1/* List implementation of a partition of consecutive integers.
2   Copyright (C) 2000, 2001 Free Software Foundation, Inc.
3   Contributed by CodeSourcery, LLC.
4
5   This file is part of GNU CC.
6
7   GNU CC is free software; you can redistribute it and/or modify
8   it under the terms of the GNU General Public License as published by
9   the Free Software Foundation; either version 2, or (at your option)
10   any later version.
11
12   GNU CC is distributed in the hope that it will be useful,
13   but WITHOUT ANY WARRANTY; without even the implied warranty of
14   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15   GNU General Public License for more details.
16
17   You should have received a copy of the GNU General Public License
18   along with GNU CC; see the file COPYING.  If not, write to
19   the Free Software Foundation, 51 Franklin Street - Fifth Floor,
20   Boston, MA 02110-1301, USA.  */
21
22#ifdef HAVE_CONFIG_H
23#include "config.h"
24#endif
25
26#ifdef HAVE_STDLIB_H
27#include <stdlib.h>
28#endif
29
30#ifdef HAVE_STRING_H
31#include <string.h>
32#endif
33
34#include "libiberty.h"
35#include "partition.h"
36
37static int elem_compare (const void *, const void *);
38
39/* Creates a partition of NUM_ELEMENTS elements.  Initially each
40   element is in a class by itself.  */
41
42partition
43partition_new (int num_elements)
44{
45  int e;
46
47  partition part = (partition)
48    xmalloc (sizeof (struct partition_def) +
49	     (num_elements - 1) * sizeof (struct partition_elem));
50  part->num_elements = num_elements;
51  for (e = 0; e < num_elements; ++e)
52    {
53      part->elements[e].class_element = e;
54      part->elements[e].next = &(part->elements[e]);
55      part->elements[e].class_count = 1;
56    }
57
58  return part;
59}
60
61/* Freeds a partition.  */
62
63void
64partition_delete (partition part)
65{
66  free (part);
67}
68
69/* Unites the classes containing ELEM1 and ELEM2 into a single class
70   of partition PART.  If ELEM1 and ELEM2 are already in the same
71   class, does nothing.  Returns the canonical element of the
72   resulting union class.  */
73
74int
75partition_union (partition part, int elem1, int elem2)
76{
77  struct partition_elem *elements = part->elements;
78  struct partition_elem *e1;
79  struct partition_elem *e2;
80  struct partition_elem *p;
81  struct partition_elem *old_next;
82  /* The canonical element of the resulting union class.  */
83  int class_element = elements[elem1].class_element;
84
85  /* If they're already in the same class, do nothing.  */
86  if (class_element == elements[elem2].class_element)
87    return class_element;
88
89  /* Make sure ELEM1 is in the larger class of the two.  If not, swap
90     them.  This way we always scan the shorter list.  */
91  if (elements[elem1].class_count < elements[elem2].class_count)
92    {
93      int temp = elem1;
94      elem1 = elem2;
95      elem2 = temp;
96      class_element = elements[elem1].class_element;
97    }
98
99  e1 = &(elements[elem1]);
100  e2 = &(elements[elem2]);
101
102  /* Keep a count of the number of elements in the list.  */
103  elements[class_element].class_count
104    += elements[e2->class_element].class_count;
105
106  /* Update the class fields in elem2's class list.  */
107  e2->class_element = class_element;
108  for (p = e2->next; p != e2; p = p->next)
109    p->class_element = class_element;
110
111  /* Splice ELEM2's class list into ELEM1's.  These are circular
112     lists.  */
113  old_next = e1->next;
114  e1->next = e2->next;
115  e2->next = old_next;
116
117  return class_element;
118}
119
120/* Compare elements ELEM1 and ELEM2 from array of integers, given a
121   pointer to each.  Used to qsort such an array.  */
122
123static int
124elem_compare (const void *elem1, const void *elem2)
125{
126  int e1 = * (const int *) elem1;
127  int e2 = * (const int *) elem2;
128  if (e1 < e2)
129    return -1;
130  else if (e1 > e2)
131    return 1;
132  else
133    return 0;
134}
135
136/* Prints PART to the file pointer FP.  The elements of each
137   class are sorted.  */
138
139void
140partition_print (partition part, FILE *fp)
141{
142  char *done;
143  int num_elements = part->num_elements;
144  struct partition_elem *elements = part->elements;
145  int *class_elements;
146  int e;
147
148  /* Flag the elements we've already printed.  */
149  done = (char *) xmalloc (num_elements);
150  memset (done, 0, num_elements);
151
152  /* A buffer used to sort elements in a class.  */
153  class_elements = (int *) xmalloc (num_elements * sizeof (int));
154
155  fputc ('[', fp);
156  for (e = 0; e < num_elements; ++e)
157    /* If we haven't printed this element, print its entire class.  */
158    if (! done[e])
159      {
160	int c = e;
161	int count = elements[elements[e].class_element].class_count;
162	int i;
163
164      /* Collect the elements in this class.  */
165	for (i = 0; i < count; ++i) {
166	  class_elements[i] = c;
167	  done[c] = 1;
168	  c = elements[c].next - elements;
169	}
170	/* Sort them.  */
171	qsort ((void *) class_elements, count, sizeof (int), elem_compare);
172	/* Print them.  */
173	fputc ('(', fp);
174	for (i = 0; i < count; ++i)
175	  fprintf (fp, i == 0 ? "%d" : " %d", class_elements[i]);
176	fputc (')', fp);
177      }
178  fputc (']', fp);
179
180  free (class_elements);
181  free (done);
182}
183
184