/* A splay-tree datatype. | |

Copyright (C) 1998, 1999, 2000 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 <stdio.h> | |

#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_s)); | |

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. 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 = (*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_s)); | |

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 (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 | |

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; | |

} | |

/* 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 leftmost element of the right 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. | |

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; | |

} |