From 87412882128fc3ae807f47db23884552f5841e74 Mon Sep 17 00:00:00 2001 From: "Joel E. Denny" Date: Tue, 25 Aug 2009 01:12:37 -0400 Subject: Some code and documentation improvements. * data/c.m4 (b4_table_value_equals): New macro to capture some repeated code. * data/glr.c (yyis_pact_ninf): Use it here. (yyis_table_ninf): Likewise. (yyreportSyntaxError): Improve internal comments. * data/yacc.c (yyis_pact_ninf): New macro copied from glr.c. Use it everywhere possible. (yyis_table_ninf): Likewise. (yysyntax_error): Improve internal comments. * data/lalr1.cc (yysyntax_error_): Likewise. * data/lalr1.java (yysyntax_error): Likewise. * src/tables.h: Improve comments about yypact, yytable, etc. --- ChangeLog | 16 ++++++++++++++++ data/c.m4 | 10 ++++++++++ data/glr.c | 11 ++++------- data/lalr1.cc | 3 ++- data/lalr1.java | 3 ++- data/yacc.c | 15 +++++++++++---- src/tables.h | 13 +++++++++++-- 7 files changed, 56 insertions(+), 15 deletions(-) diff --git a/ChangeLog b/ChangeLog index b831d116..dc11d517 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,19 @@ +2009-08-25 Joel E. Denny + + Some code and documentation improvements. + * data/c.m4 (b4_table_value_equals): New macro to capture + some repeated code. + * data/glr.c (yyis_pact_ninf): Use it here. + (yyis_table_ninf): Likewise. + (yyreportSyntaxError): Improve internal comments. + * data/yacc.c (yyis_pact_ninf): New macro copied from glr.c. + Use it everywhere possible. + (yyis_table_ninf): Likewise. + (yysyntax_error): Improve internal comments. + * data/lalr1.cc (yysyntax_error_): Likewise. + * data/lalr1.java (yysyntax_error): Likewise. + * src/tables.h: Improve comments about yypact, yytable, etc. + 2009-08-21 Joel E. Denny Use locale when quoting. diff --git a/data/c.m4 b/data/c.m4 index 33a4186c..3ba48db5 100644 --- a/data/c.m4 +++ b/data/c.m4 @@ -157,6 +157,16 @@ m4_define([b4_int_type_for], [b4_int_type($1_min, $1_max)]) +# b4_table_value_equals(TABLE, VALUE, LITERAL) +# -------------------------------------------- +# Without inducing a comparison warning from the compiler, check if the +# literal value LITERAL equals VALUE from table TABLE, which must have +# TABLE_min and TABLE_max defined. +m4_define([b4_table_value_equals], +[m4_if(m4_eval($3 < m4_indir([b4_]$1[_min]) + || m4_indir([b4_]$1[_max]) < $3), [1], + [[YYID (0)]], + [[((]$2[) == (]$3[))]])]) ## ---------## ## Values. ## diff --git a/data/glr.c b/data/glr.c index a4b921f1..b0ad1003 100644 --- a/data/glr.c +++ b/data/glr.c @@ -954,9 +954,7 @@ yylhsNonterm (yyRuleNum yyrule) } #define yyis_pact_ninf(yystate) \ - ]m4_if(m4_eval(b4_pact_ninf < b4_pact_min), [1], - [0], - [((yystate) == YYPACT_NINF)])[ + ]b4_table_value_equals([[pact]], [[yystate]], [b4_pact_ninf])[ /** True iff LR state STATE has only a default reduction (regardless * of token). */ @@ -974,9 +972,7 @@ yydefaultAction (yyStateNum yystate) } #define yyis_table_ninf(yytable_value) \ - ]m4_if(m4_eval(b4_table_ninf < b4_table_min), [1], - [YYID (0)], - [((yytable_value) == YYTABLE_NINF)])[ + ]b4_table_value_equals([[table]], [[yytable_value]], [b4_table_ninf])[ /** Set *YYACTION to the action to take in YYSTATE on seeing YYTOKEN. * Result R means @@ -2048,7 +2044,8 @@ yyreportSyntaxError (yyGLRStack* yystackp]b4_user_formals[) char const *yyarg[YYERROR_VERBOSE_ARGS_MAXIMUM]; /* Start YYX at -YYN if negative to avoid negative indexes in - YYCHECK. */ + YYCHECK. In other words, skip the first -YYN actions for this + state because they are default actions. */ int yyxbegin = yyn < 0 ? -yyn : 0; /* Stay within bounds of both yycheck and yytname. */ diff --git a/data/lalr1.cc b/data/lalr1.cc index 2a9316de..5ce0b47b 100644 --- a/data/lalr1.cc +++ b/data/lalr1.cc @@ -954,7 +954,8 @@ b4_error_verbose_if([state_type yystate, int yytoken], if (yypact_ninf_ < yyn && yyn <= yylast_) { /* Start YYX at -YYN if negative to avoid negative indexes in - YYCHECK. */ + YYCHECK. In other words, skip the first -YYN actions for this + state because they are default actions. */ int yyxbegin = yyn < 0 ? -yyn : 0; /* Stay within bounds of both yycheck and yytname. */ diff --git a/data/lalr1.java b/data/lalr1.java index e68650d9..7e274d64 100644 --- a/data/lalr1.java +++ b/data/lalr1.java @@ -735,7 +735,8 @@ m4_popdef([b4_at_dollar])])dnl StringBuffer res; /* Start YYX at -YYN if negative to avoid negative indexes in - YYCHECK. */ + YYCHECK. In other words, skip the first -YYN actions for this + state because they are default actions. */ int yyxbegin = yyn < 0 ? -yyn : 0; /* Stay within bounds of both yycheck and yytname. */ diff --git a/data/yacc.c b/data/yacc.c index fa14cc54..96892231 100644 --- a/data/yacc.c +++ b/data/yacc.c @@ -525,8 +525,14 @@ static const ]b4_int_type_for([b4_toknum])[ yytoknum[] = #define YYPACT_NINF ]b4_pact_ninf[ +#define yyis_pact_ninf(yystate) \ + ]b4_table_value_equals([[pact]], [[yystate]], [b4_pact_ninf])[ + #define YYTABLE_NINF ]b4_table_ninf[ +#define yyis_table_ninf(yytable_value) \ + ]b4_table_value_equals([[table]], [[yytable_value]], [b4_table_ninf])[ + ]b4_parser_tables_define[ #define yyerrok (yyerrstatus = 0) @@ -848,7 +854,8 @@ yysyntax_error (char *yyresult, int yystate, int yytoken) char const *yyarg[YYERROR_VERBOSE_ARGS_MAXIMUM]; /* Start YYX at -YYN if negative to avoid negative indexes in - YYCHECK. */ + YYCHECK. In other words, skip the first -YYN actions for this + state because they are default actions. */ int yyxbegin = yyn < 0 ? -yyn : 0; /* Stay within bounds of both yycheck and yytname. */ @@ -1271,7 +1278,7 @@ yybackup: /* First try to decide what to do without reference to lookahead token. */ yyn = yypact[yystate]; - if (yyn == YYPACT_NINF) + if (yyis_pact_ninf (yyn)) goto yydefault; /* Not known => get a lookahead token if don't already have one. */ @@ -1321,7 +1328,7 @@ yyread_pushed_token:]])[ yyn = yytable[yyn]; if (yyn <= 0) { - if (yyn == 0 || yyn == YYTABLE_NINF) + if (yyn == 0 || yyis_table_ninf (yyn)) goto yyerrlab; yyn = -yyn; goto yyreduce; @@ -1505,7 +1512,7 @@ yyerrlab1: for (;;) { yyn = yypact[yystate]; - if (yyn != YYPACT_NINF) + if (!yyis_pact_ninf (yyn)) { yyn += YYTERROR; if (0 <= yyn && yyn <= YYLAST && yycheck[yyn] == YYTERROR) diff --git a/src/tables.h b/src/tables.h index a44cdb86..b21fa7b0 100644 --- a/src/tables.h +++ b/src/tables.h @@ -54,8 +54,15 @@ something else to do. YYPACT[S] = index in YYTABLE of the portion describing state S. - The lookahead token's type is used to index that portion to find - out what to do. + The lookahead token's number, I, is used to index that portion of + YYTABLE to find out what action to perform. + + If YYPACT[S] == YYPACT_NINF, if YYPACT[S] + I is outside the bounds + of YYTABLE (from 0 to YYLAST), or if YYCHECK indicates that I is + outside the bounds of the portion for S, then the default action + (from YYDEFACT and YYDEFGOTO) should be used instead of YYTABLE. + Otherwise, the value YYTABLE[YYPACT[S] + I] should be used even if + YYPACT[S] < 0. If the value in YYTABLE is positive, we shift the token and go to that state. @@ -64,6 +71,8 @@ If the value is zero, the default action from YYDEFACT[S] is used. + If the value is YYTABLE_NINF, it's a syntax error. + YYPGOTO[I] = the index in YYTABLE of the portion describing what to do after reducing a rule that derives variable I + NTOKENS. This portion is indexed by the parser state number, S, as of before the -- cgit v1.2.1