* partition.c: New file.

libiberty/partition.c

@@ -0,0 +1,185 @@
+/* List implentation of a partition of consecutive integers.
+   Copyright (C) 2000 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, 59 Temple Place - Suite 330,
+   Boston, MA 02111-1307, USA.  */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#ifdef HAVE_STDLIB_H
+#include <stdlib.h>
+#endif
+
+#include "libiberty.h"
+#include "partition.h"
+
+/* Creates a partition of NUM_ELEMENTS elements.  Initially each
+   element is in a class by itself.  */
+
+partition
+partition_new (num_elements)
+     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 (part)
+      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 (part, elem1, elem2)
+     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 (elem1, elem2)
+     const void *elem1;
+     const void *elem2;
+{
+  int e1 = * (int *) elem1;
+  int e2 = * (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 (part, fp)
+     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 (done);
+}
+