ucx: src/cx/tree.h@13068743197f (annotated)

src/cx/tree.h@13068743197f (annotated)

src/cx/tree.h

Mon, 19 Feb 2024 22:08:09 +0100

author: Mike Becker <universe@uap-core.de>
date: Mon, 19 Feb 2024 22:08:09 +0100
changeset 835: 13068743197f
parent 833: 5c926801f052
child 840: 4f02995ce44e
permissions: -rw-r--r--

set tree iterator stack pointer to NULL on dispose to avoid accidental double-frees

 /*
  * 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.
  */
 /**
  * \file tree.h
  * \brief Interface for tree implementations.
  * \author Mike Becker
  * \author Olaf Wintermann
  * \copyright 2-Clause BSD License
  */
 #ifndef UCX_TREE_H
 #define UCX_TREE_H
 #include "common.h"
 #include "iterator.h"
 #ifdef __cplusplus
 extern "C" {
 #endif
 /**
  * Tree iterator.
  *
  * This iterator is not position-aware in a strict sense, as it does not assume a particular order of elements in the
  * tree. However, the iterator keeps track of the number of nodes it has passed in a counter variable.
  * Each node, regardless of the number of passes, is counted only once.
  *
  * @note Objects that are pointed to by an iterator are mutable through that iterator. However, if the
  * underlying data structure is mutated by other means than this iterator (e.g. elements added or removed),
  * the iterator becomes invalid (regardless of what cxIteratorValid() returns).
  *
  * @see CxIterator
  */
 typedef struct cx_tree_iterator_s {
     /**
      * The base properties of this iterator.
      */
     struct cx_iterator_base_s base;
     /**
      * Set to true, when the iterator shall visit a node again
      * when all it's children have been processed.
      */
     bool visit_on_exit;
     /**
      * True, if this iterator is currently leaving the node.
      */
     bool exiting;
     /**
      * Offset in the node struct for the children linked list.
      */
     off_t loc_children;
     /**
      * Offset in the node struct for the next pointer.
      */
     off_t loc_next;
     /**
      * The total number of distinct nodes that have been passed so far.
      */
     size_t counter;
     /**
      * The currently observed node.
      *
      * This is the same what cxIteratorCurrent() would return.
      */
     void *node;
     /**
      * Internal stack.
      * Will be automatically freed once the iterator becomes invalid.
      *
      * If you want to discard the iterator before, you need to manually
      * call cxTreeIteratorDispose().
      */
     void **stack;
     /**
      * Internal capacity of the stack.
      */
     size_t stack_capacity;
     union {
         /**
          * Internal stack size.
          */
         size_t stack_size;
         /**
          * The current depth in the tree.
          */
         size_t depth;
     };
 } CxTreeIterator;
 /**
  * Releases internal memory of the given tree iterator.
  * @param iter the iterator
  */
 static inline void cxTreeIteratorDispose(CxTreeIterator *iter) {
     free(iter->stack);
     iter->stack = NULL;
 }
 /**
  * Links a node to a (new) parent.
  *
  * If the node has already a parent, it is unlinked, first.
  * If the parent has children already, the node is prepended to the list
  * of all currently existing children.
  *
  * @param parent the parent node
  * @param node the node that shall be linked
  * @param loc_parent offset in the node struct for the parent pointer
  * @param loc_children offset in the node struct for the children linked list
  * @param loc_prev offset in the node struct for the prev pointer
  * @param loc_next offset in the node struct for the next pointer
  * @see cx_tree_unlink()
  */
 __attribute__((__nonnull__))
 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
 );
 /**
  * Unlinks a node from its parent.
  *
  * If the node has no parent, this function does nothing.
  *
  * @param node the node that shall be unlinked from its parent
  * @param loc_parent offset in the node struct for the parent pointer
  * @param loc_children offset in the node struct for the children linked list
  * @param loc_prev offset in the node struct for the prev pointer
  * @param loc_next offset in the node struct for the next pointer
  * @see cx_tree_link()
  */
 __attribute__((__nonnull__))
 void cx_tree_unlink(
         void *node,
         ptrdiff_t loc_parent,
         ptrdiff_t loc_children,
         ptrdiff_t loc_prev,
         ptrdiff_t loc_next
 );
 /**
  * Function pointer for a search function.
  *
  * A function of this kind shall check if the specified \p node
  * contains the given \p data or if one of the children might contain
  * the data.
  *
  * The function should use the returned integer to indicate how close the
  * match is, where a negative number means that it does not match at all.
  *
  * For example if a tree stores file path information, a node that is
  * describing a parent directory of a filename that is searched, shall
  * return a positive number to indicate that a child node might contain the
  * searched item. On the other hand, if the node denotes a path that is not a
  * prefix of the searched filename, the function would return -1 to indicate
  * that * the search does not need to be continued in that branch.
  *
  * @param node the node that is currently investigated
  * @param data the data that is searched for
  *
  * @return 0 if the node contains the data,
  * positive if one of the children might contain the data,
  * negative if neither the node, nor the children contains the data
  */
 typedef int (*cx_tree_search_func)(void const *node, void const* data);
 /**
  * Searches for data in a tree.
  *
  * When the data cannot be found exactly, the search function might return a
  * closest result which might be a good starting point for adding a new node
  * to the tree.
  *
  * Depending on the tree structure it is not necessarily guaranteed that the
  * "closest" match is uniquely defined. This function will search for a node
  * with the best match according to the \p sfunc (meaning: the return value of
  * \p sfunc which is closest to zero). If that is also ambiguous, an arbitrary
  * node matching the criteria is returned.
  *
  * @param root the root node
  * @param data the data to search for
  * @param sfunc the search function
  * @param result where the result shall be stored
  * @param loc_children offset in the node struct for the children linked list
  * @param loc_next offset in the node struct for the next pointer
  * @return zero if the node was found exactly, positive if a node was found that
  * could contain the node (but doesn't right now), negative if the tree does not
  * contain any node that might be related to the searched data
  */
 __attribute__((__nonnull__))
 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
 );
 /**
  * Creates an iterator for a tree with the specified root node.
  *
  * @note A tree iterator needs to maintain a stack of visited nodes, which is allocated using stdlib malloc().
  * When the iterator becomes invalid, this memory is automatically released. However, if you wish to cancel the
  * iteration before the iterator becomes invalid by itself, you MUST call cxTreeIteratorDispose() manually to release
  * the memory.
  *
  * @remark At the moment, the returned iterator does not support cxIteratorFlagRemoval().
  *
  * @param root the root node
  * @param visit_on_exit set to true, when the iterator shall visit a node again after processing all children
  * @param loc_children offset in the node struct for the children linked list
  * @param loc_next offset in the node struct for the next pointer
  * @return the new tree iterator
  * @see cxTreeIteratorDispose()
  */
 __attribute__((__nonnull__))
 CxTreeIterator cx_tree_iterator(
         void *root,
         bool visit_on_exit,
         ptrdiff_t loc_children,
         ptrdiff_t loc_next
 );
 #ifdef __cplusplus
 } // extern "C"
 #endif
 #endif //UCX_TREE_H

Mercurial > hg > ucx / annotate

src/cx/tree.h@13068743197f (annotated)

src/cx/tree.h