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
 * 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
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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
 * \copyright 2-Clause BSD License
 */

#ifndef UCX_LINKED_LIST_H
#define UCX_LINKED_LIST_H

#include "common.h"
#include "list.h"

#ifdef __cplusplus
extern "C" {
#endif

/**
 * The maximum item size that uses SBO swap instead of relinking.
 */
extern unsigned cx_linked_list_swap_sbo_size;

/**
 * Allocates a linked list for storing elements with \p elem_size bytes each.
 *
 * If \p elem_size is CX_STORE_POINTERS, the created list will be created as if
 * cxListStorePointers() was called immediately after creation and the compare
 * function will be automatically set to cx_cmp_ptr(), if none is given.
 *
 * @param allocator the allocator for allocating the list nodes
 * (if \c NULL the cxDefaultAllocator will be used)
 * @param comparator the comparator for the elements
 * (if \c NULL, and the list is not storing pointers, sort and find
 * functions will not work)
 * @param elem_size the size of each element in bytes
 * @return the created list
 */
CxList *cxLinkedListCreate(
        const CxAllocator *allocator,
        cx_compare_func comparator,
        size_t elem_size
);

/**
 * Allocates a linked list for storing elements with \p elem_size bytes each.
 *
 * The list will use cxDefaultAllocator and no comparator function. If you want
 * to call functions that need a comparator, you must either set one immediately
 * after list creation or use cxLinkedListCreate().
 *
 * If \p elem_size is CX_STORE_POINTERS, the created list will be created as if
 * cxListStorePointers() was called immediately after creation and the compare
 * function will be automatically set to cx_cmp_ptr().
 *
 * @param elem_size the size of each element in bytes
 * @return the created list
 */
#define cxLinkedListCreateSimple(elem_size) \
    cxLinkedListCreate(NULL, NULL, elem_size)

/**
 * 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
 */
__attribute__((__nonnull__))
void *cx_linked_list_at(
        const void *start,
        size_t start_index,
        ptrdiff_t loc_advance,
        size_t index
);

/**
 * Finds the index of an element within a linked list.
 *
 * @param start a pointer to the start node
 * @param loc_advance the location of the pointer to advance
 * @param loc_data the location of the \c data pointer within your node struct
 * @param cmp_func a compare function to compare \p elem against the node data
 * @param elem a pointer to the element to find
 * @return the index of the element or a negative value if it could not be found
 */
__attribute__((__nonnull__))
ssize_t cx_linked_list_find(
        const void *start,
        ptrdiff_t loc_advance,
        ptrdiff_t loc_data,
        cx_compare_func cmp_func,
        const void *elem
);

/**
 * Finds the node containing an element within a linked list.
 *
 * @param result a pointer to the memory where the node pointer (or \c NULL if the element
 * could not be found) shall be stored to
 * @param start a pointer to the start node
 * @param loc_advance the location of the pointer to advance
 * @param loc_data the location of the \c data pointer within your node struct
 * @param cmp_func a compare function to compare \p elem against the node data
 * @param elem a pointer to the element to find
 * @return the index of the element or a negative value if it could not be found
 */
__attribute__((__nonnull__))
ssize_t cx_linked_list_find_node(
        void **result,
        const void *start,
        ptrdiff_t loc_advance,
        ptrdiff_t loc_data,
        cx_compare_func cmp_func,
        const void *elem
);

/**
 * 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
 */
__attribute__((__nonnull__))
void *cx_linked_list_first(
        const 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
 */
__attribute__((__nonnull__))
void *cx_linked_list_last(
        const 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
 */
__attribute__((__nonnull__))
void *cx_linked_list_prev(
        const void *begin,
        ptrdiff_t loc_next,
        const 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 or \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
 */
__attribute__((__nonnull__(5)))
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 or \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
 */
__attribute__((__nonnull__(5)))
void cx_linked_list_prepend(
        void **begin,
        void **end,
        ptrdiff_t loc_prev,
        ptrdiff_t loc_next,
        void *new_node
);

/**
 * Links two nodes.
 *
 * @param left the new predecessor of \p right
 * @param right the new successor of \p left
 * @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)
 */
__attribute__((__nonnull__))
void cx_linked_list_link(
        void *left,
        void *right,
        ptrdiff_t loc_prev,
        ptrdiff_t loc_next
);

/**
 * Unlinks two nodes.
 *
 * If right is not the successor of left, the behavior is undefined.
 *
 * @param left the predecessor of \p right
 * @param right the successor of \p left
 * @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)
 */
__attribute__((__nonnull__))
void cx_linked_list_unlink(
        void *left,
        void *right,
        ptrdiff_t loc_prev,
        ptrdiff_t loc_next
);

/**
 * Inserts a new node after a given node of a linked list.
 * The new node must not be part of any list already.
 *
 * \note If you specify \c NULL as the \p node to insert after, this function needs either the \p begin or
 * the \p end pointer to determine the start of the list. Then the new node will be prepended to the list.
 *
 * @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 node the node after which to insert (\c NULL if you want to prepend the node to the list)
 * @param new_node a pointer to the node that shall be inserted
 */
__attribute__((__nonnull__(6)))
void cx_linked_list_insert(
        void **begin,
        void **end,
        ptrdiff_t loc_prev,
        ptrdiff_t loc_next,
        void *node,
        void *new_node
);

/**
 * Inserts a chain of nodes after a given node of a linked list.
 * The chain must not be part of any list already.
 *
 * If you do not explicitly specify the end of the chain, it will be determined by traversing
 * the \c next pointer.
 *
 * \note If you specify \c NULL as the \p node to insert after, this function needs either the \p begin or
 * the \p end pointer to determine the start of the list. If only the \p end pointer is specified, you also need
 * to provide a valid \p loc_prev location.
 * Then the chain will be prepended to the list.
 *
 * @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 node the node after which to insert (\c NULL to prepend the chain to the list)
 * @param insert_begin a pointer to the first node of the chain that shall be inserted
 * @param insert_end a pointer to the last node of the chain (or NULL if the last node shall be determined)
 */
__attribute__((__nonnull__(6)))
void cx_linked_list_insert_chain(
        void **begin,
        void **end,
        ptrdiff_t loc_prev,
        ptrdiff_t loc_next,
        void *node,
        void *insert_begin,
        void *insert_end
);

/**
 * Inserts a node into a sorted linked list.
 * The new node must not be part of any list already.
 *
 * If the list starting with the node pointed to by \p begin is not sorted
 * already, the behavior is undefined.
 *
 * @param begin a pointer to the begin node pointer (required)
 * @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 inserted
 * @param cmp_func a compare function that will receive the node pointers
 */
__attribute__((__nonnull__(1, 5, 6)))
void cx_linked_list_insert_sorted(
        void **begin,
        void **end,
        ptrdiff_t loc_prev,
        ptrdiff_t loc_next,
        void *new_node,
        cx_compare_func cmp_func
);

/**
 * Inserts a chain of nodes into a sorted linked list.
 * The chain must not be part of any list already.
 *
 * If either the list starting with the node pointed to by \p begin or the list
 * starting with \p insert_begin is not sorted, the behavior is undefined.
 *
 * \attention In contrast to cx_linked_list_insert_chain(), the source chain
 * will be broken and inserted into the target list so that the resulting list
 * will be sorted according to \p cmp_func. That means, each node in the source
 * chain may be re-linked with nodes from the target list.
 *
 * @param begin a pointer to the begin node pointer (required)
 * @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 insert_begin a pointer to the first node of the chain that shall be inserted
 * @param cmp_func a compare function that will receive the node pointers
 */
__attribute__((__nonnull__(1, 5, 6)))
void cx_linked_list_insert_sorted_chain(
        void **begin,
        void **end,
        ptrdiff_t loc_prev,
        ptrdiff_t loc_next,
        void *insert_begin,
        cx_compare_func cmp_func
);

/**
 * 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
 */
__attribute__((__nonnull__(5)))
void cx_linked_list_remove(
        void **begin,
        void **end,
        ptrdiff_t loc_prev,
        ptrdiff_t loc_next,
        void *node
);


/**
 * 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(
        const 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 structure:
 * \code
 * typedef struct node node;
 * struct node {
 *   node* prev;
 *   node* next;
 *   my_payload data;
 * }
 * \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 cmp_func the compare function defining the sort order
 */
__attribute__((__nonnull__(1, 6)))
void cx_linked_list_sort(
        void **begin,
        void **end,
        ptrdiff_t loc_prev,
        ptrdiff_t loc_next,
        ptrdiff_t loc_data,
        cx_compare_func cmp_func
);


/**
 * Compares two lists element wise.
 *
 * \note Both list must have the same structure.
 *
 * @param begin_left the begin of the left list (\c NULL denotes an empty list)
 * @param begin_right the begin of the right list  (\c NULL denotes an empty list)
 * @param loc_advance the location of the pointer to advance
 * @param loc_data the location of the \c data pointer within your node struct
 * @param cmp_func the function to compare the elements
 * @return the first non-zero result of invoking \p cmp_func or: negative if the left list is smaller than the
 * right list, positive if the left list is larger than the right list, zero if both lists are equal.
 */
__attribute__((__nonnull__(5)))
int cx_linked_list_compare(
        const void *begin_left,
        const void *begin_right,
        ptrdiff_t loc_advance,
        ptrdiff_t loc_data,
        cx_compare_func 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)
 */
__attribute__((__nonnull__(1)))
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