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/* List implementation of a partition of consecutive integers.
Copyright (C) 2000-2023 Free Software Foundation, Inc.
Contributed by CodeSourcery, LLC.
This file is part of GNU CC.
GNU CC is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
GNU CC is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with GNU CC; see the file COPYING. If not, write to
the Free Software Foundation, 51 Franklin Street - Fifth Floor,
Boston, MA 02110-1301, USA. */
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#ifdef HAVE_STDLIB_H
#include <stdlib.h>
#endif
#ifdef HAVE_STRING_H
#include <string.h>
#endif
#include "libiberty.h"
#include "partition.h"
static int elem_compare (const void *, const void *);
/* Creates a partition of NUM_ELEMENTS elements. Initially each
element is in a class by itself. */
partition
partition_new (int num_elements)
{
int e;
partition part = (partition)
xmalloc (sizeof (struct partition_def) +
(num_elements - 1) * sizeof (struct partition_elem));
part->num_elements = num_elements;
for (e = 0; e < num_elements; ++e)
{
part->elements[e].class_element = e;
part->elements[e].next = &(part->elements[e]);
part->elements[e].class_count = 1;
}
return part;
}
/* Freeds a partition. */
void
partition_delete (partition part)
{
free (part);
}
/* Unites the classes containing ELEM1 and ELEM2 into a single class
of partition PART. If ELEM1 and ELEM2 are already in the same
class, does nothing. Returns the canonical element of the
resulting union class. */
int
partition_union (partition part, int elem1, int elem2)
{
struct partition_elem *elements = part->elements;
struct partition_elem *e1;
struct partition_elem *e2;
struct partition_elem *p;
struct partition_elem *old_next;
/* The canonical element of the resulting union class. */
int class_element = elements[elem1].class_element;
/* If they're already in the same class, do nothing. */
if (class_element == elements[elem2].class_element)
return class_element;
/* Make sure ELEM1 is in the larger class of the two. If not, swap
them. This way we always scan the shorter list. */
if (elements[elem1].class_count < elements[elem2].class_count)
{
int temp = elem1;
elem1 = elem2;
elem2 = temp;
class_element = elements[elem1].class_element;
}
e1 = &(elements[elem1]);
e2 = &(elements[elem2]);
/* Keep a count of the number of elements in the list. */
elements[class_element].class_count
+= elements[e2->class_element].class_count;
/* Update the class fields in elem2's class list. */
e2->class_element = class_element;
for (p = e2->next; p != e2; p = p->next)
p->class_element = class_element;
/* Splice ELEM2's class list into ELEM1's. These are circular
lists. */
old_next = e1->next;
e1->next = e2->next;
e2->next = old_next;
return class_element;
}
/* Compare elements ELEM1 and ELEM2 from array of integers, given a
pointer to each. Used to qsort such an array. */
static int
elem_compare (const void *elem1, const void *elem2)
{
int e1 = * (const int *) elem1;
int e2 = * (const int *) elem2;
if (e1 < e2)
return -1;
else if (e1 > e2)
return 1;
else
return 0;
}
/* Prints PART to the file pointer FP. The elements of each
class are sorted. */
void
partition_print (partition part, FILE *fp)
{
char *done;
int num_elements = part->num_elements;
struct partition_elem *elements = part->elements;
int *class_elements;
int e;
/* Flag the elements we've already printed. */
done = (char *) xmalloc (num_elements);
memset (done, 0, num_elements);
/* A buffer used to sort elements in a class. */
class_elements = (int *) xmalloc (num_elements * sizeof (int));
fputc ('[', fp);
for (e = 0; e < num_elements; ++e)
/* If we haven't printed this element, print its entire class. */
if (! done[e])
{
int c = e;
int count = elements[elements[e].class_element].class_count;
int i;
/* Collect the elements in this class. */
for (i = 0; i < count; ++i) {
class_elements[i] = c;
done[c] = 1;
c = elements[c].next - elements;
}
/* Sort them. */
qsort ((void *) class_elements, count, sizeof (int), elem_compare);
/* Print them. */
fputc ('(', fp);
for (i = 0; i < count; ++i)
fprintf (fp, i == 0 ? "%d" : " %d", class_elements[i]);
fputc (')', fp);
}
fputc (']', fp);
free (class_elements);
free (done);
}
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