/* A splay-tree datatype.
- Copyright (C) 1998 Free Software Foundation, Inc.
+ Copyright (C) 1998, 1999, 2000 Free Software Foundation, Inc.
Contributed by Mark Mitchell (mark@markmitchell.com).
- This file is part of GNU CC.
+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 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.
+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, 675 Mass Ave, Cambridge, MA 02139, USA.
+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. */
- For an easily readable description of splay-trees, see:
+/* For an easily readable description of splay-trees, see:
Lewis, Harry R. and Denenberg, Larry. Data Structures and Their
Algorithms. Harper-Collins, Inc. 1991. */
-#if defined (IN_GCC) || defined (HAVE_CONFIG_H)
+#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <stdlib.h>
#endif
-#ifndef IN_GCC
#include "libiberty.h"
-#else /* IN_GCC */
-extern char* xmalloc ();
-#endif /* IN_GCC */
#include "splay-tree.h"
static void splay_tree_delete_helper PARAMS((splay_tree,
splay_tree_delete_key_fn delete_key_fn;
splay_tree_delete_value_fn delete_value_fn;
{
- splay_tree sp = (splay_tree) xmalloc (sizeof (struct splay_tree));
+ splay_tree sp = (splay_tree) xmalloc (sizeof (struct splay_tree_s));
sp->root = 0;
sp->comp = compare_fn;
sp->delete_key = delete_key_fn;
/* Insert a new node (associating KEY with DATA) into SP. If a
previous node with the indicated KEY exists, its data is replaced
- with the new value. */
+ with the new value. Returns the new node. */
-void
+splay_tree_node
splay_tree_insert (sp, key, value)
splay_tree sp;
splay_tree_key key;
splay_tree_value value;
{
- int comparison;
+ int comparison = 0;
splay_tree_splay (sp, key);
/* Create a new node, and insert it at the root. */
splay_tree_node node;
- node = (splay_tree_node) xmalloc (sizeof (struct splay_tree_node));
+ node = (splay_tree_node) xmalloc (sizeof (struct splay_tree_node_s));
node->key = key;
node->value = value;
sp->root = node;
}
+
+ return sp->root;
+}
+
+/* Remove KEY from SP. It is not an error if it did not exist. */
+
+void
+splay_tree_remove (sp, key)
+ splay_tree sp;
+ splay_tree_key key;
+{
+ splay_tree_splay (sp, key);
+
+ if (sp->root && (*sp->comp) (sp->root->key, key) == 0)
+ {
+ splay_tree_node left, right;
+
+ left = sp->root->left;
+ right = sp->root->right;
+
+ /* Delete the root node itself. */
+ if (sp->delete_value)
+ (*sp->delete_value) (sp->root->value);
+ free (sp->root);
+
+ /* One of the children is now the root. Doesn't matter much
+ which, so long as we preserve the properties of the tree. */
+ if (left)
+ {
+ sp->root = left;
+
+ /* If there was a right child as well, hang it off the
+ right-most leaf of the left child. */
+ if (right)
+ {
+ while (left->right)
+ left = left->right;
+ left->right = right;
+ }
+ }
+ else
+ sp->root = right;
+ }
}
/* Lookup KEY in SP, returning VALUE if present, and NULL
return 0;
}
+/* Return the immediate predecessor KEY, or NULL if there is no
+ predecessor. KEY need not be present in the tree. */
+
+splay_tree_node
+splay_tree_predecessor (sp, key)
+ splay_tree sp;
+ splay_tree_key key;
+{
+ int comparison;
+ splay_tree_node node;
+
+ /* If the tree is empty, there is certainly no predecessor. */
+ if (!sp->root)
+ return NULL;
+
+ /* Splay the tree around KEY. That will leave either the KEY
+ itself, its predecessor, or its successor at the root. */
+ splay_tree_splay (sp, key);
+ comparison = (*sp->comp)(sp->root->key, key);
+
+ /* If the predecessor is at the root, just return it. */
+ if (comparison < 0)
+ return sp->root;
+
+ /* Otherwise, find the rightmost element of the left subtree. */
+ node = sp->root->left;
+ if (node)
+ while (node->right)
+ node = node->right;
+
+ return node;
+}
+
+/* Return the immediate successor KEY, or NULL if there is no
+ predecessor. KEY need not be present in the tree. */
+
+splay_tree_node
+splay_tree_successor (sp, key)
+ splay_tree sp;
+ splay_tree_key key;
+{
+ int comparison;
+ splay_tree_node node;
+
+ /* If the tree is empty, there is certainly no predecessor. */
+ if (!sp->root)
+ return NULL;
+
+ /* Splay the tree around KEY. That will leave either the KEY
+ itself, its predecessor, or its successor at the root. */
+ splay_tree_splay (sp, key);
+ comparison = (*sp->comp)(sp->root->key, key);
+
+ /* If the successor is at the root, just return it. */
+ if (comparison > 0)
+ return sp->root;
+
+ /* Otherwise, find the rightmost element of the left subtree. */
+ node = sp->root->right;
+ if (node)
+ while (node->left)
+ node = node->left;
+
+ return node;
+}
+
/* Call FN, passing it the DATA, for every node in SP, following an
in-order traversal. If FN every returns a non-zero value, the
iteration ceases immediately, and the value is returned.
{
return splay_tree_foreach_helper (sp, sp->root, fn, data);
}
+
+/* Splay-tree comparison function, treating the keys as ints. */
+
+int
+splay_tree_compare_ints (k1, k2)
+ splay_tree_key k1;
+ splay_tree_key k2;
+{
+ if ((int) k1 < (int) k2)
+ return -1;
+ else if ((int) k1 > (int) k2)
+ return 1;
+ else
+ return 0;
+}
+
+/* Splay-tree comparison function, treating the keys as pointers. */
+
+int
+splay_tree_compare_pointers (k1, k2)
+ splay_tree_key k1;
+ splay_tree_key k2;
+{
+ if ((char*) k1 < (char*) k2)
+ return -1;
+ else if ((char*) k1 > (char*) k2)
+ return 1;
+ else
+ return 0;
+}
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