/*
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
*
* Copyright 2024 Mike Becker, Olaf Wintermann All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include "cx/tree.h"
#include "cx/array_list.h"
#include <assert.h>
#define CX_TREE_PTR(cur, off) (*(void**)(((char*)(cur))+(off)))
#define tree_parent(node) CX_TREE_PTR(node, loc_parent)
#define tree_children(node) CX_TREE_PTR(node, loc_children)
#define tree_last_child(node) CX_TREE_PTR(node, loc_last_child)
#define tree_prev(node) CX_TREE_PTR(node, loc_prev)
#define tree_next(node) CX_TREE_PTR(node, loc_next)
#define cx_tree_ptr_locations \
loc_parent, loc_children, loc_last_child, loc_prev, loc_next
static void cx_tree_zero_pointers(
void *node,
ptrdiff_t loc_parent,
ptrdiff_t loc_children,
ptrdiff_t loc_last_child,
ptrdiff_t loc_prev,
ptrdiff_t loc_next
) {
tree_parent(node) = NULL;
tree_prev(node) = NULL;
tree_next(node) = NULL;
tree_children(node) = NULL;
if (loc_last_child >= 0) {
tree_last_child(node) = NULL;
}
}
void cx_tree_link(
void *restrict parent,
void *restrict node,
ptrdiff_t loc_parent,
ptrdiff_t loc_children,
ptrdiff_t loc_last_child,
ptrdiff_t loc_prev,
ptrdiff_t loc_next
) {
void *current_parent = tree_parent(node);
if (current_parent == parent) return;
if (current_parent != NULL) {
cx_tree_unlink(node, cx_tree_ptr_locations);
}
if (tree_children(parent) == NULL) {
tree_children(parent) = node;
if (loc_last_child >= 0) {
tree_last_child(parent) = node;
}
} else {
if (loc_last_child >= 0) {
void *child = tree_last_child(parent);
tree_prev(node) = child;
tree_next(child) = node;
tree_last_child(parent) = node;
} else {
void *child = tree_children(parent);
void *next;
while ((next = tree_next(child)) != NULL) {
child = next;
}
tree_prev(node) = child;
tree_next(child) = node;
}
}
tree_parent(node) = parent;
}
void cx_tree_unlink(
void *node,
ptrdiff_t loc_parent,
ptrdiff_t loc_children,
ptrdiff_t loc_last_child,
ptrdiff_t loc_prev,
ptrdiff_t loc_next
) {
if (tree_parent(node) == NULL) return;
void *left = tree_prev(node);
void *right = tree_next(node);
void *parent = tree_parent(node);
assert(left == NULL || tree_children(parent) != node);
assert(right == NULL || loc_last_child < 0 ||
tree_last_child(parent) != node);
if (left == NULL) {
tree_children(parent) = right;
} else {
tree_next(left) = right;
}
if (right == NULL) {
if (loc_last_child >= 0) {
tree_last_child(parent) = left;
}
} else {
tree_prev(right) = left;
}
tree_parent(node) = NULL;
tree_prev(node) = NULL;
tree_next(node) = NULL;
}
int cx_tree_search(
const void *root,
const void *node,
cx_tree_search_func sfunc,
void **result,
ptrdiff_t loc_children,
ptrdiff_t loc_next
) {
int ret;
*result = NULL;
// shortcut: compare root before doing anything else
ret = sfunc(root, node);
if (ret < 0) {
return ret;
} else if (ret == 0 || tree_children(root) == NULL) {
*result = (void*)root;
return ret;
}
// create a working stack
CX_ARRAY_DECLARE(const void *, work);
cx_array_initialize(work, 32);
// add the children of root to the working stack
{
void *c = tree_children(root);
while (c != NULL) {
cx_array_simple_add(work, c);
c = tree_next(c);
}
}
// remember a candidate for adding the data
// also remember the exact return code from sfunc
void *candidate = (void *) root;
int ret_candidate = ret;
// process the working stack
while (work_size > 0) {
// pop element
const void *elem = work[--work_size];
// apply the search function
ret = sfunc(elem, node);
if (ret == 0) {
// if found, exit the search
*result = (void *) elem;
work_size = 0;
break;
} else if (ret > 0) {
// if children might contain the data, add them to the stack
void *c = tree_children(elem);
while (c != NULL) {
cx_array_simple_add(work, c);
c = tree_next(c);
}
// remember this node in case no child is suitable
if (ret < ret_candidate) {
candidate = (void *) elem;
ret_candidate = ret;
}
}
}
// not found, but was there a candidate?
if (ret != 0 && candidate != NULL) {
ret = ret_candidate;
*result = candidate;
}
// free the working queue and return
free(work);
return ret;
}
int cx_tree_search_data(
const void *root,
const void *data,
cx_tree_search_data_func sfunc,
void **result,
ptrdiff_t loc_children,
ptrdiff_t loc_next
) {
// it is basically the same implementation
return cx_tree_search(
root, data,
(cx_tree_search_func) sfunc,
result,
loc_children, loc_next);
}
static bool cx_tree_iter_valid(const void *it) {
const struct cx_tree_iterator_s *iter = it;
return iter->node != NULL;
}
static void *cx_tree_iter_current(const void *it) {
const struct cx_tree_iterator_s *iter = it;
return iter->node;
}
static void cx_tree_iter_next(void *it) {
struct cx_tree_iterator_s *iter = it;
ptrdiff_t const loc_next = iter->loc_next;
ptrdiff_t const loc_children = iter->loc_children;
// protect us from misuse
if (!iter->base.valid(iter)) return;
void *children;
// check if we are currently exiting or entering nodes
if (iter->exiting) {
children = NULL;
// skipping on exit is pointless, just clear the flag
iter->skip = false;
} else {
if (iter->skip) {
// skip flag is set, pretend that there are no children
iter->skip = false;
children = NULL;
} else {
// try to enter the children (if any)
children = tree_children(iter->node);
}
}
if (children == NULL) {
// search for the next node
void *next;
cx_tree_iter_search_next:
// check if there is a sibling
if (iter->exiting) {
next = iter->node_next;
} else {
next = tree_next(iter->node);
iter->node_next = next;
}
if (next == NULL) {
// no sibling, we are done with this node and exit
if (iter->visit_on_exit && !iter->exiting) {
// iter is supposed to visit the node again
iter->exiting = true;
} else {
iter->exiting = false;
if (iter->depth == 1) {
// there is no parent - we have iterated the entire tree
// invalidate the iterator and free the node stack
iter->node = iter->node_next = NULL;
iter->stack_capacity = iter->depth = 0;
free(iter->stack);
iter->stack = NULL;
} else {
// the parent node can be obtained from the top of stack
// this way we can avoid the loc_parent in the iterator
iter->depth--;
iter->node = iter->stack[iter->depth - 1];
// retry with the parent node to find a sibling
goto cx_tree_iter_search_next;
}
}
} else {
if (iter->visit_on_exit && !iter->exiting) {
// iter is supposed to visit the node again
iter->exiting = true;
} else {
iter->exiting = false;
// move to the sibling
iter->counter++;
iter->node = next;
// new top of stack is the sibling
iter->stack[iter->depth - 1] = next;
}
}
} else {
// node has children, push the first child onto the stack and enter it
cx_array_simple_add(iter->stack, children);
iter->node = children;
iter->counter++;
}
}
CxTreeIterator cx_tree_iterator(
void *root,
bool visit_on_exit,
ptrdiff_t loc_children,
ptrdiff_t loc_next
) {
CxTreeIterator iter;
iter.loc_children = loc_children;
iter.loc_next = loc_next;
iter.visit_on_exit = visit_on_exit;
// initialize members
iter.node_next = NULL;
iter.exiting = false;
iter.skip = false;
// assign base iterator functions
iter.base.mutating = false;
iter.base.remove = false;
iter.base.current_impl = NULL;
iter.base.valid = cx_tree_iter_valid;
iter.base.next = cx_tree_iter_next;
iter.base.current = cx_tree_iter_current;
// visit the root node
iter.node = root;
if (root != NULL) {
iter.stack_capacity = 16;
iter.stack = malloc(sizeof(void *) * 16);
iter.stack[0] = root;
iter.counter = 1;
iter.depth = 1;
} else {
iter.stack_capacity = 0;
iter.stack = NULL;
iter.counter = 0;
iter.depth = 0;
}
return iter;
}
static bool cx_tree_visitor_valid(const void *it) {
const struct cx_tree_visitor_s *iter = it;
return iter->node != NULL;
}
static void *cx_tree_visitor_current(const void *it) {
const struct cx_tree_visitor_s *iter = it;
return iter->node;
}
__attribute__((__nonnull__))
static void cx_tree_visitor_enqueue_siblings(
struct cx_tree_visitor_s *iter, void *node, ptrdiff_t loc_next) {
node = tree_next(node);
while (node != NULL) {
struct cx_tree_visitor_queue_s *q;
q = malloc(sizeof(struct cx_tree_visitor_queue_s));
q->depth = iter->queue_last->depth;
q->node = node;
iter->queue_last->next = q;
iter->queue_last = q;
node = tree_next(node);
}
iter->queue_last->next = NULL;
}
static void cx_tree_visitor_next(void *it) {
struct cx_tree_visitor_s *iter = it;
// protect us from misuse
if (!iter->base.valid(iter)) return;
ptrdiff_t const loc_next = iter->loc_next;
ptrdiff_t const loc_children = iter->loc_children;
// add the children of the current node to the queue
// unless the skip flag is set
void *children;
if (iter->skip) {
iter->skip = false;
children = NULL;
} else {
children = tree_children(iter->node);
}
if (children != NULL) {
struct cx_tree_visitor_queue_s *q;
q = malloc(sizeof(struct cx_tree_visitor_queue_s));
q->depth = iter->depth + 1;
q->node = children;
if (iter->queue_last == NULL) {
assert(iter->queue_next == NULL);
iter->queue_next = q;
} else {
iter->queue_last->next = q;
}
iter->queue_last = q;
cx_tree_visitor_enqueue_siblings(iter, children, loc_next);
}
// check if there is a next node
if (iter->queue_next == NULL) {
iter->node = NULL;
return;
}
// dequeue the next node
iter->node = iter->queue_next->node;
iter->depth = iter->queue_next->depth;
{
struct cx_tree_visitor_queue_s *q = iter->queue_next;
iter->queue_next = q->next;
if (iter->queue_next == NULL) {
assert(iter->queue_last == q);
iter->queue_last = NULL;
}
free(q);
}
// increment the node counter
iter->counter++;
}
CxTreeVisitor cx_tree_visitor(
void *root,
ptrdiff_t loc_children,
ptrdiff_t loc_next
) {
CxTreeVisitor iter;
iter.loc_children = loc_children;
iter.loc_next = loc_next;
// initialize members
iter.skip = false;
iter.queue_next = NULL;
iter.queue_last = NULL;
// assign base iterator functions
iter.base.mutating = false;
iter.base.remove = false;
iter.base.current_impl = NULL;
iter.base.valid = cx_tree_visitor_valid;
iter.base.next = cx_tree_visitor_next;
iter.base.current = cx_tree_visitor_current;
// visit the root node
iter.node = root;
if (root != NULL) {
iter.counter = 1;
iter.depth = 1;
} else {
iter.counter = 0;
iter.depth = 0;
}
return iter;
}
static void cx_tree_add_link_duplicate(
void *original, void *duplicate,
ptrdiff_t loc_parent, ptrdiff_t loc_children, ptrdiff_t loc_last_child,
ptrdiff_t loc_prev, ptrdiff_t loc_next
) {
void *shared_parent = tree_parent(original);
if (shared_parent == NULL) {
cx_tree_link(original, duplicate, cx_tree_ptr_locations);
} else {
cx_tree_link(shared_parent, duplicate, cx_tree_ptr_locations);
}
}
static void cx_tree_add_link_new(
void *parent, void *node, cx_tree_search_func sfunc,
ptrdiff_t loc_parent, ptrdiff_t loc_children, ptrdiff_t loc_last_child,
ptrdiff_t loc_prev, ptrdiff_t loc_next
) {
// check the current children one by one,
// if they could be children of the new node
void *child = tree_children(parent);
while (child != NULL) {
void *next = tree_next(child);
if (sfunc(node, child) > 0) {
// the sibling could be a child -> re-link
cx_tree_link(node, child, cx_tree_ptr_locations);
}
child = next;
}
// add new node as new child
cx_tree_link(parent, node, cx_tree_ptr_locations);
}
int cx_tree_add(
const void *src,
cx_tree_search_func sfunc,
cx_tree_node_create_func cfunc,
void *cdata,
void **cnode,
void *root,
ptrdiff_t loc_parent,
ptrdiff_t loc_children,
ptrdiff_t loc_last_child,
ptrdiff_t loc_prev,
ptrdiff_t loc_next
) {
*cnode = cfunc(src, cdata);
if (*cnode == NULL) return 1;
cx_tree_zero_pointers(*cnode, cx_tree_ptr_locations);
void *match = NULL;
int result = cx_tree_search(
root,
*cnode,
sfunc,
&match,
loc_children,
loc_next
);
if (result < 0) {
// node does not fit into the tree - return non-zero value
return 1;
} else if (result == 0) {
// data already found in the tree, link duplicate
cx_tree_add_link_duplicate(match, *cnode, cx_tree_ptr_locations);
} else {
// closest match found, add new node
cx_tree_add_link_new(match, *cnode, sfunc, cx_tree_ptr_locations);
}
return 0;
}
unsigned int cx_tree_add_look_around_depth = 3;
size_t cx_tree_add_iter(
struct cx_iterator_base_s *iter,
size_t num,
cx_tree_search_func sfunc,
cx_tree_node_create_func cfunc,
void *cdata,
void **failed,
void *root,
ptrdiff_t loc_parent,
ptrdiff_t loc_children,
ptrdiff_t loc_last_child,
ptrdiff_t loc_prev,
ptrdiff_t loc_next
) {
// erase the failed pointer
*failed = NULL;
// iter not valid? cancel...
if (!iter->valid(iter)) return 0;
size_t processed = 0;
void *current_node = root;
const void *elem;
for (void **eptr; processed < num &&
iter->valid(iter) && (eptr = iter->current(iter)) != NULL;
iter->next(iter)) {
elem = *eptr;
// create the new node
void *new_node = cfunc(elem, cdata);
if (new_node == NULL) return processed;
cx_tree_zero_pointers(new_node, cx_tree_ptr_locations);
// start searching from current node
void *match;
int result;
unsigned int look_around_retries = cx_tree_add_look_around_depth;
cx_tree_add_look_around_retry:
result = cx_tree_search(
current_node,
new_node,
sfunc,
&match,
loc_children,
loc_next
);
if (result < 0) {
// traverse upwards and try to find better parents
void *parent = tree_parent(current_node);
if (parent != NULL) {
if (look_around_retries > 0) {
look_around_retries--;
current_node = parent;
} else {
// look around retries exhausted, start from the root
current_node = root;
}
goto cx_tree_add_look_around_retry;
} else {
// no parents. so we failed
*failed = new_node;
return processed;
}
} else if (result == 0) {
// data already found in the tree, link duplicate
cx_tree_add_link_duplicate(match, new_node, cx_tree_ptr_locations);
// but stick with the original match, in case we needed a new root
current_node = match;
} else {
// closest match found, add new node as child
cx_tree_add_link_new(match, new_node, sfunc,
cx_tree_ptr_locations);
current_node = match;
}
processed++;
}
return processed;
}
size_t cx_tree_add_array(
const void *src,
size_t num,
size_t elem_size,
cx_tree_search_func sfunc,
cx_tree_node_create_func cfunc,
void *cdata,
void **failed,
void *root,
ptrdiff_t loc_parent,
ptrdiff_t loc_children,
ptrdiff_t loc_last_child,
ptrdiff_t loc_prev,
ptrdiff_t loc_next
) {
// erase failed pointer
*failed = NULL;
// super special case: zero elements
if (num == 0) {
return 0;
}
// special case: one element does not need an iterator
if (num == 1) {
void *node;
if (0 == cx_tree_add(
src, sfunc, cfunc, cdata, &node, root,
loc_parent, loc_children, loc_last_child,
loc_prev, loc_next)) {
return 1;
} else {
*failed = node;
return 0;
}
}
// otherwise, create iterator and hand over to other function
CxIterator iter = cxIterator(src, elem_size, num);
return cx_tree_add_iter(cxIteratorRef(iter), num, sfunc,
cfunc, cdata, failed, root,
loc_parent, loc_children, loc_last_child,
loc_prev, loc_next);
}
static void cx_tree_default_destructor(CxTree *tree) {
if (tree->simple_destructor != NULL || tree->advanced_destructor != NULL) {
CxTreeIterator iter = tree->cl->iterator(tree, true);
cx_foreach(void *, node, iter) {
if (iter.exiting) {
if (tree->simple_destructor) {
tree->simple_destructor(node);
}
if (tree->advanced_destructor) {
tree->advanced_destructor(tree->destructor_data, node);
}
}
}
}
cxFree(tree->allocator, tree);
}
static CxTreeIterator cx_tree_default_iterator(
CxTree *tree,
bool visit_on_exit
) {
return cx_tree_iterator(
tree->root, visit_on_exit,
tree->loc_children, tree->loc_next
);
}
static CxTreeVisitor cx_tree_default_visitor(CxTree *tree) {
return cx_tree_visitor(tree->root, tree->loc_children, tree->loc_next);
}
static int cx_tree_default_insert_element(
CxTree *tree,
const void *data
) {
void *node;
if (tree->root == NULL) {
node = tree->node_create(data, tree);
if (node == NULL) return 1;
cx_tree_zero_pointers(node, cx_tree_node_layout(tree));
tree->root = node;
tree->size = 1;
return 0;
}
int result = cx_tree_add(data, tree->search, tree->node_create,
tree, &node, tree->root, cx_tree_node_layout(tree));
if (0 == result) {
tree->size++;
} else {
cxFree(tree->allocator, node);
}
return result;
}
static size_t cx_tree_default_insert_many(
CxTree *tree,
struct cx_iterator_base_s *iter,
size_t n
) {
size_t ins = 0;
if (!iter->valid(iter)) return 0;
if (tree->root == NULL) {
// use the first element from the iter to create the root node
void **eptr = iter->current(iter);
void *node = tree->node_create(*eptr, tree);
if (node == NULL) return 0;
cx_tree_zero_pointers(node, cx_tree_node_layout(tree));
tree->root = node;
ins = 1;
iter->next(iter);
}
void *failed;
ins += cx_tree_add_iter(iter, n, tree->search, tree->node_create,
tree, &failed, tree->root, cx_tree_node_layout(tree));
tree->size += ins;
if (ins < n) {
cxFree(tree->allocator, failed);
}
return ins;
}
static void *cx_tree_default_find(
CxTree *tree,
const void *subtree,
const void *data
) {
if (tree->root == NULL) return NULL;
void *found;
if (0 == cx_tree_search_data(
subtree,
data,
tree->search_data,
&found,
tree->loc_children,
tree->loc_next
)) {
return found;
} else {
return NULL;
}
}
static cx_tree_class cx_tree_default_class = {
cx_tree_default_destructor,
cx_tree_default_insert_element,
cx_tree_default_insert_many,
cx_tree_default_find,
cx_tree_default_iterator,
cx_tree_default_visitor
};
CxTree *cxTreeCreate(
const CxAllocator *allocator,
cx_tree_node_create_func create_func,
cx_tree_search_func search_func,
cx_tree_search_data_func search_data_func,
ptrdiff_t loc_parent,
ptrdiff_t loc_children,
ptrdiff_t loc_last_child,
ptrdiff_t loc_prev,
ptrdiff_t loc_next
) {
CxTree *tree = cxMalloc(allocator, sizeof(CxTree));
if (tree == NULL) return NULL;
tree->cl = &cx_tree_default_class;
tree->allocator = allocator;
tree->node_create = create_func;
tree->search = search_func;
tree->search_data = search_data_func;
tree->advanced_destructor = (cx_destructor_func2) cxFree;
tree->destructor_data = (void *) allocator;
tree->loc_parent = loc_parent;
tree->loc_children = loc_children;
tree->loc_last_child = loc_last_child;
tree->loc_prev = loc_prev;
tree->loc_next = loc_next;
tree->root = NULL;
tree->size = 0;
return tree;
}
CxTree *cxTreeCreateWrapped(
const CxAllocator *allocator,
void *root,
ptrdiff_t loc_parent,
ptrdiff_t loc_children,
ptrdiff_t loc_last_child,
ptrdiff_t loc_prev,
ptrdiff_t loc_next
) {
CxTree *tree = cxMalloc(allocator, sizeof(CxTree));
if (tree == NULL) return NULL;
tree->cl = &cx_tree_default_class;
// set the allocator anyway, just in case...
tree->allocator = allocator;
tree->node_create = NULL;
tree->search = NULL;
tree->search_data = NULL;
tree->simple_destructor = NULL;
tree->advanced_destructor = NULL;
tree->destructor_data = NULL;
tree->loc_parent = loc_parent;
tree->loc_children = loc_children;
tree->loc_last_child = loc_last_child;
tree->loc_prev = loc_prev;
tree->loc_next = loc_next;
tree->root = root;
tree->size = cxTreeSubtreeSize(tree, root);
return tree;
}
int cxTreeAddChild(
CxTree *tree,
void *parent,
const void *data) {
void *node = tree->node_create(data, tree);
if (node == NULL) return 1;
cx_tree_zero_pointers(node, cx_tree_node_layout(tree));
cx_tree_link(parent, node, cx_tree_node_layout(tree));
tree->size++;
return 0;
}
size_t cxTreeSubtreeSize(CxTree *tree, void *subtree_root) {
CxTreeVisitor visitor = cx_tree_visitor(
subtree_root,
tree->loc_children,
tree->loc_next
);
while (cxIteratorValid(visitor)) {
cxIteratorNext(visitor);
}
return visitor.counter;
}
size_t cxTreeSubtreeDepth(CxTree *tree, void *subtree_root) {
CxTreeVisitor visitor = cx_tree_visitor(
subtree_root,
tree->loc_children,
tree->loc_next
);
while (cxIteratorValid(visitor)) {
cxIteratorNext(visitor);
}
return visitor.depth;
}
size_t cxTreeDepth(CxTree *tree) {
CxTreeVisitor visitor = tree->cl->visitor(tree);
while (cxIteratorValid(visitor)) {
cxIteratorNext(visitor);
}
return visitor.depth;
}
int cxTreeRemove(
CxTree *tree,
void *node,
cx_tree_relink_func relink_func
) {
if (node == tree->root) return 1;
// determine the new parent
ptrdiff_t loc_parent = tree->loc_parent;
void *new_parent = tree_parent(node);
// first, unlink from the parent
cx_tree_unlink(node, cx_tree_node_layout(tree));
// then relink each child
ptrdiff_t loc_children = tree->loc_children;
ptrdiff_t loc_next = tree->loc_next;
void *child = tree_children(node);
while (child != NULL) {
// forcibly set the parent to NULL - we do not use the unlink function
// because that would unnecessarily modify the children linked list
tree_parent(child) = NULL;
// update contents, if required
if (relink_func != NULL) {
relink_func(child, node, new_parent);
}
// link to new parent
cx_tree_link(new_parent, child, cx_tree_node_layout(tree));
// proceed to next child
child = tree_next(child);
}
// clear the linked list of the removed node
tree_children(node) = NULL;
ptrdiff_t loc_last_child = tree->loc_last_child;
if (loc_last_child >= 0) tree_last_child(node) = NULL;
// the tree now has one member less
tree->size--;
return 0;
}
void cxTreeRemoveSubtree(CxTree *tree, void *node) {
if (node == tree->root) {
tree->root = NULL;
tree->size = 0;
return;
}
size_t subtree_size = cxTreeSubtreeSize(tree, node);
cx_tree_unlink(node, cx_tree_node_layout(tree));
tree->size -= subtree_size;
}