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 /*

  * 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

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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

 /**

  * Set this flag to true, if you want to disable the use of SBO for

  * linked list swap operations.

  */

 extern bool CX_DISABLE_LINKED_LIST_SWAP_SBO;

 /**

  * Allocates a linked list for storing elements with \p item_size bytes each.

  *

  * If \p item_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 item_size the size of each element in bytes

  * @return the created list

  */

 CxList *cxLinkedListCreate(

         CxAllocator const *allocator,

         cx_compare_func comparator,

         size_t item_size

 );

 /**

  * Allocates a linked list for storing elements with \p item_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 item_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 item_size the size of each element in bytes

  * @return the created list

  */

 #define cxLinkedListCreateSimple(item_size) \

     cxLinkedListCreate(NULL, NULL, item_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

  */

 void *cx_linked_list_at(

         void const *start,

         size_t start_index,

         ptrdiff_t loc_advance,

         size_t index

 ) __attribute__((__nonnull__));

 /**

  * 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

  */

 ssize_t cx_linked_list_find(

         void const *start,

         ptrdiff_t loc_advance,

         ptrdiff_t loc_data,

         cx_compare_func cmp_func,

         void const *elem

 ) __attribute__((__nonnull__));

 /**

  * 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

  */

 void *cx_linked_list_first(

         void const *node,

         ptrdiff_t loc_prev

 ) __attribute__((__nonnull__));

 /**

  * 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

  */

 void *cx_linked_list_last(

         void const *node,

         ptrdiff_t loc_next

 ) __attribute__((__nonnull__));

 /**

  * 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 const *begin,

         ptrdiff_t loc_next,

         void const *node

 ) __attribute__((__nonnull__));

 /**

  * 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

  */

 void cx_linked_list_add(

         void **begin,

         void **end,

         ptrdiff_t loc_prev,

         ptrdiff_t loc_next,

         void *new_node

 ) __attribute__((__nonnull__(5)));

 /**

  * 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

  */

 void cx_linked_list_prepend(

         void **begin,

         void **end,

         ptrdiff_t loc_prev,

         ptrdiff_t loc_next,

         void *new_node

 ) __attribute__((__nonnull__(5)));

 /**

  * 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)

  */

 void cx_linked_list_link(

         void *left,

         void *right,

         ptrdiff_t loc_prev,

         ptrdiff_t loc_next

 ) __attribute__((__nonnull__));

 /**

  * 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)

  */

 void cx_linked_list_unlink(

         void *left,

         void *right,

         ptrdiff_t loc_prev,

         ptrdiff_t loc_next

 ) __attribute__((__nonnull__));

 /**

  * 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 prepended

  */

 void cx_linked_list_insert(

         void **begin,

         void **end,

         ptrdiff_t loc_prev,

         ptrdiff_t loc_next,

         void *node,

         void *new_node

 ) __attribute__((__nonnull__(6)));

 /**

  * 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)

  */

 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

 ) __attribute__((__nonnull__(6)));

 /**

  * 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 const *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

  */

 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

 ) __attribute__((__nonnull__(1, 6)));

 /**

  * 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.

  */

 int cx_linked_list_compare(

         void const *begin_left,

         void const *begin_right,

         ptrdiff_t loc_advance,

         ptrdiff_t loc_data,

         cx_compare_func cmp_func

 ) __attribute__((__nonnull__(5)));

 /**

  * 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

 ) __attribute__((__nonnull__(1)));

 #ifdef __cplusplus

 } // extern "C"

 #endif

 #endif // UCX_LINKED_LIST_H