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Diffstat (limited to 'libiberty/splay-tree.c')
| -rw-r--r-- | libiberty/splay-tree.c | 368 |
1 files changed, 368 insertions, 0 deletions
diff --git a/libiberty/splay-tree.c b/libiberty/splay-tree.c new file mode 100644 index 00000000000..b6bb5a6a8f0 --- /dev/null +++ b/libiberty/splay-tree.c @@ -0,0 +1,368 @@ +/* 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, 59 Temple Place - Suite 330, +Boston, MA 02111-1307, 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. */ + +#ifdef HAVE_CONFIG_H +#include "config.h" +#endif + +#ifdef HAVE_STDLIB_H +#include <stdlib.h> +#endif + +#include "libiberty.h" +#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. */ + +static 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); +} + +/* 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; +} |