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1 /* Match rules with nonterminals for bison,
2 Copyright (C) 1984, 1989, 2000, 2001, 2002 Free Software Foundation, Inc.
3
4 This file is part of Bison, the GNU Compiler Compiler.
5
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.
10
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.
15
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. */
20
21
22 #include "system.h"
23 #include "getargs.h"
24 #include "symtab.h"
25 #include "reader.h"
26 #include "gram.h"
27 #include "derives.h"
28
29 /* Linked list of rule numbers. */
30 typedef struct rule_list_s
31 {
32 struct rule_list_s *next;
33 rule_t *value;
34 } rule_list_t;
35
36 rule_t ***derives = NULL;
37
38 static void
39 print_derives (void)
40 {
41 int i;
42
43 fputs ("DERIVES\n", stderr);
44
45 for (i = ntokens; i < nsyms; i++)
46 {
47 rule_t **rp;
48 fprintf (stderr, "\t%s derives\n", symbols[i]->tag);
49 for (rp = derives[i]; *rp; ++rp)
50 {
51 fprintf (stderr, "\t\t%3d ", (*rp)->user_number);
52 rule_rhs_print (*rp, stderr);
53 }
54 }
55
56 fputs ("\n\n", stderr);
57 }
58
59
60 void
61 derives_compute (void)
62 {
63 symbol_number_t i;
64 int r;
65 rule_t **q;
66
67 /* DSET[NTERM] -- A linked list of the numbers of the rules whose
68 LHS is NTERM. */
69 rule_list_t **dset = XCALLOC (rule_list_t *, nvars) - ntokens;
70
71 /* DELTS[RULE] -- There are NRULES rule number to attach to nterms.
72 Instead of performing NRULES allocations for each, have an array
73 indexed by rule numbers. */
74 rule_list_t *delts = XCALLOC (rule_list_t, nrules);
75
76 for (r = nrules - 1; r >= 0; --r)
77 {
78 symbol_number_t lhs = rules[r].lhs->number;
79 rule_list_t *p = &delts[r];
80 /* A new LHS is found. */
81 p->next = dset[lhs];
82 p->value = &rules[r];
83 dset[lhs] = p;
84 }
85
86 /* DSET contains what we need under the form of a linked list. Make
87 it a single array. */
88
89 derives = XCALLOC (rule_t **, nvars) - ntokens;
90 q = XCALLOC (rule_t *, nvars + int_of_rule_number (nrules));
91
92 for (i = ntokens; i < nsyms; i++)
93 {
94 rule_list_t *p = dset[i];
95 derives[i] = q;
96 while (p)
97 {
98 *q++ = p->value;
99 p = p->next;
100 }
101 *q++ = NULL;
102 }
103
104 if (trace_flag & trace_sets)
105 print_derives ();
106
107 free (dset + ntokens);
108 free (delts);
109 }
110
111
112 void
113 derives_free (void)
114 {
115 XFREE (derives[ntokens]);
116 XFREE (derives + ntokens);
117 }