+++ /dev/null
-/* Grammar reduction for Bison.
- Copyright (C) 2002 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
- 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.
-
- 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: Look for injections. Akim Demaille. */
-
-#include "system.h"
-#include "quotearg.h"
-#include "bitsetv.h"
-#include "bitsetv-print.h"
-#include "complain.h"
-#include "gram.h"
-#include "getargs.h"
-#include "derives.h"
-#include "injections.h"
-
-/* Set of all nonterminals which are not useless. */
-static bitsetv injects;
-
-#define INJECTS(Var) injects[(Var) - ntokens]
-
-/*-----------------------------------------------------------.
-| Free the global sets used to compute the reduced grammar. |
-`-----------------------------------------------------------*/
-
-void
-injections_new (void)
-{
- if (!injects)
- injects = bitsetv_create (nvars, nvars, BITSET_FIXED);
- else
- bitsetv_zero (injects);
-}
-
-void
-injections_free (void)
-{
- bitsetv_free (injects);
- injects = NULL;
-}
-
-
-/*------------------------------.
-| Dump the list of injections. |
-`------------------------------*/
-
-static void
-injections_print (const char *title)
-{
- int i, j;
-
- fprintf (stderr, "%s\n", title);
- for (i = ntokens; i < nsyms; i++)
- if (bitset_count (INJECTS (i)))
- {
- fprintf (stderr, "\t%s injects\n",
- quotearg_style (escape_quoting_style, symbols[i]->tag));
- for (j = 0; j < nvars; j++)
- if (bitset_test (INJECTS (i), j))
- fprintf (stderr, "\t\t%s\n",
- quotearg_style (escape_quoting_style,
- symbols[j + ntokens]->tag));
- }
- fprintf (stderr, "\n\n");
-}
-
-
-/*-----------------------------------------------------------------.
-| Set INJECTS[i, j] if the nonterminal j derives the nonterminal j |
-| (typically, `i -> j' is a rule, plus transitive closure). |
-`-----------------------------------------------------------------*/
-
-static void
-injections_compute (void)
-{
- int i, j;
-
- injections_new ();
- for (i = ntokens; i < nsyms; i++)
- for (j = 0; derives[i][j] >= 0; ++j)
- {
- int symbol = rules[derives[i][j]].rhs[0];
- if (ISVAR (symbol) && rules[derives[i][j]].rhs[1] < 0)
- bitset_set (INJECTS (i), symbol - ntokens);
- }
-
- if (trace_flag & trace_sets)
- injections_print ("syntactic direct injections");
- bitsetv_transitive_closure (injects);
- if (trace_flag & trace_sets)
- injections_print ("syntactic injections");
-}
-
-
-
-/*--------------------------------------------------------------.
-| Look for infinitely ambiguous grammars: they contain cycles. |
-`--------------------------------------------------------------*/
-
-void
-injections_check_cycles (void)
-{
- int i;
-
- injections_compute ();
- for (i = ntokens; i < nsyms; i++)
- if (bitset_test (INJECTS (i), i - ntokens))
- complain (_("infinitely ambiguous grammar: %s derives itself"),
- symbols[i]->tag);
-}