X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/ceed8467b7db3615d3c9bfa9f3e5525d54c6a161..17ee7397a87c4c4ccd45f956e0b88b824a3689f9:/src/reduce.c diff --git a/src/reduce.c b/src/reduce.c index a654f0c7..fa09b497 100644 --- a/src/reduce.c +++ b/src/reduce.c @@ -1,598 +1,467 @@ /* Grammar reduction for Bison. - Copyright (C) 1988, 1989 Free Software Foundation, Inc. + Copyright (C) 1988, 1989, 2000, 2001, 2002 Free Software Foundation, Inc. -This file is part of Bison, the GNU Compiler Compiler. + This file is part of Bison, the GNU Compiler Compiler. -Bison 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, or (at your option) -any later version. + Bison 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, or (at your option) + any later version. -Bison 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. + Bison 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 Bison; see the file COPYING. If not, write to -the Free Software Foundation, Inc., 59 Temple Place - Suite 330, -Boston, MA 02111-1307, USA. */ + You should have received a copy of the GNU General Public License + along with Bison; see the file COPYING. If not, write to + the Free Software Foundation, Inc., 59 Temple Place - Suite 330, + Boston, MA 02111-1307, USA. */ -/* - * Reduce the grammar: Find and eliminate unreachable terminals, - * nonterminals, and productions. David S. Bakin. - */ +/* Reduce the grammar: Find and eliminate unreachable terminals, + nonterminals, and productions. David S. Bakin. */ -/* - * Don't eliminate unreachable terminals: They may be used by the user's - * parser. - */ +/* Don't eliminate unreachable terminals: They may be used by the + user's parser. */ #include "system.h" -#include "getargs.h" -#include "files.h" -#include "gram.h" -#include "alloc.h" -#include "complain.h" - - -extern char **tags; /* reader.c */ -static int statisticsflag; /* XXXXXXX */ -extern int fixed_outfiles; -#ifndef TRUE -#define TRUE (1) -#define FALSE (0) -#endif -typedef int bool; -typedef unsigned *BSet; -typedef short *rule; +#include +#include +#include "complain.h" +#include "files.h" +#include "getargs.h" +#include "gram.h" +#include "reader.h" +#include "reduce.h" +#include "symtab.h" -/* - * N is set of all nonterminals which are not useless. P is set of all rules - * which have no useless nonterminals in their RHS. V is the set of all - * accessible symbols. - */ - -static BSet N, P, V, V1; - -static int nuseful_productions, nuseless_productions, - nuseful_nonterminals, nuseless_nonterminals; +/* Set of all nonterminals which are not useless. */ +static bitset N; +/* Set of all rules which have no useless nonterminals in their RHS. */ +static bitset P; -extern void reduce_grammar PARAMS((void)); -static bool bits_equal PARAMS((BSet, BSet, int)); -static int nbits PARAMS((unsigned)); -static int bits_size PARAMS((BSet, int)); -static void useless_nonterminals PARAMS((void)); -static void inaccessable_symbols PARAMS((void)); -static void reduce_grammar_tables PARAMS((void)); -static void print_results PARAMS((void)); -static void print_notices PARAMS((void)); +/* Set of all accessible symbols. */ +static bitset V; -#if 0 /* XXX currently unused. */ -static void dump_grammar PARAMS((void)); -#endif +/* Set of symbols used to define rule precedence (so they are + `useless', but no warning should be issued). */ +static bitset V1; +static rule_number nuseful_productions; +rule_number nuseless_productions; +static int nuseful_nonterminals; +symbol_number nuseless_nonterminals; +/*-------------------------------------------------------------------. +| Another way to do this would be with a set for each production and | +| then do subset tests against N0, but even for the C grammar the | +| whole reducing process takes only 2 seconds on my 8Mhz AT. | +`-------------------------------------------------------------------*/ static bool -bits_equal (BSet L, BSet R, int n) +useful_production (rule_number r, bitset N0) { - int i; - - for (i = n - 1; i >= 0; i--) - if (L[i] != R[i]) - return FALSE; - return TRUE; -} + item_number *rhsp; + /* A production is useful if all of the nonterminals in its appear + in the set of useful nonterminals. */ -static int -nbits (unsigned i) -{ - int count = 0; - - while (i != 0) { - i ^= (i & ((unsigned) (- (int) i))); - ++count; - } - return count; + for (rhsp = rules[r].rhs; *rhsp >= 0; ++rhsp) + if (ISVAR (*rhsp) && !bitset_test (N0, *rhsp - ntokens)) + return false; + return true; } -static int -bits_size (BSet S, int n) -{ - int i, count = 0; +/*---------------------------------------------------------. +| Remember that rules are 1-origin, symbols are 0-origin. | +`---------------------------------------------------------*/ - for (i = n - 1; i >= 0; i--) - count += nbits(S[i]); - return count; -} - -void -reduce_grammar (void) +static void +useless_nonterminals (void) { - bool reduced; - - /* Allocate the global sets used to compute the reduced grammar */ - - N = NEW2(WORDSIZE(nvars), unsigned); - P = NEW2(WORDSIZE(nrules + 1), unsigned); - V = NEW2(WORDSIZE(nsyms), unsigned); - V1 = NEW2(WORDSIZE(nsyms), unsigned); - - useless_nonterminals(); - inaccessable_symbols(); - - reduced = (bool) (nuseless_nonterminals + nuseless_productions > 0); - - if (verboseflag) - print_results(); + bitset Np, Ns; + rule_number r; - if (reduced == FALSE) - goto done_reducing; + /* N is set as built. Np is set being built this iteration. P is + set of all productions which have a RHS all in N. */ - print_notices(); - - if (!BITISSET(N, start_symbol - ntokens)) - fatal (_("Start symbol %s does not derive any sentence"), - tags[start_symbol]); - - reduce_grammar_tables(); -#if 0 - if (verboseflag) - { - fprintf(foutput, "REDUCED GRAMMAR\n\n"); - dump_grammar(); - } -#endif - /**/ statisticsflag = FALSE; /* someday getopts should handle this */ - if (statisticsflag == TRUE) - fprintf(stderr, - _("reduced %s defines %d terminal%s, %d nonterminal%s\ -, and %d production%s.\n"), infile, - ntokens, (ntokens == 1 ? "" : "s"), - nvars, (nvars == 1 ? "" : "s"), - nrules, (nrules == 1 ? "" : "s")); - - done_reducing: - - /* Free the global sets used to compute the reduced grammar */ - - FREE(N); - FREE(V); - FREE(P); - -} - -/* - * Another way to do this would be with a set for each production and then do - * subset tests against N0, but even for the C grammar the whole reducing - * process takes only 2 seconds on my 8Mhz AT. - */ + Np = bitset_create (nvars, BITSET_FIXED); -static bool -useful_production (int i, BSet N0) -{ - rule r; - short n; - - /* - * A production is useful if all of the nonterminals in its RHS - * appear in the set of useful nonterminals. - */ - - for (r = &ritem[rrhs[i]]; *r > 0; r++) - if (ISVAR(n = *r)) - if (!BITISSET(N0, n - ntokens)) - return FALSE; - return TRUE; -} + /* The set being computed is a set of nonterminals which can derive + the empty string or strings consisting of all terminals. At each + iteration a nonterminal is added to the set if there is a + production with that nonterminal as its LHS for which all the + nonterminals in its RHS are already in the set. Iterate until + the set being computed remains unchanged. Any nonterminals not + in the set at that point are useless in that they will never be + used in deriving a sentence of the language. -/* Remember that rules are 1-origin, symbols are 0-origin. */ + This iteration doesn't use any special traversal over the + productions. A set is kept of all productions for which all the + nonterminals in the RHS are in useful. Only productions not in + this set are scanned on each iteration. At the end, this set is + saved to be used when finding useful productions: only + productions in this set will appear in the final grammar. */ -static void -useless_nonterminals (void) -{ - BSet Np, Ns; - int i, n; - - /* - * N is set as built. Np is set being built this iteration. P is set - * of all productions which have a RHS all in N. - */ - - Np = NEW2(WORDSIZE(nvars), unsigned); - - /* - * The set being computed is a set of nonterminals which can derive - * the empty string or strings consisting of all terminals. At each - * iteration a nonterminal is added to the set if there is a - * production with that nonterminal as its LHS for which all the - * nonterminals in its RHS are already in the set. Iterate until the - * set being computed remains unchanged. Any nonterminals not in the - * set at that point are useless in that they will never be used in - * deriving a sentence of the language. - * - * This iteration doesn't use any special traversal over the - * productions. A set is kept of all productions for which all the - * nonterminals in the RHS are in useful. Only productions not in - * this set are scanned on each iteration. At the end, this set is - * saved to be used when finding useful productions: only productions - * in this set will appear in the final grammar. - */ - - n = 0; while (1) { - for (i = WORDSIZE(nvars) - 1; i >= 0; i--) - Np[i] = N[i]; - for (i = 1; i <= nrules; i++) - { - if (!BITISSET(P, i)) - { - if (useful_production(i, N)) - { - SETBIT(Np, rlhs[i] - ntokens); - SETBIT(P, i); - } - } - } - if (bits_equal(N, Np, WORDSIZE(nvars))) + bitset_copy (Np, N); + for (r = 0; r < nrules; r++) + if (!bitset_test (P, r) + && useful_production (r, N)) + { + bitset_set (Np, rules[r].lhs->number - ntokens); + bitset_set (P, r); + } + if (bitset_equal_p (N, Np)) break; Ns = Np; Np = N; N = Ns; } - FREE(N); + bitset_free (N); N = Np; } - + + static void inaccessable_symbols (void) { - BSet Vp, Vs, Pp; - int i, n; - short t; - rule r; - - /* - * Find out which productions are reachable and which symbols are - * used. Starting with an empty set of productions and a set of - * symbols which only has the start symbol in it, iterate over all - * productions until the set of productions remains unchanged for an - * iteration. For each production which has a LHS in the set of - * reachable symbols, add the production to the set of reachable - * productions, and add all of the nonterminals in the RHS of the - * production to the set of reachable symbols. - * - * Consider only the (partially) reduced grammar which has only - * nonterminals in N and productions in P. - * - * The result is the set P of productions in the reduced grammar, and - * the set V of symbols in the reduced grammar. - * - * Although this algorithm also computes the set of terminals which are - * reachable, no terminal will be deleted from the grammar. Some - * terminals might not be in the grammar but might be generated by - * semantic routines, and so the user might want them available with - * specified numbers. (Is this true?) However, the nonreachable - * terminals are printed (if running in verbose mode) so that the user - * can know. - */ - - Vp = NEW2(WORDSIZE(nsyms), unsigned); - Pp = NEW2(WORDSIZE(nrules + 1), unsigned); + bitset Vp, Vs, Pp; + + /* Find out which productions are reachable and which symbols are + used. Starting with an empty set of productions and a set of + symbols which only has the start symbol in it, iterate over all + productions until the set of productions remains unchanged for an + iteration. For each production which has a LHS in the set of + reachable symbols, add the production to the set of reachable + productions, and add all of the nonterminals in the RHS of the + production to the set of reachable symbols. + + Consider only the (partially) reduced grammar which has only + nonterminals in N and productions in P. + + The result is the set P of productions in the reduced grammar, + and the set V of symbols in the reduced grammar. + + Although this algorithm also computes the set of terminals which + are reachable, no terminal will be deleted from the grammar. Some + terminals might not be in the grammar but might be generated by + semantic routines, and so the user might want them available with + specified numbers. (Is this true?) However, the nonreachable + terminals are printed (if running in verbose mode) so that the + user can know. */ + + Vp = bitset_create (nsyms, BITSET_FIXED); + Pp = bitset_create (nrules, BITSET_FIXED); /* If the start symbol isn't useful, then nothing will be useful. */ - if (!BITISSET(N, start_symbol - ntokens)) - goto end_iteration; - - SETBIT(V, start_symbol); - - n = 0; - while (1) + if (bitset_test (N, accept->number - ntokens)) { - for (i = WORDSIZE(nsyms) - 1; i >= 0; i--) - Vp[i] = V[i]; - for (i = 1; i <= nrules; i++) + bitset_set (V, accept->number); + + while (1) { - if (!BITISSET(Pp, i) && BITISSET(P, i) && - BITISSET(V, rlhs[i])) + rule_number r; + bitset_copy (Vp, V); + for (r = 0; r < nrules; r++) { - for (r = &ritem[rrhs[i]]; *r >= 0; r++) + if (!bitset_test (Pp, r) + && bitset_test (P, r) + && bitset_test (V, rules[r].lhs->number)) { - if (ISTOKEN(t = *r) - || BITISSET(N, t - ntokens)) - { - SETBIT(Vp, t); - } + item_number *rhsp; + for (rhsp = rules[r].rhs; *rhsp >= 0; rhsp++) + if (ISTOKEN (*rhsp) || bitset_test (N, *rhsp - ntokens)) + bitset_set (Vp, *rhsp); + bitset_set (Pp, r); } - SETBIT(Pp, i); } + if (bitset_equal_p (V, Vp)) + break; + Vs = Vp; + Vp = V; + V = Vs; } - if (bits_equal(V, Vp, WORDSIZE(nsyms))) - { - break; - } - Vs = Vp; - Vp = V; - V = Vs; } - end_iteration: - FREE(V); + bitset_free (V); V = Vp; /* Tokens 0, 1, and 2 are internal to Bison. Consider them useful. */ - SETBIT(V, 0); /* end-of-input token */ - SETBIT(V, 1); /* error token */ - SETBIT(V, 2); /* some undefined token */ + bitset_set (V, endtoken->number); /* end-of-input token */ + bitset_set (V, errtoken->number); /* error token */ + bitset_set (V, undeftoken->number); /* some undefined token */ - FREE(P); + bitset_free (P); P = Pp; - nuseful_productions = bits_size(P, WORDSIZE(nrules + 1)); + nuseful_productions = bitset_count (P); nuseless_productions = nrules - nuseful_productions; nuseful_nonterminals = 0; - for (i = ntokens; i < nsyms; i++) - if (BITISSET(V, i)) - nuseful_nonterminals++; + { + symbol_number i; + for (i = ntokens; i < nsyms; i++) + if (bitset_test (V, i)) + nuseful_nonterminals++; + } nuseless_nonterminals = nvars - nuseful_nonterminals; /* A token that was used in %prec should not be warned about. */ - for (i = 1; i < nrules; i++) - if (rprecsym[i] != 0) - SETBIT(V1, rprecsym[i]); + { + rule_number r; + for (r = 0; r < nrules; ++r) + if (rules[r].precsym != 0) + bitset_set (V1, rules[r].precsym->number); + } } - -static void -reduce_grammar_tables (void) -{ -/* This is turned off because we would need to change the numbers - in the case statements in the actions file. */ -#if 0 - /* remove useless productions */ - if (nuseless_productions > 0) - { - short np, pn, ni, pi; - np = 0; - ni = 0; - for (pn = 1; pn <= nrules; pn++) - { - if (BITISSET(P, pn)) - { - np++; - if (pn != np) - { - rlhs[np] = rlhs[pn]; - rline[np] = rline[pn]; - rprec[np] = rprec[pn]; - rassoc[np] = rassoc[pn]; - rrhs[np] = rrhs[pn]; - if (rrhs[np] != ni) - { - pi = rrhs[np]; - rrhs[np] = ni; - while (ritem[pi] >= 0) - ritem[ni++] = ritem[pi++]; - ritem[ni++] = -np; - } - } else { - while (ritem[ni++] >= 0); - } - } - } - ritem[ni] = 0; - nrules -= nuseless_productions; - nitems = ni; - - /* - * Is it worth it to reduce the amount of memory for the - * grammar? Probably not. - */ - } -#endif /* 0 */ - /* Disable useless productions, - since they may contain useless nonterms - that would get mapped below to -1 and confuse everyone. */ - if (nuseless_productions > 0) - { - int pn; +/*-------------------------------------------------------------------. +| Put the useless productions at the end of RULES, and adjust NRULES | +| accordingly. | +`-------------------------------------------------------------------*/ - for (pn = 1; pn <= nrules; pn++) - { - if (!BITISSET(P, pn)) - { - rlhs[pn] = -1; - } - } - } +static void +reduce_grammar_tables (void) +{ + /* Report and flag useless productions. */ + { + rule_number r; + for (r = 0; r < nrules; r++) + rules[r].useful = bitset_test (P, r); + grammar_rules_never_reduced_report (_("useless rule")); + } - /* remove useless symbols */ - if (nuseless_nonterminals > 0) - { + /* Map the nonterminals to their new index: useful first, useless + afterwards. Kept for later report. */ + { + int useful = 0; + int useless = nrules - nuseless_productions; + rule *rules_sorted = XMALLOC (rule, nrules); + rule_number r; + for (r = 0; r < nrules; ++r) + rules_sorted[rules[r].useful ? useful++ : useless++] = rules[r]; + free (rules); + rules = rules_sorted; + + /* Renumber the rules markers in RITEMS. */ + for (r = 0; r < nrules; ++r) + { + item_number *rhsp = rules[r].rhs; + for (/* Nothing. */; *rhsp >= 0; ++rhsp) + /* Nothing. */; + *rhsp = rule_number_as_item_number (r); + rules[r].number = r; + } + nrules -= nuseless_productions; + } - int i, n; -/* short j; JF unused */ - short *nontermmap; - rule r; + /* Adjust NRITEMS. */ + { + int r; + int length; + for (r = nrules; r < nrules + nuseless_productions; ++r) + { + length = rule_rhs_length (&rules[r]); + nritems -= length + 1; + } + } +} - /* - * create a map of nonterminal number to new nonterminal - * number. -1 in the map means it was useless and is being - * eliminated. - */ - nontermmap = NEW2(nvars, short) - ntokens; - for (i = ntokens; i < nsyms; i++) - nontermmap[i] = -1; +/*------------------------------. +| Remove useless nonterminals. | +`------------------------------*/ - n = ntokens; - for (i = ntokens; i < nsyms; i++) - if (BITISSET(V, i)) - nontermmap[i] = n++; +static void +nonterminals_reduce (void) +{ + symbol_number i, n; - /* Shuffle elements of tables indexed by symbol number. */ + /* Map the nonterminals to their new index: useful first, useless + afterwards. Kept for later report. */ - for (i = ntokens; i < nsyms; i++) - { - n = nontermmap[i]; - if (n >= 0) - { - sassoc[n] = sassoc[i]; - sprec[n] = sprec[i]; - tags[n] = tags[i]; - } else { - free(tags[i]); - } - } + symbol_number *nontermmap = XCALLOC (symbol_number, nvars) - ntokens; + n = ntokens; + for (i = ntokens; i < nsyms; i++) + if (bitset_test (V, i)) + nontermmap[i] = n++; + for (i = ntokens; i < nsyms; i++) + if (!bitset_test (V, i)) + { + nontermmap[i] = n++; + warn_at (symbols[i]->location, _("useless nonterminal: %s"), + symbols[i]->tag); + } + + + /* Shuffle elements of tables indexed by symbol number. */ + { + symbol **symbols_sorted = XMALLOC (symbol *, nvars) - ntokens; + + for (i = ntokens; i < nsyms; i++) + symbols[i]->number = nontermmap[i]; + for (i = ntokens; i < nsyms; i++) + symbols_sorted[nontermmap[i]] = symbols[i]; + for (i = ntokens; i < nsyms; i++) + symbols[i] = symbols_sorted[i]; + free (symbols_sorted + ntokens); + } - /* Replace all symbol numbers in valid data structures. */ + { + rule_number r; + for (r = 0; r < nrules; ++r) + { + item_number *rhsp; + for (rhsp = rules[r].rhs; *rhsp >= 0; ++rhsp) + if (ISVAR (*rhsp)) + *rhsp = symbol_number_as_item_number (nontermmap[*rhsp]); + } + accept->number = nontermmap[accept->number]; + } - for (i = 1; i <= nrules; i++) - { - /* Ignore the rules disabled above. */ - if (rlhs[i] >= 0) - rlhs[i] = nontermmap[rlhs[i]]; - if (ISVAR (rprecsym[i])) - /* Can this happen? */ - rprecsym[i] = nontermmap[rprecsym[i]]; - } + nsyms -= nuseless_nonterminals; + nvars -= nuseless_nonterminals; - for (r = ritem; *r; r++) - if (ISVAR(*r)) - *r = nontermmap[*r]; + free (nontermmap + ntokens); +} - start_symbol = nontermmap[start_symbol]; - nsyms -= nuseless_nonterminals; - nvars -= nuseless_nonterminals; +/*------------------------------------------------------------------. +| Output the detailed results of the reductions. For FILE.output. | +`------------------------------------------------------------------*/ - free(&nontermmap[ntokens]); - } -} - -static void -print_results (void) +void +reduce_output (FILE *out) { - int i; -/* short j; JF unused */ - rule r; - bool b; - if (nuseless_nonterminals > 0) { - fprintf(foutput, _("Useless nonterminals:\n\n")); - for (i = ntokens; i < nsyms; i++) - if (!BITISSET(V, i)) - fprintf(foutput, " %s\n", tags[i]); + int i; + fprintf (out, "%s\n\n", _("Useless nonterminals")); + for (i = 0; i < nuseless_nonterminals; ++i) + fprintf (out, " %s\n", symbols[nsyms + i]->tag); + fputs ("\n\n", out); } - b = FALSE; - for (i = 0; i < ntokens; i++) - { - if (!BITISSET(V, i) && !BITISSET(V1, i)) + + { + bool b = false; + int i; + for (i = 0; i < ntokens; i++) + if (!bitset_test (V, i) && !bitset_test (V1, i)) { if (!b) - { - fprintf(foutput, _("\n\nTerminals which are not used:\n\n")); - b = TRUE; - } - fprintf(foutput, " %s\n", tags[i]); + fprintf (out, "%s\n\n", _("Terminals which are not used")); + b = true; + fprintf (out, " %s\n", symbols[i]->tag); } - } + if (b) + fputs ("\n\n", out); + } if (nuseless_productions > 0) - { - fprintf(foutput, _("\n\nUseless rules:\n\n")); - for (i = 1; i <= nrules; i++) - { - if (!BITISSET(P, i)) - { - fprintf(foutput, "#%-4d ", i); - fprintf(foutput, "%s :\t", tags[rlhs[i]]); - for (r = &ritem[rrhs[i]]; *r >= 0; r++) - { - fprintf(foutput, " %s", tags[*r]); - } - fprintf(foutput, ";\n"); - } - } - } - if (nuseless_nonterminals > 0 || nuseless_productions > 0 || b) - fprintf(foutput, "\n\n"); + grammar_rules_partial_print (out, _("Useless rules"), + rule_useless_p); } -#if 0 /* XXX currently unused. */ -static void -dump_grammar (void) -{ - int i; - rule r; - - fprintf(foutput, - "ntokens = %d, nvars = %d, nsyms = %d, nrules = %d, nitems = %d\n\n", - ntokens, nvars, nsyms, nrules, nitems); - fprintf(foutput, _("Variables\n---------\n\n")); - fprintf(foutput, _("Value Sprec Sassoc Tag\n")); - for (i = ntokens; i < nsyms; i++) - fprintf(foutput, "%5d %5d %5d %s\n", - i, sprec[i], sassoc[i], tags[i]); - fprintf(foutput, "\n\n"); - fprintf(foutput, _("Rules\n-----\n\n")); - for (i = 1; i <= nrules; i++) - { - fprintf(foutput, "%-5d(%5d%5d)%5d : (@%-5d)", - i, rprec[i], rassoc[i], rlhs[i], rrhs[i]); - for (r = &ritem[rrhs[i]]; *r > 0; r++) - fprintf(foutput, "%5d", *r); - fprintf(foutput, " [%d]\n", -(*r)); - } - fprintf(foutput, "\n\n"); - fprintf(foutput, _("Rules interpreted\n-----------------\n\n")); - for (i = 1; i <= nrules; i++) - { - fprintf(foutput, "%-5d %s :", i, tags[rlhs[i]]); - for (r = &ritem[rrhs[i]]; *r > 0; r++) - fprintf(foutput, " %s", tags[*r]); - fprintf(foutput, "\n"); - } - fprintf(foutput, "\n\n"); -} -#endif + + +/*-------------------------------. +| Report the results to STDERR. | +`-------------------------------*/ + static void -print_notices (void) +reduce_print (void) { - if (fixed_outfiles && nuseless_productions) - fprintf(stderr, _("%d rules never reduced\n"), nuseless_productions); + if (yacc_flag && nuseless_productions) + fprintf (stderr, ngettext ("%d rule never reduced\n", + "%d rules never reduced\n", + nuseless_productions), + nuseless_productions); - fprintf(stderr, _("%s contains "), infile); + fprintf (stderr, "%s: %s: ", grammar_file, _("warning")); if (nuseless_nonterminals > 0) - { - fprintf(stderr, _("%d useless nonterminal%s"), - nuseless_nonterminals, - (nuseless_nonterminals == 1 ? "" : "s")); - } + fprintf (stderr, ngettext ("%d useless nonterminal", + "%d useless nonterminals", + nuseless_nonterminals), + nuseless_nonterminals); + if (nuseless_nonterminals > 0 && nuseless_productions > 0) - fprintf(stderr, _(" and ")); + fprintf (stderr, _(" and ")); + + if (nuseless_productions > 0) + fprintf (stderr, ngettext ("%d useless rule", + "%d useless rules", + nuseless_productions), + nuseless_productions); + fprintf (stderr, "\n"); + fflush (stderr); +} + +void +reduce_grammar (void) +{ + bool reduced; + + /* Allocate the global sets used to compute the reduced grammar */ + + N = bitset_create (nvars, BITSET_FIXED); + P = bitset_create (nrules, BITSET_FIXED); + V = bitset_create (nsyms, BITSET_FIXED); + V1 = bitset_create (nsyms, BITSET_FIXED); + + useless_nonterminals (); + inaccessable_symbols (); + + reduced = (bool) (nuseless_nonterminals + nuseless_productions > 0); + if (!reduced) + return; + + reduce_print (); + if (!bitset_test (N, accept->number - ntokens)) + fatal_at (startsymbol_location, + _("start symbol %s does not derive any sentence"), + startsymbol->tag); + + /* First reduce the nonterminals, as they renumber themselves in the + whole grammar. If you change the order, nonterms would be + renumbered only in the reduced grammar. */ + if (nuseless_nonterminals > 0) + nonterminals_reduce (); if (nuseless_productions > 0) + reduce_grammar_tables (); + + if (trace_flag & trace_grammar) { - fprintf(stderr, _("%d useless rule%s"), - nuseless_productions, - (nuseless_productions == 1 ? "" : "s")); + grammar_dump (stderr, "Reduced Grammar"); + + fprintf (stderr, "reduced %s defines %d terminals, %d nonterminals\ +, and %d productions.\n", + grammar_file, ntokens, nvars, nrules); } - fprintf(stderr, "\n"); - fflush(stderr); +} + + +/*-----------------------------------------------------------. +| Free the global sets used to compute the reduced grammar. | +`-----------------------------------------------------------*/ + +void +reduce_free (void) +{ + bitset_free (N); + bitset_free (V); + bitset_free (V1); + bitset_free (P); }