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mirror_qemu/util/qtree.c

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/*
* GLIB - Library of useful routines for C programming
* Copyright (C) 1995-1997 Peter Mattis, Spencer Kimball and Josh MacDonald
*
* SPDX-License-Identifier: LGPL-2.1-or-later
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, see <http://www.gnu.org/licenses/>.
*/
/*
* Modified by the GLib Team and others 1997-2000. See the AUTHORS
* file for a list of people on the GLib Team. See the ChangeLog
* files for a list of changes. These files are distributed with
* GLib at ftp://ftp.gtk.org/pub/gtk/.
*/
/*
* MT safe
*/
#include "qemu/osdep.h"
#include "qemu/qtree.h"
/**
* SECTION:trees-binary
* @title: Balanced Binary Trees
* @short_description: a sorted collection of key/value pairs optimized
* for searching and traversing in order
*
* The #QTree structure and its associated functions provide a sorted
* collection of key/value pairs optimized for searching and traversing
* in order. This means that most of the operations (access, search,
* insertion, deletion, ...) on #QTree are O(log(n)) in average and O(n)
* in worst case for time complexity. But, note that maintaining a
* balanced sorted #QTree of n elements is done in time O(n log(n)).
*
* To create a new #QTree use q_tree_new().
*
* To insert a key/value pair into a #QTree use q_tree_insert()
* (O(n log(n))).
*
* To remove a key/value pair use q_tree_remove() (O(n log(n))).
*
* To look up the value corresponding to a given key, use
* q_tree_lookup() and q_tree_lookup_extended().
*
* To find out the number of nodes in a #QTree, use q_tree_nnodes(). To
* get the height of a #QTree, use q_tree_height().
*
* To traverse a #QTree, calling a function for each node visited in
* the traversal, use q_tree_foreach().
*
* To destroy a #QTree, use q_tree_destroy().
**/
#define MAX_GTREE_HEIGHT 40
/**
* QTree:
*
* The QTree struct is an opaque data structure representing a
* [balanced binary tree][glib-Balanced-Binary-Trees]. It should be
* accessed only by using the following functions.
*/
struct _QTree {
QTreeNode *root;
GCompareDataFunc key_compare;
GDestroyNotify key_destroy_func;
GDestroyNotify value_destroy_func;
gpointer key_compare_data;
guint nnodes;
gint ref_count;
};
struct _QTreeNode {
gpointer key; /* key for this node */
gpointer value; /* value stored at this node */
QTreeNode *left; /* left subtree */
QTreeNode *right; /* right subtree */
gint8 balance; /* height (right) - height (left) */
guint8 left_child;
guint8 right_child;
};
static QTreeNode *q_tree_node_new(gpointer key,
gpointer value);
static QTreeNode *q_tree_insert_internal(QTree *tree,
gpointer key,
gpointer value,
gboolean replace);
static gboolean q_tree_remove_internal(QTree *tree,
gconstpointer key,
gboolean steal);
static QTreeNode *q_tree_node_balance(QTreeNode *node);
static QTreeNode *q_tree_find_node(QTree *tree,
gconstpointer key);
static QTreeNode *q_tree_node_search(QTreeNode *node,
GCompareFunc search_func,
gconstpointer data);
static QTreeNode *q_tree_node_rotate_left(QTreeNode *node);
static QTreeNode *q_tree_node_rotate_right(QTreeNode *node);
#ifdef Q_TREE_DEBUG
static void q_tree_node_check(QTreeNode *node);
#endif
static QTreeNode*
q_tree_node_new(gpointer key,
gpointer value)
{
QTreeNode *node = g_new(QTreeNode, 1);
node->balance = 0;
node->left = NULL;
node->right = NULL;
node->left_child = FALSE;
node->right_child = FALSE;
node->key = key;
node->value = value;
return node;
}
/**
* q_tree_new:
* @key_compare_func: the function used to order the nodes in the #QTree.
* It should return values similar to the standard strcmp() function -
* 0 if the two arguments are equal, a negative value if the first argument
* comes before the second, or a positive value if the first argument comes
* after the second.
*
* Creates a new #QTree.
*
* Returns: a newly allocated #QTree
*/
QTree *
q_tree_new(GCompareFunc key_compare_func)
{
g_return_val_if_fail(key_compare_func != NULL, NULL);
return q_tree_new_full((GCompareDataFunc) key_compare_func, NULL,
NULL, NULL);
}
/**
* q_tree_new_with_data:
* @key_compare_func: qsort()-style comparison function
* @key_compare_data: data to pass to comparison function
*
* Creates a new #QTree with a comparison function that accepts user data.
* See q_tree_new() for more details.
*
* Returns: a newly allocated #QTree
*/
QTree *
q_tree_new_with_data(GCompareDataFunc key_compare_func,
gpointer key_compare_data)
{
g_return_val_if_fail(key_compare_func != NULL, NULL);
return q_tree_new_full(key_compare_func, key_compare_data,
NULL, NULL);
}
/**
* q_tree_new_full:
* @key_compare_func: qsort()-style comparison function
* @key_compare_data: data to pass to comparison function
* @key_destroy_func: a function to free the memory allocated for the key
* used when removing the entry from the #QTree or %NULL if you don't
* want to supply such a function
* @value_destroy_func: a function to free the memory allocated for the
* value used when removing the entry from the #QTree or %NULL if you
* don't want to supply such a function
*
* Creates a new #QTree like q_tree_new() and allows to specify functions
* to free the memory allocated for the key and value that get called when
* removing the entry from the #QTree.
*
* Returns: a newly allocated #QTree
*/
QTree *
q_tree_new_full(GCompareDataFunc key_compare_func,
gpointer key_compare_data,
GDestroyNotify key_destroy_func,
GDestroyNotify value_destroy_func)
{
QTree *tree;
g_return_val_if_fail(key_compare_func != NULL, NULL);
tree = g_new(QTree, 1);
tree->root = NULL;
tree->key_compare = key_compare_func;
tree->key_destroy_func = key_destroy_func;
tree->value_destroy_func = value_destroy_func;
tree->key_compare_data = key_compare_data;
tree->nnodes = 0;
tree->ref_count = 1;
return tree;
}
/**
* q_tree_node_first:
* @tree: a #QTree
*
* Returns the first in-order node of the tree, or %NULL
* for an empty tree.
*
* Returns: (nullable) (transfer none): the first node in the tree
*
* Since: 2.68 in GLib. Internal in Qtree, i.e. not in the public API.
*/
static QTreeNode *
q_tree_node_first(QTree *tree)
{
QTreeNode *tmp;
g_return_val_if_fail(tree != NULL, NULL);
if (!tree->root) {
return NULL;
}
tmp = tree->root;
while (tmp->left_child) {
tmp = tmp->left;
}
return tmp;
}
/**
* q_tree_node_previous
* @node: a #QTree node
*
* Returns the previous in-order node of the tree, or %NULL
* if the passed node was already the first one.
*
* Returns: (nullable) (transfer none): the previous node in the tree
*
* Since: 2.68 in GLib. Internal in Qtree, i.e. not in the public API.
*/
static QTreeNode *
q_tree_node_previous(QTreeNode *node)
{
QTreeNode *tmp;
g_return_val_if_fail(node != NULL, NULL);
tmp = node->left;
if (node->left_child) {
while (tmp->right_child) {
tmp = tmp->right;
}
}
return tmp;
}
/**
* q_tree_node_next
* @node: a #QTree node
*
* Returns the next in-order node of the tree, or %NULL
* if the passed node was already the last one.
*
* Returns: (nullable) (transfer none): the next node in the tree
*
* Since: 2.68 in GLib. Internal in Qtree, i.e. not in the public API.
*/
static QTreeNode *
q_tree_node_next(QTreeNode *node)
{
QTreeNode *tmp;
g_return_val_if_fail(node != NULL, NULL);
tmp = node->right;
if (node->right_child) {
while (tmp->left_child) {
tmp = tmp->left;
}
}
return tmp;
}
/**
* q_tree_remove_all:
* @tree: a #QTree
*
* Removes all nodes from a #QTree and destroys their keys and values,
* then resets the #QTree’s root to %NULL.
*
* Since: 2.70 in GLib. Internal in Qtree, i.e. not in the public API.
*/
static void QEMU_DISABLE_CFI
q_tree_remove_all(QTree *tree)
{
QTreeNode *node;
QTreeNode *next;
g_return_if_fail(tree != NULL);
node = q_tree_node_first(tree);
while (node) {
next = q_tree_node_next(node);
if (tree->key_destroy_func) {
tree->key_destroy_func(node->key);
}
if (tree->value_destroy_func) {
tree->value_destroy_func(node->value);
}
g_free(node);
#ifdef Q_TREE_DEBUG
g_assert(tree->nnodes > 0);
tree->nnodes--;
#endif
node = next;
}
#ifdef Q_TREE_DEBUG
g_assert(tree->nnodes == 0);
#endif
tree->root = NULL;
#ifndef Q_TREE_DEBUG
tree->nnodes = 0;
#endif
}
/**
* q_tree_ref:
* @tree: a #QTree
*
* Increments the reference count of @tree by one.
*
* It is safe to call this function from any thread.
*
* Returns: the passed in #QTree
*
* Since: 2.22
*/
QTree *
q_tree_ref(QTree *tree)
{
g_return_val_if_fail(tree != NULL, NULL);
g_atomic_int_inc(&tree->ref_count);
return tree;
}
/**
* q_tree_unref:
* @tree: a #QTree
*
* Decrements the reference count of @tree by one.
* If the reference count drops to 0, all keys and values will
* be destroyed (if destroy functions were specified) and all
* memory allocated by @tree will be released.
*
* It is safe to call this function from any thread.
*
* Since: 2.22
*/
void
q_tree_unref(QTree *tree)
{
g_return_if_fail(tree != NULL);
if (g_atomic_int_dec_and_test(&tree->ref_count)) {
q_tree_remove_all(tree);
g_free(tree);
}
}
/**
* q_tree_destroy:
* @tree: a #QTree
*
* Removes all keys and values from the #QTree and decreases its
* reference count by one. If keys and/or values are dynamically
* allocated, you should either free them first or create the #QTree
* using q_tree_new_full(). In the latter case the destroy functions
* you supplied will be called on all keys and values before destroying
* the #QTree.
*/
void
q_tree_destroy(QTree *tree)
{
g_return_if_fail(tree != NULL);
q_tree_remove_all(tree);
q_tree_unref(tree);
}
/**
* q_tree_insert_node:
* @tree: a #QTree
* @key: the key to insert
* @value: the value corresponding to the key
*
* Inserts a key/value pair into a #QTree.
*
* If the given key already exists in the #QTree its corresponding value
* is set to the new value. If you supplied a @value_destroy_func when
* creating the #QTree, the old value is freed using that function. If
* you supplied a @key_destroy_func when creating the #QTree, the passed
* key is freed using that function.
*
* The tree is automatically 'balanced' as new key/value pairs are added,
* so that the distance from the root to every leaf is as small as possible.
* The cost of maintaining a balanced tree while inserting new key/value
* result in a O(n log(n)) operation where most of the other operations
* are O(log(n)).
*
* Returns: (transfer none): the inserted (or set) node.
*
* Since: 2.68 in GLib. Internal in Qtree, i.e. not in the public API.
*/
static QTreeNode *
q_tree_insert_node(QTree *tree,
gpointer key,
gpointer value)
{
QTreeNode *node;
g_return_val_if_fail(tree != NULL, NULL);
node = q_tree_insert_internal(tree, key, value, FALSE);
#ifdef Q_TREE_DEBUG
q_tree_node_check(tree->root);
#endif
return node;
}
/**
* q_tree_insert:
* @tree: a #QTree
* @key: the key to insert
* @value: the value corresponding to the key
*
* Inserts a key/value pair into a #QTree.
*
* Inserts a new key and value into a #QTree as q_tree_insert_node() does,
* only this function does not return the inserted or set node.
*/
void
q_tree_insert(QTree *tree,
gpointer key,
gpointer value)
{
q_tree_insert_node(tree, key, value);
}
/**
* q_tree_replace_node:
* @tree: a #QTree
* @key: the key to insert
* @value: the value corresponding to the key
*
* Inserts a new key and value into a #QTree similar to q_tree_insert_node().
* The difference is that if the key already exists in the #QTree, it gets
* replaced by the new key. If you supplied a @value_destroy_func when
* creating the #QTree, the old value is freed using that function. If you
* supplied a @key_destroy_func when creating the #QTree, the old key is
* freed using that function.
*
* The tree is automatically 'balanced' as new key/value pairs are added,
* so that the distance from the root to every leaf is as small as possible.
*
* Returns: (transfer none): the inserted (or set) node.
*
* Since: 2.68 in GLib. Internal in Qtree, i.e. not in the public API.
*/
static QTreeNode *
q_tree_replace_node(QTree *tree,
gpointer key,
gpointer value)
{
QTreeNode *node;
g_return_val_if_fail(tree != NULL, NULL);
node = q_tree_insert_internal(tree, key, value, TRUE);
#ifdef Q_TREE_DEBUG
q_tree_node_check(tree->root);
#endif
return node;
}
/**
* q_tree_replace:
* @tree: a #QTree
* @key: the key to insert
* @value: the value corresponding to the key
*
* Inserts a new key and value into a #QTree as q_tree_replace_node() does,
* only this function does not return the inserted or set node.
*/
void
q_tree_replace(QTree *tree,
gpointer key,
gpointer value)
{
q_tree_replace_node(tree, key, value);
}
/* internal insert routine */
static QTreeNode * QEMU_DISABLE_CFI
q_tree_insert_internal(QTree *tree,
gpointer key,
gpointer value,
gboolean replace)
{
QTreeNode *node, *retnode;
QTreeNode *path[MAX_GTREE_HEIGHT];
int idx;
g_return_val_if_fail(tree != NULL, NULL);
if (!tree->root) {
tree->root = q_tree_node_new(key, value);
tree->nnodes++;
return tree->root;
}
idx = 0;
path[idx++] = NULL;
node = tree->root;
while (1) {
int cmp = tree->key_compare(key, node->key, tree->key_compare_data);
if (cmp == 0) {
if (tree->value_destroy_func) {
tree->value_destroy_func(node->value);
}
node->value = value;
if (replace) {
if (tree->key_destroy_func) {
tree->key_destroy_func(node->key);
}
node->key = key;
} else {
/* free the passed key */
if (tree->key_destroy_func) {
tree->key_destroy_func(key);
}
}
return node;
} else if (cmp < 0) {
if (node->left_child) {
path[idx++] = node;
node = node->left;
} else {
QTreeNode *child = q_tree_node_new(key, value);
child->left = node->left;
child->right = node;
node->left = child;
node->left_child = TRUE;
node->balance -= 1;
tree->nnodes++;
retnode = child;
break;
}
} else {
if (node->right_child) {
path[idx++] = node;
node = node->right;
} else {
QTreeNode *child = q_tree_node_new(key, value);
child->right = node->right;
child->left = node;
node->right = child;
node->right_child = TRUE;
node->balance += 1;
tree->nnodes++;
retnode = child;
break;
}
}
}
/*
* Restore balance. This is the goodness of a non-recursive
* implementation, when we are done with balancing we 'break'
* the loop and we are done.
*/
while (1) {
QTreeNode *bparent = path[--idx];
gboolean left_node = (bparent && node == bparent->left);
g_assert(!bparent || bparent->left == node || bparent->right == node);
if (node->balance < -1 || node->balance > 1) {
node = q_tree_node_balance(node);
if (bparent == NULL) {
tree->root = node;
} else if (left_node) {
bparent->left = node;
} else {
bparent->right = node;
}
}
if (node->balance == 0 || bparent == NULL) {
break;
}
if (left_node) {
bparent->balance -= 1;
} else {
bparent->balance += 1;
}
node = bparent;
}
return retnode;
}
/**
* q_tree_remove:
* @tree: a #QTree
* @key: the key to remove
*
* Removes a key/value pair from a #QTree.
*
* If the #QTree was created using q_tree_new_full(), the key and value
* are freed using the supplied destroy functions, otherwise you have to
* make sure that any dynamically allocated values are freed yourself.
* If the key does not exist in the #QTree, the function does nothing.
*
* The cost of maintaining a balanced tree while removing a key/value
* result in a O(n log(n)) operation where most of the other operations
* are O(log(n)).
*
* Returns: %TRUE if the key was found (prior to 2.8, this function
* returned nothing)
*/
gboolean
q_tree_remove(QTree *tree,
gconstpointer key)
{
gboolean removed;
g_return_val_if_fail(tree != NULL, FALSE);
removed = q_tree_remove_internal(tree, key, FALSE);
#ifdef Q_TREE_DEBUG
q_tree_node_check(tree->root);
#endif
return removed;
}
/**
* q_tree_steal:
* @tree: a #QTree
* @key: the key to remove
*
* Removes a key and its associated value from a #QTree without calling
* the key and value destroy functions.
*
* If the key does not exist in the #QTree, the function does nothing.
*
* Returns: %TRUE if the key was found (prior to 2.8, this function
* returned nothing)
*/
gboolean
q_tree_steal(QTree *tree,
gconstpointer key)
{
gboolean removed;
g_return_val_if_fail(tree != NULL, FALSE);
removed = q_tree_remove_internal(tree, key, TRUE);
#ifdef Q_TREE_DEBUG
q_tree_node_check(tree->root);
#endif
return removed;
}
/* internal remove routine */
static gboolean QEMU_DISABLE_CFI
q_tree_remove_internal(QTree *tree,
gconstpointer key,
gboolean steal)
{
QTreeNode *node, *parent, *balance;
QTreeNode *path[MAX_GTREE_HEIGHT];
int idx;
gboolean left_node;
g_return_val_if_fail(tree != NULL, FALSE);
if (!tree->root) {
return FALSE;
}
idx = 0;
path[idx++] = NULL;
node = tree->root;
while (1) {
int cmp = tree->key_compare(key, node->key, tree->key_compare_data);
if (cmp == 0) {
break;
} else if (cmp < 0) {
if (!node->left_child) {
return FALSE;
}
path[idx++] = node;
node = node->left;
} else {
if (!node->right_child) {
return FALSE;
}
path[idx++] = node;
node = node->right;
}
}
/*
* The following code is almost equal to q_tree_remove_node,
* except that we do not have to call q_tree_node_parent.
*/
balance = parent = path[--idx];
g_assert(!parent || parent->left == node || parent->right == node);
left_node = (parent && node == parent->left);
if (!node->left_child) {
if (!node->right_child) {
if (!parent) {
tree->root = NULL;
} else if (left_node) {
parent->left_child = FALSE;
parent->left = node->left;
parent->balance += 1;
} else {
parent->right_child = FALSE;
parent->right = node->right;
parent->balance -= 1;
}
} else {
/* node has a right child */
QTreeNode *tmp = q_tree_node_next(node);
tmp->left = node->left;
if (!parent) {
tree->root = node->right;
} else if (left_node) {
parent->left = node->right;
parent->balance += 1;
} else {
parent->right = node->right;
parent->balance -= 1;
}
}
} else {
/* node has a left child */
if (!node->right_child) {
QTreeNode *tmp = q_tree_node_previous(node);
tmp->right = node->right;
if (parent == NULL) {
tree->root = node->left;
} else if (left_node) {
parent->left = node->left;
parent->balance += 1;
} else {
parent->right = node->left;
parent->balance -= 1;
}
} else {
/* node has a both children (pant, pant!) */
QTreeNode *prev = node->left;
QTreeNode *next = node->right;
QTreeNode *nextp = node;
int old_idx = idx + 1;
idx++;
/* path[idx] == parent */
/* find the immediately next node (and its parent) */
while (next->left_child) {
path[++idx] = nextp = next;
next = next->left;
}
path[old_idx] = next;
balance = path[idx];
/* remove 'next' from the tree */
if (nextp != node) {
if (next->right_child) {
nextp->left = next->right;
} else {
nextp->left_child = FALSE;
}
nextp->balance += 1;
next->right_child = TRUE;
next->right = node->right;
} else {
node->balance -= 1;
}
/* set the prev to point to the right place */
while (prev->right_child) {
prev = prev->right;
}
prev->right = next;
/* prepare 'next' to replace 'node' */
next->left_child = TRUE;
next->left = node->left;
next->balance = node->balance;
if (!parent) {
tree->root = next;
} else if (left_node) {
parent->left = next;
} else {
parent->right = next;
}
}
}
/* restore balance */
if (balance) {
while (1) {
QTreeNode *bparent = path[--idx];
g_assert(!bparent ||
bparent->left == balance ||
bparent->right == balance);
left_node = (bparent && balance == bparent->left);
if (balance->balance < -1 || balance->balance > 1) {
balance = q_tree_node_balance(balance);
if (!bparent) {
tree->root = balance;
} else if (left_node) {
bparent->left = balance;
} else {
bparent->right = balance;
}
}
if (balance->balance != 0 || !bparent) {
break;
}
if (left_node) {
bparent->balance += 1;
} else {
bparent->balance -= 1;
}
balance = bparent;
}
}
if (!steal) {
if (tree->key_destroy_func) {
tree->key_destroy_func(node->key);
}
if (tree->value_destroy_func) {
tree->value_destroy_func(node->value);
}
}
g_free(node);
tree->nnodes--;
return TRUE;
}
/**
* q_tree_lookup_node:
* @tree: a #QTree
* @key: the key to look up
*
* Gets the tree node corresponding to the given key. Since a #QTree is
* automatically balanced as key/value pairs are added, key lookup
* is O(log n) (where n is the number of key/value pairs in the tree).
*
* Returns: (nullable) (transfer none): the tree node corresponding to
* the key, or %NULL if the key was not found
*
* Since: 2.68 in GLib. Internal in Qtree, i.e. not in the public API.
*/
static QTreeNode *
q_tree_lookup_node(QTree *tree,
gconstpointer key)
{
g_return_val_if_fail(tree != NULL, NULL);
return q_tree_find_node(tree, key);
}
/**
* q_tree_lookup:
* @tree: a #QTree
* @key: the key to look up
*
* Gets the value corresponding to the given key. Since a #QTree is
* automatically balanced as key/value pairs are added, key lookup
* is O(log n) (where n is the number of key/value pairs in the tree).
*
* Returns: the value corresponding to the key, or %NULL
* if the key was not found
*/
gpointer
q_tree_lookup(QTree *tree,
gconstpointer key)
{
QTreeNode *node;
node = q_tree_lookup_node(tree, key);
return node ? node->value : NULL;
}
/**
* q_tree_lookup_extended:
* @tree: a #QTree
* @lookup_key: the key to look up
* @orig_key: (out) (optional) (nullable): returns the original key
* @value: (out) (optional) (nullable): returns the value associated with
* the key
*
* Looks up a key in the #QTree, returning the original key and the
* associated value. This is useful if you need to free the memory
* allocated for the original key, for example before calling
* q_tree_remove().
*
* Returns: %TRUE if the key was found in the #QTree
*/
gboolean
q_tree_lookup_extended(QTree *tree,
gconstpointer lookup_key,
gpointer *orig_key,
gpointer *value)
{
QTreeNode *node;
g_return_val_if_fail(tree != NULL, FALSE);
node = q_tree_find_node(tree, lookup_key);
if (node) {
if (orig_key) {
*orig_key = node->key;
}
if (value) {
*value = node->value;
}
return TRUE;
} else {
return FALSE;
}
}
/**
* q_tree_foreach:
* @tree: a #QTree
* @func: the function to call for each node visited.
* If this function returns %TRUE, the traversal is stopped.
* @user_data: user data to pass to the function
*
* Calls the given function for each of the key/value pairs in the #QTree.
* The function is passed the key and value of each pair, and the given
* @data parameter. The tree is traversed in sorted order.
*
* The tree may not be modified while iterating over it (you can't
* add/remove items). To remove all items matching a predicate, you need
* to add each item to a list in your #GTraverseFunc as you walk over
* the tree, then walk the list and remove each item.
*/
void
q_tree_foreach(QTree *tree,
GTraverseFunc func,
gpointer user_data)
{
QTreeNode *node;
g_return_if_fail(tree != NULL);
if (!tree->root) {
return;
}
node = q_tree_node_first(tree);
while (node) {
if ((*func)(node->key, node->value, user_data)) {
break;
}
node = q_tree_node_next(node);
}
}
/**
* q_tree_search_node:
* @tree: a #QTree
* @search_func: a function used to search the #QTree
* @user_data: the data passed as the second argument to @search_func
*
* Searches a #QTree using @search_func.
*
* The @search_func is called with a pointer to the key of a key/value
* pair in the tree, and the passed in @user_data. If @search_func returns
* 0 for a key/value pair, then the corresponding node is returned as
* the result of q_tree_search(). If @search_func returns -1, searching
* will proceed among the key/value pairs that have a smaller key; if
* @search_func returns 1, searching will proceed among the key/value
* pairs that have a larger key.
*
* Returns: (nullable) (transfer none): the node corresponding to the
* found key, or %NULL if the key was not found
*
* Since: 2.68 in GLib. Internal in Qtree, i.e. not in the public API.
*/
static QTreeNode *
q_tree_search_node(QTree *tree,
GCompareFunc search_func,
gconstpointer user_data)
{
g_return_val_if_fail(tree != NULL, NULL);
if (!tree->root) {
return NULL;
}
return q_tree_node_search(tree->root, search_func, user_data);
}
/**
* q_tree_search:
* @tree: a #QTree
* @search_func: a function used to search the #QTree
* @user_data: the data passed as the second argument to @search_func
*
* Searches a #QTree using @search_func.
*
* The @search_func is called with a pointer to the key of a key/value
* pair in the tree, and the passed in @user_data. If @search_func returns
* 0 for a key/value pair, then the corresponding value is returned as
* the result of q_tree_search(). If @search_func returns -1, searching
* will proceed among the key/value pairs that have a smaller key; if
* @search_func returns 1, searching will proceed among the key/value
* pairs that have a larger key.
*
* Returns: the value corresponding to the found key, or %NULL
* if the key was not found
*/
gpointer
q_tree_search(QTree *tree,
GCompareFunc search_func,
gconstpointer user_data)
{
QTreeNode *node;
node = q_tree_search_node(tree, search_func, user_data);
return node ? node->value : NULL;
}
/**
* q_tree_height:
* @tree: a #QTree
*
* Gets the height of a #QTree.
*
* If the #QTree contains no nodes, the height is 0.
* If the #QTree contains only one root node the height is 1.
* If the root node has children the height is 2, etc.
*
* Returns: the height of @tree
*/
gint
q_tree_height(QTree *tree)
{
QTreeNode *node;
gint height;
g_return_val_if_fail(tree != NULL, 0);
if (!tree->root) {
return 0;
}
height = 0;
node = tree->root;
while (1) {
height += 1 + MAX(node->balance, 0);
if (!node->left_child) {
return height;
}
node = node->left;
}
}
/**
* q_tree_nnodes:
* @tree: a #QTree
*
* Gets the number of nodes in a #QTree.
*
* Returns: the number of nodes in @tree
*/
gint
q_tree_nnodes(QTree *tree)
{
g_return_val_if_fail(tree != NULL, 0);
return tree->nnodes;
}
static QTreeNode *
q_tree_node_balance(QTreeNode *node)
{
if (node->balance < -1) {
if (node->left->balance > 0) {
node->left = q_tree_node_rotate_left(node->left);
}
node = q_tree_node_rotate_right(node);
} else if (node->balance > 1) {
if (node->right->balance < 0) {
node->right = q_tree_node_rotate_right(node->right);
}
node = q_tree_node_rotate_left(node);
}
return node;
}
static QTreeNode * QEMU_DISABLE_CFI
q_tree_find_node(QTree *tree,
gconstpointer key)
{
QTreeNode *node;
gint cmp;
node = tree->root;
if (!node) {
return NULL;
}
while (1) {
cmp = tree->key_compare(key, node->key, tree->key_compare_data);
if (cmp == 0) {
return node;
} else if (cmp < 0) {
if (!node->left_child) {
return NULL;
}
node = node->left;
} else {
if (!node->right_child) {
return NULL;
}
node = node->right;
}
}
}
static QTreeNode *
q_tree_node_search(QTreeNode *node,
GCompareFunc search_func,
gconstpointer data)
{
gint dir;
if (!node) {
return NULL;
}
while (1) {
dir = (*search_func)(node->key, data);
if (dir == 0) {
return node;
} else if (dir < 0) {
if (!node->left_child) {
return NULL;
}
node = node->left;
} else {
if (!node->right_child) {
return NULL;
}
node = node->right;
}
}
}
static QTreeNode *
q_tree_node_rotate_left(QTreeNode *node)
{
QTreeNode *right;
gint a_bal;
gint b_bal;
right = node->right;
if (right->left_child) {
node->right = right->left;
} else {
node->right_child = FALSE;
right->left_child = TRUE;
}
right->left = node;
a_bal = node->balance;
b_bal = right->balance;
if (b_bal <= 0) {
if (a_bal >= 1) {
right->balance = b_bal - 1;
} else {
right->balance = a_bal + b_bal - 2;
}
node->balance = a_bal - 1;
} else {
if (a_bal <= b_bal) {
right->balance = a_bal - 2;
} else {
right->balance = b_bal - 1;
}
node->balance = a_bal - b_bal - 1;
}
return right;
}
static QTreeNode *
q_tree_node_rotate_right(QTreeNode *node)
{
QTreeNode *left;
gint a_bal;
gint b_bal;
left = node->left;
if (left->right_child) {
node->left = left->right;
} else {
node->left_child = FALSE;
left->right_child = TRUE;
}
left->right = node;
a_bal = node->balance;
b_bal = left->balance;
if (b_bal <= 0) {
if (b_bal > a_bal) {
left->balance = b_bal + 1;
} else {
left->balance = a_bal + 2;
}
node->balance = a_bal - b_bal + 1;
} else {
if (a_bal <= -1) {
left->balance = b_bal + 1;
} else {
left->balance = a_bal + b_bal + 2;
}
node->balance = a_bal + 1;
}
return left;
}
#ifdef Q_TREE_DEBUG
static gint
q_tree_node_height(QTreeNode *node)
{
gint left_height;
gint right_height;
if (node) {
left_height = 0;
right_height = 0;
if (node->left_child) {
left_height = q_tree_node_height(node->left);
}
if (node->right_child) {
right_height = q_tree_node_height(node->right);
}
return MAX(left_height, right_height) + 1;
}
return 0;
}
static void q_tree_node_check(QTreeNode *node)
{
gint left_height;
gint right_height;
gint balance;
QTreeNode *tmp;
if (node) {
if (node->left_child) {
tmp = q_tree_node_previous(node);
g_assert(tmp->right == node);
}
if (node->right_child) {
tmp = q_tree_node_next(node);
g_assert(tmp->left == node);
}
left_height = 0;
right_height = 0;
if (node->left_child) {
left_height = q_tree_node_height(node->left);
}
if (node->right_child) {
right_height = q_tree_node_height(node->right);
}
balance = right_height - left_height;
g_assert(balance == node->balance);
if (node->left_child) {
q_tree_node_check(node->left);
}
if (node->right_child) {
q_tree_node_check(node->right);
}
}
}
#endif
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