main job of most actions. The semantic values of the components of the rule are referred to as `$1', `$2', and so on.  File: bison.info, Node: Rpcalc Input, Next: Rpcalc Line, Prev: Rpcalc Rules, Up: RPN Calc Explanation of `input' ...................... Consider the definition of `input': input: /* empty */ | input line ; This definition reads as follows: "A complete input is either an empty string, or a complete input followed by an input line". Notice that "complete input" is defined in terms of itself. This definition is said to be "left recursive" since `input' appears always as the leftmost symbol in the sequence. *Note Recursion::. The first alternative is empty because there are no symbols between the colon and the first `|'; this means that `input' can match an empty string of input (no tokens). We write the rules this way because it is legitimate to type `Ctrl-d' right after you start the calculator. It's conventional to put an empty alternative first and write the comment `/* empty */' in it. The second alternate rule (`input line') handles all nontrivial input. It means, "After reading any number of lines, read one more line if possible." The left recursion makes this rule into a loop. Since the first alternative matches empty input, the loop can be executed zero or more times. The parser function `yyparse' continues to process input until a grammatical error is seen or the lexical analyzer says there are no more input tokens; we will arrange for the latter to happen at end of file.  File: bison.info, Node: Rpcalc Line, Next: Rpcalc Expr, Prev: Rpcalc Input, Up: RPN Calc Explanation of `line' ..................... Now consider the definition of `line': line: '\n' | exp '\n' { printf ("\t%.10g\n", $1); } ; The first alternative is a token which is a newline character; this means that rpcalc accepts a blank line (and ignores it, since there is no action). The second alternative is an expression followed by a newline. This is the alternative that makes rpcalc useful. The semantic value of the `exp' grouping is the value of `$1' because the `exp' in question is the first symbol in the alternative. The action prints this value, which is the result of the computation the user asked for. This action is unusual because it does not assign a value to `$$'. As a consequence, the semantic value associated with the `line' is uninitialized (its value will be unpredictable). This would be a bug if that value were ever used, but we don't use it: once rpcalc has printed the value of the user's input line, that value is no longer needed.  File: bison.info, Node: Rpcalc Expr, Next: Rpcalc Lexer, Prev: Rpcalc Line, Up: RPN Calc Explanation of `expr' ..................... The `exp' grouping has several rules, one for each kind of expression. The first rule handles the simplest expressions: those that are just numbers. The second handles an addition-expression, which looks like two expressions followed by a plus-sign. The third handles subtraction, and so on. exp: NUM | exp exp '+' { $$ = $1 + $2; } | exp exp '-' { $$ = $1 - $2; } ... ; We have used `|' to join all the rules for `exp', but we could equally well have written them separately: exp: NUM ; exp: exp exp '+' { $$ = $1 + $2; } ; exp: exp exp '-' { $$ = $1 - $2; } ; ... Most of the rules have actions that compute the value of the expression in terms of the value of its parts. For example, in the rule for addition, `$1' refers to the first component `exp' and `$2' refers to the second one. The third component, `'+'', has no meaningful associated semantic value, but if it had one you could refer to it as `$3'. When `yyparse' recognizes a sum expression using this rule, the sum of the two subexpressions' values is produced as the value of the entire expression. *Note Actions::. You don't have to give an action for every rule. When a rule has no action, Bison by default copies the value of `$1' into `$$'. This is what happens in the first rule (the one that uses `NUM'). The formatting shown here is the recommended convention, but Bison does not require it. You can add or change whitespace as much as you wish. For example, this: exp : NUM | exp exp '+' {$$ = $1 + $2; } | ... means the same thing as this: exp: NUM | exp exp '+' { $$ = $1 + $2; } | ... The latter, however, is much more readable. ./usr/emacs/info/bison.info-2 644 0 0 143304 5303476055 14370 0ustar rootwheelThis is Info file bison.info, produced by Makeinfo-1.47 from the input file /home/gd/gnu/bison/bison.texinfo. This file documents the Bison parser generator. Copyright (C) 1988, 1989, 1990 Free Software Foundation, Inc. Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided also that the sections entitled "GNU General Public License" and "Conditions for Using Bison" are included exactly as in the original, and provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one. Permission is granted to copy and distribute translations of this manual into another language, under the above conditions for modified versions, except that the sections entitled "GNU General Public License", "Conditions for Using Bison" and this permission notice may be included in translations approved by the Free Software Foundation instead of in the original English.  File: bison.info, Node: Rpcalc Lexer, Next: Rpcalc Main, Prev: Rpcalc Expr, Up: RPN Calc The `rpcalc' Lexical Analyzer ----------------------------- The lexical analyzer's job is low-level parsing: converting characters or sequences of characters into tokens. The Bison parser gets its tokens by calling the lexical analyzer. *Note Lexical::. Only a simple lexical analyzer is needed for the RPN calculator. This lexical analyzer skips blanks and tabs, then reads in numbers as `double' and returns them as `NUM' tokens. Any other character that isn't part of a number is a separate token. Note that the token-code for such a single-character token is the character itself. The return value of the lexical analyzer function is a numeric code which represents a token type. The same text used in Bison rules to stand for this token type is also a C expression for the numeric code for the type. This works in two ways. If the token type is a character literal, then its numeric code is the ASCII code for that character; you can use the same character literal in the lexical analyzer to express the number. If the token type is an identifier, that identifier is defined by Bison as a C macro whose definition is the appropriate number. In this example, therefore, `NUM' becomes a macro for `yylex' to use. The semantic value of the token (if it has one) is stored into the global variable `yylval', which is where the Bison parser will look for it. (The C data type of `yylval' is `YYSTYPE', which was defined at the beginning of the grammar; *note Rpcalc Decls::..) A token type code of zero is returned if the end-of-file is encountered. (Bison recognizes any nonpositive value as indicating the end of the input.) Here is the code for the lexical analyzer: /* Lexical analyzer returns a double floating point number on the stack and the token NUM, or the ASCII character read if not a number. Skips all blanks and tabs, returns 0 for EOF. */ #include yylex () { int c; /* skip white space */ while ((c = getchar ()) == ' ' || c == '\t') ; /* process numbers */ if (c == '.' || isdigit (c)) { ungetc (c, stdin); scanf ("%lf", &yylval); return NUM; } /* return end-of-file */ if (c == EOF) return 0; /* return single chars */ return c; }  File: bison.info, Node: Rpcalc Main, Next: Rpcalc Error, Prev: Rpcalc Lexer, Up: RPN Calc The Controlling Function ------------------------ In keeping with the spirit of this example, the controlling function is kept to the bare minimum. The only requirement is that it call `yyparse' to start the process of parsing. main () { yyparse (); }  File: bison.info, Node: Rpcalc Error, Next: Rpcalc Gen, Prev: Rpcalc Main, Up: RPN Calc The Error Reporting Routine --------------------------- When `yyparse' detects a syntax error, it calls the error reporting function `yyerror' to print an error message (usually but not always `"parse error"'). It is up to the programmer to supply `yyerror' (*note Interface::.), so here is the definition we will use: #include yyerror (s) /* Called by yyparse on error */ char *s; { printf ("%s\n", s); } After `yyerror' returns, the Bison parser may recover from the error and continue parsing if the grammar contains a suitable error rule (*note Error Recovery::.). Otherwise, `yyparse' returns nonzero. We have not written any error rules in this example, so any invalid input will cause the calculator program to exit. This is not clean behavior for a real calculator, but it is adequate in the first example.  File: bison.info, Node: Rpcalc Gen, Next: Rpcalc Compile, Prev: Rpcalc Error, Up: RPN Calc Running Bison to Make the Parser -------------------------------- Before running Bison to produce a parser, we need to decide how to arrange all the source code in one or more source files. For such a simple example, the easiest thing is to put everything in one file. The definitions of `yylex', `yyerror' and `main' go at the end, in the "additional C code" section of the file (*note Grammar Layout::.). For a large project, you would probably have several source files, and use `make' to arrange to recompile them. With all the source in a single file, you use the following command to convert it into a parser file: bison FILE_NAME.y In this example the file was called `rpcalc.y' (for "Reverse Polish CALCulator"). Bison produces a file named `FILE_NAME.tab.c', removing the `.y' from the original file name. The file output by Bison contains the source code for `yyparse'. The additional functions in the input file (`yylex', `yyerror' and `main') are copied verbatim to the output.  File: bison.info, Node: Rpcalc Compile, Prev: Rpcalc Gen, Up: RPN Calc Compiling the Parser File ------------------------- Here is how to compile and run the parser file: # List files in current directory. % ls rpcalc.tab.c rpcalc.y # Compile the Bison parser. # `-lm' tells compiler to search math library for `pow'. % cc rpcalc.tab.c -lm -o rpcalc # List files again. % ls rpcalc rpcalc.tab.c rpcalc.y The file `rpcalc' now contains the executable code. Here is an example session using `rpcalc'. % rpcalc 4 9 + 13 3 7 + 3 4 5 *+- -13 3 7 + 3 4 5 * + - n Note the unary minus, `n' 13 5 6 / 4 n + -3.166666667 3 4 ^ Exponentiation 81 ^D End-of-file indicator %  File: bison.info, Node: Infix Calc, Next: Simple Error Recovery, Prev: RPN Calc, Up: Examples Infix Notation Calculator: `calc' ================================= We now modify rpcalc to handle infix operators instead of postfix. Infix notation involves the concept of operator precedence and the need for parentheses nested to arbitrary depth. Here is the Bison code for `calc.y', an infix desk-top calculator. /* Infix notation calculator--calc */ %{ #define YYSTYPE double #include %} /* BISON Declarations */ %token NUM %left '-' '+' %left '*' '/' %left NEG /* negation--unary minus */ %right '^' /* exponentiation */ /* Grammar follows */ %% input: /* empty string */ | input line ; line: '\n' | exp '\n' { printf ("\t%.10g\n", $1); } ; exp: NUM { $$ = $1; } | exp '+' exp { $$ = $1 + $3; } | exp '-' exp { $$ = $1 - $3; } | exp '*' exp { $$ = $1 * $3; } | exp '/' exp { $$ = $1 / $3; } | '-' exp %prec NEG { $$ = -$2; } | exp '^' exp { $$ = pow ($1, $3); } | '(' exp ')' { $$ = $2; } ; %% The functions `yylex', `yyerror' and `main' can be the same as before. There are two important new features shown in this code. In the second section (Bison declarations), `%left' declares token types and says they are left-associative operators. The declarations `%left' and `%right' (right associativity) take the place of `%token' which is used to declare a token type name without associativity. (These tokens are single-character literals, which ordinarily don't need to be declared. We declare them here to specify the associativity.) Operator precedence is determined by the line ordering of the declarations; the higher the line number of the declaration (lower on the page or screen), the higher the precedence. Hence, exponentiation has the highest precedence, unary minus (`NEG') is next, followed by `*' and `/', and so on. *Note Precedence::. The other important new feature is the `%prec' in the grammar section for the unary minus operator. The `%prec' simply instructs Bison that the rule `| '-' exp' has the same precedence as `NEG'--in this case the next-to-highest. *Note Contextual Precedence::. Here is a sample run of `calc.y': % calc 4 + 4.5 - (34/(8*3+-3)) 6.880952381 -56 + 2 -54 3 ^ 2 9  File: bison.info, Node: Simple Error Recovery, Next: Multi-function Calc, Prev: Infix Calc, Up: Examples Simple Error Recovery ===================== Up to this point, this manual has not addressed the issue of "error recovery"--how to continue parsing after the parser detects a syntax error. All we have handled is error reporting with `yyerror'. Recall that by default `yyparse' returns after calling `yyerror'. This means that an erroneous input line causes the calculator program to exit. Now we show how to rectify this deficiency. The Bison language itself includes the reserved word `error', which may be included in the grammar rules. In the example below it has been added to one of the alternatives for `line': line: '\n' | exp '\n' { printf ("\t%.10g\n", $1); } | error '\n' { yyerrok; } ; This addition to the grammar allows for simple error recovery in the event of a parse error. If an expression that cannot be evaluated is read, the error will be recognized by the third rule for `line', and parsing will continue. (The `yyerror' function is still called upon to print its message as well.) The action executes the statement `yyerrok', a macro defined automatically by Bison; its meaning is that error recovery is complete (*note Error Recovery::.). Note the difference between `yyerrok' and `yyerror'; neither one is a misprint. This form of error recovery deals with syntax errors. There are other kinds of errors; for example, division by zero, which raises an exception signal that is normally fatal. A real calculator program must handle this signal and use `longjmp' to return to `main' and resume parsing input lines; it would also have to discard the rest of the current line of input. We won't discuss this issue further because it is not specific to Bison programs.  File: bison.info, Node: Multi-function Calc, Next: Exercises, Prev: Simple Error Recovery, Up: Examples Multi-Function Calculator: `mfcalc' =================================== Now that the basics of Bison have been discussed, it is time to move on to a more advanced problem. The above calculators provided only five functions, `+', `-', `*', `/' and `^'. It would be nice to have a calculator that provides other mathematical functions such as `sin', `cos', etc. It is easy to add new operators to the infix calculator as long as they are only single-character literals. The lexical analyzer `yylex' passes back all non-number characters as tokens, so new grammar rules suffice for adding a new operator. But we want something more flexible: built-in functions whose syntax has this form: FUNCTION_NAME (ARGUMENT) At the same time, we will add memory to the calculator, by allowing you to create named variables, store values in them, and use them later. Here is a sample session with the multi-function calculator: % acalc pi = 3.141592653589 3.1415926536 sin(pi) 0.0000000000 alpha = beta1 = 2.3 2.3000000000 alpha 2.3000000000 ln(alpha) 0.8329091229 exp(ln(beta1)) 2.3000000000 % Note that multiple assignment and nested function calls are permitted. * Menu: * Decl: Mfcalc Decl. Bison declarations for multi-function calculator. * Rules: Mfcalc Rules. Grammar rules for the calculator. * Symtab: Mfcalc Symtab. Symbol table management subroutines.  File: bison.info, Node: Mfcalc Decl, Next: Mfcalc Rules, Prev: Multi-function Calc, Up: Multi-function Calc Declarations for `mfcalc' ------------------------- Here are the C and Bison declarations for the multi-function calculator. %{ #include /* For math functions, cos(), sin(), etc. */ #include "calc.h" /* Contains definition of `symrec' */ %} %union { double val; /* For returning numbers. */ symrec *tptr; /* For returning symbol-table pointers */ } %token NUM /* Simple double precision number */ %token VAR FNCT /* Variable and Function */ %type exp %right '=' %left '-' '+' %left '*' '/' %left NEG /* Negation--unary minus */ %right '^' /* Exponentiation */ /* Grammar follows */ %% The above grammar introduces only two new features of the Bison language. These features allow semantic values to have various data types (*note Multiple Types::.). The `%union' declaration specifies the entire list of possible types; this is instead of defining `YYSTYPE'. The allowable types are now double-floats (for `exp' and `NUM') and pointers to entries in the symbol table. *Note Union Decl::. Since values can now have various types, it is necessary to associate a type with each grammar symbol whose semantic value is used. These symbols are `NUM', `VAR', `FNCT', and `exp'. Their declarations are augmented with information about their data type (placed between angle brackets). The Bison construct `%type' is used for declaring nonterminal symbols, just as `%token' is used for declaring token types. We have not used `%type' before because nonterminal symbols are normally declared implicitly by the rules that define them. But `exp' must be declared explicitly so we can specify its value type. *Note Type Decl::.  File: bison.info, Node: Mfcalc Rules, Next: Mfcalc Symtab, Prev: Mfcalc Decl, Up: Multi-function Calc Grammar Rules for `mfcalc' -------------------------- Here are the grammar rules for the multi-function calculator. Most of them are copied directly from `calc'; three rules, those which mention `VAR' or `FNCT', are new. input: /* empty */ | input line ; line: '\n' | exp '\n' { printf ("\t%.10g\n", $1); } | error '\n' { yyerrok; } ; exp: NUM { $$ = $1; } | VAR { $$ = $1->value.var; } | VAR '=' exp { $$ = $3; $1->value.var = $3; } | FNCT '(' exp ')' { $$ = (*($1->value.fnctptr))($3); } | exp '+' exp { $$ = $1 + $3; } | exp '-' exp { $$ = $1 - $3; } | exp '*' exp { $$ = $1 * $3; } | exp '/' exp { $$ = $1 / $3; } | '-' exp %prec NEG { $$ = -$2; } | exp '^' exp { $$ = pow ($1, $3); } | '(' exp ')' { $$ = $2; } ; /* End of grammar */ %%  File: bison.info, Node: Mfcalc Symtab, Prev: Mfcalc Rules, Up: Multi-function Calc The `mfcalc' Symbol Table ------------------------- The multi-function calculator requires a symbol table to keep track of the names and meanings of variables and functions. This doesn't affect the grammar rules (except for the actions) or the Bison declarations, but it requires some additional C functions for support. The symbol table itself consists of a linked list of records. Its definition, which is kept in the header `calc.h', is as follows. It provides for either functions or variables to be placed in the table. /* Data type for links in the chain of symbols. */ struct symrec { char *name; /* name of symbol */ int type; /* type of symbol: either VAR or FNCT */ union { double var; /* value of a VAR */ double (*fnctptr)(); /* value of a FNCT */ } value; struct symrec *next; /* link field */ }; typedef struct symrec symrec; /* The symbol table: a chain of `struct symrec'. */ extern symrec *sym_table; symrec *putsym (); symrec *getsym (); The new version of `main' includes a call to `init_table', a function that initializes the symbol table. Here it is, and `init_table' as well: #include main () { init_table (); yyparse (); } yyerror (s) /* Called by yyparse on error */ char *s; { printf ("%s\n", s); } struct init { char *fname; double (*fnct)(); }; struct init arith_fncts[] = { "sin", sin, "cos", cos, "atan", atan, "ln", log, "exp", exp, "sqrt", sqrt, 0, 0 }; /* The symbol table: a chain of `struct symrec'. */ symrec *sym_table = (symrec *)0; init_table () /* puts arithmetic functions in table. */ { int i; symrec *ptr; for (i = 0; arith_fncts[i].fname != 0; i++) { ptr = putsym (arith_fncts[i].fname, FNCT); ptr->value.fnctptr = arith_fncts[i].fnct; } } By simply editing the initialization list and adding the necessary include files, you can add additional functions to the calculator. Two important functions allow look-up and installation of symbols in the symbol table. The function `putsym' is passed a name and the type (`VAR' or `FNCT') of the object to be installed. The object is linked to the front of the list, and a pointer to the object is returned. The function `getsym' is passed the name of the symbol to look up. If found, a pointer to that symbol is returned; otherwise zero is returned. symrec * putsym (sym_name,sym_type) char *sym_name; int sym_type; { symrec *ptr; ptr = (symrec *) malloc (sizeof (symrec)); ptr->name = (char *) malloc (strlen (sym_name) + 1); strcpy (ptr->name,sym_name); ptr->type = sym_type; ptr->value.var = 0; /* set value to 0 even if fctn. */ ptr->next = (struct symrec *)sym_table; sym_table = ptr; return ptr; } symrec * getsym (sym_name) char *sym_name; { symrec *ptr; for (ptr = sym_table; ptr != (symrec *) 0; ptr = (symrec *)ptr->next) if (strcmp (ptr->name,sym_name) == 0) return ptr; return 0; } The function `yylex' must now recognize variables, numeric values, and the single-character arithmetic operators. Strings of alphanumeric characters with a leading nondigit are recognized as either variables or functions depending on what the symbol table says about them. The string is passed to `getsym' for look up in the symbol table. If the name appears in the table, a pointer to its location and its type (`VAR' or `FNCT') is returned to `yyparse'. If it is not already in the table, then it is installed as a `VAR' using `putsym'. Again, a pointer and its type (which must be `VAR') is returned to `yyparse'. No change is needed in the handling of numeric values and arithmetic operators in `yylex'. #include yylex () { int c; /* Ignore whitespace, get first nonwhite character. */ while ((c = getchar ()) == ' ' || c == '\t'); if (c == EOF) return 0; /* Char starts a number => parse the number. */ if (c == '.' || isdigit (c)) { ungetc (c, stdin); scanf ("%lf", &yylval.val); return NUM; } /* Char starts an identifier => read the name. */ if (isalpha (c)) { symrec *s; static char *symbuf = 0; static int length = 0; int i; /* Initially make the buffer long enough for a 40-character symbol name. */ if (length == 0) length = 40, symbuf = (char *)malloc (length + 1); i = 0; do { /* If buffer is full, make it bigger. */ if (i == length) { length *= 2; symbuf = (char *)realloc (symbuf, length + 1); } /* Add this character to the buffer. */ symbuf[i++] = c; /* Get another character. */ c = getchar (); } while (c != EOF && isalnum (c)); ungetc (c, stdin); symbuf[i] = '\0'; s = getsym (symbuf); if (s == 0) s = putsym (symbuf, VAR); yylval.tptr = s; return s->type; } /* Any other character is a token by itself. */ return c; } This program is both powerful and flexible. You may easily add new functions, and it is a simple job to modify this code to install predefined variables such as `pi' or `e' as well.  File: bison.info, Node: Exercises, Prev: Multi-function calc, Up: Examples Exercises ========= 1. Add some new functions from `math.h' to the initialization list. 2. Add another array that contains constants and their values. Then modify `init_table' to add these constants to the symbol table. It will be easiest to give the constants type `VAR'. 3. Make the program report an error if the user refers to an uninitialized variable in any way except to store a value in it.  File: bison.info, Node: Grammar File, Next: Interface, Prev: Examples, Up: Top Bison Grammar Files ******************* Bison takes as input a context-free grammar specification and produces a C-language function that recognizes correct instances of the grammar. The Bison grammar input file conventionally has a name ending in `.y'. * Menu: * Grammar Outline:: Overall layout of the grammar file. * Symbols:: Terminal and nonterminal symbols. * Rules:: How to write grammar rules. * Recursion:: Writing recursive rules. * Semantics:: Semantic values and actions. * Declarations:: All kinds of Bison declarations are described here. * Multiple Parsers:: Putting more than one Bison parser in one program.  File: bison.info, Node: Grammar Outline, Next: Symbols, Prev: Grammar File, Up: Grammar File Outline of a Bison Grammar ========================== A Bison grammar file has four main sections, shown here with the appropriate delimiters: %{ C DECLARATIONS %} BISON DECLARATIONS %% GRAMMAR RULES %% ADDITIONAL C CODE Comments enclosed in `/* ... */' may appear in any of the sections. * Menu: * C Declarations:: Syntax and usage of the C declarations section. * Bison Declarations:: Syntax and usage of the Bison declarations section. * Grammar Rules:: Syntax and usage of the grammar rules section. * C Code:: Syntax and usage of the additional C code section.  File: bison.info, Node: C Declarations, Next: Bison Declarations, Prev: Grammar Outline, Up: Grammar Outline The C Declarations Section -------------------------- The C DECLARATIONS section contains macro definitions and declarations of functions and variables that are used in the actions in the grammar rules. These are copied to the beginning of the parser file so that they precede the definition of `yyparse'. You can use `#include' to get the declarations from a header file. If you don't need any C declarations, you may omit the `%{' and `%}' delimiters that bracket this section.  File: bison.info, Node: Bison Declarations, Next: Grammar Rules, Prev: C Declarations, Up: Grammar Outline The Bison Declarations Section ------------------------------ The BISON DECLARATIONS section contains declarations that define terminal and nonterminal symbols, specify precedence, and so on. In some simple grammars you may not need any declarations. *Note Declarations::.  File: bison.info, Node: Grammar Rules, Next: C Code, Prev: Bison Declarations, Up: Grammar Outline The Grammar Rules Section ------------------------- The "grammar rules" section contains one or more Bison grammar rules, and nothing else. *Note Rules::. There must always be at least one grammar rule, and the first `%%' (which precedes the grammar rules) may never be omitted even if it is the first thing in the file.  File: bison.info, Node: C Code, Prev: Grammar Rules, Up: Grammar Outline The Additional C Code Section ----------------------------- The ADDITIONAL C CODE section is copied verbatim to the end of the parser file, just as the C DECLARATIONS section is copied to the beginning. This is the most convenient place to put anything that you want to have in the parser file but which need not come before the definition of `yyparse'. For example, the definitions of `yylex' and `yyerror' often go here. *Note Interface::. If the last section is empty, you may omit the `%%' that separates it from the grammar rules. The Bison parser itself contains many static variables whose names start with `yy' and many macros whose names start with `YY'. It is a good idea to avoid using any such names (except those documented in this manual) in the additional C code section of the grammar file.  File: bison.info, Node: Symbols, Next: Rules, Prev: Grammar Outline, Up: Grammar File Symbols, Terminal and Nonterminal ================================= "Symbols" in Bison grammars represent the grammatical classifications of the language. A "terminal symbol" (also known as a "token type") represents a class of syntactically equivalent tokens. You use the symbol in grammar rules to mean that a token in that class is allowed. The symbol is represented in the Bison parser by a numeric code, and the `yylex' function returns a token type code to indicate what kind of token has been read. You don't need to know what the code value is; you can use the symbol to stand for it. A "nonterminal symbol" stands for a class of syntactically equivalent groupings. The symbol name is used in writing grammar rules. By convention, it should be all lower case. Symbol names can contain letters, digits (not at the beginning), underscores and periods. Periods make sense only in nonterminals. There are two ways of writing terminal symbols in the grammar: * A "named token type" is written with an identifier, like an identifier in C. By convention, it should be all upper case. Each such name must be defined with a Bison declaration such as `%token'. *Note Token Decl::. * A "character token type" (or "literal token") is written in the grammar using the same syntax used in C for character constants; for example, `'+'' is a character token type. A character token type doesn't need to be declared unless you need to specify its semantic value data type (*note Value Type::.), associativity, or precedence (*note Precedence::.). By convention, a character token type is used only to represent a token that consists of that particular character. Thus, the token type `'+'' is used to represent the character `+' as a token. Nothing enforces this convention, but if you depart from it, your program will confuse other readers. All the usual escape sequences used in character literals in C can be used in Bison as well, but you must not use the null character as a character literal because its ASCII code, zero, is the code `yylex' returns for end-of-input (*note Calling Convention::.). How you choose to write a terminal symbol has no effect on its grammatical meaning. That depends only on where it appears in rules and on when the parser function returns that symbol. The value returned by `yylex' is always one of the terminal symbols (or 0 for end-of-input). Whichever way you write the token type in the grammar rules, you write it the same way in the definition of `yylex'. The numeric code for a character token type is simply the ASCII code for the character, so `yylex' can use the identical character constant to generate the requisite code. Each named token type becomes a C macro in the parser file, so `yylex' can use the name to stand for the code. (This is why periods don't make sense in terminal symbols.) *Note Calling Convention::. If `yylex' is defined in a separate file, you need to arrange for the token-type macro definitions to be available there. Use the `-d' option when you run Bison, so that it will write these macro definitions into a separate header file `NAME.tab.h' which you can include in the other source files that need it. *Note Invocation::. The symbol `error' is a terminal symbol reserved for error recovery (*note Error Recovery::.); you shouldn't use it for any other purpose. In particular, `yylex' should never return this value.  File: bison.info, Node: Rules, Next: Recursion, Prev: Symbols, Up: Grammar File Syntax of Grammar Rules ======================= A Bison grammar rule has the following general form: RESULT: COMPONENTS... ; where RESULT is the nonterminal symbol that this rule describes and COMPONENTS are various terminal and nonterminal symbols that are put together by this rule (*note Symbols::.). For example, exp: exp '+' exp ; says that two groupings of type `exp', with a `+' token in between, can be combined into a larger grouping of type `exp'. Whitespace in rules is significant only to separate symbols. You can add extra whitespace as you wish. Scattered among the components can be ACTIONS that determine the semantics of the rule. An action looks like this: {C STATEMENTS} Usually there is only one action and it follows the components. *Note Actions::. Multiple rules for the same RESULT can be written separately or can be joined with the vertical-bar character `|' as follows: RESULT: RULE1-COMPONENTS... | RULE2-COMPONENTS... ... ; They are still considered distinct rules even when joined in this way. If COMPONENTS in a rule is empty, it means that RESULT can match the empty string. For example, here is how to define a comma-separated sequence of zero or more `exp' groupings: expseq: /* empty */ | expseq1 ; expseq1: exp | expseq1 ',' exp ; It is customary to write a comment `/* empty */' in each rule with no components.  File: bison.info, Node: Recursion, Next: Semantics, Prev: Rules, Up: Grammar File Recursive Rules =============== A rule is called "recursive" when its RESULT nonterminal appears also on its right hand side. Nearly all Bison grammars need to use recursion, because that is the only way to define a sequence of any number of somethings. Consider this recursive definition of a comma-separated sequence of one or more expressions: expseq1: exp | expseq1 ',' exp ; Since the recursive use of `expseq1' is the leftmost symbol in the right hand side, we call this "left recursion". By contrast, here the same construct is defined using "right recursion": expseq1: exp | exp ',' expseq1 ; Any kind of sequence can be defined using either left recursion or right recursion, but you should always use left recursion, because it can parse a sequence of any number of elements with bounded stack space. Right recursion uses up space on the Bison stack in proportion to the number of elements in the sequence, because all the elements must be shifted onto the stack before the rule can be applied even once. *Note The Algorithm of the Bison Parser: Algorithm, for further explanation of this. "Indirect" or "mutual" recursion occurs when the result of the rule does not appear directly on its right hand side, but does appear in rules for other nonterminals which do appear on its right hand side. For example: expr: primary | primary '+' primary ; primary: constant | '(' expr ')' ; defines two mutually-recursive nonterminals, since each refers to the other.  File: bison.info, Node: Semantics, Next: Declarations, Prev: Recursion, Up: Grammar File Defining Language Semantics =========================== The grammar rules for a language determine only the syntax. The semantics are determined by the semantic values associated with various tokens and groupings, and by the actions taken when various groupings are recognized. For example, the calculator calculates properly because the value associated with each expression is the proper number; it adds properly because the action for the grouping `X + Y' is to add the numbers associated with X and Y. * Menu: * Value Type:: Specifying one data type for all semantic values. * Multiple Types:: Specifying several alternative data types. * Actions:: An action is the semantic definition of a grammar rule. * Action Types:: Specifying data types for actions to operate on. * Mid-Rule Actions:: Most actions go at the end of a rule. This says when, why and how to use the exceptional action in the middle of a rule.  File: bison.info, Node: Value Type, Next: Multiple Types, Prev: Semantics, Up: Semantics Data Types of Semantic Values ----------------------------- In a simple program it may be sufficient to use the same data type for the semantic values of all language constructs. This was true in the RPN and infix calculator examples (*note RPN Calc::.). Bison's default is to use type `int' for all semantic values. To specify some other type, define `YYSTYPE' as a macro, like this: #define YYSTYPE double This macro definition must go in the C declarations section of the grammar file (*note Grammar Outline::.).  File: bison.info, Node: Multiple Types, Next: Actions, Prev: Value Type, Up: Semantics More Than One Value Type ------------------------ In most programs, you will need different data types for different kinds of tokens and groupings. For example, a numeric constant may need type `int' or `long', while a string constant needs type `char *', and an identifier might need a pointer to an entry in the symbol table. To use more than one data type for semantic values in one parser, Bison requires you to do two things: * Specify the entire collection of possible data types, with the `%union' Bison declaration (*note Union Decl::.). * Choose one of those types for each symbol (terminal or nonterminal) for which semantic values are used. This is done for tokens with the `%token' Bison declaration (*note Token Decl::.) and for groupings with the `%type' Bison declaration (*note Type Decl::.).  File: bison.info, Node: Actions, Next: Action Types, Prev: Multiple Types, Up: Semantics Actions ------- An action accompanies a syntactic rule and contains C code to be executed each time an instance of that rule is recognized. The task of most actions is to compute a semantic value for the grouping built by the rule from the semantic values associated with tokens or smaller groupings. An action consists of C statements surrounded by braces, much like a compound statement in C. It can be placed at any position in the rule; it is executed at that position. Most rules have just one action at the end of the rule, following all the components. Actions in the middle of a rule are tricky and used only for special purposes (*note Mid-Rule Actions::.). The C code in an action can refer to the semantic values of the components matched by the rule with the construct `$N', which stands for the value of the Nth component. The semantic value for the grouping being constructed is `$$'. (Bison translates both of these constructs into array element references when it copies the actions into the parser file.) Here is a typical example: exp: ... | exp '+' exp { $$ = $1 + $3; } This rule constructs an `exp' from two smaller `exp' groupings connected by a plus-sign token. In the action, `$1' and `$3' refer to the semantic values of the two component `exp' groupings, which are the first and third symbols on the right hand side of the rule. The sum is stored into `$$' so that it becomes the semantic value of the addition-expression just recognized by the rule. If there were a useful semantic value associated with the `+' token, it could be referred to as `$2'. `$N' with N zero or negative is allowed for reference to tokens and groupings on the stack *before* those that match the current rule. This is a very risky practice, and to use it reliably you must be certain of the context in which the rule is applied. Here is a case in which you can use this reliably: foo: expr bar '+' expr { ... } | expr bar '-' expr { ... } ; bar: /* empty */ { previous_expr = $0; } ; As long as `bar' is used only in the fashion shown here, `$0' always refers to the `expr' which precedes `bar' in the definition of `foo'.  File: bison.info, Node: Action Types, Next: Mid-Rule Actions, Prev: Actions, Up: Semantics Data Types of Values in Actions ------------------------------- If you have chosen a single data type for semantic values, the `$$' and `$N' constructs always have that data type. If you have used `%union' to specify a variety of data types, then you must declare a choice among these types for each terminal or nonterminal symbol that can have a semantic value. Then each time you use `$$' or `$N', its data type is determined by which symbol it refers to in the rule. In this example, exp: ... | exp '+' exp { $$ = $1 + $3; } `$1' and `$3' refer to instances of `exp', so they all have the data type declared for the nonterminal symbol `exp'. If `$2' were used, it would have the data type declared for the terminal symbol `'+'', whatever that might be. Alternatively, you can specify the data type when you refer to the value, by inserting `' after the `$' at the beginning of the reference. For example, if you have defined types as shown here: %union { int itype; double dtype; } then you can write `$1' to refer to the first subunit of the rule as an integer, or `$1' to refer to it as a double.  File: bison.info, Node: Mid-Rule Actions, Prev: Action Types, Up: Semantics Actions in Mid-Rule ------------------- Occasionally it is useful to put an action in the middle of a rule. These actions are written just like usual end-of-rule actions, but they are executed before the parser even recognizes the following components. A mid-rule action may refer to the components preceding it using `$N', but it may not refer to subsequent components because it is run before they are parsed. The mid-rule action itself counts as one of the components of the rule. This makes a difference when there is another action later in the same rule (and usually there is another at the end): you have to count the actions along with the symbols when working out which number N to use in `$N'. The mid-rule action can also have a semantic value. This can be set within that action by an assignment to `$$', and can referred to by actions later in the rule using `$N'. Since there is no symbol to name the action, there is no way to declare a data type for the value in advance, so you must use the `$<...>' construct to specify a data type each time you refer to this value. There is no way to set the value of the entire rule with a mid-rule action, because assignments to `$$' do not have that effect. The only way to set the value for the entire rule is with an ordinary action at the end of the rule. Here is an example from a hypothetical compiler, handling a `let' statement that looks like `let (VARIABLE) STATEMENT' and serves to create a variable named VARIABLE temporarily for the duration of STATEMENT. To parse this construct, we must put VARIABLE into the symbol table while STATEMENT is parsed, then remove it afterward. Here is how it is done: stmt: LET '(' var ')' { $$ = push_context (); declare_variable ($3); } stmt { $$ = $6; pop_context ($5); } As soon as `let (VARIABLE)' has been recognized, the first action is run. It saves a copy of the current semantic context (the list of accessible variables) as its semantic value, using alternative `context' in the data-type union. Then it calls `declare_variable' to add the new variable to that list. Once the first action is finished, the embedded statement `stmt' can be parsed. Note that the mid-rule action is component number 5, so the `stmt' is component number 6. After the embedded statement is parsed, its semantic value becomes the value of the entire `let'-statement. Then the semantic value from the earlier action is used to restore the prior list of variables. This removes the temporary `let'-variable from the list so that it won't appear to exist while the rest of the program is parsed. Taking action before a rule is completely recognized often leads to conflicts since the parser must commit to a parse in order to execute the action. For example, the following two rules, without mid-rule actions, can coexist in a working parser because the parser can shift the open-brace token and look at what follows before deciding whether there is a declaration or not: compound: '{' declarations statements '}' | '{' statements '}' ; But when we add a mid-rule action as follows, the rules become nonfunctional: compound: { prepare_for_local_variables (); } '{' declarations statements '}' | '{' statements '}' ; Now the parser is forced to decide whether to run the mid-rule action when it has read no farther than the open-brace. In other words, it must commit to using one rule or the other, without sufficient information to do it correctly. (The open-brace token is what is called the "look-ahead" token at this time, since the parser is still deciding what to do about it. *Note Look-Ahead::.) You might think that you could correct the problem by putting identical actions into the two rules, like this: compound: { prepare_for_local_variables (); } '{' declarations statements '}' | { prepare_for_local_variables (); } '{' statements '}' ; But this does not help, because Bison does not realize that the two actions are identical. (Bison never tries to understand the C code in an action.) If the grammar is such that a declaration can be distinguished from a statement by the first token (which is true in C), then one solution which does work is to put the action after the open-brace, like this: compound: '{' { prepare_for_local_variables (); } declarations statements '}' | '{' statements '}' ; Now the first token of the following declaration or statement, which would in any case tell Bison which rule to use, can still do so. Another solution is to bury the action inside a nonterminal symbol which serves as a subroutine: subroutine: /* empty */ { prepare_for_local_variables (); } ; compound: subroutine '{' declarations statements '}' | subroutine '{' statements '}' ; Now Bison can execute the action in the rule for `subroutine' without deciding which rule for `compound' it will eventually use. Note that the action is now at the end of its rule. Any mid-rule action can be converted to an end-of-rule action in this way, and this is what Bison actually does to implement mid-rule actions.  File: bison.info, Node: Declarations, Next: Multiple Parsers, Prev: Semantics, Up: Grammar File Bison Declarations ================== The "Bison declarations" section of a Bison grammar defines the symbols used in formulating the grammar and the data types of semantic values. *Note Symbols::. All token type names (but not single-character literal tokens such as `'+'' and `'*'') must be declared. Nonterminal symbols must be declared if you need to specify which data type to use for the semantic value (*note Multiple Types::.). The first rule in the file also specifies the start symbol, by default. If you want some other symbol to be the start symbol, you must declare it explicitly (*note Language and Grammar::.). * Menu: * Token Decl:: Declaring terminal symbols. * Precedence Decl:: Declaring terminals with precedence and associativity. * Union Decl:: Declaring the set of all semantic value types. * Type Decl:: Declaring the choice of type for a nonterminal symbol. * Expect Decl:: Suppressing warnings about shift/reduce conflicts. * Start Decl:: Specifying the start symbol. * Pure Decl:: Requesting a reentrant parser. * Decl Summary:: Table of all Bison declarations.  File: bison.info, Node: Token Decl, Next: Precedence Decl, Prev: Declarations, Up: Declarations Token Type Names ---------------- The basic way to declare a token type name (terminal symbol) is as follows: %token NAME Bison will convert this into a `#define' directive in the parser, so that the function `yylex' (if it is in this file) can use the name NAME to stand for this token type's code. Alternatively you can use `%left', `%right', or `%nonassoc' instead of `%token', if you wish to specify precedence. *Note Precedence Decl::. You can explicitly specify the numeric code for a token type by appending an integer value in the field immediately following the token name: %token NUM 300 It is generally best, however, to let Bison choose the numeric codes for all token types. Bison will automatically select codes that don't conflict with each other or with ASCII characters. In the event that the stack type is a union, you must augment the `%token' or other token declaration to include the data type alternative delimited by angle-brackets (*note Multiple Types::.). For example: %union { /* define stack type */ double val; symrec *tptr; } %token NUM /* define token NUM and its type */  File: bison.info, Node: Precedence Decl, Next: Union Decl, Prev: Token Decl, Up: Declarations Operator Precedence ------------------- Use the `%left', `%right' or `%nonassoc' declaration to declare a token and specify its precedence and associativity, all at once. These are called "precedence declarations". *Note Precedence::, for general information on operator precedence. The syntax of a precedence declaration is the same as that of `%token': either %left SYMBOLS... or %left SYMBOLS... And indeed any of these declarations serves the purposes of `%token'. But in addition, they specify the associativity and relative precedence for all the SYMBOLS: * The associativity of an operator OP determines how repeated uses of the operator nest: whether `X OP Y OP Z' is parsed by grouping X with Y first or by grouping Y with Z first. `%left' specifies left-associativity (grouping X with Y first) and `%right' specifies right-associativity (grouping Y with Z first). `%nonassoc' specifies no associativity, which means that `X OP Y OP Z' is considered a syntax error. * The precedence of an operator determines how it nests with other operators. All the tokens declared in a single precedence declaration have equal precedence and nest together according to their associativity. When two tokens declared in different precedence declarations associate, the one declared later has the higher precedence and is grouped first.  File: bison.info, Node: Union Decl, Next: Type Decl, Prev: Precedence Decl, Up: Declarations The Collection of Value Types ----------------------------- The `%union' declaration specifies the entire collection of possible data types for semantic values. The keyword `%union' is followed by a pair of braces containing the same thing that goes inside a `union' in C. For example: %union { double val; symrec *tptr; } This says that the two alternative types are `double' and `symrec *'. They are given names `val' and `tptr'; these names are used in the `%token' and `%type' declarations to pick one of the types for a terminal or nonterminal symbol (*note Type Decl::.). Note that, unlike making a `union' declaration in C, you do not write a semicolon after the closing brace. ./usr/emacs/info/bison.info-3 644 0 0 140172 5303476055 14371 0ustar rootwheelThis is Info file bison.info, produced by Makeinfo-1.47 from the input file /home/gd/gnu/bison/bison.texinfo. This file documents the Bison parser generator. Copyright (C) 1988, 1989, 1990 Free Software Foundation, Inc. Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided also that the sections entitled "GNU General Public License" and "Conditions for Using Bison" are included exactly as in the original, and provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one. Permission is granted to copy and distribute translations of this manual into another language, under the above conditions for modified versions, except that the sections entitled "GNU General Public License", "Conditions for Using Bison" and this permission notice may be included in translations approved by the Free Software Foundation instead of in the original English.  File: bison.info, Node: Type Decl, Next: Expect Decl, Prev: Union Decl, Up: Declarations Nonterminal Symbols ------------------- When you use `%union' to specify multiple value types, you must declare the value type of each nonterminal symbol for which values are used. This is done with a `%type' declaration, like this: %type NONTERMINAL... Here NONTERMINAL is the name of a nonterminal symbol, and TYPE is the name given in the `%union' to the alternative that you want (*note Union Decl::.). You can give any number of nonterminal symbols in the same `%type' declaration, if they have the same value type. Use spaces to separate the symbol names.  File: bison.info, Node: Expect Decl, Next: Start Decl, Prev: Type Decl, Up: Declarations Suppressing Conflict Warnings ----------------------------- Bison normally warns if there are any conflicts in the grammar (*note Shift/Reduce::.), but most real grammars have harmless shift/reduce conflicts which are resolved in a predictable way and would be difficult to eliminate. It is desirable to suppress the warning about these conflicts unless the number of conflicts changes. You can do this with the `%expect' declaration. The declaration looks like this: %expect N Here N is a decimal integer. The declaration says there should be no warning if there are N shift/reduce conflicts and no reduce/reduce conflicts. The usual warning is given if there are either more or fewer conflicts, or if there are any reduce/reduce conflicts. In general, using `%expect' involves these steps: * Compile your grammar without `%expect'. Use the `-v' option to get a verbose list of where the conflicts occur. Bison will also print the number of conflicts. * Check each of the conflicts to make sure that Bison's default resolution is what you really want. If not, rewrite the grammar and go back to the beginning. * Add an `%expect' declaration, copying the number N from the number which Bison printed. Now Bison will stop annoying you about the conflicts you have checked, but it will warn you again if changes in the grammer result in additional conflicts.  File: bison.info, Node: Start Decl, Next: Pure Decl, Prev: Expect Decl, Up: Declarations The Start-Symbol ---------------- Bison assumes by default that the start symbol for the grammar is the first nonterminal specified in the grammar specification section. The programmer may override this restriction with the `%start' declaration as follows: %start SYMBOL  File: bison.info, Node: Pure Decl, Next: Decl Summary, Prev: Start Decl, Up: Declarations A Pure (Reentrant) Parser ------------------------- A "reentrant" program is one which does not alter in the course of execution; in other words, it consists entirely of "pure" (read-only) code. Reentrancy is important whenever asynchronous execution is possible; for example, a nonreentrant program may not be safe to call from a signal handler. In systems with multiple threads of control, a nonreentrant program must be called only within interlocks. The Bison parser is not normally a reentrant program, because it uses statically allocated variables for communication with `yylex'. These variables include `yylval' and `yylloc'. The Bison declaration `%pure_parser' says that you want the parser to be reentrant. It looks like this: %pure_parser The effect is that the two communication variables become local variables in `yyparse', and a different calling convention is used for the lexical analyzer function `yylex'. *Note Pure Calling::, for the details of this. The variable `yynerrs' also becomes local in `yyparse' (*note Error Reporting::.). The convention for calling `yyparse' itself is unchanged.  File: bison.info, Node: Decl Summary, Prev: Pure Decl, Up: Declarations Bison Declaration Summary ------------------------- Here is a summary of all Bison declarations: `%union' Declare the collection of data types that semantic values may have (*note Union Decl::.). `%token' Declare a terminal symbol (token type name) with no precedence or associativity specified (*note Token Decl::.). `%right' Declare a terminal symbol (token type name) that is right-associative (*note Precedence Decl::.). `%left' Declare a terminal symbol (token type name) that is left-associative (*note Precedence Decl::.). `%nonassoc' Declare a terminal symbol (token type name) that is nonassociative (using it in a way that would be associative is a syntax error) (*note Precedence Decl::.). `%type' Declare the type of semantic values for a nonterminal symbol (*note Type Decl::.). `%start' Specify the grammar's start symbol (*note Start Decl::.). `%expect' Declare the expected number of shift-reduce conflicts (*note Expect Decl::.). `%pure_parser' Request a pure (reentrant) parser program (*note Pure Decl::.).  File: bison.info, Node: Multiple Parsers, Prev: Declarations, Up: Grammar File Multiple Parsers in the Same Program ==================================== Most programs that use Bison parse only one language and therefore contain only one Bison parser. But what if you want to parse more than one language with the same program? Then you need to avoid a name conflict between different definitions of `yyparse', `yylval', and so on. The easy way to do this is to use the option `-p PREFIX' (*note Invocation::.). This renames the interface functions and variables of the Bison parser to start with PREFIX instead of `yy'. You can use this to give each parser distinct names that do not conflict. The precise list of symbols renamed is `yyparse', `yylex', `yyerror', `yylval', `yychar' and `yydebug'. For example, if you use `-p c', the names become `cparse', `clex', and so on. *All the other variables and macros associated with Bison are not renamed.* These others are not global; there is no conflict if the same name is used in different parsers. For example, `YYSTYPE' is not renamed, but defining this in different ways in different parsers causes no trouble (*note Value Type::.). The `-p' option works by adding macro definitions to the beginning of the parser source file, defining `yyparse' as `PREFIXparse', and so on. This effectively substitutes one name for the other in the entire parser file.  File: bison.info, Node: Interface, Next: Algorithm, Prev: Grammar File, Up: Top Parser C-Language Interface *************************** The Bison parser is actually a C function named `yyparse'. Here we describe the interface conventions of `yyparse' and the other functions that it needs to use. Keep in mind that the parser uses many C identifiers starting with `yy' and `YY' for internal purposes. If you use such an identifier (aside from those in this manual) in an action or in additional C code in the grammar file, you are likely to run into trouble. * Menu: * Parser Function:: How to call `yyparse' and what it returns. * Lexical:: You must supply a function `yylex' which reads tokens. * Error Reporting:: You must supply a function `yyerror'. * Action Features:: Special features for use in actions.  File: bison.info, Node: Parser Function, Next: Lexical, Prev: Interface, Up: Interface The Parser Function `yyparse' ============================= You call the function `yyparse' to cause parsing to occur. This function reads tokens, executes actions, and ultimately returns when it encounters end-of-input or an unrecoverable syntax error. You can also write an action which directs `yyparse' to return immediately without reading further. The value returned by `yyparse' is 0 if parsing was successful (return is due to end-of-input). The value is 1 if parsing failed (return is due to a syntax error). In an action, you can cause immediate return from `yyparse' by using these macros: `YYACCEPT' Return immediately with value 0 (to report success). `YYABORT' Return immediately with value 1 (to report failure).  File: bison.info, Node: Lexical, Next: Error Reporting, Prev: Parser Function, Up: Interface The Lexical Analyzer Function `yylex' ===================================== The "lexical analyzer" function, `yylex', recognizes tokens from the input stream and returns them to the parser. Bison does not create this function automatically; you must write it so that `yyparse' can call it. The function is sometimes referred to as a lexical scanner. In simple programs, `yylex' is often defined at the end of the Bison grammar file. If `yylex' is defined in a separate source file, you need to arrange for the token-type macro definitions to be available there. To do this, use the `-d' option when you run Bison, so that it will write these macro definitions into a separate header file `NAME.tab.h' which you can include in the other source files that need it. *Note Invocation::. * Menu: * Calling Convention:: How `yyparse' calls `yylex'. * Token Values:: How `yylex' must return the semantic value of the token it has read. * Token Positions:: How `yylex' must return the text position (line number, etc.) of the token, if the actions want that. * Pure Calling:: How the calling convention differs in a pure parser (*note Pure Decl::.).  File: bison.info, Node: Calling Convention, Next: Token Values, Prev: Lexical, Up: Lexical Calling Convention for `yylex' ------------------------------ The value that `yylex' returns must be the numeric code for the type of token it has just found, or 0 for end-of-input. When a token is referred to in the grammar rules by a name, that name in the parser file becomes a C macro whose definition is the proper numeric code for that token type. So `yylex' can use the name to indicate that type. *Note Symbols::. When a token is referred to in the grammar rules by a character literal, the numeric code for that character is also the code for the token type. So `yylex' can simply return that character code. The null character must not be used this way, because its code is zero and that is what signifies end-of-input. Here is an example showing these things: yylex () { ... if (c == EOF) /* Detect end of file. */ return 0; ... if (c == '+' || c == '-') return c; /* Assume token type for `+' is '+'. */ ... return INT; /* Return the type of the token. */ ... } This interface has been designed so that the output from the `lex' utility can be used without change as the definition of `yylex'.  File: bison.info, Node: Token Values, Next: Token Positions, Prev: Calling Convention, Up: Lexical Semantic Values of Tokens ------------------------- In an ordinary (nonreentrant) parser, the semantic value of the token must be stored into the global variable `yylval'. When you are using just one data type for semantic values, `yylval' has that type. Thus, if the type is `int' (the default), you might write this in `yylex': ... yylval = value; /* Put value onto Bison stack. */ return INT; /* Return the type of the token. */ ... When you are using multiple data types, `yylval''s type is a union made from the `%union' declaration (*note Union Decl::.). So when you store a token's value, you must use the proper member of the union. If the `%union' declaration looks like this: %union { int intval; double val; symrec *tptr; } then the code in `yylex' might look like this: ... yylval.intval = value; /* Put value onto Bison stack. */ return INT; /* Return the type of the token. */ ...  File: bison.info, Node: Token Positions, Next: Pure Calling, Prev: Token Values, Up: Lexical Textual Positions of Tokens --------------------------- If you are using the `@N'-feature (*note Action Features::.) in actions to keep track of the textual locations of tokens and groupings, then you must provide this information in `yylex'. The function `yyparse' expects to find the textual location of a token just parsed in the global variable `yylloc'. So `yylex' must store the proper data in that variable. The value of `yylloc' is a structure and you need only initialize the members that are going to be used by the actions. The four members are called `first_line', `first_column', `last_line' and `last_column'. Note that the use of this feature makes the parser noticeably slower. The data type of `yylloc' has the name `YYLTYPE'.  File: bison.info, Node: Pure Calling, Prev: Token Positions, Up: Lexical Calling for Pure Parsers ------------------------ When you use the Bison declaration `%pure_parser' to request a pure, reentrant parser, the global communication variables `yylval' and `yylloc' cannot be used. (*Note Pure Decl::.) In such parsers the two global variables are replaced by pointers passed as arguments to `yylex'. You must declare them as shown here, and pass the information back by storing it through those pointers. yylex (lvalp, llocp) YYSTYPE *lvalp; YYLTYPE *llocp; { ... *lvalp = value; /* Put value onto Bison stack. */ return INT; /* Return the type of the token. */ ... } If the grammar file does not use the `@' constructs to refer to textual positions, then the type `YYLTYPE' will not be defined. In this case, omit the second argument; `yylex' will be called with only one argument.  File: bison.info, Node: Error Reporting, Next: Action Features, Prev: Lexical, Up: Interface The Error Reporting Function `yyerror' ====================================== The Bison parser detects a "parse error" or "syntax error" whenever it reads a token which cannot satisfy any syntax rule. A action in the grammar can also explicitly proclaim an error, using the macro `YYERROR' (*note Action Features::.). The Bison parser expects to report the error by calling an error reporting function named `yyerror', which you must supply. It is called by `yyparse' whenever a syntax error is found, and it receives one argument. For a parse error, the string is always `"parse error"'. The parser can detect one other kind of error: stack overflow. This happens when the input contains constructions that are very deeply nested. It isn't likely you will encounter this, since the Bison parser extends its stack automatically up to a very large limit. But if overflow happens, `yyparse' calls `yyerror' in the usual fashion, except that the argument string is `"parser stack overflow"'. The following definition suffices in simple programs: yyerror (s) char *s; { fprintf (stderr, "%s\n", s); } After `yyerror' returns to `yyparse', the latter will attempt error recovery if you have written suitable error recovery grammar rules (*note Error Recovery::.). If recovery is impossible, `yyparse' will immediately return 1. The variable `yynerrs' contains the number of syntax errors encountered so far. Normally this variable is global; but if you request a pure parser (*note Pure Decl::.) then it is a local variable which only the actions can access.  File: bison.info, Node: Action Features, Prev: Error Reporting, Up: Interface Special Features for Use in Actions =================================== Here is a table of Bison constructs, variables and macros that are useful in actions. `$$' Acts like a variable that contains the semantic value for the grouping made by the current rule. *Note Actions::. `$N' Acts like a variable that contains the semantic value for the Nth component of the current rule. *Note Actions::. `$$' Like `$$' but specifies alternative TYPEALT in the union specified by the `%union' declaration. *Note Action Types::. `$N' Like `$N' but specifies alternative TYPEALT in the union specified by the `%union' declaration. *Note Action Types::. `YYABORT;' Return immediately from `yyparse', indicating failure. *Note Parser Function::. `YYACCEPT;' Return immediately from `yyparse', indicating success. *Note Parser Function::. `YYBACKUP (TOKEN, VALUE);' Unshift a token. This macro is allowed only for rules that reduce a single value, and only when there is no look-ahead token. It installs a look-ahead token with token type TOKEN and semantic value VALUE; then it discards the value that was going to be reduced by this rule. If the macro is used when it is not valid, such as when there is a look-ahead token already, then it reports a syntax error with a message `cannot back up' and performs ordinary error recovery. In either case, the rest of the action is not executed. `YYEMPTY' Value stored in `yychar' when there is no look-ahead token. `YYERROR;' Cause an immediate syntax error. This statement initiates error recovery just as if the parser itself had detected an error; however, it does not call `yyerror', and does not print any message. If you want to print an error message, call `yyerror' explicitly before the `YYERROR;' statement. *Note Error Recovery::. `YYRECOVERING' This macro stands for an expression that has the value 1 when the parser is recovering from a syntax error, and 0 the rest of the time. *Note Error Recovery::. `yychar' Variable containing the current look-ahead token. (In a pure parser, this is actually a local variable within `yyparse'.) When there is no look-ahead token, the value `YYEMPTY' is stored in the variable. *Note Look-Ahead::. `yyclearin;' Discard the current look-ahead token. This is useful primarily in error rules. *Note Error Recovery::. `yyerrok;' Resume generating error messages immediately for subsequent syntax errors. This is useful primarily in error rules. *Note Error Recovery::. `@N' Acts like a structure variable containing information on the line numbers and column numbers of the Nth component of the current rule. The structure has four members, like this: struct { int first_line, last_line; int first_column, last_column; }; Thus, to get the starting line number of the third component, use `@3.first_line'. In order for the members of this structure to contain valid information, you must make `yylex' supply this information about each token. If you need only certain members, then `yylex' need only fill in those members. The use of this feature makes the parser noticeably slower.  File: bison.info, Node: Algorithm, Next: Error Recovery, Prev: Interface, Up: Top The Bison Parser Algorithm ************************** As Bison reads tokens, it pushes them onto a stack along with their semantic values. The stack is called the "parser stack". Pushing a token is traditionally called "shifting". For example, suppose the infix calculator has read `1 + 5 *', with a `3' to come. The stack will have four elements, one for each token that was shifted. But the stack does not always have an element for each token read. When the last N tokens and groupings shifted match the components of a grammar rule, they can be combined according to that rule. This is called "reduction". Those tokens and groupings are replaced on the stack by a single grouping whose symbol is the result (left hand side) of that rule. Running the rule's action is part of the process of reduction, because this is what computes the semantic value of the resulting grouping. For example, if the infix calculator's parser stack contains this: 1 + 5 * 3 and the next input token is a newline character, then the last three elements can be reduced to 15 via the rule: expr: expr '*' expr; Then the stack contains just these three elements: 1 + 15 At this point, another reduction can be made, resulting in the single value 16. Then the newline token can be shifted. The parser tries, by shifts and reductions, to reduce the entire input down to a single grouping whose symbol is the grammar's start-symbol (*note Language and Grammar::.). This kind of parser is known in the literature as a bottom-up parser. * Menu: * Look-Ahead:: Parser looks one token ahead when deciding what to do. * Shift/Reduce:: Conflicts: when either shifting or reduction is valid. * Precedence:: Operator precedence works by resolving conflicts. * Contextual Precedence:: When an operator's precedence depends on context. * Parser States:: The parser is a finite-state-machine with stack. * Reduce/Reduce:: When two rules are applicable in the same situation. * Mystery Conflicts:: Reduce/reduce conflicts that look unjustified. * Stack Overflow:: What happens when stack gets full. How to avoid it.  File: bison.info, Node: Look-Ahead, Next: Shift/Reduce, Prev: Algorithm, Up: Algorithm Look-Ahead Tokens ================= The Bison parser does *not* always reduce immediately as soon as the last N tokens and groupings match a rule. This is because such a simple strategy is inadequate to handle most languages. Instead, when a reduction is possible, the parser sometimes "looks ahead" at the next token in order to decide what to do. When a token is read, it is not immediately shifted; first it becomes the "look-ahead token", which is not on the stack. Now the parser can perform one or more reductions of tokens and groupings on the stack, while the look-ahead token remains off to the side. When no more reductions should take place, the look-ahead token is shifted onto the stack. This does not mean that all possible reductions have been done; depending on the token type of the look-ahead token, some rules may choose to delay their application. Here is a simple case where look-ahead is needed. These three rules define expressions which contain binary addition operators and postfix unary factorial operators (`!'), and allow parentheses for grouping. expr: term '+' expr | term ; term: '(' expr ')' | term '!' | NUMBER ; Suppose that the tokens `1 + 2' have been read and shifted; what should be done? If the following token is `)', then the first three tokens must be reduced to form an `expr'. This is the only valid course, because shifting the `)' would produce a sequence of symbols `term ')'', and no rule allows this. If the following token is `!', then it must be shifted immediately so that `2 !' can be reduced to make a `term'. If instead the parser were to reduce before shifting, `1 + 2' would become an `expr'. It would then be impossible to shift the `!' because doing so would produce on the stack the sequence of symbols `expr '!''. No rule allows that sequence. The current look-ahead token is stored in the variable `yychar'. *Note Action Features::.  File: bison.info, Node: Shift/Reduce, Next: Precedence, Prev: Look-Ahead, Up: Algorithm Shift/Reduce Conflicts ====================== Suppose we are parsing a language which has if-then and if-then-else statements, with a pair of rules like this: if_stmt: IF expr THEN stmt | IF expr THEN stmt ELSE stmt ; (Here we assume that `IF', `THEN' and `ELSE' are terminal symbols for specific keyword tokens.) When the `ELSE' token is read and becomes the look-ahead token, the contents of the stack (assuming the input is valid) are just right for reduction by the first rule. But it is also legitimate to shift the `ELSE', because that would lead to eventual reduction by the second rule. This situation, where either a shift or a reduction would be valid, is called a "shift/reduce conflict". Bison is designed to resolve these conflicts by choosing to shift, unless otherwise directed by operator precedence declarations. To see the reason for this, let's contrast it with the other alternative. Since the parser prefers to shift the `ELSE', the result is to attach the else-clause to the innermost if-statement, making these two inputs equivalent: if x then if y then win (); else lose; if x then do; if y then win (); else lose; end; But if the parser chose to reduce when possible rather than shift, the result would be to attach the else-clause to the outermost if-statement, making these two inputs equivalent: if x then if y then win (); else lose; if x then do; if y then win (); end; else lose; The conflict exists because the grammar as written is ambiguous: either parsing of the simple nested if-statement is legitimate. The established convention is that these ambiguities are resolved by attaching the else-clause to the innermost if-statement; this is what Bison accomplishes by choosing to shift rather than reduce. (It would ideally be cleaner to write an unambiguous grammar, but that is very hard to do in this case.) This particular ambiguity was first encountered in the specifications of Algol 60 and is called the "dangling `else'" ambiguity. To avoid warnings from Bison about predictable, legitimate shift/reduce conflicts, use the `%expect N' declaration. There will be no warning as long as the number of shift/reduce conflicts is exactly N. *Note Expect Decl::.  File: bison.info, Node: Precedence, Next: Contextual Precedence, Prev: Shift/Reduce, Up: Algorithm Operator Precedence =================== Another situation where shift/reduce conflicts appear is in arithmetic expressions. Here shifting is not always the preferred resolution; the Bison declarations for operator precedence allow you to specify when to shift and when to reduce. * Menu: * Why Precedence:: An example showing why precedence is needed. * Using Precedence:: How to specify precedence in Bison grammars. * Precedence Examples:: How these features are used in the previous example. * How Precedence:: How they work.  File: bison.info, Node: Why Precedence, Next: Using Precedence, Prev: Precedence, Up: Precedence When Precedence is Needed ------------------------- Consider the following ambiguous grammar fragment (ambiguous because the input `1 - 2 * 3' can be parsed in two different ways): expr: expr '-' expr | expr '*' expr | expr '<' expr | '(' expr ')' ... ; Suppose the parser has seen the tokens `1', `-' and `2'; should it reduce them via the rule for the addition operator? It depends on the next token. Of course, if the next token is `)', we must reduce; shifting is invalid because no single rule can reduce the token sequence `- 2 )' or anything starting with that. But if the next token is `*' or `<', we have a choice: either shifting or reduction would allow the parse to complete, but with different results. To decide which one Bison should do, we must consider the results. If the next operator token OP is shifted, then it must be reduced first in order to permit another opportunity to reduce the sum. The result is (in effect) `1 - (2 OP 3)'. On the other hand, if the subtraction is reduced before shifting OP, the result is `(1 - 2) OP 3'. Clearly, then, the choice of shift or reduce should depend on the relative precedence of the operators `-' and OP: `*' should be shifted first, but not `<'. What about input such as `1 - 2 - 5'; should this be `(1 - 2) - 5' or should it be `1 - (2 - 5)'? For most operators we prefer the former, which is called "left association". The latter alternative, "right association", is desirable for assignment operators. The choice of left or right association is a matter of whether the parser chooses to shift or reduce when the stack contains `1 - 2' and the look-ahead token is `-': shifting makes right-associativity.  File: bison.info, Node: Using Precedence, Next: Precedence Examples, Prev: Why Precedence, Up: Precedence Specifying Operator Precedence ------------------------------ Bison allows you to specify these choices with the operator precedence declarations `%left' and `%right'. Each such declaration contains a list of tokens, which are operators whose precedence and associativity is being declared. The `%left' declaration makes all those operators left-associative and the `%right' declaration makes them right-associative. A third alternative is `%nonassoc', which declares that it is a syntax error to find the same operator twice "in a row". The relative precedence of different operators is controlled by the order in which they are declared. The first `%left' or `%right' declaration in the file declares the operators whose precedence is lowest, the next such declaration declares the operators whose precedence is a little higher, and so on.  File: bison.info, Node: Precedence Examples, Next: How Precedence, Prev: Using Precedence, Up: Precedence Precedence Examples ------------------- In our example, we would want the following declarations: %left '<' %left '-' %left '*' In a more complete example, which supports other operators as well, we would declare them in groups of equal precedence. For example, `'+'' is declared with `'-'': %left '<' '>' '=' NE LE GE %left '+' '-' %left '*' '/' (Here `NE' and so on stand for the operators for "not equal" and so on. We assume that these tokens are more than one character long and therefore are represented by names, not character literals.)  File: bison.info, Node: How Precedence, Prev: Precedence Examples, Up: Precedence How Precedence Works -------------------- The first effect of the precedence declarations is to assign precedence levels to the terminal symbols declared. The second effect is to assign precedence levels to certain rules: each rule gets its precedence from the last terminal symbol mentioned in the components. (You can also specify explicitly the precedence of a rule. *Note Contextual Precedence::.) Finally, the resolution of conflicts works by comparing the precedence of the rule being considered with that of the look-ahead token. If the token's precedence is higher, the choice is to shift. If the rule's precedence is higher, the choice is to reduce. If they have equal precedence, the choice is made based on the associativity of that precedence level. The verbose output file made by `-v' (*note Invocation::.) says how each conflict was resolved. Not all rules and not all tokens have precedence. If either the rule or the look-ahead token has no precedence, then the default is to shift.  File: bison.info, Node: Contextual Precedence, Next: Parser States, Prev: Precedence, Up: Algorithm Context-Dependent Precedence ============================ Often the precedence of an operator depends on the context. This sounds outlandish at first, but it is really very common. For example, a minus sign typically has a very high precedence as a unary operator, and a somewhat lower precedence (lower than multiplication) as a binary operator. The Bison precedence declarations, `%left', `%right' and `%nonassoc', can only be used once for a given token; so a token has only one precedence declared in this way. For context-dependent precedence, you need to use an additional mechanism: the `%prec' modifier for rules. The `%prec' modifier declares the precedence of a particular rule by specifying a terminal symbol whose precedence should be used for that rule. It's not necessary for that symbol to appear otherwise in the rule. The modifier's syntax is: %prec TERMINAL-SYMBOL and it is written after the components of the rule. Its effect is to assign the rule the precedence of TERMINAL-SYMBOL, overriding the precedence that would be deduced for it in the ordinary way. The altered rule precedence then affects how conflicts involving that rule are resolved (*note Precedence::.). Here is how `%prec' solves the problem of unary minus. First, declare a precedence for a fictitious terminal symbol named `UMINUS'. There are no tokens of this type, but the symbol serves to stand for its precedence: ... %left '+' '-' %left '*' %left UMINUS Now the precedence of `UMINUS' can be used in specific rules: exp: ... | exp '-' exp ... | '-' exp %prec UMINUS  File: bison.info, Node: Parser States, Next: Reduce/Reduce, Prev: Contextual Precedence, Up: Algorithm Parser States ============= The function `yyparse' is implemented using a finite-state machine. The values pushed on the parser stack are not simply token type codes; they represent the entire sequence of terminal and nonterminal symbols at or near the top of the stack. The current state collects all the information about previous input which is relevant to deciding what to do next. Each time a look-ahead token is read, the current parser state together with the type of look-ahead token are looked up in a table. This table entry can say, "Shift the look-ahead token." In this case, it also specifies the new parser state, which is pushed onto the top of the parser stack. Or it can say, "Reduce using rule number N." This means that a certain of tokens or groupings are taken off the top of the stack, and replaced by one grouping. In other words, that number of states are popped from the stack, and one new state is pushed. There is one other alternative: the table can say that the look-ahead token is erroneous in the current state. This causes error processing to begin (*note Error Recovery::.).  File: bison.info, Node: Reduce/Reduce, Next: Mystery Conflicts, Prev: Parser States, Up: Algorithm Reduce/Reduce Conflicts ======================= A reduce/reduce conflict occurs if there are two or more rules that apply to the same sequence of input. This usually indicates a serious error in the grammar. For example, here is an erroneous attempt to define a sequence of zero or more `word' groupings. sequence: /* empty */ { printf ("empty sequence\n"); } | word { printf ("single word %s\n", $1); } | sequence word { printf ("added word %s\n", $2); } ; The error is an ambiguity: there is more than one way to parse a single `word' into a `sequence'. It could be reduced directly via the second rule. Alternatively, nothing-at-all could be reduced into a `sequence' via the first rule, and this could be combined with the `word' using the third rule. You might think that this is a distinction without a difference, because it does not change whether any particular input is valid or not. But it does affect which actions are run. One parsing order runs the second rule's action; the other runs the first rule's action and the third rule's action. In this example, the output of the program changes. Bison resolves a reduce/reduce conflict by choosing to use the rule that appears first in the grammar, but it is very risky to rely on this. Every reduce/reduce conflict must be studied and usually eliminated. Here is the proper way to define `sequence': sequence: /* empty */ { printf ("empty sequence\n"); } | sequence word { printf ("added word %s\n", $2); } ; Here is another common error that yields a reduce/reduce conflict: sequence: /* empty */ | sequence words | sequence redirects ; words: /* empty */ | words word ; redirects:/* empty */ | redirects redirect ; The intention here is to define a sequence which can contain either `word' or `redirect' groupings. The individual definitions of `sequence', `words' and `redirects' are error-free, but the three together make a subtle ambiguity: even an empty input can be parsed in infinitely many ways! Consider: nothing-at-all could be a `words'. Or it could be two `words' in a row, or three, or any number. It could equally well be a `redirects', or two, or any number. Or it could be a `words' followed by three `redirects' and another `words'. And so on. Here are two ways to correct these rules. First, to make it a single level of sequence: sequence: /* empty */ | sequence word | sequence redirect ; Second, to prevent either a `words' or a `redirects' from being empty: sequence: /* empty */ | sequence words | sequence redirects ; words: word | words word ; redirects:redirect | redirects redirect ;  File: bison.info, Node: Mystery Conflicts, Next: Stack Overflow, Prev: Reduce/Reduce, Up: Algorithm Mysterious Reduce/Reduce Conflicts ================================== Sometimes reduce/reduce conflicts can occur that don't look warranted. Here is an example: %token ID %% def: param_spec return_spec ',' ; param_spec: type | name_list ':' type ; return_spec: type | name ':' type ; type: ID ; name: ID ; name_list: name | name ',' name_list ; It would seem that this grammar can be parsed with only a single token of look-ahead: when a `param_spec' is being read, an `ID' is a `name' if a comma or colon follows, or a `type' if another `ID' follows. In other words, this grammar is LR(1). However, Bison, like most parser generators, cannot actually handle all LR(1) grammars. In this grammar, two contexts, that after an `ID' at the beginning of a `param_spec' and likewise at the beginning of a `return_spec', are similar enough that Bison assumes they are the same. They appear similar because the same set of rules would be active--the rule for reducing to a `name' and that for reducing to a `type'. Bison is unable to determine at that stage of processing that the rules would require different look-ahead tokens in the two contexts, so it makes a single parser state for them both. Combining the two contexts causes a conflict later. In parser terminology, this occurrence means that the grammar is not LALR(1). In general, it is better to fix deficiencies than to document them. But this particular deficiency is intrinsically hard to fix; parser generators that can handle LR(1) grammars are hard to write and tend to produce parsers that are very large. In practice, Bison is more useful as it is now. When the problem arises, you can often fix it by identifying the two parser states that are being confused, and adding something to make them look distinct. In the above example, adding one rule to `return_spec' as follows makes the problem go away: %token BOGUS ... %% ... return_spec: type | name ':' type /* This rule is never used. */ | ID BOGUS ; This corrects the problem because it introduces the possibility of an additional active rule in the context after the `ID' at the beginning of `return_spec'. This rule is not active in the corresponding context in a `param_spec', so the two contexts receive distinct parser states. As long as the token `BOGUS' is never generated by `yylex', the added rule cannot alter the way actual input is parsed. In this particular example, there is another way to solve the problem: rewrite the rule for `return_spec' to use `ID' directly instead of via `name'. This also causes the two confusing contexts to have different sets of active rules, because the one for `return_spec' activates the altered rule for `return_spec' rather than the one for `name'. param_spec: type | name_list ':' type ; return_spec: type | ID ':' type ;  File: bison.info, Node: Stack Overflow, Prev: Mystery Conflicts, Up: Algorithm Stack Overflow, and How to Avoid It =================================== The Bison parser stack can overflow if too many tokens are shifted and not reduced. When this happens, the parser function `yyparse' returns a nonzero value, pausing only to call `yyerror' to report the overflow. By defining the macro `YYMAXDEPTH', you can control how deep the parser stack can become before a stack overflow occurs. Define the macro with a value that is an integer. This value is the maximum number of tokens that can be shifted (and not reduced) before overflow. It must be a constant expression whose value is known at compile time. The stack space allowed is not necessarily allocated. If you specify a large value for `YYMAXDEPTH', the parser actually allocates a small stack at first, and then makes it bigger by stages as needed. This increasing allocation happens automatically and silently. Therefore, you do not need to make `YYMAXDEPTH' painfully small merely to save space for ordinary inputs that do not need much stack. The default value of `YYMAXDEPTH', if you do not define it, is 10000. You can control how much stack is allocated initially by defining the macro `YYINITDEPTH'. This value too must be a compile-time constant integer. The default is 200.  File: bison.info, Node: Error Recovery, Next: Context Dependency, Prev: Algorithm, Up: Top Error Recovery ************** It is not usually acceptable to have a program terminate on a parse error. For example, a compiler should recover sufficiently to parse the rest of the input file and check it for errors; a calculator should accept another expression. In a simple interactive command parser where each input is one line, it may be sufficient to allow `yyparse' to return 1 on error and have the caller ignore the rest of the input line when that happens (and then call `yyparse' again). But this is inadequate for a compiler, because it forgets all the syntactic context leading up to the error. A syntax error deep within a function in the compiler input should not cause the compiler to treat the following line like the beginning of a source file. You can define how to recover from a syntax error by writing rules to recognize the special token `error'. This is a terminal symbol that is always defined (you need not declare it) and reserved for error handling. The Bison parser generates an `error' token whenever a syntax error happens; if you have provided a rule to recognize this token in the current context, the parse can continue. For example: stmnts: /* empty string */ | stmnts '\n' | stmnts exp '\n' | stmnts error '\n' The fourth rule in this example says that an error followed by a newline makes a valid addition to any `stmnts'. What happens if a syntax error occurs in the middle of an `exp'? The error recovery rule, interpreted strictly, applies to the precise sequence of a `stmnts', an `error' and a newline. If an error occurs in the middle of an `exp', there will probably be some additional tokens and subexpressions on the stack after the last `stmnts', and there will be tokens to read before the next newline. So the rule is not applicable in the ordinary way. But Bison can force the situation to fit the rule, by discarding part of the semantic context and part of the input. First it discards states and objects from the stack until it gets back to a state in which the `error' token is acceptable. (This means that the subexpressions already parsed are discarded, back to the last complete `stmnts'.) At this point the `error' token can be shifted. Then, if the old look-ahead token is not acceptable to be shifted next, the parser reads tokens and discards them until it finds a token which is acceptable. In this example, Bison reads and discards input until the next newline so that the fourth rule can apply. The choice of error rules in the grammar is a choice of strategies for error recovery. A simple and useful strategy is simply to skip the rest of the current input line or current statement if an error is detected: stmnt: error ';' /* on error, skip until ';' is read */ It is also useful to recover to the matching close-delimiter of an opening-delimiter that has already been parsed. Otherwise the close-delimiter will probably appear to be unmatched, and generate another, spurious error message: primary: '(' expr ')' | '(' error ')' ... ; Error recovery strategies are necessarily guesses. When they guess wrong, one syntax error often leads to another. In the above example, the error recovery rule guesses that an error is due to bad input within one `stmnt'. Suppose that instead a spurious semicolon is inserted in the middle of a valid `stmnt'. After the error recovery rule recovers from the first error, another syntax error will be found straightaway, since the text following the spurious semicolon is also an invalid `stmnt'. To prevent an outpouring of error messages, the parser will output no error message for another syntax error that happens shortly after the first; only after three consecutive input tokens have been successfully shifted will error messages resume. Note that rules which accept the `error' token may have actions, just as any other rules can. You can make error messages resume immediately by using the macro `yyerrok' in an action. If you do this in the error rule's action, no error messages will be suppressed. This macro requires no arguments; `yyerrok;' is a valid C statement. The previous look-ahead token is reanalyzed immediately after an error. If this is unacceptable, then the macro `yyclearin' may be used to clear this token. Write the statement `yyclearin;' in the error rule's action. For example, suppose that on a parse error, an error handling routine is called that advances the input stream to some point where parsing should once again commence. The next symbol returned by the lexical scanner is probably correct. The previous look-ahead token ought to be discarded with `yyclearin;'. The macro `YYRECOVERING' stands for an expression that has the value 1 when the parser is recovering from a syntax error, and 0 the rest of the time. A value of 1 indicates that error messages are currently suppressed for new syntax errors.  File: bison.info, Node: Context Dependency, Next: Debugging, Prev: Error Recovery, Up: Top Handling Context Dependencies ***************************** The Bison paradigm is to parse tokens first, then group them into larger syntactic units. In many languages, the meaning of a token is affected by its context. Although this violates the Bison paradigm, certain techniques (known as "kludges") may enable you to write Bison parsers for such languages. * Menu: * Semantic Tokens:: Token parsing can depend on the semantic context. * Lexical Tie-ins:: Token parsing can depend on the syntactic context. * Tie-in Recovery:: Lexical tie-ins have implications for how error recovery rules must be written. (Actually, "kludge" means any technique that gets its job done but is neither clean nor robust.) ./usr/emacs/info/bison.info-4 644 0 0 112647 5303476055 14400 0ustar rootwheelThis is Info file bison.info, produced by Makeinfo-1.47 from the input file /home/gd/gnu/bison/bison.texinfo. This file documents the Bison parser generator. Copyright (C) 1988, 1989, 1990 Free Software Foundation, Inc. Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided also that the sections entitled "GNU General Public License" and "Conditions for Using Bison" are included exactly as in the original, and provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one. Permission is granted to copy and distribute translations of this manual into another language, under the above conditions for modified versions, except that the sections entitled "GNU General Public License", "Conditions for Using Bison" and this permission notice may be included in translations approved by the Free Software Foundation instead of in the original English.  File: bison.info, Node: Semantic Tokens, Next: Lexical Tie-ins, Prev: Context Dependency, Up: Context Dependency Semantic Info in Token Types ============================ The C language has a context dependency: the way an identifier is used depends on what its current meaning is. For example, consider this: foo (x); This looks like a function call statement, but if `foo' is a typedef name, then this is actually a declaration of `x'. How can a Bison parser for C decide how to parse this input? The method used in GNU C is to have two different token types, `IDENTIFIER' and `TYPENAME'. When `yylex' finds an identifier, it looks up the current declaration of the identifier in order to decide which token type to return: `TYPENAME' if the identifier is declared as a typedef, `IDENTIFIER' otherwise. The grammar rules can then express the context dependency by the choice of token type to recognize. `IDENTIFIER' is accepted as an expression, but `TYPENAME' is not. `TYPENAME' can start a declaration, but `IDENTIFIER' cannot. In contexts where the meaning of the identifier is *not* significant, such as in declarations that can shadow a typedef name, either `TYPENAME' or `IDENTIFIER' is accepted--there is one rule for each of the two token types. This technique is simple to use if the decision of which kinds of identifiers to allow is made at a place close to where the identifier is parsed. But in C this is not always so: C allows a declaration to redeclare a typedef name provided an explicit type has been specified earlier: typedef int foo, bar, lose; static foo (bar); /* redeclare `bar' as static variable */ static int foo (lose); /* redeclare `foo' as function */ Unfortunately, the name being declared is separated from the declaration construct itself by a complicated syntactic structure--the "declarator". As a result, the part of Bison parser for C needs to be duplicated, with all the nonterminal names changed: once for parsing a declaration in which a typedef name can be redefined, and once for parsing a declaration in which that can't be done. Here is a part of the duplication, with actions omitted for brevity: initdcl: declarator maybeasm '=' init | declarator maybeasm ; notype_initdcl: notype_declarator maybeasm '=' init | notype_declarator maybeasm ; Here `initdcl' can redeclare a typedef name, but `notype_initdcl' cannot. The distinction between `declarator' and `notype_declarator' is the same sort of thing. There is some similarity between this technique and a lexical tie-in (described next), in that information which alters the lexical analysis is changed during parsing by other parts of the program. The difference is here the information is global, and is used for other purposes in the program. A true lexical tie-in has a special-purpose flag controlled by the syntactic context.  File: bison.info, Node: Lexical Tie-ins, Next: Tie-in Recovery, Prev: Semantic Tokens, Up: Context Dependency Lexical Tie-ins =============== One way to handle context-dependency is the "lexical tie-in": a flag which is set by Bison actions, whose purpose is to alter the way tokens are parsed. For example, suppose we have a language vaguely like C, but with a special construct `hex (HEX-EXPR)'. After the keyword `hex' comes an expression in parentheses in which all integers are hexadecimal. In particular, the token `a1b' must be treated as an integer rather than as an identifier if it appears in that context. Here is how you can do it: %{ int hexflag; %} %% ... expr: IDENTIFIER | constant | HEX '(' { hexflag = 1; } expr ')' { hexflag = 0; $$ = $4; } | expr '+' expr { $$ = make_sum ($1, $3); } ... ; constant: INTEGER | STRING ; Here we assume that `yylex' looks at the value of `hexflag'; when it is nonzero, all integers are parsed in hexadecimal, and tokens starting with letters are parsed as integers if possible. The declaration of `hexflag' shown in the C declarations section of the parser file is needed to make it accessible to the actions (*note C Declarations::.). You must also write the code in `yylex' to obey the flag.  File: bison.info, Node: Tie-in Recovery, Prev: Lexical Tie-ins, Up: Context Dependency Lexical Tie-ins and Error Recovery ================================== Lexical tie-ins make strict demands on any error recovery rules you have. *Note Error Recovery::. The reason for this is that the purpose of an error recovery rule is to abort the parsing of one construct and resume in some larger construct. For example, in C-like languages, a typical error recovery rule is to skip tokens until the next semicolon, and then start a new statement, like this: stmt: expr ';' | IF '(' expr ')' stmt { ... } ... error ';' { hexflag = 0; } ; If there is a syntax error in the middle of a `hex (EXPR)' construct, this error rule will apply, and then the action for the completed `hex (EXPR)' will never run. So `hexflag' would remain set for the entire rest of the input, or until the next `hex' keyword, causing identifiers to be misinterpreted as integers. To avoid this problem the error recovery rule itself clears `hexflag'. There may also be an error recovery rule that works within expressions. For example, there could be a rule which applies within parentheses and skips to the close-parenthesis: expr: ... | '(' expr ')' { $$ = $2; } | '(' error ')' ... If this rule acts within the `hex' construct, it is not going to abort that construct (since it applies to an inner level of parentheses within the construct). Therefore, it should not clear the flag: the rest of the `hex' construct should be parsed with the flag still in effect. What if there is an error recovery rule which might abort out of the `hex' construct or might not, depending on circumstances? There is no way you can write the action to determine whether a `hex' construct is being aborted or not. So if you are using a lexical tie-in, you had better make sure your error recovery rules are not of this kind. Each rule must be such that you can be sure that it always will, or always won't, have to clear the flag.  File: bison.info, Node: Debugging, Next: Invocation, Prev: Context Dependency, Up: Top Debugging Your Parser ********************* If a Bison grammar compiles properly but doesn't do what you want when it runs, the `yydebug' parser-trace feature can help you figure out why. To enable compilation of trace facilities, you must define the macro `YYDEBUG' when you compile the parser. You could use `-DYYDEBUG=1' as a compiler option or you could put `#define YYDEBUG 1' in the C declarations section of the grammar file (*note C Declarations::.). Alternatively, use the `-t' option when you run Bison (*note Invocation::.). We always define `YYDEBUG' so that debugging is always possible. The trace facility uses `stderr', so you must add `#include ' to the C declarations section unless it is already there. Once you have compiled the program with trace facilities, the way to request a trace is to store a nonzero value in the variable `yydebug'. You can do this by making the C code do it (in `main', perhaps), or you can alter the value with a C debugger. Each step taken by the parser when `yydebug' is nonzero produces a line or two of trace information, written on `stderr'. The trace messages tell you these things: * Each time the parser calls `yylex', what kind of token was read. * Each time a token is shifted, the depth and complete contents of the state stack (*note Parser States::.). * Each time a rule is reduced, which rule it is, and the complete contents of the state stack afterward. To make sense of this information, it helps to refer to the listing file produced by the Bison `-v' option (*note Invocation::.). This file shows the meaning of each state in terms of positions in various rules, and also what each state will do with each possible input token. As you read the successive trace messages, you can see that the parser is functioning according to its specification in the listing file. Eventually you will arrive at the place where something undesirable happens, and you will see which parts of the grammar are to blame. The parser file is a C program and you can use C debuggers on it, but it's not easy to interpret what it is doing. The parser function is a finite-state machine interpreter, and aside from the actions it executes the same code over and over. Only the values of variables show where in the grammar it is working. The debugging information normally gives the token type of each token read, but not its semantic value. You can optionally define a macro named `YYPRINT' to provide a way to print the value. If you define `YYPRINT', it should take three arguments. The parser will pass a standard I/O stream, the numeric code for the token type, and the token value (from `yylval'). Here is an example of `YYPRINT' suitable for the multi-function calculator (*note Mfcalc Decl::.): #define YYPRINT(file, type, value) yyprint (file, type, value) static void yyprint (file, type, value) FILE *file; int type; YYSTYPE value; { if (type == VAR) fprintf (file, " %s", value.tptr->name); else if (type == NUM) fprintf (file, " %d", value.val); }  File: bison.info, Node: Invocation, Next: Table of Symbols, Prev: Debugging, Up: Top Invoking Bison ************** The usual way to invoke Bison is as follows: bison INFILE Here INFILE is the grammar file name, which usually ends in `.y'. The parser file's name is made by replacing the `.y' with `.tab.c'. Thus, the `bison foo.y' filename yields `foo.tab.c', and the `bison hack/foo.y' filename yields `hack/foo.tab.c'. * Menu: * Bison Options:: All the options described in detail, in alphabetical order by short options. * Option Cross Key:: Alphabetical list of long options. * VMS Invocation:: Bison command syntax on VMS.  File: bison.info, Node: Bison Options, Next: Option Cross Key, Up: Invocation Bison Options ============= Bison supports both traditional single-letter options and mnemonic long option names. Long option names are indicated with `--' instead of `-'. Abbreviations for option names are allowed as long as they are unique. When a long option takes an argument, like `--file-prefix', connect the option name and the argument with `='. Here is a list of options that can be used with Bison, alphabetized by short option. It is followed by a cross key alphabetized by long option. `-b FILE-PREFIX' `--file-prefix=PREFIX' Specify a prefix to use for all Bison output file names. The names are chosen as if the input file were named `PREFIX.c'. `-d' `--defines' Write an extra output file containing macro definitions for the token type names defined in the grammar and the semantic value type `YYSTYPE', as well as a few `extern' variable declarations. If the parser output file is named `NAME.c' then this file is named `NAME.h'. This output file is essential if you wish to put the definition of `yylex' in a separate source file, because `yylex' needs to be able to refer to token type codes and the variable `yylval'. *Note Token Values::. `-l' `--no-lines' Don't put any `#line' preprocessor commands in the parser file. Ordinarily Bison puts them in the parser file so that the C compiler and debuggers will associate errors with your source file, the grammar file. This option causes them to associate errors with the parser file, treating it an independent source file in its own right. `-o OUTFILE' `--output-file=OUTFILE' Specify the name OUTFILE for the parser file. The other output files' names are constructed from OUTFILE as described under the `-v' and `-d' switches. `-p PREFIX' `--name-prefix=PREFIX' Rename the external symbols used in the parser so that they start with PREFIX instead of `yy'. The precise list of symbols renamed is `yyparse', `yylex', `yyerror', `yylval', `yychar' and `yydebug'. For example, if you use `-p c', the names become `cparse', `clex', and so on. *Note Multiple Parsers::. `-t' `--debug' Output a definition of the macro `YYDEBUG' into the parser file, so that the debugging facilities are compiled. *Note Debugging::. `-v' `--verbose' Write an extra output file containing verbose descriptions of the parser states and what is done for each type of look-ahead token in that state. This file also describes all the conflicts, both those resolved by operator precedence and the unresolved ones. The file's name is made by removing `.tab.c' or `.c' from the parser output file name, and adding `.output' instead. Therefore, if the input file is `foo.y', then the parser file is called `foo.tab.c' by default. As a consequence, the verbose output file is called `foo.output'. `-V' `--version' Print the version number of Bison. `-y' `--yacc' `--fixed-output-files' Equivalent to `-o y.tab.c'; the parser output file is called `y.tab.c', and the other outputs are called `y.output' and `y.tab.h'. The purpose of this switch is to imitate Yacc's output file name conventions. Thus, the following shell script can substitute for Yacc: bison -y $*  File: bison.info, Node: Option Cross Key, Next: VMS Invocation, Prev: Bison Options, Up: Invocation Option Cross Key ================ Here is a list of options, alphabetized by long option, to help you find the corresponding short option. --debug -t --defines -d --file-prefix=PREFIX -b FILE-PREFIX --fixed-output-files --yacc -y --name-prefix -p --no-lines -l --output-file=OUTFILE -o OUTFILE --verbose -v --version -V  File: bison.info, Node: VMS Invocation, Prev: Option Cross Key, Up: Invocation Invoking Bison under VMS ======================== The command line syntax for Bison on VMS is a variant of the usual Bison command syntax--adapted to fit VMS conventions. To find the VMS equivalent for any Bison option, start with the long option, and substitute a `/' for the leading `--', and substitute a `_' for each `-' in the name of the long option. For example, the following invocation under VMS: bison /debug/name_prefix=bar foo.y is equivalent to the following command under POSIX. bison --debug --name-prefix=bar foo.y The VMS filesystem does not permit filenames such as `foo.tab.c'. In the above example, the output file would instead be named `foo_tab.c'.  File: bison.info, Node: Table of Symbols, Next: Glossary, Prev: Invocation, Up: Top Bison Symbols ************* `error' A token name reserved for error recovery. This token may be used in grammar rules so as to allow the Bison parser to recognize an error in the grammar without halting the process. In effect, a sentence containing an error may be recognized as valid. On a parse error, the token `error' becomes the current look-ahead token. Actions corresponding to `error' are then executed, and the look-ahead token is reset to the token that originally caused the violation. *Note Error Recovery::. `YYABORT' Macro to pretend that an unrecoverable syntax error has occurred, by making `yyparse' return 1 immediately. The error reporting function `yyerror' is not called. *Note Parser Function::. `YYACCEPT' Macro to pretend that a complete utterance of the language has been read, by making `yyparse' return 0 immediately. *Note Parser Function::. `YYBACKUP' Macro to discard a value from the parser stack and fake a look-ahead token. *Note Action Features::. `YYERROR' Macro to pretend that a syntax error has just been detected: call `yyerror' and then perform normal error recovery if possible (*note Error Recovery::.), or (if recovery is impossible) make `yyparse' return 1. *Note Error Recovery::. `YYINITDEPTH' Macro for specifying the initial size of the parser stack. *Note Stack Overflow::. `YYLTYPE' Macro for the data type of `yylloc'; a structure with four members. *Note Token Positions::. `YYMAXDEPTH' Macro for specifying the maximum size of the parser stack. *Note Stack Overflow::. `YYRECOVERING' Macro whose value indicates whether the parser is recovering from a syntax error. *Note Action Features::. `YYSTYPE' Macro for the data type of semantic values; `int' by default. *Note Value Type::. `yychar' External integer variable that contains the integer value of the current look-ahead token. (In a pure parser, it is a local variable within `yyparse'.) Error-recovery rule actions may examine this variable. *Note Action Features::. `yyclearin' Macro used in error-recovery rule actions. It clears the previous look-ahead token. *Note Error Recovery::. `yydebug' External integer variable set to zero by default. If `yydebug' is given a nonzero value, the parser will output information on input symbols and parser action. *Note Debugging::. `yyerrok' Macro to cause parser to recover immediately to its normal mode after a parse error. *Note Error Recovery::. `yyerror' User-supplied function to be called by `yyparse' on error. The function receives one argument, a pointer to a character string containing an error message. *Note Error Reporting::. `yylex' User-supplied lexical analyzer function, called with no arguments to get the next token. *Note Lexical::. `yylval' External variable in which `yylex' should place the semantic value associated with a token. (In a pure parser, it is a local variable within `yyparse', and its address is passed to `yylex'.) *Note Token Values::. `yylloc' External variable in which `yylex' should place the line and column numbers associated with a token. (In a pure parser, it is a local variable within `yyparse', and its address is passed to `yylex'.) You can ignore this variable if you don't use the `@' feature in the grammar actions. *Note Token Positions::. `yynerrs' Global variable which Bison increments each time there is a parse error. (In a pure parser, it is a local variable within `yyparse'.) *Note Error Reporting::. `yyparse' The parser function produced by Bison; call this function to start parsing. *Note Parser Function::. `%left' Bison declaration to assign left associativity to token(s). *Note Precedence Decl::. `%nonassoc' Bison declaration to assign nonassociativity to token(s). *Note Precedence Decl::. `%prec' Bison declaration to assign a precedence to a specific rule. *Note Contextual Precedence::. `%pure_parser' Bison declaration to request a pure (reentrant) parser. *Note Pure Decl::. `%right' Bison declaration to assign right associativity to token(s). *Note Precedence Decl::. `%start' Bison declaration to specify the start symbol. *Note Start Decl::. `%token' Bison declaration to declare token(s) without specifying precedence. *Note Token Decl::. `%type' Bison declaration to declare nonterminals. *Note Type Decl::. `%union' Bison declaration to specify several possible data types for semantic values. *Note Union Decl::. These are the punctuation and delimiters used in Bison input: `%%' Delimiter used to separate the grammar rule section from the Bison declarations section or the additional C code section. *Note Grammar Layout::. `%{ %}' All code listed between `%{' and `%}' is copied directly to the output file uninterpreted. Such code forms the "C declarations" section of the input file. *Note Grammar Outline::. `/*...*/' Comment delimiters, as in C. `:' Separates a rule's result from its components. *Note Rules::. `;' Terminates a rule. *Note Rules::. `|' Separates alternate rules for the same result nonterminal. *Note Rules::.  File: bison.info, Node: Glossary, Next: Index, Prev: Table of Symbols, Up: top Glossary ******** Backus-Naur Form (BNF) Formal method of specifying context-free grammars. BNF was first used in the `ALGOL-60' report, 1963. *Note Language and Grammar::. Context-free grammars Grammars specified as rules that can be applied regardless of context. Thus, if there is a rule which says that an integer can be used as an expression, integers are allowed *anywhere* an expression is permitted. *Note Language and Grammar::. Dynamic allocation Allocation of memory that occurs during execution, rather than at compile time or on entry to a function. Empty string Analogous to the empty set in set theory, the empty string is a character string of length zero. Finite-state stack machine A "machine" that has discrete states in which it is said to exist at each instant in time. As input to the machine is processed, the machine moves from state to state as specified by the logic of the machine. In the case of the parser, the input is the language being parsed, and the states correspond to various stages in the grammar rules. *Note Algorithm::. Grouping A language construct that is (in general) grammatically divisible; for example, `expression' or `declaration' in C. *Note Language and Grammar::. Infix operator An arithmetic operator that is placed between the operands on which it performs some operation. Input stream A continuous flow of data between devices or programs. Language construct One of the typical usage schemas of the language. For example, one of the constructs of the C language is the `if' statement. *Note Language and Grammar::. Left associativity Operators having left associativity are analyzed from left to right: `a+b+c' first computes `a+b' and then combines with `c'. *Note Precedence::. Left recursion A rule whose result symbol is also its first component symbol; for example, `expseq1 : expseq1 ',' exp;'. *Note Recursion::. Left-to-right parsing Parsing a sentence of a language by analyzing it token by token from left to right. *Note Algorithm::. Lexical analyzer (scanner) A function that reads an input stream and returns tokens one by one. *Note Lexical::. Lexical tie-in A flag, set by actions in the grammar rules, which alters the way tokens are parsed. *Note Lexical Tie-ins::. Look-ahead token A token already read but not yet shifted. *Note Look-Ahead::. LALR(1) The class of context-free grammars that Bison (like most other parser generators) can handle; a subset of LR(1). *Note Mysterious Reduce/Reduce Conflicts: Mystery Conflicts. LR(1) The class of context-free grammars in which at most one token of look-ahead is needed to disambiguate the parsing of any piece of input. Nonterminal symbol A grammar symbol standing for a grammatical construct that can be expressed through rules in terms of smaller constructs; in other words, a construct that is not a token. *Note Symbols::. Parse error An error encountered during parsing of an input stream due to invalid syntax. *Note Error Recovery::. Parser A function that recognizes valid sentences of a language by analyzing the syntax structure of a set of tokens passed to it from a lexical analyzer. Postfix operator An arithmetic operator that is placed after the operands upon which it performs some operation. Reduction Replacing a string of nonterminals and/or terminals with a single nonterminal, according to a grammar rule. *Note Algorithm::. Reentrant A reentrant subprogram is a subprogram which can be in invoked any number of times in parallel, without interference between the various invocations. *Note Pure Decl::. Reverse polish notation A language in which all operators are postfix operators. Right recursion A rule whose result symbol is also its last component symbol; for example, `expseq1: exp ',' expseq1;'. *Note Recursion::. Semantics In computer languages, the semantics are specified by the actions taken for each instance of the language, i.e., the meaning of each statement. *Note Semantics::. Shift A parser is said to shift when it makes the choice of analyzing further input from the stream rather than reducing immediately some already-recognized rule. *Note Algorithm::. Single-character literal A single character that is recognized and interpreted as is. *Note Grammar in Bison::. Start symbol The nonterminal symbol that stands for a complete valid utterance in the language being parsed. The start symbol is usually listed as the first nonterminal symbol in a language specification. *Note Start Decl::. Symbol table A data structure where symbol names and associated data are stored during parsing to allow for recognition and use of existing information in repeated uses of a symbol. *Note Multi-function Calc::. Token A basic, grammatically indivisible unit of a language. The symbol that describes a token in the grammar is a terminal symbol. The input of the Bison parser is a stream of tokens which comes from the lexical analyzer. *Note Symbols::. Terminal symbol A grammar symbol that has no rules in the grammar and therefore is grammatically indivisible. The piece of text it represents is a token. *Note Language and Grammar::.  File: bison.info, Node: Index, Prev: Glossary, Up: top Index ***** * Menu: * $$: Actions. * $N: Actions. * %expect: Expect Decl. * %left: Using Precedence. * %nonassoc: Using Precedence. * %prec: Contextual Precedence. * %pure_parser: Pure Decl. * %right: Using Precedence. * %start: Start Decl. * %token: Token Decl. * %type: Type Decl. * %union: Union Decl. * @N: Action Features. * calc: Infix Calc. * else, dangling: Shift/Reduce. * mfcalc: Multi-function Calc. * rpcalc: RPN Calc. * BNF: Language and Grammar. * Backus-Naur form: Language and Grammar. * Bison declaration summary: Decl Summary. * Bison declarations: Declarations. * Bison declarations (introduction): Bison Declarations. * Bison grammar: Grammar in Bison. * Bison invocation: Invocation. * Bison parser: Bison Parser. * Bison parser algorithm: Algorithm. * Bison symbols, table of: Table of Symbols. * Bison utility: Bison Parser. * C code, section for additional: C Code. * C declarations section: C Declarations. * C-language interface: Interface. * LALR(1): Mystery Conflicts. * LR(1): Mystery Conflicts. * VMS: VMS Invocation. * YYABORT: Parser Function. * YYACCEPT: Parser Function. * YYBACKUP: Action Features. * YYDEBUG: Debugging. * YYEMPTY: Action Features. * YYERROR: Action Features. * YYINITDEPTH: Stack Overflow. * YYLTYPE: Token Positions. * YYMAXDEPTH: Stack Overflow. * YYPRINT: Debugging. * YYRECOVERING: Error Recovery. * action: Actions. * action data types: Action Types. * action features summary: Action Features. * actions in mid-rule: Mid-Rule Actions. * actions, semantic: Semantic Actions. * additional C code section: C Code. * algorithm of parser: Algorithm. * associativity: Why Precedence. * calculator, infix notation: Infix Calc. * calculator, multi-function: Multi-function Calc. * calculator, simple: RPN Calc. * character token: Symbols. * compiling the parser: Rpcalc Compile. * conflicts: Shift/Reduce. * conflicts, reduce/reduce: Reduce/Reduce. * conflicts, suppressing warnings of: Expect Decl. * context-dependent precedence: Contextual Precedence. * context-free grammar: Language and Grammar. * controlling function: Rpcalc Main. * dangling else: Shift/Reduce. * data types in actions: Action Types. * data types of semantic values: Value Type. * debugging: Debugging. * declaration summary: Decl Summary. * declarations, Bison: Declarations. * declarations, Bison (introduction): Bison Declarations. * declarations, C: C Declarations. * declaring operator precedence: Precedence Decl. * declaring the start symbol: Start Decl. * declaring token type names: Token Decl. * declaring value types: Union Decl. * declaring value types, nonterminals: Type Decl. * defining language semantics: Semantics. * error: Error Recovery. * error recovery: Error Recovery. * error recovery, simple: Simple Error Recovery. * error reporting function: Error Reporting. * error reporting routine: Rpcalc Error. * examples, simple: Examples. * exercises: Exercises. * file format: Grammar Layout. * finite-state machine: Parser States. * formal grammar: Grammar in Bison. * format of grammar file: Grammar Layout. * glossary: Glossary. * grammar file: Grammar Layout. * grammar rule syntax: Rules. * grammar rules section: Grammar Rules. * grammar, Bison: Grammar in Bison. * grammar, context-free: Language and Grammar. * grouping, syntactic: Language and Grammar. * infix notation calculator: Infix Calc. * interface: Interface. * introduction: Introduction. * invoking Bison: Invocation. * invoking Bison under VMS: VMS Invocation. * language semantics, defining: Semantics. * layout of Bison grammar: Grammar Layout. * left recursion: Recursion. * lexical analyzer: Lexical. * lexical analyzer, purpose: Bison Parser. * lexical analyzer, writing: Rpcalc Lexer. * lexical tie-in: Lexical Tie-ins. * literal token: Symbols. * look-ahead token: Look-Ahead. * main function in simple example: Rpcalc Main. * mid-rule actions: Mid-Rule Actions. * multi-function calculator: Multi-function Calc. * mutual recursion: Recursion. * nonterminal symbol: Symbols. * operator precedence: Precedence. * operator precedence, declaring: Precedence Decl. * options for invoking Bison: Invocation. * overflow of parser stack: Stack Overflow. * parse error: Error Reporting. * parser: Bison Parser. * parser stack: Algorithm. * parser stack overflow: Stack Overflow. * parser state: Parser States. * polish notation calculator: RPN Calc. * precedence declarations: Precedence Decl. * precedence of operators: Precedence. * precedence, context-dependent: Contextual Precedence. * precedence, unary operator: Contextual Precedence. * preventing warnings about conflicts: Expect Decl. * pure parser: Pure Decl. * recovery from errors: Error Recovery. * recursive rule: Recursion. * reduce/reduce conflict: Reduce/Reduce. * reduction: Algorithm. * reentrant parser: Pure Decl. * reverse polish notation: RPN Calc. * right recursion: Recursion. * rule syntax: Rules. * rules section for grammar: Grammar Rules. * running Bison (introduction): Rpcalc Gen. * semantic actions: Semantic Actions. * semantic value: Semantic Values. * semantic value type: Value Type. * shift/reduce conflicts: Shift/Reduce. * shifting: Algorithm. * simple examples: Examples. * single-character literal: Symbols. * stack overflow: Stack Overflow. * stack, parser: Algorithm. * stages in using Bison: Stages. * start symbol: Language and Grammar. * start symbol, declaring: Start Decl. * state (of parser): Parser States. * summary, Bison declaration: Decl Summary. * summary, action features: Action Features. * suppressing conflict warnings: Expect Decl. * symbol: Symbols. * symbol table example: Mfcalc Symtab. * symbols (abstract): Language and Grammar. * symbols in Bison, table of: Table of Symbols. * syntactic grouping: Language and Grammar. * syntax error: Error Reporting. * syntax of grammar rules: Rules. * terminal symbol: Symbols. * token: Language and Grammar. * token type: Symbols. * token type names, declaring: Token Decl. * tracing the parser: Debugging. * unary operator precedence: Contextual Precedence. * using Bison: Stages. * value type, semantic: Value Type. * value types, declaring: Union Decl. * value types, nonterminals, declaring: Type Decl. * value, semantic: Semantic Values. * warnings, preventing: Expect Decl. * writing a lexical analyzer: Rpcalc Lexer. * yychar: Look-Ahead. * yyclearin: Error Recovery. * yydebug: Debugging. * yyerrok: Error Recovery. * yyerror: Error Reporting. * yylex: Lexical. * yylloc: Token Positions. * yylval: Token Values. * yynerrs: Error Reporting. * yyparse: Parser Function. * |: Rules. ./usr/lib/bison.hairy 644 0 0 14515 5303476054 13115 0ustar rootwheel extern int timeclock; int yyerror; /* Yyerror and yycost are set by guards. */ int yycost; /* If yyerror is set to a nonzero value by a */ /* guard, the reduction with which the guard */ /* is associated is not performed, and the */ /* error recovery mechanism is invoked. */ /* Yycost indicates the cost of performing */ /* the reduction given the attributes of the */ /* symbols. */ /* YYMAXDEPTH indicates the size of the parser's state and value */ /* stacks. */ #ifndef YYMAXDEPTH #define YYMAXDEPTH 500 #endif /* YYMAXRULES must be at least as large as the number of rules that */ /* could be placed in the rule queue. That number could be determined */ /* from the grammar and the size of the stack, but, as yet, it is not. */ #ifndef YYMAXRULES #define YYMAXRULES 100 #endif #ifndef YYMAXBACKUP #define YYMAXBACKUP 100 #endif short yyss[YYMAXDEPTH]; /* the state stack */ YYSTYPE yyvs[YYMAXDEPTH]; /* the semantic value stack */ YYLTYPE yyls[YYMAXDEPTH]; /* the location stack */ short yyrq[YYMAXRULES]; /* the rule queue */ int yychar; /* the lookahead symbol */ YYSTYPE yylval; /* the semantic value of the */ /* lookahead symbol */ YYSTYPE yytval; /* the semantic value for the state */ /* at the top of the state stack. */ YYSTYPE yyval; /* the variable used to return */ /* semantic values from the action */ /* routines */ YYLTYPE yylloc; /* location data for the lookahead */ /* symbol */ YYLTYPE yytloc; /* location data for the state at the */ /* top of the state stack */ int yynunlexed; short yyunchar[YYMAXBACKUP]; YYSTYPE yyunval[YYMAXBACKUP]; YYLTYPE yyunloc[YYMAXBACKUP]; short *yygssp; /* a pointer to the top of the state */ /* stack; only set during error */ /* recovery. */ YYSTYPE *yygvsp; /* a pointer to the top of the value */ /* stack; only set during error */ /* recovery. */ YYLTYPE *yyglsp; /* a pointer to the top of the */ /* location stack; only set during */ /* error recovery. */ /* Yyget is an interface between the parser and the lexical analyzer. */ /* It is costly to provide such an interface, but it avoids requiring */ /* the lexical analyzer to be able to back up the scan. */ yyget() { if (yynunlexed > 0) { yynunlexed--; yychar = yyunchar[yynunlexed]; yylval = yyunval[yynunlexed]; yylloc = yyunloc[yynunlexed]; } else if (yychar <= 0) yychar = 0; else { yychar = yylex(); if (yychar < 0) yychar = 0; else yychar = YYTRANSLATE(yychar); } } yyunlex(chr, val, loc) int chr; YYSTYPE val; YYLTYPE loc; { yyunchar[yynunlexed] = chr; yyunval[yynunlexed] = val; yyunloc[yynunlexed] = loc; yynunlexed++; } yyrestore(first, last) register short *first; register short *last; { register short *ssp; register short *rp; register int symbol; register int state; register int tvalsaved; ssp = yygssp; yyunlex(yychar, yylval, yylloc); tvalsaved = 0; while (first != last) { symbol = yystos[*ssp]; if (symbol < YYNTBASE) { yyunlex(symbol, yytval, yytloc); tvalsaved = 1; ssp--; } ssp--; if (first == yyrq) first = yyrq + YYMAXRULES; first--; for (rp = yyrhs + yyprhs[*first]; symbol = *rp; rp++) { if (symbol < YYNTBASE) state = yytable[yypact[*ssp] + symbol]; else { state = yypgoto[symbol - YYNTBASE] + *ssp; if (state >= 0 && state <= YYLAST && yycheck[state] == *ssp) state = yytable[state]; else state = yydefgoto[symbol - YYNTBASE]; } *++ssp = state; } } if ( ! tvalsaved && ssp > yyss) { yyunlex(yystos[*ssp], yytval, yytloc); ssp--; } yygssp = ssp; } int yyparse() { register int yystate; register int yyn; register short *yyssp; register short *yyrq0; register short *yyptr; register YYSTYPE *yyvsp; int yylen; YYLTYPE *yylsp; short *yyrq1; short *yyrq2; yystate = 0; yyssp = yyss - 1; yyvsp = yyvs - 1; yylsp = yyls - 1; yyrq0 = yyrq; yyrq1 = yyrq0; yyrq2 = yyrq0; yychar = yylex(); if (yychar < 0) yychar = 0; else yychar = YYTRANSLATE(yychar); yynewstate: if (yyssp >= yyss + YYMAXDEPTH - 1) { yyabort("Parser Stack Overflow"); YYABORT; } *++yyssp = yystate; yyresume: yyn = yypact[yystate]; if (yyn == YYFLAG) goto yydefault; yyn += yychar; if (yyn < 0 || yyn > YYLAST || yycheck[yyn] != yychar) goto yydefault; yyn = yytable[yyn]; if (yyn < 0) { yyn = -yyn; goto yyreduce; } else if (yyn == 0) goto yyerrlab; yystate = yyn; yyptr = yyrq2; while (yyptr != yyrq1) { yyn = *yyptr++; yylen = yyr2[yyn]; yyvsp -= yylen; yylsp -= yylen; yyguard(yyn, yyvsp, yylsp); if (yyerror) goto yysemerr; yyaction(yyn, yyvsp, yylsp); *++yyvsp = yyval; yylsp++; if (yylen == 0) { yylsp->timestamp = timeclock; yylsp->first_line = yytloc.first_line; yylsp->first_column = yytloc.first_column; yylsp->last_line = (yylsp-1)->last_line; yylsp->last_column = (yylsp-1)->last_column; yylsp->text = 0; } else { yylsp->last_line = (yylsp+yylen-1)->last_line; yylsp->last_column = (yylsp+yylen-1)->last_column; } if (yyptr == yyrq + YYMAXRULES) yyptr = yyrq; } if (yystate == YYFINAL) YYACCEPT; yyrq2 = yyptr; yyrq1 = yyrq0; *++yyvsp = yytval; *++yylsp = yytloc; yytval = yylval; yytloc = yylloc; yyget(); goto yynewstate; yydefault: yyn = yydefact[yystate]; if (yyn == 0) goto yyerrlab; yyreduce: *yyrq0++ = yyn; if (yyrq0 == yyrq + YYMAXRULES) yyrq0 = yyrq; if (yyrq0 == yyrq2) { yyabort("Parser Rule Queue Overflow"); YYABORT; } yyssp -= yyr2[yyn]; yyn = yyr1[yyn]; yystate = yypgoto[yyn - YYNTBASE] + *yyssp; if (yystate >= 0 && yystate <= YYLAST && yycheck[yystate] == *yyssp) yystate = yytable[yystate]; else yystate = yydefgoto[yyn - YYNTBASE]; goto yynewstate; yysemerr: *--yyptr = yyn; yyrq2 = yyptr; yyvsp += yyr2[yyn]; yyerrlab: yygssp = yyssp; yygvsp = yyvsp; yyglsp = yylsp; yyrestore(yyrq0, yyrq2); yyrecover(); yystate = *yygssp; yyssp = yygssp; yyvsp = yygvsp; yyrq0 = yyrq; yyrq1 = yyrq0; yyrq2 = yyrq0; goto yyresume; } $ ./usr/lib/bison.simple 644 0 0 36177 5303476054 13302 0ustar rootwheel/* -*-C-*- Note some compilers choke on comments on `#line' lines. */ #line 3 "/usr/lib/bison.simple" /* Skeleton output parser for bison, Copyright (C) 1984, 1989, 1990 Bob Corbett and Richard Stallman This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 1, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ #ifndef alloca #ifdef __GNUC__ #define alloca __builtin_alloca #else /* not GNU C. */ #if (!defined (__STDC__) && defined (sparc)) || defined (__sparc__) || defined (__sparc) #include #else /* not sparc */ #if defined (MSDOS) && !defined (__TURBOC__) #include #else /* not MSDOS, or __TURBOC__ */ #if defined(_AIX) #include #pragma alloca #endif /* not _AIX */ #endif /* not MSDOS, or __TURBOC__ */ #endif /* not sparc. */ #endif /* not GNU C. */ #endif /* alloca not defined. */ /* This is the parser code that is written into each bison parser when the %semantic_parser declaration is not specified in the grammar. It was written by Richard Stallman by simplifying the hairy parser used when %semantic_parser is specified. */ /* Note: there must be only one dollar sign in this file. It is replaced by the list of actions, each action as one case of the switch. */ #define yyerrok (yyerrstatus = 0) #define yyclearin (yychar = YYEMPTY) #define YYEMPTY -2 #define YYEOF 0 #define YYACCEPT return(0) #define YYABORT return(1) #define YYERROR goto yyerrlab1 /* Like YYERROR except do call yyerror. This remains here temporarily to ease the transition to the new meaning of YYERROR, for GCC. Once GCC version 2 has supplanted version 1, this can go. */ #define YYFAIL goto yyerrlab #define YYRECOVERING() (!!yyerrstatus) #define YYBACKUP(token, value) \ do \ if (yychar == YYEMPTY && yylen == 1) \ { yychar = (token), yylval = (value); \ yychar1 = YYTRANSLATE (yychar); \ YYPOPSTACK; \ goto yybackup; \ } \ else \ { yyerror ("syntax error: cannot back up"); YYERROR; } \ while (0) #define YYTERROR 1 #define YYERRCODE 256 #ifndef YYPURE #define YYLEX yylex() #endif #ifdef YYPURE #ifdef YYLSP_NEEDED #define YYLEX yylex(&yylval, &yylloc) #else #define YYLEX yylex(&yylval) #endif #endif /* If nonreentrant, generate the variables here */ #ifndef YYPURE int yychar; /* the lookahead symbol */ YYSTYPE yylval; /* the semantic value of the */ /* lookahead symbol */ #ifdef YYLSP_NEEDED YYLTYPE yylloc; /* location data for the lookahead */ /* symbol */ #endif int yynerrs; /* number of parse errors so far */ #endif /* not YYPURE */ #if YYDEBUG != 0 int yydebug; /* nonzero means print parse trace */ /* Since this is uninitialized, it does not stop multiple parsers from coexisting. */ #endif /* YYINITDEPTH indicates the initial size of the parser's stacks */ #ifndef YYINITDEPTH #define YYINITDEPTH 200 #endif /* YYMAXDEPTH is the maximum size the stacks can grow to (effective only if the built-in stack extension method is used). */ #if YYMAXDEPTH == 0 #undef YYMAXDEPTH #endif #ifndef YYMAXDEPTH #define YYMAXDEPTH 10000 #endif #if __GNUC__ > 1 /* GNU C and GNU C++ define this. */ #define __yy_bcopy(FROM,TO,COUNT) __builtin_memcpy(TO,FROM,COUNT) #else /* not GNU C or C++ */ #ifndef __cplusplus /* This is the most reliable way to avoid incompatibilities in available built-in functions on various systems. */ static void __yy_bcopy (from, to, count) char *from; char *to; int count; { register char *f = from; register char *t = to; register int i = count; while (i-- > 0) *t++ = *f++; } #else /* __cplusplus */ /* This is the most reliable way to avoid incompatibilities in available built-in functions on various systems. */ static void __yy_bcopy (char *from, char *to, int count) { register char *f = from; register char *t = to; register int i = count; while (i-- > 0) *t++ = *f++; } #endif #endif #line 169 "/usr/lib/bison.simple" int yyparse() { register int yystate; register int yyn; register short *yyssp; register YYSTYPE *yyvsp; int yyerrstatus; /* number of tokens to shift before error messages enabled */ int yychar1; /* lookahead token as an internal (translated) token number */ short yyssa[YYINITDEPTH]; /* the state stack */ YYSTYPE yyvsa[YYINITDEPTH]; /* the semantic value stack */ short *yyss = yyssa; /* refer to the stacks thru separate pointers */ YYSTYPE *yyvs = yyvsa; /* to allow yyoverflow to reallocate them elsewhere */ #ifdef YYLSP_NEEDED YYLTYPE yylsa[YYINITDEPTH]; /* the location stack */ YYLTYPE *yyls = yylsa; YYLTYPE *yylsp; #define YYPOPSTACK (yyvsp--, yyssp--, yylsp--) #else #define YYPOPSTACK (yyvsp--, yyssp--) #endif int yystacksize = YYINITDEPTH; #ifdef YYPURE int yychar; YYSTYPE yylval; int yynerrs; #ifdef YYLSP_NEEDED YYLTYPE yylloc; #endif #endif YYSTYPE yyval; /* the variable used to return */ /* semantic values from the action */ /* routines */ int yylen; #if YYDEBUG != 0 if (yydebug) fprintf(stderr, "Starting parse\n"); #endif yystate = 0; yyerrstatus = 0; yynerrs = 0; yychar = YYEMPTY; /* Cause a token to be read. */ /* Initialize stack pointers. Waste one element of value and location stack so that they stay on the same level as the state stack. The wasted elements are never initialized. */ yyssp = yyss - 1; yyvsp = yyvs; #ifdef YYLSP_NEEDED yylsp = yyls; #endif /* Push a new state, which is found in yystate . */ /* In all cases, when you get here, the value and location stacks have just been pushed. so pushing a state here evens the stacks. */ yynewstate: *++yyssp = yystate; if (yyssp >= yyss + yystacksize - 1) { /* Give user a chance to reallocate the stack */ /* Use copies of these so that the &'s don't force the real ones into memory. */ YYSTYPE *yyvs1 = yyvs; short *yyss1 = yyss; #ifdef YYLSP_NEEDED YYLTYPE *yyls1 = yyls; #endif /* Get the current used size of the three stacks, in elements. */ int size = yyssp - yyss + 1; #ifdef yyoverflow /* Each stack pointer address is followed by the size of the data in use in that stack, in bytes. */ yyoverflow("parser stack overflow", &yyss1, size * sizeof (*yyssp), &yyvs1, size * sizeof (*yyvsp), #ifdef YYLSP_NEEDED &yyls1, size * sizeof (*yylsp), #endif &yystacksize); yyss = yyss1; yyvs = yyvs1; #ifdef YYLSP_NEEDED yyls = yyls1; #endif #else /* no yyoverflow */ /* Extend the stack our own way. */ if (yystacksize >= YYMAXDEPTH) { yyerror("parser stack overflow"); return 2; } yystacksize *= 2; if (yystacksize > YYMAXDEPTH) yystacksize = YYMAXDEPTH; yyss = (short *) alloca (yystacksize * sizeof (*yyssp)); __yy_bcopy ((char *)yyss1, (char *)yyss, size * sizeof (*yyssp)); yyvs = (YYSTYPE *) alloca (yystacksize * sizeof (*yyvsp)); __yy_bcopy ((char *)yyvs1, (char *)yyvs, size * sizeof (*yyvsp)); #ifdef YYLSP_NEEDED yyls = (YYLTYPE *) alloca (yystacksize * sizeof (*yylsp)); __yy_bcopy ((char *)yyls1, (char *)yyls, size * sizeof (*yylsp)); #endif #endif /* no yyoverflow */ yyssp = yyss + size - 1; yyvsp = yyvs + size - 1; #ifdef YYLSP_NEEDED yylsp = yyls + size - 1; #endif #if YYDEBUG != 0 if (yydebug) fprintf(stderr, "Stack size increased to %d\n", yystacksize); #endif if (yyssp >= yyss + yystacksize - 1) YYABORT; } #if YYDEBUG != 0 if (yydebug) fprintf(stderr, "Entering state %d\n", yystate); #endif goto yybackup; yybackup: /* Do appropriate processing given the current state. */ /* Read a lookahead token if we need one and don't already have one. */ /* yyresume: */ /* First try to decide what to do without reference to lookahead token. */ yyn = yypact[yystate]; if (yyn == YYFLAG) goto yydefault; /* Not known => get a lookahead token if don't already have one. */ /* yychar is either YYEMPTY or YYEOF or a valid token in external form. */ if (yychar == YYEMPTY) { #if YYDEBUG != 0 if (yydebug) fprintf(stderr, "Reading a token: "); #endif yychar = YYLEX; } /* Convert token to internal form (in yychar1) for indexing tables with */ if (yychar <= 0) /* This means end of input. */ { yychar1 = 0; yychar = YYEOF; /* Don't call YYLEX any more */ #if YYDEBUG != 0 if (yydebug) fprintf(stderr, "Now at end of input.\n"); #endif } else { yychar1 = YYTRANSLATE(yychar); #if YYDEBUG != 0 if (yydebug) { fprintf (stderr, "Next token is %d (%s", yychar, yytname[yychar1]); /* Give the individual parser a way to print the precise meaning of a token, for further debugging info. */ #ifdef YYPRINT YYPRINT (stderr, yychar, yylval); #endif fprintf (stderr, ")\n"); } #endif } yyn += yychar1; if (yyn < 0 || yyn > YYLAST || yycheck[yyn] != yychar1) goto yydefault; yyn = yytable[yyn]; /* yyn is what to do for this token type in this state. Negative => reduce, -yyn is rule number. Positive => shift, yyn is new state. New state is final state => don't bother to shift, just return success. 0, or most negative number => error. */ if (yyn < 0) { if (yyn == YYFLAG) goto yyerrlab; yyn = -yyn; goto yyreduce; } else if (yyn == 0) goto yyerrlab; if (yyn == YYFINAL) YYACCEPT; /* Shift the lookahead token. */ #if YYDEBUG != 0 if (yydebug) fprintf(stderr, "Shifting token %d (%s), ", yychar, yytname[yychar1]); #endif /* Discard the token being shifted unless it is eof. */ if (yychar != YYEOF) yychar = YYEMPTY; *++yyvsp = yylval; #ifdef YYLSP_NEEDED *++yylsp = yylloc; #endif /* count tokens shifted since error; after three, turn off error status. */ if (yyerrstatus) yyerrstatus--; yystate = yyn; goto yynewstate; /* Do the default action for the current state. */ yydefault: yyn = yydefact[yystate]; if (yyn == 0) goto yyerrlab; /* Do a reduction. yyn is the number of a rule to reduce with. */ yyreduce: yylen = yyr2[yyn]; yyval = yyvsp[1-yylen]; /* implement default value of the action */ #if YYDEBUG != 0 if (yydebug) { int i; fprintf (stderr, "Reducing via rule %d (line %d), ", yyn, yyrline[yyn]); /* Print the symbols being reduced, and their result. */ for (i = yyprhs[yyn]; yyrhs[i] > 0; i++) fprintf (stderr, "%s ", yytname[yyrhs[i]]); fprintf (stderr, " -> %s\n", yytname[yyr1[yyn]]); } #endif $ /* the action file gets copied in in place of this dollarsign */ #line 442 "/usr/lib/bison.simple" yyvsp -= yylen; yyssp -= yylen; #ifdef YYLSP_NEEDED yylsp -= yylen; #endif #if YYDEBUG != 0 if (yydebug) { short *ssp1 = yyss - 1; fprintf (stderr, "state stack now"); while (ssp1 != yyssp) fprintf (stderr, " %d", *++ssp1); fprintf (stderr, "\n"); } #endif *++yyvsp = yyval; #ifdef YYLSP_NEEDED yylsp++; if (yylen == 0) { yylsp->first_line = yylloc.first_line; yylsp->first_column = yylloc.first_column; yylsp->last_line = (yylsp-1)->last_line; yylsp->last_column = (yylsp-1)->last_column; yylsp->text = 0; } else { yylsp->last_line = (yylsp+yylen-1)->last_line; yylsp->last_column = (yylsp+yylen-1)->last_column; } #endif /* Now "shift" the result of the reduction. Determine what state that goes to, based on the state we popped back to and the rule number reduced by. */ yyn = yyr1[yyn]; yystate = yypgoto[yyn - YYNTBASE] + *yyssp; if (yystate >= 0 && yystate <= YYLAST && yycheck[yystate] == *yyssp) yystate = yytable[yystate]; else yystate = yydefgoto[yyn - YYNTBASE]; goto yynewstate; yyerrlab: /* here on detecting error */ if (! yyerrstatus) /* If not already recovering from an error, report this error. */ { ++yynerrs; #ifdef YYERROR_VERBOSE yyn = yypact[yystate]; if (yyn > YYFLAG && yyn < YYLAST) { int size = 0; char *msg; int x, count; count = 0; for (x = 0; x < (sizeof(yytname) / sizeof(char *)); x++) if (yycheck[x + yyn] == x) size += strlen(yytname[x]) + 15, count++; msg = (char *) malloc(size + 15); if (msg != 0) { strcpy(msg, "parse error"); if (count < 5) { count = 0; for (x = 0; x < (sizeof(yytname) / sizeof(char *)); x++) if (yycheck[x + yyn] == x) { strcat(msg, count == 0 ? ", expecting `" : " or `"); strcat(msg, yytname[x]); strcat(msg, "'"); count++; } } yyerror(msg); free(msg); } else yyerror ("parse error; also virtual memory exceeded"); } else #endif /* YYERROR_VERBOSE */ yyerror("parse error"); } goto yyerrlab1; yyerrlab1: /* here on error raised explicitly by an action */ if (yyerrstatus == 3) { /* if just tried and failed to reuse lookahead token after an error, discard it. */ /* return failure if at end of input */ if (yychar == YYEOF) YYABORT; #if YYDEBUG != 0 if (yydebug) fprintf(stderr, "Discarding token %d (%s).\n", yychar, yytname[yychar1]); #endif yychar = YYEMPTY; } /* Else will try to reuse lookahead token after shifting the error token. */ yyerrstatus = 3; /* Each real token shifted decrements this */ goto yyerrhandle; yyerrdefault: /* current state does not do anything special for the error token. */ #if 0 /* This is wrong; only states that explicitly want error tokens should shift them. */ yyn = yydefact[yystate]; /* If its default is to accept any token, ok. Otherwise pop it.*/ if (yyn) goto yydefault; #endif yyerrpop: /* pop the current state because it cannot handle the error token */ if (yyssp == yyss) YYABORT; yyvsp--; yystate = *--yyssp; #ifdef YYLSP_NEEDED yylsp--; #endif #if YYDEBUG != 0 if (yydebug) { short *ssp1 = yyss - 1; fprintf (stderr, "Error: state stack now"); while (ssp1 != yyssp) fprintf (stderr, " %d", *++ssp1); fprintf (stderr, "\n"); } #endif yyerrhandle: yyn = yypact[yystate]; if (yyn == YYFLAG) goto yyerrdefault; yyn += YYTERROR; if (yyn < 0 || yyn > YYLAST || yycheck[yyn] != YYTERROR) goto yyerrdefault; yyn = yytable[yyn]; if (yyn < 0) { if (yyn == YYFLAG) goto yyerrpop; yyn = -yyn; goto yyreduce; } else if (yyn == 0) goto yyerrpop; if (yyn == YYFINAL) YYACCEPT; #if YYDEBUG != 0 if (yydebug) fprintf(stderr, "Shifting error token, "); #endif *++yyvsp = yylval; #ifdef YYLSP_NEEDED *++yylsp = yylloc; #endif yystate = yyn; goto yynewstate; } ./usr/src/bison-1.19/COPYING 600 0 0 43076 5022247405 13507 0ustar rootwheel GNU GENERAL PUBLIC LICENSE Version 2, June 1991 Copyright (C) 1989, 1991 Free Software Foundation, Inc. 675 Mass Ave, Cambridge, MA 02139, USA Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed. Preamble The licenses for most software are designed to take away your freedom to share and change it. By contrast, the GNU General Public License is intended to guarantee your freedom to share and change free software--to make sure the software is free for all its users. This General Public License applies to most of the Free Software Foundation's software and to any other program whose authors commit to using it. (Some other Free Software Foundation software is covered by the GNU Library General Public License instead.) You can apply it to your programs, too. When we speak of free software, we are referring to freedom, not price. Our General Public Licenses are designed to make sure that you have the freedom to distribute copies of free software (and charge for this service if you wish), that you receive source code or can get it if you want it, that you can change the software or use pieces of it in new free programs; and that you know you can do these things. To protect your rights, we need to make restrictions that forbid anyone to deny you these rights or to ask you to surrender the rights. These restrictions translate to certain responsibilities for you if you distribute copies of the software, or if you modify it. For example, if you distribute copies of such a program, whether gratis or for a fee, you must give the recipients all the rights that you have. You must make sure that they, too, receive or can get the source code. And you must show them these terms so they know their rights. We protect your rights with two steps: (1) copyright the software, and (2) offer you this license which gives you legal permission to copy, distribute and/or modify the software. Also, for each author's protection and ours, we want to make certain that everyone understands that there is no warranty for this free software. If the software is modified by someone else and passed on, we want its recipients to know that what they have is not the original, so that any problems introduced by others will not reflect on the original authors' reputations. Finally, any free program is threatened constantly by software patents. We wish to avoid the danger that redistributors of a free program will individually obtain patent licenses, in effect making the program proprietary. To prevent this, we have made it clear that any patent must be licensed for everyone's free use or not licensed at all. The precise terms and conditions for copying, distribution and modification follow. GNU GENERAL PUBLIC LICENSE TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION 0. This License applies to any program or other work which contains a notice placed by the copyright holder saying it may be distributed under the terms of this General Public License. The "Program", below, refers to any such program or work, and a "work based on the Program" means either the Program or any derivative work under copyright law: that is to say, a work containing the Program or a portion of it, either verbatim or with modifications and/or translated into another language. (Hereinafter, translation is included without limitation in the term "modification".) Each licensee is addressed as "you". Activities other than copying, distribution and modification are not covered by this License; they are outside its scope. The act of running the Program is not restricted, and the output from the Program is covered only if its contents constitute a work based on the Program (independent of having been made by running the Program). Whether that is true depends on what the Program does. 1. You may copy and distribute verbatim copies of the Program's source code as you receive it, in any medium, provided that you conspicuously and appropriately publish on each copy an appropriate copyright notice and disclaimer of warranty; keep intact all the notices that refer to this License and to the absence of any warranty; and give any other recipients of the Program a copy of this License along with the Program. You may charge a fee for the physical act of transferring a copy, and you may at your option offer warranty protection in exchange for a fee. 2. You may modify your copy or copies of the Program or any portion of it, thus forming a work based on the Program, and copy and distribute such modifications or work under the terms of Section 1 above, provided that you also meet all of these conditions: a) You must cause the modified files to carry prominent notices stating that you changed the files and the date of any change. b) You must cause any work that you distribute or publish, that in whole or in part contains or is derived from the Program or any part thereof, to be licensed as a whole at no charge to all third parties under the terms of this License. c) If the modified program normally reads commands interactively when run, you must cause it, when started running for such interactive use in the most ordinary way, to print or display an announcement including an appropriate copyright notice and a notice that there is no warranty (or else, saying that you provide a warranty) and that users may redistribute the program under these conditions, and telling the user how to view a copy of this License. (Exception: if the Program itself is interactive but does not normally print such an announcement, your work based on the Program is not required to print an announcement.) These requirements apply to the modified work as a whole. If identifiable sections of that work are not derived from the Program, and can be reasonably considered independent and separate works in themselves, then this License, and its terms, do not apply to those sections when you distribute them as separate works. But when you distribute the same sections as part of a whole which is a work based on the Program, the distribution of the whole must be on the terms of this License, whose permissions for other licensees extend to the entire whole, and thus to each and every part regardless of who wrote it. Thus, it is not the intent of this section to claim rights or contest your rights to work written entirely by you; rather, the intent is to exercise the right to control the distribution of derivative or collective works based on the Program. In addition, mere aggregation of another work not based on the Program with the Program (or with a work based on the Program) on a volume of a storage or distribution medium does not bring the other work under the scope of this License. 3. You may copy and distribute the Program (or a work based on it, under Section 2) in object code or executable form under the terms of Sections 1 and 2 above provided that you also do one of the following: a) Accompany it with the complete corresponding machine-readable source code, which must be distributed under the terms of Sections 1 and 2 above on a medium customarily used for software interchange; or, b) Accompany it with a written offer, valid for at least three years, to give any third party, for a charge no more than your cost of physically performing source distribution, a complete machine-readable copy of the corresponding source code, to be distributed under the terms of Sections 1 and 2 above on a medium customarily used for software interchange; or, c) Accompany it with the information you received as to the offer to distribute corresponding source code. (This alternative is allowed only for noncommercial distribution and only if you received the program in object code or executable form with such an offer, in accord with Subsection b above.) The source code for a work means the preferred form of the work for making modifications to it. For an executable work, complete source code means all the source code for all modules it contains, plus any associated interface definition files, plus the scripts used to control compilation and installation of the executable. However, as a special exception, the source code distributed need not include anything that is normally distributed (in either source or binary form) with the major components (compiler, kernel, and so on) of the operating system on which the executable runs, unless that component itself accompanies the executable. If distribution of executable or object code is made by offering access to copy from a designated place, then offering equivalent access to copy the source code from the same place counts as distribution of the source code, even though third parties are not compelled to copy the source along with the object code. 4. You may not copy, modify, sublicense, or distribute the Program except as expressly provided under this License. Any attempt otherwise to copy, modify, sublicense or distribute the Program is void, and will automatically terminate your rights under this License. However, parties who have received copies, or rights, from you under this License will not have their licenses terminated so long as such parties remain in full compliance. 5. You are not required to accept this License, since you have not signed it. However, nothing else grants you permission to modify or distribute the Program or its derivative works. These actions are prohibited by law if you do not accept this License. Therefore, by modifying or distributing the Program (or any work based on the Program), you indicate your acceptance of this License to do so, and all its terms and conditions for copying, distributing or modifying the Program or works based on it. 6. Each time you redistribute the Program (or any work based on the Program), the recipient automatically receives a license from the original licensor to copy, distribute or modify the Program subject to these terms and conditions. You may not impose any further restrictions on the recipients' exercise of the rights granted herein. You are not responsible for enforcing compliance by third parties to this License. 7. If, as a consequence of a court judgment or allegation of patent infringement or for any other reason (not limited to patent issues), conditions are imposed on you (whether by court order, agreement or otherwise) that contradict the conditions of this License, they do not excuse you from the conditions of this License. If you cannot distribute so as to satisfy simultaneously your obligations under this License and any other pertinent obligations, then as a consequence you may not distribute the Program at all. For example, if a patent license would not permit royalty-free redistribution of the Program by all those who receive copies directly or indirectly through you, then the only way you could satisfy both it and this License would be to refrain entirely from distribution of the Program. If any portion of this section is held invalid or unenforceable under any particular circumstance, the balance of the section is intended to apply and the section as a whole is intended to apply in other circumstances. It is not the purpose of this section to induce you to infringe any patents or other property right claims or to contest validity of any such claims; this section has the sole purpose of protecting the integrity of the free software distribution system, which is implemented by public license practices. Many people have made generous contributions to the wide range of software distributed through that system in reliance on consistent application of that system; it is up to the author/donor to decide if he or she is willing to distribute software through any other system and a licensee cannot impose that choice. This section is intended to make thoroughly clear what is believed to be a consequence of the rest of this License. 8. If the distribution and/or use of the Program is restricted in certain countries either by patents or by copyrighted interfaces, the original copyright holder who places the Program under this License may add an explicit geographical distribution limitation excluding those countries, so that distribution is permitted only in or among countries not thus excluded. In such case, this License incorporates the limitation as if written in the body of this License. 9. The Free Software Foundation may publish revised and/or new versions of the General Public License from time to time. Such new versions will be similar in spirit to the present version, but may differ in detail to address new problems or concerns. Each version is given a distinguishing version number. If the Program specifies a version number of this License which applies to it and "any later version", you have the option of following the terms and conditions either of that version or of any later version published by the Free Software Foundation. If the Program does not specify a version number of this License, you may choose any version ever published by the Free Software Foundation. 10. If you wish to incorporate parts of the Program into other free programs whose distribution conditions are different, write to the author to ask for permission. For software which is copyrighted by the Free Software Foundation, write to the Free Software Foundation; we sometimes make exceptions for this. Our decision will be guided by the two goals of preserving the free status of all derivatives of our free software and of promoting the sharing and reuse of software generally. NO WARRANTY 11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR OR CORRECTION. 12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. END OF TERMS AND CONDITIONS Appendix: How to Apply These Terms to Your New Programs If you develop a new program, and you want it to be of the greatest possible use to the public, the best way to achieve this is to make it free software which everyone can redistribute and change under these terms. To do so, attach the following notices to the program. It is safest to attach them to the start of each source file to most effectively convey the exclusion of warranty; and each file should have at least the "copyright" line and a pointer to where the full notice is found. Copyright (C) 19yy This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. Also add information on how to contact you by electronic and paper mail. If the program is interactive, make it output a short notice like this when it starts in an interactive mode: Gnomovision version 69, Copyright (C) 19yy name of author Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'. This is free software, and you are welcome to redistribute it under certain conditions; type `show c' for details. The hypothetical commands `show w' and `show c' should show the appropriate parts of the General Public License. Of course, the commands you use may be called something other than `show w' and `show c'; they could even be mouse-clicks or menu items--whatever suits your program. You should also get your employer (if you work as a programmer) or your school, if any, to sign a "copyright disclaimer" for the program, if necessary. Here is a sample; alter the names: Yoyodyne, Inc., hereby disclaims all copyright interest in the program `Gnomovision' (which makes passes at compilers) written by James Hacker. , 1 April 1989 Ty Coon, President of Vice This General Public License does not permit incorporating your program into proprietary programs. If your program is a subroutine library, you may consider it more useful to permit linking proprietary applications with the library. If this is what you want to do, use the GNU Library General Public License instead of this License. ./usr/src/bison-1.19/ChangeLog 600 0 1 75254 5261613720 14373 0ustar rootdaemonFri Sep 25 18:06:28 1992 Richard Stallman (rms@mole.gnu.ai.mit.edu) * Version 1.19 released. * reader.c (parse_union_decl): Fix ending of C++ comment; don't lose the char after the newline. * configure.bat: New file. Thu Sep 24 16:23:15 1992 Richard Stallman (rms@mole.gnu.ai.mit.edu) * conflicts.c: Check for using alloca.h as getopt.c does. Sun Sep 6 08:01:53 1992 Karl Berry (karl@hayley) * files.c (openfiles): open `fdefines' after we have assigned a name to `tmpdefsfile', and only if `definesflag' is set. (done): only create the real .tab.h file if `definesflag' is set. * reader.c (packsymbols): don't close `fdefines' here. Sat Sep 5 15:02:11 1992 Richard Stallman (rms@mole.gnu.ai.mit.edu) * files.c (openfiles): Open fdefines as temp file, like ftable. (done): Copy temp defines file to real one, like main output file. Fri Aug 21 12:47:48 1992 Richard Stallman (rms@mole.gnu.ai.mit.edu) * Makefile.in (dist): Don't release mergedir.awk (install): Use sed, not awk. Don't depend on mergedir.awk. * mergedir.awk: File effectively deleted. Wed Jul 29 00:53:25 1992 Richard Stallman (rms@mole.gnu.ai.mit.edu) * bison.simple: Test __sparc along with __sparc__. Sat Jul 11 14:08:33 1992 Richard Stallman (rms@mole.gnu.ai.mit.edu) * lex.c (skip_white_space): Count \n just once at end of c++ comment. Fri Jun 26 00:00:30 1992 Richard Stallman (rms@mole.gnu.ai.mit.edu) * bison.simple: Comment fix; #line command updated. Wed Jun 24 15:12:42 1992 Richard Stallman (rms@mole.gnu.ai.mit.edu) * Makefile.in (install): Specify full new file name for the executable. Mon Jun 22 16:38:24 1992 Richard Stallman (rms@mole.gnu.ai.mit.edu) * Makefile.in (dist): Include bison.rnh in distribution. Sun Jun 21 22:42:13 1992 Eric Youngdale (youngdale@v6550c.nrl.navy.mil) Clean up rough edges in VMS port of bison, add support for remaining command line options. * bison.cld: Add /version, /yacc, /file_prefix, and /name_prefix switches. * build.com: General cleanup: add logic to automatically sense which C compiler is present; add code to cwd to the directory that contains bison sources; do not define XPFILE, XPFILE1 (correct defaults are applied in file.c). * files.c: Append _tab, not .tab when using /file_prefix under VMS. * system.h: Include string.h instead of strings.h (a la USG). * vmsgetargs.c: Add support for all switches added to bison.cld. Sun Jun 21 15:53:26 1992 Richard Stallman (rms@mole.gnu.ai.mit.edu) * Makefile.in (install): Always specify new file name for install. Redirect awk output to temp file and install that. Wed May 27 22:27:50 1992 Richard Stallman (rms@mole.gnu.ai.mit.edu) * bison.simple (yyparse): Make yybackup and yyerrlab1 always be used. Fri May 22 14:58:42 1992 Richard Stallman (rms@mole.gnu.ai.mit.edu) * Makefile.in (dist): Depend on bison.info (bison.info): Delete spurious <. Sun May 17 21:48:55 1992 Richard Stallman (rms@mole.gnu.ai.mit.edu) * Makefile.in (.c.o): New rule. Use $(DEFS) directly. (CFLAGS): Use just -g by default. (CDEBUG): Variable deleted. Thu May 7 00:03:37 1992 Richard Stallman (rms@mole.gnu.ai.mit.edu) * reader.c (copy_guard): Fix typo skipping comment. Mon May 4 01:23:21 1992 Richard Stallman (rms@mole.gnu.ai.mit.edu) * Version 1.18. * getargs.c (getargs): Change '0' to 0 in case for long options. Sun Apr 19 10:17:52 1992 Richard Stallman (rms@mole.gnu.ai.mit.edu) * reader.c (packsymbols): Handle -p when declaring yylval. Sat Apr 18 18:18:48 1992 Richard Stallman (rms@mole.gnu.ai.mit.edu) * output.c (output_gram): Output #endif properly at end of decl. Mon Mar 30 01:13:41 1992 Richard Stallman (rms@mole.gnu.ai.mit.edu) * Version 1.17. * Makefile.in (clean): Don't delete configuration files or TAGS. (distclean): New target; do delete those. Sat Mar 28 17:18:50 1992 Richard Stallman (rms@mole.gnu.ai.mit.edu) * output.c (output_gram): Conditionalize yyprhs on YYDEBUG. * LR0.c (augment_automaton): If copying sp->shifts to insert new shift, handle case of inserting at end. Sat Mar 21 23:25:47 1992 Richard Stallman (rms@mole.gnu.ai.mit.edu) * lex.c (skip_white_space): Handle C++ comments. * reader.c (copy_definition, parse_union_decl, copy_guard): (copy_action): Likewise. Sun Mar 8 01:22:21 1992 Richard Stallman (rms@mole.gnu.ai.mit.edu) * bison.simple (YYPOPSTACK): Fix typo. Sat Feb 29 03:53:06 1992 Richard Stallman (rms@mole.gnu.ai.mit.edu) * Makefile.in (install): Install bison.info* files one by one. Fri Feb 28 19:55:30 1992 David J. MacKenzie (djm@wookumz.gnu.ai.mit.edu) * bison.1: Document long options as starting with `--', not `+'. Sat Feb 1 00:08:09 1992 Richard Stallman (rms@mole.gnu.ai.mit.edu) * getargs.c (getargs): Accept value 0 from getopt_long. Thu Jan 30 23:39:15 1992 Richard Stallman (rms@mole.gnu.ai.mit.edu) * Makefile.in (mostlyclean): Renamed from `clean'. (clean): Renamed from 'distclean'. Dep on mostlyclean, not realclean. (realclean): Dep on clean. Mon Jan 27 21:59:19 1992 Richard Stallman (rms@mole.gnu.ai.mit.edu) * bison.simple: Use malloc, not xmalloc, and handle failure explicitly. Sun Jan 26 22:40:04 1992 Richard Stallman (rms@mole.gnu.ai.mit.edu) * conflicts.c (total_conflicts): Delete unused arg to fprintf. Tue Jan 21 23:17:44 1992 Richard Stallman (rms@mole.gnu.ai.mit.edu) * Version 1.16. Mon Jan 6 16:50:11 1992 Richard Stallman (rms at mole.gnu.ai.mit.edu) * Makefile (distclean): Depend on clean, not realclean. Don't rm TAGS. (realclean): rm TAGS here. * symtab.c (free_symtab): Don't free the type names. Sun Dec 29 22:25:40 1991 Richard Stallman (rms at mole.gnu.ai.mit.edu) * machine.h: MSDOS has 32-bit ints if __GO32__. Wed Dec 25 22:09:07 1991 David J. MacKenzie (djm at wookumz.gnu.ai.mit.edu) * bison.simple [_AIX]: Indent `#pragma alloca', so old C compilers don't choke on it. Mon Dec 23 02:10:16 1991 Richard Stallman (rms at mole.gnu.ai.mit.edu) * getopt.c, getopt1.c, getopt.h: Link them to standard source location. * alloca.c: Likewise. * Makefile.in (dist): Copy those files from current dir. * getargs.c: Update usage message. * LR0.c (augment_automaton): Put new shift in proper order. Fri Dec 20 18:39:20 1991 Richard Stallman (rms at mole.gnu.ai.mit.edu) * conflicts.c: Use memcpy if ANSI C library. * closure.c (set_fderives): Delete redundant assignment to vrow. * closure.c (print_firsts): Fix bounds and offset checking tags. * closure.c (tags): Declare just once at start of file. * LR0.c (allocate_itemsets): Eliminate unused var max. (augment_automaton): Test sp is non-null. * lalr.c (initialize_LA): Make the vectors at least 1 element long. * reader.c (readgram): Remove separate YYSTYPE default for MSDOS. Wed Dec 18 02:40:32 1991 Richard Stallman (rms at mole.gnu.ai.mit.edu) * print.c (print_grammar): Don't print disabled rules. Tue Dec 17 03:48:07 1991 Richard Stallman (rms at mole.gnu.ai.mit.edu) * lex.c (lex): Parse hex escapes properly. Handle \v when filling token_buffer. * lex.c: Include new.h. (token_buffer): Change to a pointer. (init_lex): Allocate initial buffer. (grow_token_buffer): New function. (lex, parse_percent_token): Use that. * reader.c (read_declarations): Call open_extra_files just once. (parse_token_decl): Don't free previous typename value. Don't increment nvars if symbol is already a nonterminal. (parse_union_decl): Catch unmatched close-brace. (parse_expect_decl): Null-terminate buffer. (copy_guard): Set brace_flag for {, not for }. * reader.c: Fix %% in calls to fatal. * reader.c (token_buffer): Just one extern decl, at top level. Declare as pointer. * symtab.c (free_symtab): Free type_name fields. Free symtab itself. Mon Nov 25 23:04:31 1991 Richard Stallman (rms at mole.gnu.ai.mit.edu) * bison.simple: Handle alloca for AIX. * Makefile.in (mandir): Compute default using manext. Sat Nov 2 21:39:32 1991 David J. MacKenzie (djm at wookumz.gnu.ai.mit.edu) * Update all files to GPL version 2. Fri Sep 6 01:51:36 1991 Richard Stallman (rms at mole.gnu.ai.mit.edu) * bison.simple (__yy_bcopy): Use builtin if GCC version 2. Mon Aug 26 22:09:12 1991 Richard Stallman (rms at mole.gnu.ai.mit.edu) * reader.c (parse_assoc_decl): Error if same symbol gets two precs. Mon Aug 26 16:42:09 1991 David J. MacKenzie (djm at pogo.gnu.ai.mit.edu) * Makefile.in, configure: Only put $< in Makefile if using VPATH, because older makes don't understand it. Fri Aug 23 00:05:54 1991 David J. MacKenzie (djm at apple-gunkies) * conflicts.c [_AIX]: #pragma alloca. * reduce.c: Don't define TRUE and FALSE if already defined. Mon Aug 12 22:49:58 1991 Richard Stallman (rms at mole.gnu.ai.mit.edu) * Makefile.in: Add deps on system.h. (install): Add some deps. Fri Aug 2 12:19:20 1991 David J. MacKenzie (djm at apple-gunkies) * Makefile.in (dist): Include texinfo.tex. * configure: Create config.status. Remove it and Makefile if interrupted while creating them. Thu Aug 1 23:14:01 1991 David J. MacKenzie (djm at apple-gunkies) * configure: Check for +srcdir etc. arg and look for Makefile.in in that directory. Set VPATH if srcdir is not `.'. * Makefile.in (prefix): Renamed from DESTDIR. Wed Jul 31 21:29:47 1991 Richard Stallman (rms at mole.gnu.ai.mit.edu) * print.c (print_grammar): Make output prettier. Break lines. Tue Jul 30 22:38:01 1991 Richard Stallman (rms at mole.gnu.ai.mit.edu) * print.c (print_grammar): New function. (verbose): Call it instead of printing token names here. Mon Jul 22 16:39:54 1991 Richard Stallman (rms at mole.gnu.ai.mit.edu) * vmsgetargs.c (spec_name_prefix, spec_file_prefix): Define variables. Wed Jul 10 01:38:25 1991 David J. MacKenzie (djm at wookumz.gnu.ai.mit.edu) * configure, Makefile.in: $(INSTALLPROG) -> $(INSTALL), $(INSTALLTEXT) -> $(INSTALLDATA). Tue Jul 9 00:53:58 1991 David J. MacKenzie (djm at wookumz.gnu.ai.mit.edu) * bison.simple: Don't include malloc.h if __TURBOC__. Sat Jul 6 15:18:12 1991 David J. MacKenzie (djm at geech.gnu.ai.mit.edu) * Replace Makefile with configure and Makefile.in. Update README with current compilation instructions. Mon Jul 1 23:12:20 1991 Richard Stallman (rms at mole.gnu.ai.mit.edu) * reader.c (reader): Make the output define YYBISON. Thu Jun 20 16:52:51 1991 David J. MacKenzie (djm at geech.gnu.ai.mit.edu) * Makefile (MANDIR, MANEXT): Install man page in /usr/local/man/man1/bison.1 by default, instead of /usr/man/manl/bison.l, for consistency with other GNU programs. * Makefile: Rename BINDIR et al. to lowercase to conform to GNU coding standards. (install): Make man page non-executable. Fri May 31 23:22:13 1991 Richard Stallman (rms at mole.gnu.ai.mit.edu) * Makefile (bison.info): New target. (realclean): New target. Thu May 2 16:36:19 1991 Richard Stallman (rms at mole.gnu.ai.mit.edu) * bison.simple: Use YYPRINT to print a token, if it's defined. Mon Apr 29 12:22:55 1991 Richard Stallman (rms at mole.gnu.ai.mit.edu) * lalr.c (transpose): Rename R to R_arg. (initialize_LA): Avoid shadowing variable j. * reader.c (packsymbols): Avoid shadowing variable i. * files.c: Declare exit and perror. * machine.h: Define MAXSHORT and MINSHORT for the eta-10. Tue Apr 2 20:49:12 1991 Richard Stallman (rms at mole.gnu.ai.mit.edu) * allocate.c (mallocate): Always allocate at least one byte. Tue Mar 19 22:17:19 1991 Richard Stallman (rms at mole.gnu.ai.mit.edu) * Makefile (dist): Put alloca.c into distribution. Wed Mar 6 17:45:42 1991 Richard Stallman (rms at mole.ai.mit.edu) * print.c (print_actions): Nicer output for final states. Thu Feb 21 20:39:53 1991 Richard Stallman (rms at mole.ai.mit.edu) * output.c (output_rule_data): Break lines in yytline based on hpos. Thu Feb 7 12:54:36 1991 Richard Stallman (rms at mole.ai.mit.edu) * bison.simple (yyparse): Move decl of yylsa before use. Tue Jan 15 23:41:33 1991 Richard Stallman (rms at mole.ai.mit.edu) * Version 1.14. * output.c (output_rule_data): Handle NULL in tags[i]. Fri Jan 11 17:27:24 1991 Richard Stallman (rms at mole.ai.mit.edu) * bison.simple: On MSDOS, include malloc.h. Sat Dec 29 19:59:55 1990 David J. MacKenzie (djm at wookumz.ai.mit.edu) * files.c: Use `mallocate' instead of `xmalloc' so no extra decl is needed. Wed Dec 19 18:31:21 1990 Richard Stallman (rms at mole.ai.mit.edu) * reader.c (readgram): Alternate YYSTYPE defn for MSDOS. * files.c [MSDOS]: Declare xmalloc. Thu Dec 13 12:45:54 1990 Richard Stallman (rms at mole.ai.mit.edu) * output.c (output_rule_data): Put all symbols in yytname. * bison.simple (yyparse): Delete extra fprintf arg when printing a result of reduction. Mon Dec 10 13:55:15 1990 Richard Stallman (rms at mole.ai.mit.edu) * reader.c (packsymbols): Don't declare yylval if pure_parser. Tue Oct 30 23:38:09 1990 Richard Stallman (rms at mole.ai.mit.edu) * Version 1.12. * LR0.c (augment_automaton): Fix bugs adding sp2 to chain of shifts. Tue Oct 23 17:41:49 1990 Richard Stallman (rms at mole.ai.mit.edu) * bison.simple: Don't define alloca if already defined. Sun Oct 21 22:10:53 1990 Richard Stallman (rms at mole.ai.mit.edu) * getopt.c: On VMS, use string.h. * main.c (main): Return type int. Mon Sep 10 16:59:01 1990 Richard Stallman (rms at mole.ai.mit.edu) * output.c (output_headers): Output macro defs for -p. * reader.c (readgram): Handle consecutive actions. * getargs.c (getargs): Rename -a to -p. * files.c (openfiles): Change names used for -b. Mon Aug 27 00:30:15 1990 Richard Stallman (rms at mole.ai.mit.edu) * reduce.c (reduce_grammar_tables): Don't map rlhs of disabled rule. Sun Aug 26 13:43:32 1990 Richard Stallman (rms at mole.ai.mit.edu) * closure.c (print_firsts, print_fderives): Use BITISSET to test bits. Thu Aug 23 22:13:40 1990 Richard Stallman (rms at mole.ai.mit.edu) * closure.c (print_firsts): vrowsize => varsetsize. (print_fderives): rrowsize => rulesetsize. Fri Aug 10 15:32:11 1990 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * bison.simple (alloca): Don't define if already defined. (__yy_bcopy): Alternate definition for C++. Wed Jul 11 00:46:03 1990 David J. MacKenzie (djm at albert.ai.mit.edu) * getargs.c (getargs): Mention +yacc in usage message. Tue Jul 10 17:29:08 1990 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * reader.c (parse_token_decl, copy_action): Set value_components_used if appropriate. (readgram): Inhibit output of YYSTYPE definition in that case. Sat Jun 30 13:47:57 1990 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * output.c (output_parser): Define YYPURE if pure, and not otherwise. Don't define YYIMPURE. * bison.simple: Adjust conditionals accordingly. * bison.simple (YYLEX): If locations not in use, don't pass &yylloc. Thu Jun 28 12:32:21 1990 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * getargs.c (longopts): Add `yacc'. Thu Jun 28 00:40:21 1990 David J. MacKenzie (djm at apple-gunkies) * getargs.c (getargs): Add long options. * Makefile: Link with getopt1.o and add getopt1.c and getopt.h to dist. * Move version number and description back into version.c from Makefile and getargs.c. * Makefile (dist): Extract version number from version.c. Tue Jun 26 13:16:35 1990 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * output.c (output): Always call output_gram. * bison.simple (yyparse): Print rhs and lhs symbols of reduction rule. Thu Jun 21 00:15:40 1990 David J. MacKenzie (djm at albert.ai.mit.edu) * main.c: New global var `program_name' to hold argv[0] for error messages. * allocate.c, files.c, getargs.c, reader.c: Use `program_name' in messages instead of hardcoded "bison". Wed Jun 20 23:38:34 1990 David J. MacKenzie (djm at albert.ai.mit.edu) * Makefile: Specify Bison version here. Add rule to pass it to version.c. Encode it in distribution directory and tar file names. * version.c: Use version number from Makefile. * getargs.c (getargs): Print additional text that used to be part of version_string in version.c. Use -V instead of -version to print Bison version info. Print a usage message and exit if given an invalid option. Tue Jun 19 01:15:18 1990 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * bison.simple: Fix a #line. * Makefile (INSTALL): New parameter. (install): Use that. (CFLAGS): Move definition to top. Sun Jun 17 17:10:21 1990 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * reader.c (parse_type_decl): Ignore semicolon. Remove excess % from error messages. Sat Jun 16 19:15:48 1990 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * Version 1.11. * Makefile (install): Ensure installed files readable. Tue Jun 12 12:50:56 EDT 1990 Jay Fenlason (hack@ai.mit.edu) * getargs.c: Declare spec_file_prefix * lex.c (lex): \a is '\007' instead of '007' * reader.c: include machine.h * files.h: Declare extern spec_name_prefix. Trivial patch from Thorsten Ohl (td12@ddagsi3.bitnet) Thu May 31 22:00:16 1990 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * Version 1.10. * bison.simple (YYBACKUP, YYRECOVERING): New macros. (YYINITDEPTH): This is what used to be YYMAXDEPTH. (YYMAXDEPTH): This is what used to be YYMAXLIMIT. If the value is 0, use the default instead. (yyparse): Return 2 on stack overflow. Wed May 30 21:09:07 1990 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * bison.simple (YYERROR): Jump to new label; don't print error message. (yyparse): Define label yyerrlab1. Wed May 16 13:23:58 1990 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * files.c (openfiles): Support -b. * getargs.c (getargs): Likewise. * reader.c (readgram): Error if too many symbols. * lex.c (lex): Handle \a. Make error msgs more reliable. * reader.c (read_declarations): Make error msgs more reliable. Sun May 13 15:03:37 1990 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * Version 1.09. * reduce.c (reduce_grammar_tables): Fix backward test. Sat May 12 21:05:34 1990 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * Makefile (bison-dist.*): Rename targets and files to bison.*. (bison.tar): Make tar file to unpack into subdirectory named `bison'. Mon Apr 30 03:46:58 1990 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * reduce.c (reduce_grammar_tables): Set rlhs to -1 for useless rules. * nullable.c (set_nullable): Ignore those rules. * derives.c (set_derives): Likewise. Mon Apr 23 15:16:09 1990 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * bison.simple (yyparse): Mention rule number as well as line number. Thu Mar 29 00:00:43 1990 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * bison.simple (__yy_bcopy): New function. (yyparse): Use that, not bcopy. Wed Mar 28 15:23:51 1990 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * print.c (print_actions): Don't alter i and j spuriously when errp==0. Mon Mar 12 16:22:18 1990 Jim Kingdon (kingdon at pogo.ai.mit.edu) * bison.simple [__GNUC__]: Use builtin_alloca. Wed Mar 7 21:11:36 1990 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * Makefile (install): Use mergedir.awk to process bison.simple for installation. * bison.simple (yyparse): New feature to include possible valid tokens in parse error message. Sat Mar 3 14:10:56 1990 Richard Stallman (rms at geech) * Version 1.08. Mon Feb 26 16:32:21 1990 Jim Kingdon (kingdon at pogo.ai.mit.edu) * print.c (print_actions) conflicts.c (print_reductions): Change "shift %d" to "shift, and go to state %d" and "reduce %d" to "reduce using rule %d" and "goto %d" to "go to state %d". print.c (print_core): Change "(%d)" to "(rule %d)". Tue Feb 20 14:22:47 EST 1990 Jay Fenlason (hack @ wookumz.ai.mit.edu) * bison.simple: Comment out unused yyresume: label. Fri Feb 9 16:14:34 EST 1990 Jay Fenlason (hack @ wookumz.ai.mit.edu) * bison.simple : surround all declarations and (remaining) uses of yyls* and yylloc with #ifdef YYLSP_NEEDED This will significantly cut down on stack usage, and gets rid of unused-variable msgs from GCC. Wed Jan 31 13:06:08 1990 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * files.c (done) [VMS]: Don't delete files that weren't used. [VMS]: Let user override XPFILE and XPFILE1. Wed Jan 3 15:52:28 1990 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * Version 1.07. Sat Dec 16 15:50:21 1989 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * gram.c (dummy): New function. * reader.c (readgram): Detect error if two consec actions. Wed Nov 15 02:06:08 1989 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * reduce.c (reduce_grammar_tables): Update rline like other tables. * Makefile (install): Install the man page. Sat Nov 11 03:21:58 1989 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * output.c (output_rule_data): Write #if YYDEBUG around yyrline. Wed Oct 18 13:07:55 1989 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * Version 1.06. * vmsgetargs.c (getargs): Downcase specified output file name. Fri Oct 13 17:48:14 1989 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * reader.c (readgram): Warn if there is no default to use for $$ and one is needed. Fri Sep 29 12:51:53 1989 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * Version 1.05. * vmsgetargs.h (getargs): Process outfile option. Fri Sep 8 03:05:14 1989 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * Version 1.04. * reader.c (parse_union_decl): Count newlines even in comments. Wed Sep 6 22:03:19 1989 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * files.c (openfiles): short_base_length was always == base_length. Thu Aug 24 16:55:06 1989 Richard Stallman (rms at apple-gunkies.ai.mit.edu) * Version 1.03. * files.c (openfiles): Write output into same dir as input, by default. Wed Aug 23 15:03:07 1989 Jay Fenlason (hack at gnu) * Makefile: Include system.h in bison-dist.tar Tue Aug 15 22:30:42 1989 Richard Stallman (rms at hobbes.ai.mit.edu) * version 1.03. * reader.c (reader): Output LTYPESTR to fdefines only after reading the grammar. Sun Aug 6 16:55:23 1989 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * reader.c (read_declarations): Put space before comment to avoid bug in Green Hills C compiler. Mon Jun 19 20:14:01 1989 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * allocate.c (xmalloc): New function. Fri Jun 16 23:59:40 1989 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * build.com: Compile and link reduce.c. Fri Jun 9 23:00:54 1989 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * reduce.c (reduce_grammar_tables): Adjust start_symbol when #s change. Sat May 27 17:57:29 1989 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * reader.c (copy_definition, copy_guard): Don't object to \-newline inside strings. Mon May 22 12:30:59 1989 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * files.c (openfiles): Alternate file names for MSDOS. (open_extra_files): Likewise. (done): On MSDOS, unlink temp files here, not in openfiles. * machine.h (BITS_PER_WORD): 16 on MSDOS. (MAXTABLE): Now defined in this file. * system.h: New file includes system-dependent headers. All relevant .c files include it. Thu Apr 27 17:00:47 1989 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * version.c: Version 1.01. Tue Apr 18 12:46:05 1989 Randall Smith (randy at apple-gunkies.ai.mit.edu) * conflicts.c (total_conflicts): Fixed typo in yacc style output; mention conflicts if > 0. Sat Apr 15 17:36:18 1989 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * reader.c (packsymbols): Start new symbols after 256. Wed Apr 12 14:09:09 1989 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * reader.c (reader): Always assign code 256 to `error' token. Always set `translations' to 1 so this code gets handled. * bison.simple (YYERRCODE): Define it. Tue Apr 11 19:26:32 1989 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * conflicts.c: If GNU C, use builtin alloca. * Makefile (install): Delete parser files before copying them. Thu Mar 30 13:51:17 1989 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * getargs.c (getargs): Turn off checking of name Bison was invoked by. * Makefile (dist): Include ChangeLog in distrib. Thu Mar 23 15:19:41 1989 Jay Fenlason (hack at apple-gunkies.ai.mit.edu) * LR0.c closure.c conflicts.c derives.c files.c getargs.c lalr.c lex.c main.c nullable.c output.c print.c reader.c reduce.c symtab.c warshall.c: A first pass at getting gcc -Wall to shut up. Mostly declared functions as void, etc. * reduce.c moved 'extern int fixed_outfiles;' into print_notices() where it belongs. Wed Mar 1 12:33:28 1989 Randall Smith (randy at apple-gunkies.ai.mit.edu) * types.h, symtab.h, state.h, new.h, machine.h, lex.h, gram.h, files.h, closure.c, vmsgetargs.c, warshall.c, symtab.c, reduce.c, reader.c, print.c, output.c, nullable.c, main.c, lex.c, lalr.c, gram.c, getargs.c, files.c, derives.c, conflicts.c, allocate.c, LR0.c, Makefile, bison.simple: Changed copyright notices to be in accord with the new General Public License. * COPYING: Made a link to the new copying file. Wed Feb 22 06:18:20 1989 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * new.h (FREE): Alternate definition for __STDC__ avoids error if `free' returns void. Tue Feb 21 15:03:34 1989 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * reader.c (read_declarations): Double a `%' in a format string. (copy_definition, parse_start_decl, parse_token_decl): Likewise. (parse_type_decl, parse_union_decl, copy_guard, readgram, get_type). (copy_action): change a `fatal' to `fatals'. * lalr.c (map_goto): Initial high-end of binary search was off by 1. Sat Feb 18 08:49:57 1989 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * bison.simple [sparc]: Include alloca.h. Wed Feb 15 06:24:36 1989 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * reader.c (packsymbols): Write decl of yylval into .tab.h file. Sat Jan 28 18:19:05 1989 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * bison.simple: Avoid comments on `#line' lines. * reader.c (LTYPESTR): Rearrange to avoid whitespace after \-newline. Mon Jan 9 18:43:08 1989 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * conflicts.c (total_conflicts): if -y, use output syntax POSIX wants. * reduce.c (print_notices): likewise. * lex.c (lex): Handle \v, and \x hex escapes. * reader.c (reader): Merge output_ltype into here. Don't output YYLTYPE definition to .tab.h file unless the @ construct is used. * bison.simple: Define YYERROR, YYABORT, YYACCEPT here. * reader.c (output_ltype): Don't output them here. * bison.simple: YYDEBUG now should be 0 or 1. * output.c (output): For YYDEBUG, output conditional to define it only if not previously defined. Mon Jan 2 11:29:55 1989 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * bison.simple (yyparse) [YYPURE]: Add local yynerrs. (yydebug): Declare global, but don't initialize, regardless of YYPURE. (yyparse): Don't declare yydebug here. Thu Dec 22 22:01:22 1988 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * reduce.c (print_notices): Typo in message. Sun Dec 11 11:32:07 1988 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * output.c (pack_table): Free only nonzero the elts of froms & tos. Thu Dec 8 16:26:46 1988 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * gram.c (rprecsym): New vector indicates the %prec symbol for a rule. * reader.c (packgram): Allocate it and fill it in. * reduce.c (inaccessable_symbols): Use it to set V1. * reduce.c (print_results): Don't complain about useless token if it's in V1. Mon Dec 5 14:33:17 1988 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * machine.h (RESETBIT, BITISSET): New macros. (SETBIT, WORDSIZE): Change to use BITS_PER_WORD. * reduce.c: New file, by David Bakin. Reduces the grammar. * Makefile: Compile it, link it, put it in dist. * main.c (main): Call reduce_grammar (in reduce.c). Thu Nov 17 18:33:04 1988 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * conflicts.c: Don't declare alloca if including alloca.h. * bison.cld: Define qualifiers `nolines', `debug'. * vmsgetargs.c (getargs): Handle them. * output.c (output_program): Notice `nolinesflag'. * output.c (output_parser): Simplify logic for -l and #line. Avoid writing EOF char into output. Wed Oct 12 18:00:03 1988 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * Implement `-l' option. * getopt.c: Set flag `nolinesflag'. * reader.c (copy_definition, parse_union_decl, copy_guard, copy_action) Obey that flag; don't generate #line. * output.c (output_parser): Discard #line's when copying the parser. Mon Sep 12 16:33:17 1988 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * reader.c (copy_guard): Fix brace-counting for brace-surrounded guard. Thu Sep 8 20:09:53 1988 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * bison.simple: Correct number in #line command. (yyparse): Call YYABORT instead of YYERROR, due to last change in output_ltype. Mon Sep 5 14:55:30 1988 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * Makefile: New variable LIBS. Alternatives for USG. * conflicts.c [USG]: Define bcopy. * symtab.c [USG]: Include string.h instead of strings.h. * conflicts.c [sparc]: Include alloca.h. Tue Aug 2 08:38:38 1988 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * reader.c (parse_token_decl): Ignore commas. Sat Jun 25 10:29:20 1988 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * reader.c (output_ltype): Make YYERROR yacc-compatible (like YYFAIL). Fri Jun 24 11:25:11 1988 Richard Stallman (rms at sugar-bombs.ai.mit.edu) * getargs.c (getargs): -t sets debugflag. Eliminate upper case duplicate options. * output.c (output): If debugflag, output `#define YYDEBUG'. Thu May 26 06:04:21 1988 Richard Stallman (rms at frosted-flakes.ai.mit.edu) * allocate.c (mallocate): New name for `allocate' (which loses in VMS). Calls changed in LR0.c, conflicts.c, symtab.c, new.h. * getargs.c (getargs): If argv[0] is "yacc", set fixed_outfiles. Tue May 17 12:15:30 1988 Richard Stallman (rms at frosted-flakes.ai.mit.edu) * conflicts.c: Declare alloca. * reader.c: Declare realloc. * warshall.c (TC): Fix one arithmetic op that was omitted last time. Thu May 5 14:36:03 1988 Richard Stallman (rms at frosted-flakes.ai.mit.edu) * bison.simple: Conditionalize most refs to yylsp on YYLSP_NEEDED. * reader.c (copy_guard, copy_action): Notice if `@' is used. (reader): If it was, output `#define YYLSP_NEEDED'. Mon Apr 18 04:54:32 1988 Richard Stallman (rms at rice-krispies.ai.mit.edu) * bison.simple: New variable yynerr counts calls to yyerror. * lex.c (lex, case '='): Update lineno when skipping a newline. * reader.c (parse_expect_decl): ungetc the char that ends the number; don't read any further. This handles multi-line comments right and avoids incorrect lineno. * reader.c: Delete duplicate decl of symval. * warshall.c (RTC, TC): Cast ptrs to char *, not unsigned, for arith. Local Variables: mode: indented-text left-margin: 8 fill-column: 76 version-control: never End: ./usr/src/bison-1.19/README 600 0 1 1147 5174462631 13455 0ustar rootdaemonThis directory contains the Bison parser generator. See the file INSTALL for compilation and installation instructions. It was once true that, when installing Bison on Sequent (or Pyramid?) systems, you had to be in the Berkeley universe. This may no longer be true; we have no way to tell. On VMS, you will probably have to create Makefile from Makefile.in by hand. Remember to do `SET COMMAND BISON' to install the data in `BISON.CLD'. Send bug reports to bug-gnu-utils@prep.ai.mit.edu. Please include the version number from `bison --version', and a complete, self-contained test case in each bug report. ./usr/src/bison-1.19/REFERENCES 600 0 1 2255 4161426723 14137 0ustar rootdaemonFrom phr Tue Jul 8 10:36:19 1986 Date: Tue, 8 Jul 86 00:52:24 EDT From: phr (Paul Rubin) To: riferguson%watmath.waterloo.edu@CSNET-RELAY.ARPA, tower Subject: Re: Bison documentation? The main difference between Bison and Yacc that I know of is that Bison supports the @N construction, which gives you access to the starting and ending line number and character number associated with any of the symbols in the current rule. Also, Bison supports the command `%expect N' which says not to mention the conflicts if there are N shift/reduce conflicts and no reduce/reduce conflicts. The differences in the algorithms stem mainly from the horrible kludges that Johnson had to perpetrate to make Yacc fit in a PDP-11. Also, Bison uses a faster but less space-efficient encoding for the parse tables (see Corbett's PhD thesis from Berkeley, "Static Semantics in Compiler Error Recovery", June 1985, Report No. UCB/CSD 85/251), and more modern technique for generating the lookahead sets. (See "Efficient Construction of LALR(1) Lookahead Sets" by F. DeRemer and A. Pennello, in ACM TOPLS Vol 4 No 4, October 1982. Their technique is the standard one now.) paul rubin free software foundation ./usr/src/bison-1.19/bsn119A.Dist 700 0 0 406 5303476545 14361 0ustar rootwheel#!/bin/sh # Create binary distribution in bsn119.taz cd / gtar zcvf /dist/bsn119A.taz ./usr/bin/bison \ ./usr/man/man1/bison.1 \ ./usr/emacs/info/bison.info* \ ./usr/lib/bison.* \ ./usr/src/bison-1.19/C* ./usr/src/bison-1.19/R* \ ./usr/src/bison-1.19/bsn119A.* ./usr/src/bison-1.19/bsn119A.Notes 600 0 0 1522 5303476651 14563 0ustar rootwheelGNU bison 1.19 Binaries for Linux prepared by faith@cs.unc.edu, Sat Nov 21 18:08:14 1992 Compiled with gcc 2.2.2d (-O6) Linked with jump-4.1 libraries (-s) To install from Linux binary distribution: 1) Get binary distribution (bsn119.taz) from ftp.cs.unc.edu:/pub/faith/linux/utils or from tsx-11.mit.edu:/pub/linux/binaries/FSF 2) cd / 3) gtar zpxvf bsn119.taz Alternatively, the SLS sysinstall program can be used. To uninstall this binary distribution, do the following: cd /usr/src/bison-1.19 ./bsn119.Unins To install from source: 1) Get source from: prep.ai.mit.edu:/pub/gnu/bison-1.19.tar.Z 2) Untar bison-1.19.tar.Z in /usr/src 3) cd bison-1.19 4) ./configure --prefix=/usr 5) make CC=gcc CFLAGS=-O6 LDFLAGS=-s infodir=/usr/emacs/info 6) make CC=gcc CFLAGS=-O6 LDFLAGS=-s infodir=/usr/emacs/info install 7) Edit /usr/emacs/info/dir ./usr/src/bison-1.19/bsn119A.Unins 700 0 0 260 5303476545 14550 0ustar rootwheel#!/bin/sh # Uninstall the bsn119A binary distribution cd /usr/man/man1 rm -f bison.1 cd /usr/emacs/info rm -f bison.* cd /usr/lib rm -f bison.info* cd /usr/bin rm -f bison