ucx: src/tree.c@2672a2f79484 (annotated)

src/tree.c@2672a2f79484 (annotated)

src/tree.c

Mon, 19 Feb 2024 22:09:16 +0100

author: Mike Becker <universe@uap-core.de>
date: Mon, 19 Feb 2024 22:09:16 +0100
changeset 836: 2672a2f79484
parent 834: 04c53b3c8378
child 838: 1ce90ab4fab9
permissions: -rw-r--r--

implement basic (enter only) tree iterator

relates to #371

 /*
  * 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;
     off_t const loc_next = iter->loc_next;
     off_t const loc_children = iter->loc_children;
     // TODO: support mutating iterator
     // TODO: support visit_on_exit
     void *children = tree_children(iter->node);
     if (children == NULL) {
         // search for the next node
         void *current = iter->node;
         do {
             // check if there is a sibling
             void *next = tree_next(current);
             if (next == NULL) {
                 // no sibling, check again for parent node
                 --iter->depth;
                 if (iter->depth == 0) {
                     // there is no parent - we have iterated the entire tree
                     // invalidate the iterator and free the node stack
                     iter->node = NULL;
                     current = NULL;
                     iter->stack_capacity = 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
                     current = iter->stack[iter->depth - 1];
                 }
             } else {
                 // move to the sibling and break the loop
                 current = NULL;
                 iter->counter++;
                 iter->node = next;
                 // new top of stack is the sibling
                 iter->stack[iter->depth - 1] = next;
             }
         } while (current != NULL);
     } 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.counter = 1;
     iter.depth = 1;
     iter.stack[0] = root;
     iter.exiting = 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;
 }

Mercurial > hg > ucx / annotate

src/tree.c@2672a2f79484 (annotated)

src/tree.c