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@826:     size_t work_cap = 32;
universe@826:     size_t work_size = 0;
universe@826:     void const **work = malloc(sizeof(void*) * work_cap);
universe@826:     #define work_add(node) cx_array_add(&work, &work_size, &work_cap, \
universe@826:         sizeof(void*), &(node), cx_array_default_reallocator)
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@826:             work_add(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@826:                 work_add(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:     #undef workq_add
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_stack_add(
universe@830:         struct cx_tree_iterator_s *iter,
universe@830:         void *node
universe@830: ) {
universe@830:     cx_array_add(&iter->stack, &iter->depth, &iter->stack_capacity,
universe@830:         sizeof(void*), &node, cx_array_default_reallocator);
universe@830: }
universe@830: 
universe@830: static void cx_tree_iter_next(void *it) {
universe@830:     struct cx_tree_iterator_s *iter = it;
universe@830:     // TODO: support mutating iterator
universe@830: 
universe@830:     // TODO: implement
universe@830: }
universe@830: 
universe@830: 
universe@830: CxTreeIterator cx_tree_iterator(
universe@830:         void *root,
universe@830:         int passes,
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@830:     iter.requested_passes = passes;
universe@830: 
universe@830:     // invalidate iterator immediately when passes is invalid
universe@830:     if ((passes & (CX_TREE_ITERATOR_ENTER |
universe@830:                    CX_TREE_ITERATOR_NEXT_CHILD |
universe@830:                    CX_TREE_ITERATOR_EXIT)) == 0) {
universe@830:         iter.stack = NULL;
universe@830:         iter.node = NULL;
universe@830:         return iter;
universe@830:     }
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@830:     // determine start
universe@830:     if ((passes & CX_TREE_ITERATOR_ENTER) == 0) {
universe@830:         // we have to skip the first "entering" passes
universe@830:         void *s = NULL;
universe@830:         void *n = root;
universe@830:         iter.counter = 0;
universe@830:         do {
universe@830:             iter.counter++;
universe@830:             iter.source = s;
universe@830:             iter.node = n;
universe@830:             cx_tree_iter_stack_add(&iter, n);
universe@830:             s = n;
universe@830:             n = tree_children(n);
universe@830:         } while (n != NULL);
universe@830:         // found a leaf node s (might be root itself if it has no children)
universe@830: 
universe@830:         // check if there is a sibling
universe@830:         n = tree_next(s);
universe@830: 
universe@830:         if (n == NULL) {
universe@830:             // no sibling found, exit back to parent node
universe@830:             // TODO: implement
universe@830:         } else {
universe@830:             // there is a sibling
universe@830:             if ((passes & CX_TREE_ITERATOR_EXIT) == 0) {
universe@830:                 // no exit requested, conclude that only next_child is requested
universe@830:                 iter.source = s;
universe@830:                 iter.node = n;
universe@830:                 iter.counter++;
universe@830:                 iter.current_pass = CX_TREE_ITERATOR_NEXT_CHILD;
universe@830:             } else {
universe@830:                 // exit requested, so we have found our first pass
universe@830:                 // iter.node and iter.source are still correct
universe@830:                 iter.current_pass = CX_TREE_ITERATOR_EXIT;
universe@830:             }
universe@830:         }
universe@830:     } else {
universe@830:         // enter passes are requested, we can start by entering the root node
universe@830:         iter.source = NULL;
universe@830:         iter.node = root;
universe@830:         iter.current_pass = CX_TREE_ITERATOR_ENTER;
universe@830:         iter.counter = 1;
universe@830:         iter.depth = 1;
universe@830:         iter.stack[0] = root;
universe@830:     }
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: }