1/* Match rules with nonterminals for bison,
2
3 Copyright (C) 1984, 1989, 2000-2003, 2005, 2009-2015, 2018-2019 Free
4 Software 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 fprintf (stderr, " %s derives\n", symbols[i]->tag);
50 for (rule **rp = derives[i - ntokens]; *rp; ++rp)
51 {
52 fprintf (stderr, " %3d ", (*rp)->user_number);
53 rule_rhs_print (*rp, stderr);
54 fprintf (stderr, "\n");
55 }
56 }
57
58 fputs ("\n\n", stderr);
59}
60
61
62void
63derives_compute (void)
64{
65 /* DSET[NTERM - NTOKENS] -- A linked list of the numbers of the rules
66 whose LHS is NTERM. */
67 rule_list **dset = xcalloc (nvars, sizeof *dset);
68
69 /* DELTS[RULE] -- There are NRULES rule number to attach to nterms.
70 Instead of performing NRULES allocations for each, have an array
71 indexed by rule numbers. */
72 rule_list *delts = xnmalloc (nrules, sizeof *delts);
73
74 for (rule_number r = nrules - 1; r >= 0; --r)
75 {
76 symbol_number lhs = rules[r].lhs->number;
77 rule_list *p = &delts[r];
78 /* A new LHS is found. */
79 p->next = dset[lhs - ntokens];
80 p->value = &rules[r];
81 dset[lhs - ntokens] = p;
82 }
83
84 /* DSET contains what we need under the form of a linked list. Make
85 it a single array. */
86
87 derives = xnmalloc (nvars, sizeof *derives);
88 /* Q is the storage for DERIVES[...] (DERIVES[0] = q). */
89 rule **q = xnmalloc (nvars + nrules, sizeof *q);
90
91 for (symbol_number i = ntokens; i < nsyms; i++)
92 {
93 rule_list *p = dset[i - ntokens];
94 derives[i - ntokens] = q;
95 while (p)
96 {
97 *q++ = p->value;
98 p = p->next;
99 }
100 *q++ = NULL;
101 }
102
103 if (trace_flag & trace_sets)
104 print_derives ();
105
106 free (dset);
107 free (delts);
108}
109
110
111void
112derives_free (void)
113{
114 free (derives[0]);
115 free (derives);
116}
117