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:  * \file tree.h
universe@816:  * \brief Interface for tree implementations.
universe@816:  * \author Mike Becker
universe@816:  * \author Olaf Wintermann
universe@816:  * \copyright 2-Clause BSD License
universe@816:  */
universe@816: 
universe@816: #ifndef UCX_TREE_H
universe@816: #define UCX_TREE_H
universe@816: 
universe@816: #include "common.h"
universe@816: 
universe@827: #include "iterator.h"
universe@827: 
universe@816: #ifdef __cplusplus
universe@816: extern "C" {
universe@816: #endif
universe@816: 
universe@827: /**
universe@827:  * When entering a node.
universe@827:  */
universe@827: #define CX_TREE_ITERATOR_ENTER      0x1
universe@827: /**
universe@827:  * When advancing to the next child.
universe@827:  */
universe@827: #define CX_TREE_ITERATOR_NEXT_CHILD 0x2
universe@827: /**
universe@827:  * When exiting the node.
universe@827:  */
universe@827: #define CX_TREE_ITERATOR_EXIT       0x4
universe@827: 
universe@827: /**
universe@827:  * Tree iterator.
universe@827:  *
universe@827:  * This iterator is not position-aware in a strict sense, as it does not assume a particular order of elements in the
universe@827:  * tree. However, the iterator keeps track of the number of nodes it has passed in a counter variable.
universe@827:  * Each node, regardless of the number of passes, is counted only once.
universe@827:  *
universe@827:  * @note Objects that are pointed to by an iterator are mutable through that iterator. However, if the
universe@827:  * iterator is based on a collection and the underlying collection is mutated by other means than this iterator
universe@827:  * (e.g. elements added or removed), the iterator becomes invalid (regardless of what cxIteratorValid() returns)
universe@827:  * and MUST be re-obtained from the collection.
universe@827:  *
universe@827:  * @see CxIterator
universe@827:  */
universe@827: typedef struct cx_tree_iterator_s {
universe@827:     /**
universe@827:      * The base properties of this iterator.
universe@827:      */
universe@827:     struct cx_iterator_base_s base;
universe@827:     /**
universe@827:      * The passes that are requested by this iterator.
universe@827:      * A combination of the flags #CX_TREE_ITERATOR_ENTER, #CX_TREE_ITERATOR_NEXT_CHILD, #CX_TREE_ITERATOR_EXIT.
universe@827:      *
universe@827:      * Changing the value after beginning the iteration is unspecified.
universe@827:      */
universe@827:     uint8_t requested_passes;
universe@827:     /**
universe@827:      * The current pass.
universe@827:      *
universe@827:      * @see CX_TREE_ITERATOR_ENTER
universe@827:      * @see CX_TREE_ITERATOR_NEXT_CHILD
universe@827:      * @see CX_TREE_ITERATOR_EXIT
universe@827:      */
universe@827:     uint8_t current_pass;
universe@827:     /**
universe@827:      * Offset in the node struct for the children linked list.
universe@827:      */
universe@827:     off_t loc_children;
universe@827:     /**
universe@827:      * Offset in the node struct for the next pointer.
universe@827:      */
universe@827:     off_t loc_next;
universe@827:     /**
universe@827:      * The total number of distinct nodes that have been passed so far.
universe@827:      */
universe@827:     size_t counter;
universe@827:     /**
universe@827:      * The currently observed node.
universe@827:      *
universe@827:      * This is the same what cxIteratorCurrent() would return.
universe@827:      */
universe@827:     void *node;
universe@827:     /**
universe@827:      * The node where we came from.
universe@827:      *
universe@827:      * - When entering the root node, this is \c NULL.
universe@827:      * - When entering another node, this is the node's parent.
universe@827:      * - When advancing to the next child, this is the previous child.
universe@827:      */
universe@827:     void *source;
universe@827:     /**
universe@827:      * Internal stack.
universe@827:      * Will be automatically freed once the iterator becomes invalid.
universe@827:      *
universe@827:      * If you want to discard the iterator before, you need to manually
universe@827:      * call cxTreeIteratorDispose().
universe@827:      */
universe@827:     void **stack;
universe@828:     /**
universe@828:      * Internal capacity of the stack.
universe@828:      */
universe@828:     size_t stack_capacity;
universe@828:     /**
universe@828:      * Current depth.
universe@828:      */
universe@828:     size_t depth;
universe@827: } CxTreeIterator;
universe@827: 
universe@827: /**
universe@827:  * Releases internal memory of the given tree iterator.
universe@827:  * @param iter the iterator
universe@827:  */
universe@827: static inline void cxTreeIteratorDispose(CxTreeIterator *iter) {
universe@827:     free(iter->stack);
universe@827: }
universe@816: 
universe@822: /**
universe@822:  * Links a node to a (new) parent.
universe@822:  *
universe@822:  * If the node has already a parent, it is unlinked, first.
universe@826:  * If the parent has children already, the node is prepended to the list
universe@826:  * of all currently existing children.
universe@822:  *
universe@822:  * @param parent the parent node
universe@822:  * @param node the node that shall be linked
universe@822:  * @param loc_parent offset in the node struct for the parent pointer
universe@822:  * @param loc_children offset in the node struct for the children linked list
universe@822:  * @param loc_prev offset in the node struct for the prev pointer
universe@822:  * @param loc_next offset in the node struct for the next pointer
universe@822:  * @see cx_tree_unlink()
universe@822:  */
universe@816: __attribute__((__nonnull__))
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: 
universe@822: /**
universe@822:  * Unlinks a node from its parent.
universe@822:  *
universe@822:  * If the node has no parent, this function does nothing.
universe@822:  *
universe@822:  * @param node the node that shall be unlinked from its parent
universe@822:  * @param loc_parent offset in the node struct for the parent pointer
universe@822:  * @param loc_children offset in the node struct for the children linked list
universe@822:  * @param loc_prev offset in the node struct for the prev pointer
universe@822:  * @param loc_next offset in the node struct for the next pointer
universe@822:  * @see cx_tree_link()
universe@822:  */
universe@816: __attribute__((__nonnull__))
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: 
universe@823: /**
universe@823:  * Function pointer for a search function.
universe@823:  *
universe@823:  * A function of this kind shall check if the specified \p node
universe@823:  * contains the given \p data or if one of the children might contain
universe@823:  * the data.
universe@823:  *
universe@826:  * The function should use the returned integer to indicate how close the
universe@826:  * match is, where a negative number means that it does not match at all.
universe@826:  *
universe@823:  * For example if a tree stores file path information, a node that is
universe@823:  * describing a parent directory of a filename that is searched, shall
universe@826:  * return a positive number to indicate that a child node might contain the
universe@826:  * searched item. On the other hand, if the node denotes a path that is not a
universe@826:  * prefix of the searched filename, the function would return -1 to indicate
universe@826:  * that * the search does not need to be continued in that branch.
universe@823:  *
universe@823:  * @param node the node that is currently investigated
universe@823:  * @param data the data that is searched for
universe@823:  *
universe@823:  * @return 0 if the node contains the data,
universe@826:  * positive if one of the children might contain the data,
universe@826:  * negative if neither the node, nor the children contains the data
universe@823:  */
universe@824: typedef int (*cx_tree_search_func)(void const *node, void const* data);
universe@823: 
universe@826: 
universe@826: /**
universe@826:  * Searches for data in a tree.
universe@826:  *
universe@826:  * When the data cannot be found exactly, the search function might return a
universe@826:  * closest result which might be a good starting point for adding a new node
universe@826:  * to the tree.
universe@826:  *
universe@826:  * Depending on the tree structure it is not necessarily guaranteed that the
universe@826:  * "closest" match is uniquely defined. This function will search for a node
universe@826:  * with the best match according to the \p sfunc (meaning: the return value of
universe@826:  * \p sfunc which is closest to zero). If that is also ambiguous, an arbitrary
universe@826:  * node matching the criteria is returned.
universe@826:  *
universe@826:  * @param root the root node
universe@826:  * @param data the data to search for
universe@826:  * @param sfunc the search function
universe@826:  * @param result where the result shall be stored
universe@826:  * @param loc_children offset in the node struct for the children linked list
universe@826:  * @param loc_next offset in the node struct for the next pointer
universe@826:  * @return zero if the node was found exactly, positive if a node was found that
universe@826:  * could contain the node (but doesn't right now), negative if the tree does not
universe@826:  * contain any node that might be related to the searched data
universe@826:  */
universe@826: __attribute__((__nonnull__))
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: 
universe@828: /**
universe@828:  * Creates an iterator for a tree with the specified root node.
universe@828:  *
universe@828:  * The \p passes argument is supposed to be a combination of the flags
universe@828:  * #CX_TREE_ITERATOR_ENTER, #CX_TREE_ITERATOR_NEXT_CHILD, and #CX_TREE_ITERATOR_EXIT.
universe@828:  * Alternatively, the integer 1 is equivalent to just specifying #CX_TREE_ITERATOR_ENTER
universe@828:  * which will cause the iterator to pass every node only once (when entering the node).
universe@828:  *
universe@828:  * When #CX_TREE_ITERATOR_EXIT is set, the iterator will visit a parent node again,
universe@828:  * when \em every of it's children has been visited (including the case when the node does not have any children).
universe@828:  *
universe@828:  * When #CX_TREE_ITERATOR_NEXT_CHILD is set, the iterator will visit a parent node again,
universe@828:  * when advancing from one child to the next.
universe@828:  *
universe@828:  * @note A tree iterator needs to maintain a stack of visited nodes, which is allocated using stdlib malloc().
universe@828:  * When the iterator becomes invalid, this memory is automatically released. However, if you wish to cancel the
universe@828:  * iteration before the iterator becomes invalid by itself, you MUST call cxTreeIteratorDispose() manually to release
universe@828:  * the memory.
universe@828:  *
universe@828:  * @remark At the moment, the returned iterator does not support cxIteratorFlagRemoval().
universe@828:  *
universe@828:  * @param root the root node
universe@828:  * @param passes the passes this iterator shall perform
universe@828:  * @param loc_children offset in the node struct for the children linked list
universe@828:  * @param loc_next offset in the node struct for the next pointer
universe@828:  * @return the new tree iterator
universe@828:  * @see cxTreeIteratorDispose()
universe@828:  */
universe@828: __attribute__((__nonnull__))
universe@828: CxTreeIterator cx_tree_iterate(
universe@828:         void const *root,
universe@828:         int passes,
universe@828:         ptrdiff_t loc_children,
universe@828:         ptrdiff_t loc_next
universe@828: );
universe@828: 
universe@816: #ifdef __cplusplus
universe@816: } // extern "C"
universe@816: #endif
universe@816: 
universe@816: #endif //UCX_TREE_H