universe@816: /*
universe@816:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
universe@816:  *
universe@816:  * Copyright 2024 Mike Becker, Olaf Wintermann All rights reserved.
universe@816:  *
universe@816:  * Redistribution and use in source and binary forms, with or without
universe@816:  * modification, are permitted provided that the following conditions are met:
universe@816:  *
universe@816:  *   1. Redistributions of source code must retain the above copyright
universe@816:  *      notice, this list of conditions and the following disclaimer.
universe@816:  *
universe@816:  *   2. Redistributions in binary form must reproduce the above copyright
universe@816:  *      notice, this list of conditions and the following disclaimer in the
universe@816:  *      documentation and/or other materials provided with the distribution.
universe@816:  *
universe@816:  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
universe@816:  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
universe@816:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
universe@816:  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
universe@816:  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
universe@816:  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
universe@816:  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
universe@816:  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
universe@816:  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
universe@816:  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
universe@816:  * POSSIBILITY OF SUCH DAMAGE.
universe@816:  */
universe@816: 
universe@816: #include "cx/tree.h"
universe@816: 
universe@826: #include "cx/array_list.h"
universe@826: 
universe@816: #include <assert.h>
universe@816: 
universe@816: #define CX_TREE_PTR(cur, off) (*(void**)(((char*)(cur))+(off)))
universe@816: #define CX_TREE_PTR(cur, off) (*(void**)(((char*)(cur))+(off)))
universe@816: #define tree_parent(node) CX_TREE_PTR(node, loc_parent)
universe@816: #define tree_children(node) CX_TREE_PTR(node, loc_children)
universe@816: #define tree_prev(node) CX_TREE_PTR(node, loc_prev)
universe@816: #define tree_next(node) CX_TREE_PTR(node, loc_next)
universe@816: 
universe@816: void cx_tree_link(
universe@816:         void *restrict parent,
universe@816:         void *restrict node,
universe@816:         ptrdiff_t loc_parent,
universe@816:         ptrdiff_t loc_children,
universe@816:         ptrdiff_t loc_prev,
universe@816:         ptrdiff_t loc_next
universe@816: ) {
universe@816:     void *current_parent = tree_parent(node);
universe@816:     if (current_parent == parent) return;
universe@816:     if (current_parent != NULL) {
universe@816:         cx_tree_unlink(node, loc_parent, loc_children,
universe@816:                        loc_prev, loc_next);
universe@816:     }
universe@816: 
universe@816:     if (tree_children(parent) == NULL) {
universe@816:         tree_children(parent) = node;
universe@816:     } else {
universe@816:         void *children = tree_children(parent);
universe@816:         tree_prev(children) = node;
universe@816:         tree_next(node) = children;
universe@816:         tree_children(parent) = node;
universe@816:     }
universe@816:     tree_parent(node) = parent;
universe@816: }
universe@816: 
universe@816: void cx_tree_unlink(
universe@816:         void *node,
universe@816:         ptrdiff_t loc_parent,
universe@816:         ptrdiff_t loc_children,
universe@816:         ptrdiff_t loc_prev,
universe@816:         ptrdiff_t loc_next
universe@816: ) {
universe@816:     if (tree_parent(node) == NULL) return;
universe@816: 
universe@816:     void *left = tree_prev(node);
universe@816:     void *right = tree_next(node);
universe@816:     assert(left == NULL || tree_children(tree_parent(node)) != node);
universe@816:     if (left == NULL) {
universe@816:         tree_children(tree_parent(node)) = right;
universe@816:     } else {
universe@816:         tree_next(left) = right;
universe@816:     }
universe@816:     if (right != NULL) tree_prev(right) = left;
universe@816:     tree_parent(node) = NULL;
universe@816:     tree_prev(node) = NULL;
universe@816:     tree_next(node) = NULL;
universe@816: }
universe@826: 
universe@826: int cx_tree_search(
universe@826:         void const *root,
universe@826:         void const *data,
universe@826:         cx_tree_search_func sfunc,
universe@826:         void **result,
universe@826:         ptrdiff_t loc_children,
universe@826:         ptrdiff_t loc_next
universe@826: ) {
universe@826:     int ret;
universe@826:     *result = NULL;
universe@826: 
universe@826:     // shortcut: compare root before doing anything else
universe@826:     ret = sfunc(root, data);
universe@826:     if (ret < 0) {
universe@826:         return ret;
universe@826:     } else if (ret == 0 || tree_children(root) == NULL) {
universe@826:         *result = (void*)root;
universe@826:         return ret;
universe@826:     }
universe@826: 
universe@826:     // create a working stack
universe@834:     CX_ARRAY_DECLARE(void const*, work);
universe@833:     cx_array_initialize(work, 32);
universe@826: 
universe@826:     // add the children of root to the working stack
universe@826:     {
universe@826:         void *c = tree_children(root);
universe@826:         while (c != NULL) {
universe@833:             cx_array_simple_add(work, c);
universe@826:             c = tree_next(c);
universe@826:         }
universe@826:     }
universe@826: 
universe@826:     // remember a candidate for adding the data
universe@826:     // also remember the exact return code from sfunc
universe@826:     void *candidate = NULL;
universe@826:     int ret_candidate = -1;
universe@826: 
universe@826:     // process the working stack
universe@826:     while (work_size > 0) {
universe@826:         // pop element
universe@826:         void const *node = work[--work_size];
universe@826: 
universe@826:         // apply the search function
universe@826:         ret = sfunc(node, data);
universe@826: 
universe@826:         if (ret == 0) {
universe@826:             // if found, exit the search
universe@826:             *result = (void*) node;
universe@826:             work_size = 0;
universe@826:             break;
universe@826:         } else if (ret > 0) {
universe@826:             // if children might contain the data, add them to the stack
universe@826:             void *c = tree_children(node);
universe@826:             while (c != NULL) {
universe@833:                 cx_array_simple_add(work, c);
universe@826:                 c = tree_next(c);
universe@826:             }
universe@826: 
universe@826:             // remember this node in case no child is suitable
universe@826:             if (ret_candidate < 0 || ret < ret_candidate) {
universe@826:                 candidate = (void *) node;
universe@826:                 ret_candidate = ret;
universe@826:             }
universe@826:         }
universe@826:     }
universe@826: 
universe@826:     // not found, but was there a candidate?
universe@826:     if (ret != 0 && candidate != NULL) {
universe@826:         ret = ret_candidate;
universe@826:         *result = candidate;
universe@826:     }
universe@826: 
universe@826:     // free the working queue and return
universe@826:     free(work);
universe@826:     return ret;
universe@826: }
universe@830: 
universe@830: static bool cx_tree_iter_valid(void const *it) {
universe@830:     struct cx_tree_iterator_s const *iter = it;
universe@830:     return iter->node != NULL;
universe@830: }
universe@830: 
universe@830: static void *cx_tree_iter_current(void const *it) {
universe@830:     struct cx_tree_iterator_s const *iter = it;
universe@830:     return iter->node;
universe@830: }
universe@830: 
universe@830: static void cx_tree_iter_next(void *it) {
universe@830:     struct cx_tree_iterator_s *iter = it;
universe@845:     ptrdiff_t const loc_next = iter->loc_next;
universe@845:     ptrdiff_t const loc_children = iter->loc_children;
universe@830: 
universe@838:     void *children;
universe@838: 
universe@838:     // check if we are currently exiting or entering nodes
universe@838:     if (iter->exiting) {
universe@838:         children = NULL;
universe@848:         // skipping on exit is pointless, just clear the flag
universe@848:         iter->skip = false;
universe@838:     } else {
universe@848:         if (iter->skip) {
universe@848:             // skip flag is set, pretend that there are no children
universe@848:             iter->skip = false;
universe@848:             children = NULL;
universe@848:         } else {
universe@848:             // try to enter the children (if any)
universe@848:             children = tree_children(iter->node);
universe@848:         }
universe@838:     }
universe@838: 
universe@836:     if (children == NULL) {
universe@836:         // search for the next node
universe@838:         void *next;
universe@838:         cx_tree_iter_search_next:
universe@838:         // check if there is a sibling
universe@840:         if (iter->exiting) {
universe@840:             next = iter->next;
universe@840:         } else {
universe@840:             next = tree_next(iter->node);
universe@840:             iter->next = next;
universe@840:         }
universe@838:         if (next == NULL) {
universe@838:             // no sibling, we are done with this node and exit
universe@838:             if (iter->visit_on_exit && !iter->exiting) {
universe@838:                 // iter is supposed to visit the node again
universe@838:                 iter->exiting = true;
universe@838:             } else {
universe@838:                 iter->exiting = false;
universe@838:                 if (iter->depth == 1) {
universe@836:                     // there is no parent - we have iterated the entire tree
universe@836:                     // invalidate the iterator and free the node stack
universe@840:                     iter->node = iter->next = NULL;
universe@838:                     iter->stack_capacity = iter->depth = 0;
universe@836:                     free(iter->stack);
universe@836:                     iter->stack = NULL;
universe@836:                 } else {
universe@836:                     // the parent node can be obtained from the top of stack
universe@836:                     // this way we can avoid the loc_parent in the iterator
universe@838:                     iter->depth--;
universe@838:                     iter->node = iter->stack[iter->depth - 1];
universe@838:                     // retry with the parent node to find a sibling
universe@838:                     goto cx_tree_iter_search_next;
universe@836:                 }
universe@838:             }
universe@838:         } else {
universe@838:             if (iter->visit_on_exit && !iter->exiting) {
universe@838:                 // iter is supposed to visit the node again
universe@838:                 iter->exiting = true;
universe@836:             } else {
universe@838:                 iter->exiting = false;
universe@838:                 // move to the sibling
universe@836:                 iter->counter++;
universe@836:                 iter->node = next;
universe@836:                 // new top of stack is the sibling
universe@836:                 iter->stack[iter->depth - 1] = next;
universe@836:             }
universe@838:         }
universe@836:     } else {
universe@836:         // node has children, push the first child onto the stack and enter it
universe@836:         cx_array_simple_add(iter->stack, children);
universe@836:         iter->node = children;
universe@836:         iter->counter++;
universe@836:     }
universe@830: }
universe@830: 
universe@830: CxTreeIterator cx_tree_iterator(
universe@830:         void *root,
universe@833:         bool visit_on_exit,
universe@830:         ptrdiff_t loc_children,
universe@830:         ptrdiff_t loc_next
universe@830: ) {
universe@830:     CxTreeIterator iter;
universe@830:     iter.loc_children = loc_children;
universe@830:     iter.loc_next = loc_next;
universe@833:     iter.visit_on_exit = visit_on_exit;
universe@830: 
universe@830:     // allocate stack
universe@830:     iter.stack_capacity = 16;
universe@830:     iter.stack = malloc(sizeof(void *) * 16);
universe@830:     iter.depth = 0;
universe@830: 
universe@833:     // visit the root node
universe@833:     iter.node = root;
universe@848:     iter.next = NULL;
universe@833:     iter.counter = 1;
universe@833:     iter.depth = 1;
universe@833:     iter.stack[0] = root;
universe@833:     iter.exiting = false;
universe@848:     iter.skip = false;
universe@830: 
universe@830:     // assign base iterator functions
universe@830:     iter.base.mutating = false;
universe@830:     iter.base.remove = false;
universe@830:     iter.base.current_impl = NULL;
universe@830:     iter.base.valid = cx_tree_iter_valid;
universe@830:     iter.base.next = cx_tree_iter_next;
universe@830:     iter.base.current = cx_tree_iter_current;
universe@830: 
universe@830:     return iter;
universe@830: }
universe@845: 
universe@845: static bool cx_tree_visitor_valid(void const *it) {
universe@845:     struct cx_tree_visitor_s const *iter = it;
universe@845:     return iter->node != NULL;
universe@845: }
universe@845: 
universe@845: static void *cx_tree_visitor_current(void const *it) {
universe@845:     struct cx_tree_visitor_s const *iter = it;
universe@845:     return iter->node;
universe@845: }
universe@845: 
universe@845: __attribute__((__nonnull__))
universe@845: static void cx_tree_visitor_enqueue_siblings(
universe@845:         struct cx_tree_visitor_s *iter, void *node, ptrdiff_t loc_next) {
universe@845:     node = tree_next(node);
universe@845:     while (node != NULL) {
universe@845:         struct cx_tree_visitor_queue_s *q;
universe@845:         q = malloc(sizeof(struct cx_tree_visitor_queue_s));
universe@845:         q->depth = iter->queue_last->depth;
universe@845:         q->node = node;
universe@845:         iter->queue_last->next = q;
universe@845:         iter->queue_last = q;
universe@845:         node = tree_next(node);
universe@845:     }
universe@845:     iter->queue_last->next = NULL;
universe@845: }
universe@845: 
universe@845: static void cx_tree_visitor_next(void *it) {
universe@845:     struct cx_tree_visitor_s *iter = it;
universe@845:     ptrdiff_t const loc_next = iter->loc_next;
universe@845:     ptrdiff_t const loc_children = iter->loc_children;
universe@845: 
universe@848:     // add the children of the current node to the queue
universe@848:     // unless the skip flag is set
universe@848:     void *children;
universe@848:     if (iter->skip) {
universe@848:         iter->skip = false;
universe@848:         children = NULL;
universe@848:     } else {
universe@848:         children = tree_children(iter->node);
universe@848:     }
universe@848:     if (children != NULL) {
universe@848:         struct cx_tree_visitor_queue_s *q;
universe@848:         q = malloc(sizeof(struct cx_tree_visitor_queue_s));
universe@848:         q->depth = iter->depth + 1;
universe@848:         q->node = children;
universe@848:         if (iter->queue_last == NULL) {
universe@848:             assert(iter->queue_next == NULL);
universe@848:             iter->queue_next = q;
universe@848:         } else {
universe@848:             iter->queue_last->next = q;
universe@848:         }
universe@848:         iter->queue_last = q;
universe@848:         cx_tree_visitor_enqueue_siblings(iter, children, loc_next);
universe@848:     }
universe@848: 
universe@845:     // check if there is a next node
universe@845:     if (iter->queue_next == NULL) {
universe@845:         iter->node = NULL;
universe@845:         return;
universe@845:     }
universe@845: 
universe@845:     // dequeue the next node
universe@845:     iter->node = iter->queue_next->node;
universe@845:     iter->depth = iter->queue_next->depth;
universe@845:     {
universe@845:         struct cx_tree_visitor_queue_s *q = iter->queue_next;
universe@845:         iter->queue_next = q->next;
universe@845:         if (iter->queue_next == NULL) {
universe@845:             assert(iter->queue_last == q);
universe@845:             iter->queue_last = NULL;
universe@845:         }
universe@845:         free(q);
universe@845:     }
universe@845: 
universe@845:     // increment the node counter
universe@845:     iter->counter++;
universe@845: }
universe@845: 
universe@845: CxTreeVisitor cx_tree_visitor(
universe@845:         void *root,
universe@845:         ptrdiff_t loc_children,
universe@845:         ptrdiff_t loc_next
universe@845: ) {
universe@845:     CxTreeVisitor iter;
universe@845:     iter.loc_children = loc_children;
universe@845:     iter.loc_next = loc_next;
universe@845: 
universe@845:     // allocate stack
universe@845:     iter.depth = 0;
universe@845: 
universe@845:     // visit the root node
universe@845:     iter.node = root;
universe@845:     iter.counter = 1;
universe@845:     iter.depth = 1;
universe@848:     iter.skip = false;
universe@848:     iter.queue_next = NULL;
universe@848:     iter.queue_last = NULL;
universe@845: 
universe@845:     // assign base iterator functions
universe@845:     iter.base.mutating = false;
universe@845:     iter.base.remove = false;
universe@845:     iter.base.current_impl = NULL;
universe@845:     iter.base.valid = cx_tree_visitor_valid;
universe@845:     iter.base.next = cx_tree_visitor_next;
universe@845:     iter.base.current = cx_tree_visitor_current;
universe@845: 
universe@845:     return iter;
universe@845: }
universe@845: