/* Grammar reduction for Bison.
- Copyright 1988, 1989, 2000, 2001 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.
user's parser. */
#include "system.h"
+#include "quotearg.h"
#include "getargs.h"
#include "files.h"
#include "symtab.h"
#include "getargs.h"
#include "bitset.h"
-typedef short *rule;
-
-
/* Set of all nonterminals which are not useless. */
static bitset N;
static bitset V1;
static int nuseful_productions;
-static int nuseless_productions;
+int nuseless_productions;
static int nuseful_nonterminals;
int nuseless_nonterminals;
\f
static bool
useful_production (int i, bitset N0)
{
- rule r;
+ item_number_t *r;
short n;
/* A production is useful if all of the nonterminals in its appear
bitset Vp, Vs, Pp;
int i;
short t;
- rule r;
+ item_number_t *r;
/* Find out which productions are reachable and which symbols are
used. Starting with an empty set of productions and a set of
Pp = bitset_create (nrules + 1, BITSET_FIXED);
/* If the start symbol isn't useful, then nothing will be useful. */
- if (bitset_test (N, start_symbol - ntokens))
+ if (bitset_test (N, axiom->number - ntokens))
{
- bitset_set (V, start_symbol);
+ bitset_set (V, axiom->number);
while (1)
{
V = Vp;
/* Tokens 0, 1, and 2 are internal to Bison. Consider them useful. */
- bitset_set (V, 0); /* end-of-input token */
- bitset_set (V, 1); /* error token */
- bitset_set (V, 2); /* some undefined token */
+ 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_free (P);
P = Pp;
/* A token that was used in %prec should not be warned about. */
for (i = 1; i < nrules + 1; i++)
if (rules[i].precsym != 0)
- bitset_set (V1, rules[i].precsym);
+ bitset_set (V1, rules[i].precsym->number);
}
static void
reduce_grammar_tables (void)
{
- /* Flag useless productions. */
+ /* Report and flag useless productions. */
{
- int pn;
- for (pn = 1; pn < nrules + 1; pn++)
- rules[pn].useful = bitset_test (P, pn);
+ int r;
+ for (r = 1; r < nrules + 1; 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);
+ }
+ }
}
/* Map the nonterminals to their new index: useful first, useless
free (rules + 1);
rules = rules_sorted;
- /* Also reorder ritems. */
- {
- short *ritems_sorted = XCALLOC (short, nitems + 1);
- short *ritemsp = ritems_sorted;
- for (i = 1; i < nrules + 1; ++i)
- {
- short *rhsp = rules[i].rhs;
- rules[i].rhs = ritemsp;
- for (/* Nothing. */; *rhsp >= 0; ++rhsp)
- *ritemsp++ = *rhsp;
- *ritemsp++ = -i;
- }
- *ritemsp++ = 0;
- free (ritem);
- ritem = ritems_sorted;
- }
+ /* Renumber the rules markers in RITEMS. */
+ for (i = 1; i < nrules + 1; ++i)
+ {
+ item_number_t *rhsp = rules[i].rhs;
+ for (/* Nothing. */; *rhsp >= 0; ++rhsp)
+ /* Nothing. */;
+ *rhsp = -i;
+ rules[i].number = i;
+ }
nrules -= nuseless_productions;
}
- /* Adjust NRITEMS and NITEMS. */
+ /* Adjust NRITEMS. */
{
int r;
int length;
{
length = rule_rhs_length (&rules[r]);
nritems -= length + 1;
- nitems -= length + 1;
}
}
}
static void
nonterminals_reduce (void)
{
- int i, n;
+ symbol_number_t i, n;
/* Map the nonterminals to their new index: useful first, useless
afterwards. Kept for later report. */
- short *nontermmap = XCALLOC (short, nvars) - ntokens;
+ symbol_number_t *nontermmap = XCALLOC (symbol_number_t, 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++;
+ {
+ nontermmap[i] = n++;
+ LOCATION_PRINT (stderr, symbols[i]->location);
+ fprintf (stderr, ": %s: %s: %s\n",
+ _("warning"), _("useless nonterminal"),
+ symbol_tag_get (symbols[i]));
+ }
/* Shuffle elements of tables indexed by symbol number. */
{
- bucket **symbols_sorted = XMALLOC (bucket *, nvars) - ntokens;
+ symbol_t **symbols_sorted = XMALLOC (symbol_t *, nvars) - ntokens;
for (i = ntokens; i < nsyms; i++)
symbols[i]->number = nontermmap[i];
free (symbols_sorted + ntokens);
}
- /* Replace all symbol numbers in valid data structures. */
-
- for (i = 1; i < nrules + 1; i++)
- {
- if (ISVAR (rules[i].precsym))
- /* Can this happen? */
- rules[i].precsym = nontermmap[rules[i].precsym];
- }
-
- for (i = 0; i < nritems; ++i)
- if (ISVAR (ritem[i]))
- ritem[i] = nontermmap[ritem[i]];
-
- start_symbol = nontermmap[start_symbol];
+ {
+ int r;
+ for (r = 1; r < nrules + 1; ++r)
+ {
+ item_number_t *rhsp;
+ for (rhsp = rules[r].rhs; *rhsp >= 0; ++rhsp)
+ if (ISVAR (*rhsp))
+ *rhsp = symbol_number_as_item_number (nontermmap[*rhsp]);
+ }
+ axiom->number = nontermmap[axiom->number];
+ }
nsyms -= nuseless_nonterminals;
nvars -= nuseless_nonterminals;
int i;
fprintf (out, "%s\n\n", _("Useless nonterminals:"));
for (i = 0; i < nuseless_nonterminals; ++i)
- fprintf (out, " %s\n", symbols[nsyms + i]->tag);
+ fprintf (out, " %s\n", symbol_tag_get (symbols[nsyms + i]));
fputs ("\n\n", out);
}
if (!b)
fprintf (out, "%s\n\n", _("Terminals which are not used:"));
b = TRUE;
- fprintf (out, " %s\n", symbols[i]->tag);
+ fprintf (out, " %s\n", symbol_tag_get (symbols[i]));
}
if (b)
fputs ("\n\n", out);
fprintf (out, "%s\n\n", _("Useless rules:"));
for (i = nrules + 1; i < nuseless_productions + nrules + 1; i++)
{
- rule r;
- fprintf (out, "#%-4d ", rules[i].number - 1);
- fprintf (out, "%s:", rules[i].lhs->tag);
+ item_number_t *r;
+ fprintf (out, "#%-4d ", rules[i].user_number - 1);
+ fprintf (out, "%s:", symbol_tag_get (rules[i].lhs));
for (r = rules[i].rhs; *r >= 0; r++)
- fprintf (out, " %s", symbols[*r]->tag);
+ fprintf (out, " %s", symbol_tag_get (symbols[*r]));
fputs (";\n", out);
}
fputs ("\n\n", out);
}
}
\f
-static void
-dump_grammar (FILE *out)
-{
- int i;
- rule r;
-
- fprintf (out, "REDUCED GRAMMAR\n\n");
- fprintf (out,
- "ntokens = %d, nvars = %d, nsyms = %d, nrules = %d, nitems = %d\n\n",
- ntokens, nvars, nsyms, nrules, nitems);
- fprintf (out, "Variables\n---------\n\n");
- fprintf (out, "Value Sprec Sassoc Tag\n");
- for (i = ntokens; i < nsyms; i++)
- fprintf (out, "%5d %5d %5d %s\n",
- i,
- symbols[i]->prec, symbols[i]->assoc, symbols[i]->tag);
- fprintf (out, "\n\n");
- fprintf (out, "Rules\n-----\n\n");
- fprintf (out, "Num (Prec, Assoc, Useful, Ritem Range) Lhs -> Rhs (Ritem range) [Num]\n");
- for (i = 1; i < nrules + nuseless_productions + 1; i++)
- {
- int rhs_count = 0;
- /* Find the last RHS index in ritems. */
- for (r = rules[i].rhs; *r >= 0; ++r)
- ++rhs_count;
- fprintf (out, "%3d (%2d, %2d, %2d, %2d-%2d) %2d ->",
- i - 1,
- rules[i].prec, rules[i].assoc, rules[i].useful,
- rules[i].rhs - ritem, rules[i].rhs - ritem + rhs_count - 1,
- rules[i].lhs->number);
- /* Dumped the RHS. */
- for (r = rules[i].rhs; *r >= 0; r++)
- fprintf (out, "%3d", *r);
- fprintf (out, " [%d]\n", -(*r) - 1);
- }
- fprintf (out, "\n\n");
- fprintf (out, "Rules interpreted\n-----------------\n\n");
- for (i = 1; i < nrules + nuseless_productions + 1; i++)
- {
- fprintf (out, "%-5d %s :", i, rules[i].lhs->tag);
- for (r = rules[i].rhs; *r >= 0; r++)
- fprintf (out, " %s", symbols[*r]->tag);
- fputc ('\n', out);
- }
- fprintf (out, "\n\n");
-}
+
nuseless_productions),
nuseless_productions);
- fprintf (stderr, _("%s contains "), infile);
+ fprintf (stderr, "%s: %s: ", infile, _("warning"));
if (nuseless_nonterminals > 0)
fprintf (stderr, ngettext ("%d useless nonterminal",
reduce_print ();
- if (!bitset_test (N, start_symbol - ntokens))
+ if (!bitset_test (N, axiom->number - ntokens))
fatal (_("Start symbol %s does not derive any sentence"),
- symbols[start_symbol]->tag);
+ symbol_tag_get (symbols[axiom->number]));
- if (nuseless_productions > 0)
- reduce_grammar_tables ();
+ /* 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)
{
- dump_grammar (stderr);
+ grammar_dump (stderr, "Reduced Grammar");
fprintf (stderr, "reduced %s defines %d terminals, %d nonterminals\
, and %d productions.\n",
projects / bison.git / blobdiff