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. */
32 typedef struct rule_list
33 {
34 struct rule_list *next;
35 rule *value;
36 } rule_list;
37
38 rule ***derives;
39
40 static void
print_derives(void)41 print_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
62 void
derives_compute(void)63 derives_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
114 void
derives_free(void)115 derives_free (void)
116 {
117 free (derives[0]);
118 free (derives);
119 }
120