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122c0aac 1/* Match rules with nonterminals for bison,
cc84fd5d 2 Copyright (C) 1984, 1989, 2000 Free Software Foundation, Inc.
122c0aac 3
cc84fd5d 4 This file is part of Bison, the GNU Compiler Compiler.
122c0aac 5
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6 Bison is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2, or (at your option)
9 any later version.
122c0aac 10
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11 Bison is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
122c0aac 15
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16 You should have received a copy of the GNU General Public License
17 along with Bison; see the file COPYING. If not, write to
18 the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
19 Boston, MA 02111-1307, USA. */
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20
21
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22/* set_derives finds, for each variable (nonterminal), which rules can
23 derive it. It sets up the value of derives so that derives[i -
24 ntokens] points to a vector of rule numbers, terminated with -1.
25 */
122c0aac 26
122c0aac 27#include "system.h"
d7913476 28#include "xalloc.h"
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29#include "types.h"
30#include "gram.h"
cc84fd5d 31#include "derives.h"
4a120d45 32
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33short **derives;
34
4a120d45 35#if DEBUG
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36
37static void
38print_derives (void)
39{
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40 int i;
41 short *sp;
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42
43 printf (_("\n\n\nDERIVES\n\n"));
44
45 for (i = ntokens; i < nsyms; i++)
46 {
47 printf (_("%s derives"), tags[i]);
48 for (sp = derives[i]; *sp > 0; sp++)
49 {
50 printf (" %d", *sp);
51 }
52 putchar ('\n');
53 }
54
55 putchar ('\n');
56}
57
4a120d45 58#endif
122c0aac 59
122c0aac 60void
d2729d44 61set_derives (void)
122c0aac 62{
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63 int i;
64 int lhs;
65 shorts *p;
66 short *q;
67 shorts **dset;
68 shorts *delts;
122c0aac 69
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70 dset = XCALLOC (shorts *, nvars) - ntokens;
71 delts = XCALLOC (shorts, nrules + 1);
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72
73 p = delts;
74 for (i = nrules; i > 0; i--)
75 {
76 lhs = rlhs[i];
77 if (lhs >= 0)
78 {
79 p->next = dset[lhs];
80 p->value = i;
81 dset[lhs] = p;
82 p++;
83 }
84 }
85
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86 derives = XCALLOC (short *, nvars) - ntokens;
87 q = XCALLOC (short, nvars + nrules);
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88
89 for (i = ntokens; i < nsyms; i++)
90 {
91 derives[i] = q;
92 p = dset[i];
93 while (p)
94 {
95 *q++ = p->value;
96 p = p->next;
97 }
98 *q++ = -1;
99 }
100
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101#if DEBUG
102 print_derives ();
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103#endif
104
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105 XFREE (dset + ntokens);
106 XFREE (delts);
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107}
108
109void
d2729d44 110free_derives (void)
122c0aac 111{
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112 XFREE (derives[ntokens]);
113 XFREE (derives + ntokens);
122c0aac 114}