--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/ucx/tree.c Thu May 23 22:35:45 2024 +0200
@@ -0,0 +1,401 @@
+/*
+ * 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 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_prev(node) CX_TREE_PTR(node, loc_prev)
+#define tree_next(node) CX_TREE_PTR(node, loc_next)
+
+void cx_tree_link(
+ void *restrict parent,
+ void *restrict node,
+ ptrdiff_t loc_parent,
+ ptrdiff_t loc_children,
+ 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, loc_parent, loc_children,
+ loc_prev, loc_next);
+ }
+
+ if (tree_children(parent) == NULL) {
+ tree_children(parent) = node;
+ } else {
+ void *children = tree_children(parent);
+ tree_prev(children) = node;
+ tree_next(node) = children;
+ tree_children(parent) = node;
+ }
+ tree_parent(node) = parent;
+}
+
+void cx_tree_unlink(
+ void *node,
+ ptrdiff_t loc_parent,
+ ptrdiff_t loc_children,
+ ptrdiff_t loc_prev,
+ ptrdiff_t loc_next
+) {
+ if (tree_parent(node) == NULL) return;
+
+ void *left = tree_prev(node);
+ void *right = tree_next(node);
+ assert(left == NULL || tree_children(tree_parent(node)) != node);
+ if (left == NULL) {
+ tree_children(tree_parent(node)) = right;
+ } else {
+ tree_next(left) = right;
+ }
+ if (right != NULL) tree_prev(right) = left;
+ tree_parent(node) = NULL;
+ tree_prev(node) = NULL;
+ tree_next(node) = NULL;
+}
+
+int cx_tree_search(
+ void const *root,
+ void const *data,
+ 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, data);
+ 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(void const*, 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 = NULL;
+ int ret_candidate = -1;
+
+ // process the working stack
+ while (work_size > 0) {
+ // pop element
+ void const *node = work[--work_size];
+
+ // apply the search function
+ ret = sfunc(node, data);
+
+ if (ret == 0) {
+ // if found, exit the search
+ *result = (void*) node;
+ work_size = 0;
+ break;
+ } else if (ret > 0) {
+ // if children might contain the data, add them to the stack
+ void *c = tree_children(node);
+ while (c != NULL) {
+ cx_array_simple_add(work, c);
+ c = tree_next(c);
+ }
+
+ // remember this node in case no child is suitable
+ if (ret_candidate < 0 || ret < ret_candidate) {
+ candidate = (void *) node;
+ 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;
+}
+
+static bool cx_tree_iter_valid(void const *it) {
+ struct cx_tree_iterator_s const *iter = it;
+ return iter->node != NULL;
+}
+
+static void *cx_tree_iter_current(void const *it) {
+ struct cx_tree_iterator_s const *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;
+
+ 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;
+
+ // allocate stack
+ iter.stack_capacity = 16;
+ iter.stack = malloc(sizeof(void *) * 16);
+ iter.depth = 0;
+
+ // visit the root node
+ iter.node = root;
+ iter.node_next = NULL;
+ iter.counter = 1;
+ iter.depth = 1;
+ iter.stack[0] = root;
+ 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;
+
+ return iter;
+}
+
+static bool cx_tree_visitor_valid(void const *it) {
+ struct cx_tree_visitor_s const *iter = it;
+ return iter->node != NULL;
+}
+
+static void *cx_tree_visitor_current(void const *it) {
+ struct cx_tree_visitor_s const *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;
+ 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;
+
+ // allocate stack
+ iter.depth = 0;
+
+ // visit the root node
+ iter.node = root;
+ iter.counter = 1;
+ iter.depth = 1;
+ 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;
+
+ return iter;
+}
+