/* A splay-tree datatype. Copyright (C) 1998, 1999, 2000, 2001, 2004 Free Software Foundation, Inc. Contributed by Mark Mitchell (mark@markmitchell.com). Adapted for libmudflap from libiberty. 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. In addition to the permissions in the GNU General Public License, the Free Software Foundation gives you unlimited permission to link the compiled version of this file into combinations with other programs, and to distribute those combinations without any restriction coming from the use of this file. (The General Public License restrictions do apply in other respects; for example, they cover modification of the file, and distribution when not linked into a combine executable.) 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. */ #include #include #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*)); /* Inline comparison function specialized for libmudflap's key type. */ static inline int compare_uintptr_t (splay_tree_key k1, splay_tree_key k2) { if ((uintptr_t) k1 < (uintptr_t) k2) return -1; else if ((uintptr_t) k1 > (uintptr_t) k2) return 1; else return 0; } /* 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); (*sp->deallocate) ((char*) node, sp->allocate_data); } /* 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 = compare_uintptr_t (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; /* If we just splayed the tree with the same key, do nothing. */ if (sp->last_splayed_key_p && compare_uintptr_t (sp->last_splayed_key, key) == 0) return; splay_tree_splay_helper (sp, key, &sp->root, /*grandparent=*/0, /*parent=*/0); /* Cache this splay key. */ sp->last_splayed_key = key; sp->last_splayed_key_p = 1; } /* 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); } /* An allocator and deallocator based on xmalloc. */ static void * splay_tree_xmalloc_allocate (size, data) int size; void *data ATTRIBUTE_UNUSED; { return (void *) xmalloc (size); } static void splay_tree_xmalloc_deallocate (object, data) 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_allocate_fn allocate_fn = splay_tree_xmalloc_allocate; splay_tree_deallocate_fn deallocate_fn = splay_tree_xmalloc_deallocate; void *allocate_data = NULL; splay_tree sp = (splay_tree) (*allocate_fn) (sizeof (struct splay_tree_s), allocate_data); sp->root = 0; sp->allocate = allocate_fn; sp->deallocate = deallocate_fn; sp->allocate_data = allocate_data; sp->last_splayed_key_p = 0; return sp; } /* Deallocate SP. */ void splay_tree_delete (sp) 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 (sp, key, value) splay_tree sp; splay_tree_key key; splay_tree_value value; { int comparison = 0; splay_tree_splay (sp, key); if (sp->root) comparison = compare_uintptr_t (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. */ 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; sp->last_splayed_key_p = 0; } 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); sp->last_splayed_key_p = 0; if (sp->root && compare_uintptr_t (sp->root->key, key) == 0) { splay_tree_node left, right; left = sp->root->left; right = sp->root->right; /* Delete the root node itself. */ (*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 (sp, key) splay_tree sp; splay_tree_key key; { splay_tree_splay (sp, key); if (sp->root && compare_uintptr_t (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 (sp) 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 (sp) 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 (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 = compare_uintptr_t (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 (sp, key) 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 = compare_uintptr_t (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 (sp, fn, data) splay_tree sp; splay_tree_foreach_fn fn; void *data; { return splay_tree_foreach_helper (sp, sp->root, fn, data); }