src/cx/linked_list.h

/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright 2021 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
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 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
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/**
 * \file linked_list.h
 * \brief Linked list implementation.
 * \details Also provides several low-level functions for custom linked list implementations.
 * \author Mike Becker
 * \author Olaf Wintermann
 * \version 3.0
 * \copyright 2-Clause BSD License
 */

#ifndef UCX_LINKED_LIST_H
#define UCX_LINKED_LIST_H

#include <stddef.h>
#include "list.h"

#ifdef __cplusplus
extern "C" {
#endif

/**
 * Allocates a linked list for storing elements with \p item_size bytes each.
 *
 * Elements added to the list are copied.
 *
 * @param allocator the allocator for allocating the list nodes
 * @param comparator the comparator for the elements
 * @param item_size the size of each element in bytes
 * @return the created list
 */
CxList cxLinkedListCreate(CxAllocator allocator, CxListComparator comparator, size_t item_size);

/**
 * Allocates a linked list for storing pointers.
 *
 * If you want to store the elements directly in this list, use cxLinkedListCreate().
 *
 * @param allocator the allocator for allocating the list nodes
 * @param comparator the comparator for the elements
 * @return the created list
 */
CxList cxPointerLinkedListCreate(CxAllocator allocator, CxListComparator comparator);

/**
 * Deallocates the memory of the entire list.
 *
 * \attention If this is a pointer list, the memory the pointers are referring to is \em not freed.
 *
 * @param list the list
 */
void cxLinkedListDestroy(CxList list);

/**
 * Finds the node at a certain index.
 *
 * This function can be used to start at an arbitrary position within the list.
 * If the search index is large than the start index, \p loc_advance must denote
 * the location of some sort of \c next pointer (i.e. a pointer to the next node).
 * But it is also possible that the search index is smaller than the start index
 * (e.g. in cases where traversing a list backwards is faster) in which case
 * \p loc_advance must denote the location of some sort of \c prev pointer
 * (i.e. a pointer to the previous node).
 *
 * @param start a pointer to the start node
 * @param start_index the start index
 * @param loc_advance the location of the pointer to advance
 * @param index the search index
 * @return the node found at the specified index
 */
void *cx_linked_list_at(void *start, size_t start_index, ptrdiff_t loc_advance, size_t index);

/**
 * Finds the first node in a linked list.
 *
 * The function starts with the pointer denoted by \p node and traverses the list
 * along a prev pointer whose location within the node struct is
 * denoted by \p loc_prev.
 *
 * @param node a pointer to a node in the list
 * @param loc_prev the location of the \c prev pointer
 * @return a pointer to the first node or \c NULL if \p node is \c NULL
 */
void *cx_linked_list_first(void *node, ptrdiff_t loc_prev);

/**
 * Finds the last node in a linked list.
 *
 * The function starts with the pointer denoted by \p node and traverses the list
 * along a next pointer whose location within the node struct is
 * denoted by \p loc_next.
 *
 * @param node a pointer to a node in the list
 * @param loc_next the location of the \c next pointer
 * @return a pointer to the last node or \c NULL if \p begin is \c NULL
 */
void *cx_linked_list_last(void *node, ptrdiff_t loc_next);

/**
 * Finds the predecessor of a node in case it is not linked.
 *
 * \remark If \p node is not contained in the list starting with \p begin, the behavior is undefined.
 *
 * @param begin the node where to start the search
 * @param loc_next the location of the \c next pointer
 * @param node the successor of the node to find
 * @return the node or \c NULL if \p node has no predecessor
 */
void *cx_linked_list_prev(void *begin, ptrdiff_t loc_next, void *node);

/**
 * Adds a new node to a linked list.
 * The node must not be part of any list already.
 *
 * \remark One of the pointers \p begin and \p end may be \c NULL, but not both.
 *
 * @param begin a pointer to the begin node pointer (if your list has one)
 * @param end a pointer to the end node pointer (if your list has one)
 * @param loc_prev the location of a \c prev pointer within your node struct (negative if your struct does not have one)
 * @param loc_next the location of a \c next pointer within your node struct (required)
 * @param new_node a pointer to the node that shall be appended
 */
void cx_linked_list_add(void **begin, void **end, ptrdiff_t loc_prev, ptrdiff_t loc_next, void *new_node);

/**
 * Prepends a new node to a linked list.
 * The node must not be part of any list already.
 *
 * \remark One of the pointers \p begin and \p end may be \c NULL, but not both.
 *
 * @param begin a pointer to the begin node pointer (if your list has one)
 * @param end a pointer to the end node pointer (if your list has one)
 * @param loc_prev the location of a \c prev pointer within your node struct (negative if your struct does not have one)
 * @param loc_next the location of a \c next pointer within your node struct (required)
 * @param new_node a pointer to the node that shall be prepended
 */
void cx_linked_list_prepend(void **begin, void **end, ptrdiff_t loc_prev, ptrdiff_t loc_next, void *new_node);

/**
 * Removes a node from the linked list.
 *
 * If the node to remove is the begin (resp. end) node of the list and if \p begin (resp. \p end)
 * addresses are provided, the pointers are adjusted accordingly.
 *
 * The following combinations of arguments are valid (more arguments are optional):
 * \li \p loc_next and \p loc_prev (ancestor node is determined by using the prev pointer, overall O(1) performance)
 * \li \p loc_next and \p begin (ancestor node is determined by list traversal, overall O(n) performance)
 *
 * \remark The \c next and \c prev pointers of the removed node are not cleared by this function and may still be used
 * to traverse to a former adjacent node in the list.
 *
 * @param begin a pointer to the begin node pointer (optional)
 * @param end a pointer to the end node pointer (optional)
 * @param loc_prev the location of a \c prev pointer within your node struct (negative if your struct does not have one)
 * @param loc_next the location of a \c next pointer within your node struct (required)
 * @param node the node to remove
 */
 void cx_linked_list_remove(void **begin, void **end, ptrdiff_t loc_prev, ptrdiff_t loc_next, void *node)
 __attribute__ ((nonnull(5)));


/**
 * Determines the size of a linked list starting with \p node.
 * @param node the first node
 * @param loc_next the location of the \c next pointer within the node struct
 * @return the size of the list or zero if \p node is \c NULL
 */
size_t cx_linked_list_size(void *node, ptrdiff_t loc_next);

/**
 * Sorts a linked list based on a comparison function.
 *
 * This function can work with linked lists of the following structures:
 * \code
 * typedef struct node node;
 * struct node {
 *   node* prev;
 *   node* next;
 *   my_payload data; // in this case set follow_ptr = 0
 * }
 *
 * typedef struct ptr_node ptr_node;
 * struct ptr_node {
 *   ptr_node* prev;
 *   ptr_node* next;
 *   my_payload* data; // in this case set follow_ptr = 1
 * }
 * \endcode
 *
 * @note This is a recursive function with at most logarithmic recursion depth.
 *
 * @param begin a pointer to the begin node pointer (required)
 * @param end a pointer to the end node pointer (optional)
 * @param loc_prev the location of a \c prev pointer within your node struct (negative if not present)
 * @param loc_next the location of a \c next pointer within your node struct (required)
 * @param loc_data the location of the \c data pointer within your node struct
 * @param follow_ptr \c false if the pointer denoted by \p loc_data shall be passed to the \p cmp_func.
 * If \c true, the data at \p loc_data is dereferenced, assuming to be a pointer, and then passed to \p cmp_func.
 * @param cmp_func the compare function defining the sort order
 */
void cx_linked_list_sort(void **begin, void **end, ptrdiff_t loc_prev, ptrdiff_t loc_next,
                         ptrdiff_t loc_data, int follow_ptr, CxListComparator cmp_func);


/**
 * Reverses the order of the nodes in a linked list.
 *
 * @param begin a pointer to the begin node pointer (required)
 * @param end a pointer to the end node pointer (optional)
 * @param loc_prev the location of a \c prev pointer within your node struct (negative if your struct does not have one)
 * @param loc_next the location of a \c next pointer within your node struct (required)
 */
void cx_linked_list_reverse(void **begin, void **end, ptrdiff_t loc_prev, ptrdiff_t loc_next);

#ifdef __cplusplus
} /* extern "C" */
#endif

#endif /* UCX_LINKED_LIST_H */