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/* 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;
}
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