--- /dev/null
+/* A splay-tree datatype.
+ Copyright (C) 1998 Free Software Foundation, Inc.
+ Contributed by Mark Mitchell (mark@markmitchell.com).
+
+ 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, 675 Mass Ave, Cambridge, MA 02139, USA.
+
+ For an easily readable description of splay-trees, see:
+
+ Lewis, Harry R. and Denenberg, Larry. Data Structures and Their
+ Algorithms. Harper-Collins, Inc. 1991. */
+
+#ifndef IN_GCC
+#include "libiberty.h"
+#endif /* IN_GCC */
+#include "splay-tree.h"
+
+static void splay_tree_delete_helper PARAMS((splay_tree,
+ splay_tree_node));
+static void splay_tree_splay PARAMS((splay_tree,
+ splay_tree_key));
+static splay_tree_node splay_tree_splay_helper
+ PARAMS((splay_tree,
+ splay_tree_key,
+ splay_tree_node*,
+ splay_tree_node*,
+ splay_tree_node*));
+static int splay_tree_foreach_helper PARAMS((splay_tree,
+ splay_tree_node,
+ splay_tree_foreach_fn,
+ void*));
+
+/* Deallocate NODE (a member of SP), and all its sub-trees. */
+
+static void
+splay_tree_delete_helper (sp, node)
+ splay_tree sp;
+ splay_tree_node node;
+{
+ if (!node)
+ return;
+
+ splay_tree_delete_helper (sp, node->left);
+ splay_tree_delete_helper (sp, node->right);
+
+ if (sp->delete_key)
+ (*sp->delete_key)(node->key);
+ if (sp->delete_value)
+ (*sp->delete_value)(node->value);
+
+ free ((char*) node);
+}
+
+/* Help splay SP around KEY. PARENT and GRANDPARENT are the parent
+ and grandparent, respectively, of NODE. */
+
+static splay_tree_node
+splay_tree_splay_helper (sp, key, node, parent, grandparent)
+ splay_tree sp;
+ splay_tree_key key;
+ splay_tree_node *node;
+ splay_tree_node *parent;
+ splay_tree_node *grandparent;
+{
+ splay_tree_node *next;
+ splay_tree_node n;
+ int comparison;
+
+ n = *node;
+
+ if (!n)
+ return *parent;
+
+ comparison = (*sp->comp) (key, n->key);
+
+ if (comparison == 0)
+ /* We've found the target. */
+ next = 0;
+ else if (comparison < 0)
+ /* The target is to the left. */
+ next = &n->left;
+ else
+ /* The target is to the right. */
+ next = &n->right;
+
+ if (next)
+ {
+ /* Continue down the tree. */
+ n = splay_tree_splay_helper (sp, key, next, node, parent);
+
+ /* The recursive call will change the place to which NODE
+ points. */
+ if (*node != n)
+ return n;
+ }
+
+ if (!parent)
+ /* NODE is the root. We are done. */
+ return n;
+
+ /* First, handle the case where there is no grandparent (i.e.,
+ *PARENT is the root of the tree.) */
+ if (!grandparent)
+ {
+ if (n == (*parent)->left)
+ {
+ *node = n->right;
+ n->right = *parent;
+ }
+ else
+ {
+ *node = n->left;
+ n->left = *parent;
+ }
+ *parent = n;
+ return n;
+ }
+
+ /* Next handle the cases where both N and *PARENT are left children,
+ or where both are right children. */
+ if (n == (*parent)->left && *parent == (*grandparent)->left)
+ {
+ splay_tree_node p = *parent;
+
+ (*grandparent)->left = p->right;
+ p->right = *grandparent;
+ p->left = n->right;
+ n->right = p;
+ *grandparent = n;
+ return n;
+ }
+ else if (n == (*parent)->right && *parent == (*grandparent)->right)
+ {
+ splay_tree_node p = *parent;
+
+ (*grandparent)->right = p->left;
+ p->left = *grandparent;
+ p->right = n->left;
+ n->left = p;
+ *grandparent = n;
+ return n;
+ }
+
+ /* Finally, deal with the case where N is a left child, but *PARENT
+ is a right child, or vice versa. */
+ if (n == (*parent)->left)
+ {
+ (*parent)->left = n->right;
+ n->right = *parent;
+ (*grandparent)->right = n->left;
+ n->left = *grandparent;
+ *grandparent = n;
+ return n;
+ }
+ else
+ {
+ (*parent)->right = n->left;
+ n->left = *parent;
+ (*grandparent)->left = n->right;
+ n->right = *grandparent;
+ *grandparent = n;
+ return n;
+ }
+}
+
+/* Splay SP around KEY. */
+
+static void
+splay_tree_splay (sp, key)
+ splay_tree sp;
+ splay_tree_key key;
+{
+ if (sp->root == 0)
+ return;
+
+ splay_tree_splay_helper (sp, key, &sp->root,
+ /*grandparent=*/0, /*parent=*/0);
+}
+
+/* Call FN, passing it the DATA, for every node below NODE, all of
+ which are from SP, following an in-order traversal. If FN every
+ returns a non-zero value, the iteration ceases immediately, and the
+ value is returned. Otherwise, this function returns 0. */
+
+int
+splay_tree_foreach_helper (sp, node, fn, data)
+ splay_tree sp;
+ splay_tree_node node;
+ splay_tree_foreach_fn fn;
+ void* data;
+{
+ int val;
+
+ if (!node)
+ return 0;
+
+ val = splay_tree_foreach_helper (sp, node->left, fn, data);
+ if (val)
+ return val;
+
+ val = (*fn)(node, data);
+ if (val)
+ return val;
+
+ return splay_tree_foreach_helper (sp, node->right, fn, data);
+}
+
+/* Allocate a new splay tree, using COMPARE_FN to compare nodes,
+ DELETE_KEY_FN to deallocate keys, and DELETE_VALUE_FN to deallocate
+ values. */
+
+splay_tree
+splay_tree_new (compare_fn, delete_key_fn, delete_value_fn)
+ splay_tree_compare_fn compare_fn;
+ 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));
+ sp->root = 0;
+ sp->comp = compare_fn;
+ sp->delete_key = delete_key_fn;
+ sp->delete_value = delete_value_fn;
+
+ return sp;
+}
+
+/* Deallocate SP. */
+
+void
+splay_tree_delete (sp)
+ splay_tree sp;
+{
+ splay_tree_delete_helper (sp, sp->root);
+ free ((char*) sp);
+}
+
+/* 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. */
+
+void
+splay_tree_insert (sp, key, value)
+ splay_tree sp;
+ splay_tree_key key;
+ splay_tree_value value;
+{
+ int comparison;
+
+ splay_tree_splay (sp, key);
+
+ if (sp->root)
+ comparison = (*sp->comp)(sp->root->key, key);
+
+ if (sp->root && comparison == 0)
+ {
+ /* If the root of the tree already has the indicated KEY, just
+ replace the value with VALUE. */
+ if (sp->delete_value)
+ (*sp->delete_value)(sp->root->value);
+ sp->root->value = value;
+ }
+ else
+ {
+ /* 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->key = key;
+ node->value = value;
+
+ if (!sp->root)
+ node->left = node->right = 0;
+ else if (comparison < 0)
+ {
+ node->left = sp->root;
+ node->right = node->left->right;
+ node->left->right = 0;
+ }
+ else
+ {
+ node->right = sp->root;
+ node->left = node->right->left;
+ node->right->left = 0;
+ }
+
+ sp->root = node;
+ }
+}
+
+/* Lookup KEY in SP, returning VALUE if present, and NULL
+ otherwise. */
+
+splay_tree_node
+splay_tree_lookup (sp, key)
+ splay_tree sp;
+ splay_tree_key key;
+{
+ splay_tree_splay (sp, key);
+
+ if (sp->root && (*sp->comp)(sp->root->key, key) == 0)
+ return sp->root;
+ else
+ return 0;
+}
+
+/* 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.
+ Otherwise, this function returns 0. */
+
+int
+splay_tree_foreach (sp, fn, data)
+ splay_tree sp;
+ splay_tree_foreach_fn fn;
+ void *data;
+{
+ return splay_tree_foreach_helper (sp, sp->root, fn, data);
+}
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