1/* Match rules with nonterminals for bison,
2
3   Copyright (C) 1984, 1989, 2000-2003, 2005, 2009-2012 Free Software
4   Foundation, Inc.
5
6   This file is part of Bison, the GNU Compiler Compiler.
7
8   This program is free software: you can redistribute it and/or modify
9   it under the terms of the GNU General Public License as published by
10   the Free Software Foundation, either version 3 of the License, or
11   (at your option) any later version.
12
13   This program is distributed in the hope that it will be useful,
14   but WITHOUT ANY WARRANTY; without even the implied warranty of
15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16   GNU General Public License for more details.
17
18   You should have received a copy of the GNU General Public License
19   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
20
21#include <config.h>
22#include "system.h"
23
24#include "getargs.h"
25
26#include "derives.h"
27#include "gram.h"
28#include "reader.h"
29#include "symtab.h"
30
31/* Linked list of rule numbers.  */
32typedef struct rule_list
33{
34  struct rule_list *next;
35  rule *value;
36} rule_list;
37
38rule ***derives;
39
40static void
41print_derives (void)
42{
43  int i;
44
45  fputs ("DERIVES\n", stderr);
46
47  for (i = ntokens; i < nsyms; i++)
48    {
49      rule **rp;
50      fprintf (stderr, "\t%s derives\n", symbols[i]->tag);
51      for (rp = derives[i - ntokens]; *rp; ++rp)
52	{
53	  fprintf (stderr, "\t\t%3d ", (*rp)->user_number);
54	  rule_rhs_print (*rp, stderr);
55	}
56    }
57
58  fputs ("\n\n", stderr);
59}
60
61
62void
63derives_compute (void)
64{
65  symbol_number i;
66  rule_number r;
67  rule **q;
68
69  /* DSET[NTERM - NTOKENS] -- A linked list of the numbers of the rules
70     whose LHS is NTERM.  */
71  rule_list **dset = xcalloc (nvars, sizeof *dset);
72
73  /* DELTS[RULE] -- There are NRULES rule number to attach to nterms.
74     Instead of performing NRULES allocations for each, have an array
75     indexed by rule numbers.  */
76  rule_list *delts = xnmalloc (nrules, sizeof *delts);
77
78  for (r = nrules - 1; r >= 0; --r)
79    {
80      symbol_number lhs = rules[r].lhs->number;
81      rule_list *p = &delts[r];
82      /* A new LHS is found.  */
83      p->next = dset[lhs - ntokens];
84      p->value = &rules[r];
85      dset[lhs - ntokens] = p;
86    }
87
88  /* DSET contains what we need under the form of a linked list.  Make
89     it a single array.  */
90
91  derives = xnmalloc (nvars, sizeof *derives);
92  q = xnmalloc (nvars + nrules, sizeof *q);
93
94  for (i = ntokens; i < nsyms; i++)
95    {
96      rule_list *p = dset[i - ntokens];
97      derives[i - ntokens] = q;
98      while (p)
99	{
100	  *q++ = p->value;
101	  p = p->next;
102	}
103      *q++ = NULL;
104    }
105
106  if (trace_flag & trace_sets)
107    print_derives ();
108
109  free (dset);
110  free (delts);
111}
112
113
114void
115derives_free (void)
116{
117  free (derives[0]);
118  free (derives);
119}
120