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/* Match rules with nonterminals for bison,
Copyright (C) 1984, 1989, 2000-2003, 2005, 2009-2015, 2018-2021 Free
Software Foundation, Inc.
This file is part of Bison, the GNU Compiler Compiler.
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 3 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, see <https://www.gnu.org/licenses/>. */
#include <config.h>
#include "system.h"
#include "getargs.h"
#include "derives.h"
#include "gram.h"
#include "reader.h"
#include "symtab.h"
/* Linked list of rule numbers. */
typedef struct rule_list
{
struct rule_list *next;
rule *value;
} rule_list;
rule ***derives;
static void
print_derives (void)
{
fputs ("DERIVES\n", stderr);
for (symbol_number i = ntokens; i < nsyms; ++i)
{
fprintf (stderr, " %s derives\n", symbols[i]->tag);
for (rule **rp = derives[i - ntokens]; *rp; ++rp)
{
fprintf (stderr, " %3d ", (*rp)->code);
rule_rhs_print (*rp, stderr);
fprintf (stderr, "\n");
}
}
fputs ("\n\n", stderr);
}
void
derives_compute (void)
{
/* DSET[NTERM - NTOKENS] -- A linked list of the numbers of the rules
whose LHS is NTERM. */
rule_list **dset = xcalloc (nnterms, sizeof *dset);
/* DELTS[RULE] -- There are NRULES rule number to attach to nterms.
Instead of performing NRULES allocations for each, have an array
indexed by rule numbers. */
rule_list *delts = xnmalloc (nrules, sizeof *delts);
for (rule_number r = nrules - 1; r >= 0; --r)
{
symbol_number lhs = rules[r].lhs->number;
rule_list *p = &delts[r];
/* A new LHS is found. */
p->next = dset[lhs - ntokens];
p->value = &rules[r];
dset[lhs - ntokens] = p;
}
/* DSET contains what we need under the form of a linked list. Make
it a single array. */
derives = xnmalloc (nnterms, sizeof *derives);
/* Q is the storage for DERIVES[...] (DERIVES[0] = q). */
rule **q = xnmalloc (nnterms + nrules, sizeof *q);
for (symbol_number i = ntokens; i < nsyms; ++i)
{
rule_list *p = dset[i - ntokens];
derives[i - ntokens] = q;
while (p)
{
*q++ = p->value;
p = p->next;
}
*q++ = NULL;
}
if (trace_flag & trace_sets)
print_derives ();
free (dset);
free (delts);
}
void
derives_free (void)
{
if (derives)
{
free (derives[0]);
free (derives);
}
}
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