/* 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 inline void rotate_left (splay_tree_node *, | |

splay_tree_node, splay_tree_node); | |

static inline void rotate_right (splay_tree_node *, | |

splay_tree_node, splay_tree_node); | |

static void splay_tree_splay (splay_tree, splay_tree_key); | |

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 | |

} | |

/* Rotate the edge joining the left child N with its parent P. PP is the | |

grandparents' pointer to P. */ | |

static inline void | |

rotate_left (splay_tree_node *pp, splay_tree_node p, splay_tree_node n) | |

{ | |

splay_tree_node tmp; | |

tmp = n->right; | |

n->right = p; | |

p->left = tmp; | |

*pp = n; | |

} | |

/* Rotate the edge joining the right child N with its parent P. PP is the | |

grandparents' pointer to P. */ | |

static inline void | |

rotate_right (splay_tree_node *pp, splay_tree_node p, splay_tree_node n) | |

{ | |

splay_tree_node tmp; | |

tmp = n->left; | |

n->left = p; | |

p->right = tmp; | |

*pp = n; | |

} | |

/* Bottom up splay of key. */ | |

static void | |

splay_tree_splay (splay_tree sp, splay_tree_key key) | |

{ | |

if (sp->root == 0) | |

return; | |

do { | |

int cmp1, cmp2; | |

splay_tree_node n, c; | |

n = sp->root; | |

cmp1 = (*sp->comp) (key, n->key); | |

/* Found. */ | |

if (cmp1 == 0) | |

return; | |

/* Left or right? If no child, then we're done. */ | |

if (cmp1 < 0) | |

c = n->left; | |

else | |

c = n->right; | |

if (!c) | |

return; | |

/* Next one left or right? If found or no child, we're done | |

after one rotation. */ | |

cmp2 = (*sp->comp) (key, c->key); | |

if (cmp2 == 0 | |

|| (cmp2 < 0 && !c->left) | |

|| (cmp2 > 0 && !c->right)) | |

{ | |

if (cmp1 < 0) | |

rotate_left (&sp->root, n, c); | |

else | |

rotate_right (&sp->root, n, c); | |

return; | |

} | |

/* Now we have the four cases of double-rotation. */ | |

if (cmp1 < 0 && cmp2 < 0) | |

{ | |

rotate_left (&n->left, c, c->left); | |

rotate_left (&sp->root, n, n->left); | |

} | |

else if (cmp1 > 0 && cmp2 > 0) | |

{ | |

rotate_right (&n->right, c, c->right); | |

rotate_right (&sp->root, n, n->right); | |

} | |

else if (cmp1 < 0 && cmp2 > 0) | |

{ | |

rotate_right (&n->left, c, c->right); | |

rotate_left (&sp->root, n, n->left); | |

} | |

else if (cmp1 > 0 && cmp2 < 0) | |

{ | |

rotate_left (&n->right, c, c->left); | |

rotate_right (&sp->root, n, n->right); | |

} | |

} while (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 (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; | |

} |