/* A splay-tree datatype. Copyright (C) 1998, 1999, 2000, 2001 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, 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, 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 <stdio.h> #include "libiberty.h" #include "splay-tree.h" static void splay_tree_delete_helper (splay_tree, splay_tree_node); static void splay_tree_splay (splay_tree, splay_tree_key); static splay_tree_node splay_tree_splay_helper (splay_tree, splay_tree_key, splay_tree_node*, splay_tree_node*, splay_tree_node*); static int splay_tree_foreach_helper (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 (splay_tree sp, splay_tree_node node) { splay_tree_node pending = 0; splay_tree_node active = 0; if (!node) return; #define KDEL(x) if (sp->delete_key) (*sp->delete_key)(x); #define VDEL(x) if (sp->delete_value) (*sp->delete_value)(x); KDEL (node->key); VDEL (node->value); /* We use the "key" field to hold the "next" pointer. */ node->key = (splay_tree_key)pending; pending = (splay_tree_node)node; /* Now, keep processing the pending list until there aren't any more. This is a little more complicated than just recursing, but it doesn't toast the stack for large trees. */ while (pending) { active = pending; pending = 0; while (active) { splay_tree_node temp; /* active points to a node which has its key and value deallocated, we just need to process left and right. */ if (active->left) { KDEL (active->left->key); VDEL (active->left->value); active->left->key = (splay_tree_key)pending; pending = (splay_tree_node)(active->left); } if (active->right) { KDEL (active->right->key); VDEL (active->right->value); active->right->key = (splay_tree_key)pending; pending = (splay_tree_node)(active->right); } temp = active; active = (splay_tree_node)(temp->key); (*sp->deallocate) ((char*) temp, sp->allocate_data); } } #undef KDEL #undef VDEL } /* Help splay SP around KEY. PARENT and GRANDPARENT are the parent and grandparent, respectively, of NODE. */ static splay_tree_node splay_tree_splay_helper (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 (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 (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); } /* An allocator and deallocator based on xmalloc. */ static void * splay_tree_xmalloc_allocate (int size, void *data ATTRIBUTE_UNUSED) { return (void *) xmalloc (size); } static void splay_tree_xmalloc_deallocate (void *object, void *data ATTRIBUTE_UNUSED) { free (object); } /* Allocate a new splay tree, using COMPARE_FN to compare nodes, DELETE_KEY_FN to deallocate keys, and DELETE_VALUE_FN to deallocate values. Use xmalloc to allocate the splay tree structure, and any nodes added. */ splay_tree splay_tree_new (splay_tree_compare_fn compare_fn, splay_tree_delete_key_fn delete_key_fn, splay_tree_delete_value_fn delete_value_fn) { return (splay_tree_new_with_allocator (compare_fn, delete_key_fn, delete_value_fn, splay_tree_xmalloc_allocate, splay_tree_xmalloc_deallocate, 0)); } /* 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_with_allocator (splay_tree_compare_fn compare_fn, splay_tree_delete_key_fn delete_key_fn, splay_tree_delete_value_fn delete_value_fn, splay_tree_allocate_fn allocate_fn, splay_tree_deallocate_fn deallocate_fn, void *allocate_data) { splay_tree sp = (splay_tree) (*allocate_fn) (sizeof (struct splay_tree_s), allocate_data); sp->root = 0; sp->comp = compare_fn; sp->delete_key = delete_key_fn; sp->delete_value = delete_value_fn; sp->allocate = allocate_fn; sp->deallocate = deallocate_fn; sp->allocate_data = allocate_data; return sp; } /* Deallocate SP. */ void splay_tree_delete (splay_tree sp) { splay_tree_delete_helper (sp, sp->root); (*sp->deallocate) ((char*) sp, sp->allocate_data); } /* 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. Returns the new node. */ splay_tree_node splay_tree_insert (splay_tree sp, splay_tree_key key, splay_tree_value value) { int comparison = 0; 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) (*sp->allocate) (sizeof (struct splay_tree_node_s), sp->allocate_data)); 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; } return sp->root; } /* Remove KEY from SP. It is not an error if it did not exist. */ void splay_tree_remove (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); (*sp->deallocate) (sp->root, sp->allocate_data); /* 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 otherwise. */ splay_tree_node splay_tree_lookup (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; } /* Return the node in SP with the greatest key. */ splay_tree_node splay_tree_max (splay_tree sp) { splay_tree_node n = sp->root; if (!n) return NULL; while (n->right) n = n->right; return n; } /* Return the node in SP with the smallest key. */ splay_tree_node splay_tree_min (splay_tree sp) { splay_tree_node n = sp->root; if (!n) return NULL; while (n->left) n = n->left; return n; } /* 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 (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 successor. KEY need not be present in the tree. */ splay_tree_node splay_tree_successor (splay_tree sp, splay_tree_key key) { int comparison; splay_tree_node node; /* If the tree is empty, there is certainly no successor. */ 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 leftmost element of the right 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. Otherwise, this function returns 0. */ int splay_tree_foreach (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 (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 (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; }