1/* Binary relations.
2
3   Copyright (C) 2002, 2004-2005, 2009-2012 Free Software Foundation,
4   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 <bitsetv.h>
25
26#include "getargs.h"
27#include "relation.h"
28
29void
30relation_print (relation r, relation_node size, FILE *out)
31{
32  relation_node i;
33  relation_node j;
34
35  for (i = 0; i < size; ++i)
36    {
37      fprintf (out, "%3lu: ", (unsigned long int) i);
38      if (r[i])
39	for (j = 0; r[i][j] != END_NODE; ++j)
40	  fprintf (out, "%3lu ", (unsigned long int) r[i][j]);
41      fputc ('\n', out);
42    }
43  fputc ('\n', out);
44}
45
46
47/*---------------------------------------------------------------.
48| digraph & traverse.                                            |
49|                                                                |
50| The following variables are used as common storage between the |
51| two.                                                           |
52`---------------------------------------------------------------*/
53
54static relation R;
55static relation_nodes INDEX;
56static relation_nodes VERTICES;
57static relation_node top;
58static relation_node infinity;
59static bitsetv F;
60
61static void
62traverse (relation_node i)
63{
64  relation_node j;
65  relation_node height;
66
67  VERTICES[++top] = i;
68  INDEX[i] = height = top;
69
70  if (R[i])
71    for (j = 0; R[i][j] != END_NODE; ++j)
72      {
73	if (INDEX[R[i][j]] == 0)
74	  traverse (R[i][j]);
75
76	if (INDEX[i] > INDEX[R[i][j]])
77	  INDEX[i] = INDEX[R[i][j]];
78
79	bitset_or (F[i], F[i], F[R[i][j]]);
80      }
81
82  if (INDEX[i] == height)
83    for (;;)
84      {
85	j = VERTICES[top--];
86	INDEX[j] = infinity;
87
88	if (i == j)
89	  break;
90
91	bitset_copy (F[j], F[i]);
92      }
93}
94
95
96void
97relation_digraph (relation r, relation_node size, bitsetv *function)
98{
99  relation_node i;
100
101  infinity = size + 2;
102  INDEX = xcalloc (size + 1, sizeof *INDEX);
103  VERTICES = xnmalloc (size + 1, sizeof *VERTICES);
104  top = 0;
105
106  R = r;
107  F = *function;
108
109  for (i = 0; i < size; i++)
110    if (INDEX[i] == 0 && R[i])
111      traverse (i);
112
113  free (INDEX);
114  free (VERTICES);
115
116  *function = F;
117}
118
119
120/*-------------------------------------------.
121| Destructively transpose R_ARG, of size N.  |
122`-------------------------------------------*/
123
124void
125relation_transpose (relation *R_arg, relation_node n)
126{
127  relation r = *R_arg;
128  /* The result. */
129  relation new_R = xnmalloc (n, sizeof *new_R);
130  /* END_R[I] -- next entry of NEW_R[I]. */
131  relation end_R = xnmalloc (n, sizeof *end_R);
132  /* NEDGES[I] -- total size of NEW_R[I]. */
133  size_t *nedges = xcalloc (n, sizeof *nedges);
134  relation_node i;
135  relation_node j;
136
137  if (trace_flag & trace_sets)
138    {
139      fputs ("relation_transpose: input\n", stderr);
140      relation_print (r, n, stderr);
141    }
142
143  /* Count. */
144  for (i = 0; i < n; i++)
145    if (r[i])
146      for (j = 0; r[i][j] != END_NODE; ++j)
147	++nedges[r[i][j]];
148
149  /* Allocate. */
150  for (i = 0; i < n; i++)
151    {
152      relation_node *sp = NULL;
153      if (nedges[i] > 0)
154	{
155	  sp = xnmalloc (nedges[i] + 1, sizeof *sp);
156	  sp[nedges[i]] = END_NODE;
157	}
158      new_R[i] = sp;
159      end_R[i] = sp;
160    }
161
162  /* Store. */
163  for (i = 0; i < n; i++)
164    if (r[i])
165      for (j = 0; r[i][j] != END_NODE; ++j)
166	*end_R[r[i][j]]++ = i;
167
168  free (nedges);
169  free (end_R);
170
171  /* Free the input: it is replaced with the result. */
172  for (i = 0; i < n; i++)
173    free (r[i]);
174  free (r);
175
176  if (trace_flag & trace_sets)
177    {
178      fputs ("relation_transpose: output\n", stderr);
179      relation_print (new_R, n, stderr);
180    }
181
182  *R_arg = new_R;
183}
184