efl/src/lib/eina/eina_list.h

/* EINA - EFL data type library
 * Copyright (C) 2002-2008 Carsten Haitzler, Vincent Torri, Jorge Luis Zapata Muga
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library;
 * if not, see <http://www.gnu.org/licenses/>.
 */

#ifndef EINA_LIST_H_
#define EINA_LIST_H_

#include <stdlib.h>

#include "eina_config.h"

// magic number checks for eina list nodes - this costs extra memory and a
// few cycles for some safety = aybe during debugging/devel only?
//#define EINA_LIST_MAGIC 1

#include "eina_types.h"
#include "eina_iterator.h"
#include "eina_accessor.h"
#ifdef EINA_LIST_MAGIC
# include "eina_magic.h"
#endif

/**
 * @page eina_list_01_example_page Adding elements to Eina_List
 * @dontinclude eina_list_01.c
 *
 * Creating an @ref Eina_List and adding elements to it is very easy and can be
 * understood from an example:
 * First thing is always to include Eina.h, for this example we also
 * include stdio.h so we can use printf.
 * @skip #include
 * @until Eina.h
 *
 * Just some boilerplate code, declaring some variables and initializing eina.
 * @until eina_init
 * Here we add a sequence of elements to our list. By using append we add
 * elements to the end of the list, so the list will look like this:@n
 * @image rtf eina_list_example_01_a.png
 * @image html eina_list_example_01_a.png
 * @image latex eina_list_example_01_a.eps "" width=\textwidth
 * @until roslin
 * There are a couple of interesting things happening here, first is that we are
 * passing a NULL pointer to the first @ref eina_list_append() call, when this
 * is done a list is created. The other @b very important detail to notice is
 * that the return value is attributed to the @a list variable, this needs to
 * be done every time we use a a function that alters the contents of the list.
 *
 * Now that we have a list with some elements in it we can look at its contents.
 * @until printf
 *
 * There are many ways of accessing elements in the list, including by its
 * index:
 * @until nth
 * @note It should be noted that the index starts at 0.
 *
 * @ref eina_list_append() is not the only way to add elements to a a list. A
 * common requirement is to add an element in a specific position this can be
 * accomplished using @ref eina_list_append_relative() and
 * @ref eina_list_append_relative_list():
 * @until zarek
 * First @a "cain" is added after the second element (remember that indexes are
 * 0 based) and then we add @a "zarek" after @a "cain".
 *
 * @ref Eina_List also has prepend analogs to append functions we have used so
 * far:
 * @until lampkin
 * With this additions our list now looks like this:@n
 * @image rtf eina_list_example_01_b.png
 * @image html eina_list_example_01_b.png
 * @image latex eina_list_example_01_b.eps "" width=\textwidth
 *
 * Once done using the list it needs to be freed, and since we are done with
 * eina that also need to be shutdown:
 * @until }
 *
 * The full source code can be found on the examples folder
 * on the @ref eina_list_01_c "eina_list_01.c" file.
 */

/**
 * @page eina_list_01_c Adding elements to Eina_List example
 *
 * @include eina_list_01.c
 * @example eina_list_01.c
 */

/**
 * @page eina_list_02_example_page Sorting Eina_List elements
 * @dontinclude eina_list_02.c
 *
 * If you don't know how to create lists see
 * @ref eina_list_01_example_page.
 *
 * @skip #include
 * @until boomer
 * This is the code we have already seen to create a list. Now if we need to
 * search the list we can do it like this:
 * @until return
 *
 * However if searching the list multiple times it probably is better to sort
 * the list since the sorted_search functions are much faster:
 * @until return
 *
 * Once the list is sorted it's not a good idea to use append/prepend functions
 * since that would add the element in the wrong place, instead elements should
 * be added with @ref eina_list_sorted_insert():
 * @until sorted_insert
 *
 * A noteworthy use case is adding an element to a list only if it doesn't exist
 * already, this can accomplished by searching for the element that is closest
 * to what is being added, and if that doesn't match add:
 * @until append
 * @note @ref eina_list_search_sorted_near_list() will tell you not only the
 * nearest node to what was searched for but how it compares to your term, this
 * way it is easy to know if you have to add before or after that node.
 *
 * It is sometimes useful to get a portion of the list as another list, here we
 * take every element that comes after "boomer" and split it into "other_list":
 * @until split_list
 *
 * It is also possible to add entire lists of elements using
 * @ref eina_list_sorted_merge():
 * @until sorted_merge
 *
 * And as always release memory and shutdown eina before ending:
 * @until }
 *
 * The full source code can be found on the examples folder
 * on the @ref eina_list_02_c "eina_list_02.c" file.
 */

/**
 * @page eina_list_02_c Sorting Eina_List elements example
 *
 * @include eina_list_02.c
 * @example eina_list_02.c
 */

/**
 * @page eina_list_03_example_page Reordering Eina_List elements
 * @dontinclude eina_list_03.c
 *
 * If you don't know how to create lists see
 * @ref eina_list_01_example_page.
 *
 * We start out with code that should be familiar by now:
 * @skip #include
 * @until gemenon
 *
 * You can move elements around in a list using @ref eina_list_move() or using
 * @ref eina_list_promote_list() and @ref eina_list_demote_list() which move a
 * list node to the head and end of the list respectively:
 * @until demote
 *
 * Removing elements from a list can be done with ease:
 * @until sagittarius
 *
 * To replace an element in the list it is not necessary to remove it and then
 * re-add with the new value, it is possible to just change the value of a node:
 * @until aquarius
 *
 * We will now take a peek to see if the list still has the right number of
 * elements:
 * @until printf
 *
 * Now that the list is in alphabetical order let's create a copy of it in
 * reverse order and print every element to see if worked as expected:
 * @until iterator_free
 * @note Always remember to free your iterators when done using them.
 *
 * And as always release memory and shutdown eina before ending:
 * @until }
 *
 * The full source code can be found on the examples folder
 * on the @ref eina_list_03_c "eina_list_03.c" file.
 */

/**
 * @page eina_list_03_c Reordering Eina_List elements example
 *
 * @include eina_list_03.c
 * @example eina_list_03.c
 */

/**
 * @page eina_list_04_example_page Eina_List and memory allocation
 * @dontinclude eina_list_04.c
 *
 * If you don't know how to create lists see
 * @ref eina_list_01_example_page. In this example we also use
 * @ref Eina_Stringshare_Group, however it should be possible to understand the code
 * regardless of previous knowledge about it.
 *
 * Here we have the usual list creation code with a twist, now we are using as
 * data for the list memory that has to be freed later on.
 * @skip #include
 * @until Sharon
 *
 * This time we are going to iterate over our list in a different way:
 * @until printf
 *
 * And now we are going to iterate over the list backwards:
 * @until printf
 *
 * And now we need to free up the memory allocated during creation of the list:
 * @until stringshare_del
 * @note We don't need to use eina_list_free() since @ref EINA_LIST_FREE takes
 * care of that.
 *
 * And shut everything down:
 * @until }
 *
 * The full source code can be found on the examples folder
 * on the @ref eina_list_04_c "eina_list_04.c" file.
 */

/**
 * @page eina_list_04_c Eina_List and memory allocation example
 *
 * @include eina_list_04.c
 * @example eina_list_04.c
 */

/**
 * @addtogroup Eina_List_Group List
 *
 * @brief These functions provide double linked list management.
 *
 * Eina_List is a doubly linked list. It can store data of any type in the
 * form of void pointers. It has convenience functions to do all the common
 * operations which means it should rarely if ever be necessary to directly
 * access the struct's fields. Nevertheless it can be useful to understand the
 * inner workings of the data structure being used.
 *
 * @ref Eina_List nodes keep references to the previous node, the next node, its
 * data and to an accounting structure.
 *
 * @image rtf eina_list.png
 * @image html eina_list.png
 * @image latex eina_list.eps width=5cm
 *
 * @ref Eina_List_Accounting is used to improve the performance of some
 * functions. It is private and <b>should not</b> be modified. It contains a
 * reference to the end of the list and the number of elements in the list.
 *
 * @note Every function that modifies the contents of the list returns a pointer
 * to the head of the list and it is essential that this be pointer be used in
 * any future references to the list.
 *
 * Most functions have two versions that have the same effect but operate on
 * different arguments, the @a plain functions operate over data(e.g..:
 * @ref eina_list_append_relative, @ref eina_list_remove,
 * @ref eina_list_data_find), the @a list versions of these functions operate
 * on @ref Eina_List nodes.
 *
 * @warning You must @b always use the pointer to the first element of the list
 * as the list!
 * @warning You must @b never use a pointer to an element in the middle of the
 * list as the list!
 *
 * Here are some examples of @ref Eina_List usage:
 * @li @ref eina_list_01_example_page
 * @li @ref eina_list_02_example_page
 * @li @ref eina_list_03_example_page
 * @li @ref eina_list_04_example_page
 */

/**
 * @addtogroup Eina_Data_Types_Group Data Types
 *
 * @{
 */

/**
 * @addtogroup Eina_Containers_Group Containers
 *
 * @{
 */

/**
 * @defgroup Eina_List_Group List
 *
 * @{
 */

/**
 * @typedef Eina_List
 * Type for a generic double linked list.
 */
typedef struct _Eina_List            Eina_List;

/**
 * @typedef Eina_List_Accounting
 * Cache used to store the last element of a list and the number of
 * elements, for fast access.
 */
typedef struct _Eina_List_Accounting Eina_List_Accounting;

/**
 * @struct _Eina_List
 * Type for a generic double linked list.
 */
struct _Eina_List
{
   void                 *data; /**< Pointer to list element payload */
   Eina_List            *next; /**< Next member in the list */
   Eina_List            *prev; /**< Previous member in the list */
   Eina_List_Accounting *accounting; /**< Private list accounting info - don't touch */
#ifdef EINA_LIST_MAGIC
   EINA_MAGIC
#endif
};

/**
 * @struct _Eina_List_Accounting
 * Cache used to store the last element of a list and the number of
 * elements, for fast access. It is for private use and must not be
 * touched.
 */
struct _Eina_List_Accounting
{
   Eina_List   *last; /**< Pointer to the last element of the list - don't touch */
   unsigned int count; /**< Number of elements of the list - don't touch */
   EINA_MAGIC
};


/**
 * @brief Appends the given data to the given linked list.
 *
 * @param[in,out] list The given list.
 * @param[in] data The data to append.
 * @return A list pointer, or @c NULL on error.
 *
 * This function appends @p data to @p list. If @p list is @c NULL, a
 * new list is returned. On success, a new list pointer that should be
 * used in place of the one given to this function is
 * returned. Otherwise, the old pointer is returned.
 *
 * The following example code demonstrates how to ensure that the
 * given data has been successfully appended.
 *
 * @code
 * Eina_List *list = NULL;
 * extern void *my_data;
 *
 * list = eina_list_append(list, my_data);
 * @endcode
 *
 * @warning @p list must be a pointer to the first element of the list(or NULL).
 */
EAPI Eina_List            *eina_list_append(Eina_List *list, const void *data) EINA_ARG_NONNULL(2) EINA_WARN_UNUSED_RESULT;


/**
 * @brief Prepends the given data to the given linked list.
 *
 * @param[in,out] list The given list.
 * @param[in] data The data to prepend.
 * @return A list pointer, or @c NULL on error.
 *
 * This function prepends @p data to @p list. If @p list is @c NULL, a
 * new list is returned. On success, a new list pointer that should be
 * used in place of the one given to this function is
 * returned. Otherwise, the old pointer is returned.
 *
 * The following example code demonstrates how to ensure that the
 * given data has been successfully prepended.
 *
 * Example:
 * @code
 * Eina_List *list = NULL;
 * extern void *my_data;
 *
 * list = eina_list_prepend(list, my_data);
 * @endcode
 *
 * @warning @p list must be a pointer to the first element of the list.
 */
EAPI Eina_List            *eina_list_prepend(Eina_List *list, const void *data) EINA_ARG_NONNULL(2) EINA_WARN_UNUSED_RESULT;


/**
 * @brief Inserts the given data into the given linked list after the specified data.
 *
 * @param[in,out] list The given linked list.
 * @param[in] data The data to insert.
 * @param[in] relative The data to insert after.
 * @return A list pointer, or @c NULL on error.
 *
 * This function inserts @p data into @p list after @p relative. If
 * @p relative is not in the list, @p data is appended to
 * the list. If @p list is @c NULL, a new list is returned. If there
 * are multiple instances of @p relative in the list, @p data is
 * inserted after the first instance. On success, a new list pointer
 * that should be used in place of the one given to this function is
 * returned. Otherwise, the old pointer is returned.
 *
 * The following example code demonstrates how to ensure that the
 * given data has been successfully inserted.
 *
 * @code
 * Eina_List *list = NULL;
 * extern void *my_data;
 * extern void *relative_member;
 *
 * list = eina_list_append(list, relative_member);
 * list = eina_list_append_relative(list, my_data, relative_member);
 * @endcode
 *
 * @warning @p list must be a pointer to the first element of the list.
 */
EAPI Eina_List            *eina_list_append_relative(Eina_List *list, const void *data, const void *relative) EINA_ARG_NONNULL(2) EINA_WARN_UNUSED_RESULT;


/**
 * @brief Appends a list node to a linked list after the specified member.
 *
 * @param[in,out] list The given linked list.
 * @param[in] data The data to insert.
 * @param[in] relative The list node to insert after.
 * @return A list pointer, or @c NULL on error.
 *
 * This function inserts @p data into @p list after the list node
 * @p relative. If @p list or @p relative are @c NULL, @p data is just
 * appended to @p list using eina_list_append(). If @p list is
 * @c NULL, a  new list is returned. If there are multiple instances
 * of @p relative in the list, @p data is inserted after the first
 * instance. On success, a new list pointer that should be used in
 * place of the one given to this function is returned. Otherwise, the
 * old pointer is returned.
 *
 * @warning @p list must be a pointer to the first element of the list.
 */
EAPI Eina_List            *eina_list_append_relative_list(Eina_List *list, const void *data, Eina_List *relative) EINA_ARG_NONNULL(2) EINA_WARN_UNUSED_RESULT;


/**
 * @brief Prepends a data pointer to a linked list before the specified member.
 *
 * @param[in,out] list The given linked list.
 * @param[in] data The data to insert.
 * @param[in] relative The member that data will be inserted before.
 * @return A list pointer, or @c NULL on error.
 *
 * This function inserts @p data to @p list before @p relative. If
 * @p relative is not in the list, @p data is prepended to the list
 * with eina_list_prepend(). If @p list is @c NULL, a new list is
 * returned. If there are multiple instances of @p relative in the
 * list, @p data is inserted before the first instance. On success, a
 * new list pointer that should be used in place of the one given to
 * this function is returned. Otherwise, the old pointer is returned.
 *
 * The following code example demonstrates how to ensure that the
 * given data has been successfully inserted.
 *
 * @code
 * Eina_List *list = NULL;
 * extern void *my_data;
 * extern void *relative_member;
 *
 * list = eina_list_append(list, relative_member);
 * list = eina_list_prepend_relative(list, my_data, relative_member);
 * @endcode
 *
 * @warning @p list must be a pointer to the first element of the list.
 */
EAPI Eina_List            *eina_list_prepend_relative(Eina_List *list, const void *data, const void *relative) EINA_ARG_NONNULL(2) EINA_WARN_UNUSED_RESULT;


/**
 * @brief Prepends a list node to a linked list before the specified member.
 *
 * @param[in,out] list The given linked list.
 * @param[in] data The data to insert.
 * @param[in] relative The list node to insert before.
 * @return A list pointer, or @c NULL on error.
 *
 * This function inserts @p data to @p list before the list node
 * @p relative. If @p list or @p relative are @c NULL, @p data is just
 * prepended to @p list using eina_list_prepend(). If @p list is
 * @c NULL, a new list is returned. If there are multiple instances
 * of @p relative in the list, @p data is inserted before the first
 * instance. On success, a new list pointer that should be used in
 * place of the one given to this function is returned. Otherwise, the
 * old pointer is returned.
 *
 * @warning @p list must be a pointer to the first element of the list.
 */
EAPI Eina_List            *eina_list_prepend_relative_list(Eina_List *list, const void *data, Eina_List *relative) EINA_ARG_NONNULL(2) EINA_WARN_UNUSED_RESULT;


/**
 * @brief Inserts a new node into a sorted list.
 *
 * @param[in,out] list The given linked list, @b must be sorted.
 * @param[in] func The function called for the sort.
 * @param[in] data The data to be inserted in sorted order.
 * @return A list pointer, or @c NULL on error.
 *
 * This function inserts values into a linked list assuming it was
 * sorted and the result will be sorted. If @p list is @c NULL, a new
 * list is returned. On success, a new list pointer that should be used
 * in place of the one given to this function is returned. Otherwise,
 * the old pointer is returned.
 *
 * @note O(log2(n)) comparisons (calls to @p func) average/worst case
 * performance as it uses eina_list_search_sorted_near_list() and thus
 * is bounded to that. As said in eina_list_search_sorted_near_list(),
 * lists do not have O(1) access time, so walking to the correct node
 * can be costly, consider worst case to be almost O(n) pointer
 * dereference (list walk).
 *
 * @warning @p list must be a pointer to the first element of the list.
 */
EAPI Eina_List            *eina_list_sorted_insert(Eina_List *list, Eina_Compare_Cb func, const void *data) EINA_ARG_NONNULL(2, 3) EINA_WARN_UNUSED_RESULT;


/**
 * @brief Removes the first instance of the specified data from the given list.
 *
 * @param[in,out] list The given list.
 * @param[in] data The specified data.
 * @return A list pointer, or @c NULL on error.
 *
 * This function removes the first instance of @p data from @p list. If
 * @p data is not in the given list or is @c NULL, nothing is done and
 * the specified @p list returned. If @p list is @c NULL, @c NULL is
 * returned, otherwise a new list pointer that should be used in place
 * of the one passed to this function is returned.
 *
 * @warning @p list must be a pointer to the first element of the list.
 */
EAPI Eina_List            *eina_list_remove(Eina_List *list, const void *data) EINA_ARG_NONNULL(2) EINA_WARN_UNUSED_RESULT;


/**
 * @brief Removes the specified list node.
 *
 * @param[in,out] list The given linked list.
 * @param[in] remove_list The list node which is to be removed.
 * @return A list pointer, or @c NULL on error.
 *
 * This function removes the list node @p remove_list from @p list and
 * frees the list node structure @p remove_list. If @p list is
 * @c NULL, this function returns @c NULL. If @p remove_list is
 * @c NULL, it returns @p list; otherwise, a new list pointer that
 * should be used in place of the one passed to this function.
 *
 * The following code gives an example.  (Notice we use
 * EINA_LIST_FOREACH rather than EINA_LIST_FOREACH_SAFE because we stop
 * the loop after removing the current node.)
 *
 * @code
 * extern Eina_List *list;
 * Eina_List *l;
 * extern void *my_data;
 * void *data
 *
 * EINA_LIST_FOREACH(list, l, data)
 *   {
 *      if (data == my_data)
 *        {
 *           list = eina_list_remove_list(list, l);
 *           break;
 *        }
 *   }
 * @endcode
 *
 * @warning @p list must be a pointer to the first element of the list.
 */
EAPI Eina_List            *eina_list_remove_list(Eina_List *list, Eina_List *remove_list) EINA_ARG_NONNULL(2) EINA_WARN_UNUSED_RESULT;


/**
 * @brief Moves the specified data to the head of the list.
 *
 * @param[in,out] list The given linked list.
 * @param[in] move_list The list node to move.
 * @return A new list handle to replace the old one, or @c NULL on error.
 *
 * This function moves @p move_list to the front of @p list. If list is
 * @c NULL, @c NULL is returned. If @p move_list is @c NULL, @p list is
 * returned. Otherwise, a new list pointer that should be used in place
 * of the one passed to this function is returned.
 *
 * Example:
 * @code
 * extern Eina_List *list;
 * Eina_List *l;
 * extern void *my_data;
 * void *data;
 *
 * EINA_LIST_FOREACH(list, l, data)
 *   {
 *      if (data == my_data)
 *        {
 *           list = eina_list_promote_list(list, l);
 *           break;
 *        }
 *   }
 * @endcode
 *
 * @warning @p list must be a pointer to the first element of the list.
 */
EAPI Eina_List            *eina_list_promote_list(Eina_List *list, Eina_List *move_list) EINA_ARG_NONNULL(2) EINA_WARN_UNUSED_RESULT;


/**
 * @brief Moves the specified data to the tail of the list.
 *
 * @param[in,out] list The given linked list.
 * @param[in] move_list The list node to move.
 * @return A new list handle to replace the old one, or @c NULL on error.
 *
 * This function move @p move_list to the end of @p list. If list is @c
 * NULL, @c NULL is returned. If @p move_list is @c NULL, @p list is
 * returned. Otherwise, a new list pointer that should be used in place
 * of the one passed to this function is returned.
 *
 * Example:
 * @code
 * extern Eina_List *list;
 * Eina_List *l;
 * extern void *my_data;
 * void *data;
 *
 * EINA_LIST_FOREACH(list, l, data)
 *   {
 *      if (data == my_data)
 *        {
 *           list = eina_list_demote_list(list, l);
 *           break;
 *        }
 *   }
 * @endcode
 *
 * @warning @p list must be a pointer to the first element of the list.
 */
EAPI Eina_List            *eina_list_demote_list(Eina_List *list, Eina_List *move_list);


/**
 * @brief Finds a member of a list and returns it.
 *
 * @param[in] list The linked list to search.
 * @param[in] data The data member to find in the list.
 * @return The data member pointer if found, or @c NULL otherwise.
 *
 * This function searches in @p list from beginning to end for the
 * first member whose data pointer is @p data. If it is found, @p data
 * will be returned, otherwise @c NULL will be returned.
 *
 * Example:
 * @code
 * extern Eina_List *list;
 * extern void *my_data;
 *
 * if (eina_list_data_find(list, my_data) == my_data)
 *   {
 *      printf("Found member %p\n", my_data);
 *   }
 * @endcode
 *
 * @warning @p list must be a pointer to the first element of the list.
 */
EAPI void                 *eina_list_data_find(const Eina_List *list, const void *data) EINA_PURE EINA_ARG_NONNULL(2) EINA_WARN_UNUSED_RESULT;


/**
 * @brief Finds a member of a list and returns it as a list node.
 *
 * @param[in] list The list to search for data.
 * @param[in] data The data pointer to find in the list.
 * @return A list node containing the data member on success, @c NULL
 *         otherwise.
 *
 * This function searches @p list from beginning to end for the
 * first member whose data pointer is @p data. If it is found, the
 * list node containing the specified member is returned, otherwise
 * @c NULL is returned.