/* Grammar reduction for Bison.
- Copyright (C) 1988, 1989, 2000, 2001, 2002 Free Software Foundation, Inc.
+
+ Copyright (C) 1988-1989, 2000-2003, 2005-2015 Free Software
+ Foundation, Inc.
This file is part of Bison, the GNU Compiler Compiler.
- Bison is free software; you can redistribute it and/or modify
+ 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, or (at your option)
- any later version.
+ the Free Software Foundation, either version 3 of the License, or
+ (at your option) any later version.
- Bison is distributed in the hope that it will be useful,
+ 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 Bison; see the file COPYING. If not, write to
- the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
- Boston, MA 02111-1307, USA. */
+ along with this program. If not, see <http://www.gnu.org/licenses/>. */
/* Reduce the grammar: Find and eliminate unreachable terminals,
/* Don't eliminate unreachable terminals: They may be used by the
user's parser. */
+#include <config.h>
#include "system.h"
-#include "quotearg.h"
-#include "getargs.h"
+
+#include <bitset.h>
+
+#include "complain.h"
#include "files.h"
-#include "symtab.h"
+#include "getargs.h"
#include "gram.h"
-#include "complain.h"
-#include "reduce.h"
+#include "print-xml.h"
#include "reader.h"
-#include "getargs.h"
-#include "bitset.h"
+#include "reduce.h"
+#include "symtab.h"
/* Set of all nonterminals which are not useless. */
static bitset N;
static bitset V;
/* Set of symbols used to define rule precedence (so they are
- `useless', but no warning should be issued). */
+ 'useless', but no warning should be issued). */
static bitset V1;
-static rule_number_t nuseful_productions;
-rule_number_t nuseless_productions;
+static rule_number nuseful_productions;
+rule_number nuseless_productions;
static int nuseful_nonterminals;
-symbol_number_t nuseless_nonterminals;
+symbol_number nuseless_nonterminals;
\f
/*-------------------------------------------------------------------.
| Another way to do this would be with a set for each production and |
`-------------------------------------------------------------------*/
static bool
-useful_production (rule_number_t r, bitset N0)
+useful_production (rule_number r, bitset N0)
{
- item_number_t *rhsp;
+ item_number *rhsp;
/* A production is useful if all of the nonterminals in its appear
in the set of useful nonterminals. */
for (rhsp = rules[r].rhs; *rhsp >= 0; ++rhsp)
if (ISVAR (*rhsp) && !bitset_test (N0, *rhsp - ntokens))
- return FALSE;
- return TRUE;
+ return false;
+ return true;
}
useless_nonterminals (void)
{
bitset Np, Ns;
- rule_number_t r;
+ rule_number r;
/* 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. */
{
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_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;
+ break;
Ns = Np;
Np = N;
N = Ns;
Pp = bitset_create (nrules, BITSET_FIXED);
/* If the start symbol isn't useful, then nothing will be useful. */
- if (bitset_test (N, axiom->number - ntokens))
+ if (bitset_test (N, accept->number - ntokens))
{
- bitset_set (V, axiom->number);
+ bitset_set (V, accept->number);
while (1)
- {
- rule_number_t r;
- bitset_copy (Vp, V);
- for (r = 0; r < nrules; r++)
- {
- if (!bitset_test (Pp, r)
- && bitset_test (P, r)
- && bitset_test (V, rules[r].lhs->number))
- {
- item_number_t *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);
- }
- }
- if (bitset_equal_p (V, Vp))
- break;
- Vs = Vp;
- Vp = V;
- V = Vs;
- }
+ {
+ rule_number r;
+ bitset_copy (Vp, V);
+ for (r = 0; r < nrules; r++)
+ {
+ if (!bitset_test (Pp, r)
+ && bitset_test (P, r)
+ && bitset_test (V, rules[r].lhs->number))
+ {
+ 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);
+ }
+ }
+ if (bitset_equal_p (V, Vp))
+ break;
+ Vs = Vp;
+ Vp = V;
+ V = Vs;
+ }
}
bitset_free (V);
V = Vp;
/* Tokens 0, 1, and 2 are internal to Bison. Consider them useful. */
- bitset_set (V, eoftoken->number); /* end-of-input token */
- bitset_set (V, errtoken->number); /* error token */
- bitset_set (V, undeftoken->number); /* 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 */
bitset_free (P);
P = Pp;
nuseful_nonterminals = 0;
{
- symbol_number_t i;
+ symbol_number i;
for (i = ntokens; i < nsyms; i++)
if (bitset_test (V, i))
- nuseful_nonterminals++;
+ nuseful_nonterminals++;
}
nuseless_nonterminals = nvars - nuseful_nonterminals;
/* A token that was used in %prec should not be warned about. */
{
- rule_number_t r;
+ rule_number r;
for (r = 0; r < nrules; ++r)
if (rules[r].precsym != 0)
- bitset_set (V1, rules[r].precsym->number);
+ bitset_set (V1, rules[r].precsym->number);
}
}
{
/* Report and flag useless productions. */
{
- rule_number_t r;
+ rule_number r;
for (r = 0; r < nrules; r++)
- {
- rules[r].useful = bitset_test (P, r);
- if (!rules[r].useful)
- {
- LOCATION_PRINT (stderr, rules[r].location);
- fprintf (stderr, ": %s: %s: ", _("warning"), _("useless rule"));
- rule_print (&rules[r], stderr);
- }
- }
+ rules[r].useful = bitset_test (P, r);
+ grammar_rules_useless_report (_("rule useless in grammar"));
}
/* Map the nonterminals to their new index: useful first, useless
{
int useful = 0;
int useless = nrules - nuseless_productions;
- rule_t *rules_sorted = XMALLOC (rule_t, nrules);
- rule_number_t r;
+ rule *rules_sorted = xnmalloc (nrules, sizeof *rules_sorted);
+ rule_number r;
for (r = 0; r < nrules; ++r)
rules_sorted[rules[r].useful ? useful++ : useless++] = rules[r];
free (rules);
/* Renumber the rules markers in RITEMS. */
for (r = 0; r < nrules; ++r)
{
- item_number_t *rhsp = rules[r].rhs;
- for (/* Nothing. */; *rhsp >= 0; ++rhsp)
- /* Nothing. */;
- *rhsp = rule_number_as_item_number (r);
- rules[r].number = 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;
}
/* Adjust NRITEMS. */
{
- int r;
+ rule_number r;
int length;
for (r = nrules; r < nrules + nuseless_productions; ++r)
{
- length = rule_rhs_length (&rules[r]);
- nritems -= length + 1;
+ length = rule_rhs_length (&rules[r]);
+ nritems -= length + 1;
}
}
}
static void
nonterminals_reduce (void)
{
- symbol_number_t i, n;
-
/* Map the nonterminals to their new index: useful first, useless
afterwards. Kept for later report. */
- symbol_number_t *nontermmap = XCALLOC (symbol_number_t, nvars) - ntokens;
- n = ntokens;
+ symbol_number *nontermmap = xnmalloc (nvars, sizeof *nontermmap);
+ symbol_number n = ntokens;
+ symbol_number i;
for (i = ntokens; i < nsyms; i++)
if (bitset_test (V, i))
- nontermmap[i] = n++;
+ nontermmap[i - ntokens] = n++;
for (i = ntokens; i < nsyms; i++)
if (!bitset_test (V, i))
{
- nontermmap[i] = n++;
- LOCATION_PRINT (stderr, symbols[i]->location);
- fprintf (stderr, ": %s: %s: %s\n",
- _("warning"), _("useless nonterminal"),
- symbols[i]->tag);
+ nontermmap[i - ntokens] = n++;
+ if (symbols[i]->status != used)
+ complain (&symbols[i]->location, Wother,
+ _("nonterminal useless in grammar: %s"),
+ symbols[i]->tag);
}
/* Shuffle elements of tables indexed by symbol number. */
{
- symbol_t **symbols_sorted = XMALLOC (symbol_t *, nvars) - ntokens;
+ symbol **symbols_sorted = xnmalloc (nvars, sizeof *symbols_sorted);
for (i = ntokens; i < nsyms; i++)
- symbols[i]->number = nontermmap[i];
+ symbols[i]->number = nontermmap[i - ntokens];
for (i = ntokens; i < nsyms; i++)
- symbols_sorted[nontermmap[i]] = symbols[i];
+ symbols_sorted[nontermmap[i - ntokens] - ntokens] = symbols[i];
for (i = ntokens; i < nsyms; i++)
- symbols[i] = symbols_sorted[i];
- free (symbols_sorted + ntokens);
+ symbols[i] = symbols_sorted[i - ntokens];
+ free (symbols_sorted);
}
{
- rule_number_t r;
+ rule_number r;
for (r = 0; r < nrules; ++r)
{
- item_number_t *rhsp;
- for (rhsp = rules[r].rhs; *rhsp >= 0; ++rhsp)
- if (ISVAR (*rhsp))
- *rhsp = symbol_number_as_item_number (nontermmap[*rhsp]);
+ item_number *rhsp;
+ for (rhsp = rules[r].rhs; *rhsp >= 0; ++rhsp)
+ if (ISVAR (*rhsp))
+ *rhsp = symbol_number_as_item_number (nontermmap[*rhsp
+ - ntokens]);
}
- axiom->number = nontermmap[axiom->number];
+ accept->number = nontermmap[accept->number - ntokens];
}
nsyms -= nuseless_nonterminals;
nvars -= nuseless_nonterminals;
- free (nontermmap + ntokens);
+ free (nontermmap);
}
if (nuseless_nonterminals > 0)
{
int i;
- fprintf (out, "%s\n\n", _("Useless nonterminals:"));
+ fprintf (out, "%s\n\n", _("Nonterminals useless in grammar"));
for (i = 0; i < nuseless_nonterminals; ++i)
- fprintf (out, " %s\n", symbols[nsyms + i]->tag);
+ fprintf (out, " %s\n", symbols[nsyms + i]->tag);
fputs ("\n\n", out);
}
{
- bool b = FALSE;
+ bool b = false;
int i;
for (i = 0; i < ntokens; i++)
- if (!bitset_test (V, i) && !bitset_test (V1, i))
- {
- if (!b)
- fprintf (out, "%s\n\n", _("Terminals which are not used:"));
- b = TRUE;
- fprintf (out, " %s\n", symbols[i]->tag);
- }
+ if (reduce_token_unused_in_grammar (i))
+ {
+ if (!b)
+ fprintf (out, "%s\n\n", _("Terminals unused in grammar"));
+ b = true;
+ fprintf (out, " %s\n", symbols[i]->tag);
+ }
if (b)
fputs ("\n\n", out);
}
if (nuseless_productions > 0)
- grammar_rules_partial_print (out, _("Useless rules"),
- nrules,
- nrules + nuseless_productions);
+ grammar_rules_partial_print (out, _("Rules useless in grammar"),
+ rule_useless_in_grammar_p);
}
\f
-
-
-
/*-------------------------------.
| Report the results to STDERR. |
`-------------------------------*/
static void
reduce_print (void)
{
- 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: %s: ", infile, _("warning"));
-
if (nuseless_nonterminals > 0)
- fprintf (stderr, ngettext ("%d useless nonterminal",
- "%d useless nonterminals",
- nuseless_nonterminals),
- nuseless_nonterminals);
-
- if (nuseless_nonterminals > 0 && nuseless_productions > 0)
- fprintf (stderr, _(" and "));
-
+ complain (NULL, Wother, ngettext ("%d nonterminal useless in grammar",
+ "%d nonterminals useless in grammar",
+ nuseless_nonterminals),
+ nuseless_nonterminals);
if (nuseless_productions > 0)
- fprintf (stderr, ngettext ("%d useless rule",
- "%d useless rules",
- nuseless_productions),
- nuseless_productions);
- fprintf (stderr, "\n");
- fflush (stderr);
+ complain (NULL, Wother, ngettext ("%d rule useless in grammar",
+ "%d rules useless in grammar",
+ nuseless_productions),
+ nuseless_productions);
}
\f
void
useless_nonterminals ();
inaccessable_symbols ();
- reduced = (bool) (nuseless_nonterminals + nuseless_productions > 0);
+ reduced = (nuseless_nonterminals + nuseless_productions > 0);
if (!reduced)
return;
reduce_print ();
- if (!bitset_test (N, axiom->number - ntokens))
- fatal_at (startsymbol_location,
- _("start symbol %s does not derive any sentence"),
- startsymbol->tag);
+ if (!bitset_test (N, accept->number - ntokens))
+ complain (&startsymbol_location, fatal,
+ _("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
if (nuseless_productions > 0)
reduce_grammar_tables ();
- if (trace_flag)
+ if (trace_flag & trace_grammar)
{
grammar_dump (stderr, "Reduced Grammar");
- fprintf (stderr, "reduced %s defines %d terminals, %d nonterminals\
-, and %d productions.\n",
- infile, ntokens, nvars, nrules);
+ fprintf (stderr, "reduced %s defines %d terminals, %d nonterminals"
+ ", and %d productions.\n",
+ grammar_file, ntokens, nvars, nrules);
}
}
+bool
+reduce_token_unused_in_grammar (symbol_number i)
+{
+ aver (i < ntokens);
+ return !bitset_test (V, i) && !bitset_test (V1, i);
+}
+
+bool
+reduce_nonterminal_useless_in_grammar (symbol_number i)
+{
+ aver (ntokens <= i && i < nsyms + nuseless_nonterminals);
+ return nsyms <= i;
+}
/*-----------------------------------------------------------.
| Free the global sets used to compute the reduced grammar. |
projects / bison.git / blobdiff