345 lines
12 KiB
C
345 lines
12 KiB
C
/* EINA - EFL data type library
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* Copyright (C) 2008 Cedric Bail
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library;
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* if not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef EINA_ITERATOR_H__
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#define EINA_ITERATOR_H__
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#include "eina_config.h"
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#include "eina_types.h"
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#include "eina_magic.h"
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/**
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* @page eina_iterator_example_page Eina_Iterator usage
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* @dontinclude eina_iterator_01.c
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*
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* As always when using eina we need to include it:
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* @skip #include
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* @until Eina.h
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*
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* Here we a declare an unimpressive @ref Eina_Each_Cb "function" that prints
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* some data:
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* @until }
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* @note Returning EINA_TRUE is important so we don't stop iterating over the
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* container.
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*
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* And here a more interesting function, it uses an iterator to print the
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* contents of a container. What's interesting about it is that it doesn't care
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* the type of container, it works for anything that can provide an iterator:
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* @until }
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*
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* And on to our main function were we declare some variables and initialize
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* eina, nothing too special:
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* @until eina_init
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*
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* Next we populate both an array and a list with our strings, for more details
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* see @ref eina_list_01_example_page and @ref eina_array_01_example_page :
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* @until }
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*
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* And now we create an array and because the first element of the container
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* doesn't interest us we skip it:
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* @until iterator_next
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*
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* Having our iterator now pointing to interesting data we go ahead and print:
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* @until print_eina_container
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*
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* As always once data with a structure we free it, but just because we can we
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* do it by asking the iterator for it's container, and then of course free the
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* iterator itself:
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* @until eina_iterator_free
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*
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* But so far you're not impressed in @ref eina_array_01_example_page an array is
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* also printed, so now we go to the cool stuff and use an iterator to do same
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* stuff to a list:
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* @until eina_iterator_free
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* @note The only significant diference to the block above is in the
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* function used to create the iterator.
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*
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* And now we free the list and shut eina down:
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* @until }
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*/
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/**
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* @page eina_iterator_01_c Eina_Iterator usage
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* @page eina_iterator_01_c Eina_Iterator usage
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*
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* @include eina_iterator_01.c
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* @example eina_iterator_01.c
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*/
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/**
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* @addtogroup Eina_Iterator_Group Iterator Functions
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*
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* @brief These functions manage iterators on containers.
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*
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* These functions allow to access elements of a container in a
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* generic way, without knowing which container is used (a bit like
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* iterators in the C++ STL). Iterators only allows sequential access
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* (that is, from an element to the next one). For random access, see
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* @ref Eina_Accessor_Group.
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*
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* Getting an iterator to access elements of a given container is done through
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* the functions of that particular container. There is no function to create
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* a generic iterator as iterators absolutely depend on the container. This
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* means you won't find iterator creation function here, those can be found on
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* the documentation of the container type you're using. Though created with
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* container specific functions iterators are always deleted with the same
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* function: eina_iterator_free().
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*
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* To get the data and iterate, use eina_iterator_next(). To call a function on
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* all the elements of a container, use eina_iterator_foreach().
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*
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* Here an @ref eina_iterator_example_page "example"
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*/
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/**
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* @addtogroup Eina_Content_Access_Group Content Access
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*
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* @{
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*/
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/**
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* @defgroup Eina_Iterator_Group Iterator Functions
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*
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* @{
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*/
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/**
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* @typedef Eina_Iterator
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* Abstract type for iterators.
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*/
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typedef struct _Eina_Iterator Eina_Iterator;
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/**
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* @typedef Eina_Iterator_Next_Callback
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* Type for a callback that returns the next element in a container.
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*/
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typedef Eina_Bool (*Eina_Iterator_Next_Callback)(Eina_Iterator *it, void **data);
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/**
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* @typedef Eina_Iterator_Get_Container_Callback
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* Type for a callback that returns the container.
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*/
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typedef void *(*Eina_Iterator_Get_Container_Callback)(Eina_Iterator *it);
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/**
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* @typedef Eina_Iterator_Free_Callback
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* Type for a callback that frees the container.
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*/
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typedef void (*Eina_Iterator_Free_Callback)(Eina_Iterator *it);
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/**
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* @typedef Eina_Iterator_Lock_Callback
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* Type for a callback that lock the container.
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*/
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typedef Eina_Bool (*Eina_Iterator_Lock_Callback)(Eina_Iterator *it);
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/**
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* @struct _Eina_Iterator
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* structure of an iterator
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*
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* If creating an iterator remember to set the type using @ref EINA_MAGIC_SET.
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*/
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struct _Eina_Iterator
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{
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#define EINA_ITERATOR_VERSION 1
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int version; /**< Version of the Iterator API. */
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Eina_Iterator_Next_Callback next EINA_ARG_NONNULL(1, 2) EINA_WARN_UNUSED_RESULT; /**< Callback called when a next element is requested. */
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Eina_Iterator_Get_Container_Callback get_container EINA_ARG_NONNULL(1) EINA_WARN_UNUSED_RESULT; /**< Callback called when the container is requested. */
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Eina_Iterator_Free_Callback free EINA_ARG_NONNULL(1); /**< Callback called when the container is freed. */
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Eina_Iterator_Lock_Callback lock EINA_WARN_UNUSED_RESULT; /**< Callback called when the container is locked. */
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Eina_Iterator_Lock_Callback unlock EINA_WARN_UNUSED_RESULT; /**< Callback called when the container is unlocked. */
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#define EINA_MAGIC_ITERATOR 0x98761233
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EINA_MAGIC
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};
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/**
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* @def FUNC_ITERATOR_NEXT(Function)
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* Helper macro to cast @p Function to a Eina_Iterator_Next_Callback.
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*/
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#define FUNC_ITERATOR_NEXT(Function) ((Eina_Iterator_Next_Callback)Function)
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/**
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* @def FUNC_ITERATOR_GET_CONTAINER(Function)
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* Helper macro to cast @p Function to a Eina_Iterator_Get_Container_Callback.
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*/
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#define FUNC_ITERATOR_GET_CONTAINER(Function) ((Eina_Iterator_Get_Container_Callback)Function)
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/**
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* @def FUNC_ITERATOR_FREE(Function)
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* Helper macro to cast @p Function to a Eina_Iterator_Free_Callback.
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*/
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#define FUNC_ITERATOR_FREE(Function) ((Eina_Iterator_Free_Callback)Function)
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/**
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* @def FUNC_ITERATOR_LOCK(Function)
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* Helper macro to cast @p Function to a Eina_Iterator_Lock_Callback.
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*/
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#define FUNC_ITERATOR_LOCK(Function) ((Eina_Iterator_Lock_Callback)Function)
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/**
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* @brief Free an iterator.
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*
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* @param iterator The iterator to free.
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*
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* This function frees @p iterator if it is not @c NULL;
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*/
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EAPI void eina_iterator_free(Eina_Iterator *iterator);
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/**
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* @brief Return the container of an iterator.
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*
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* @param iterator The iterator.
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* @return The container which created the iterator.
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*
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* This function returns the container which created @p iterator. If
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* @p iterator is @c NULL, this function returns @c NULL.
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*/
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EAPI void *eina_iterator_container_get(Eina_Iterator *iterator) EINA_ARG_NONNULL(1) EINA_PURE;
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/**
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* @brief Return the value of the current element and go to the next one.
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*
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* @param iterator The iterator.
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* @param data The data of the element.
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* @return #EINA_TRUE on success, #EINA_FALSE otherwise.
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*
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* This function returns the value of the current element pointed by
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* @p iterator in @p data, then goes to the next element. If @p
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* iterator is @c NULL or if a problem occurred, #EINA_FALSE is
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* returned, otherwise #EINA_TRUE is returned.
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*/
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EAPI Eina_Bool eina_iterator_next(Eina_Iterator *iterator,
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void **data) EINA_ARG_NONNULL(2) EINA_WARN_UNUSED_RESULT;
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/**
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* @brief Iterate over the container and execute a callback on each element.
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*
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* @param iterator The iterator.
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* @param callback The callback called on each iteration.
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* @param fdata The data passed to the callback.
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*
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* This function iterates over the elements pointed by @p iterator,
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* beginning from the current element. For Each element, the callback
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* @p cb is called with the data @p fdata. If @p iterator is @c NULL,
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* the function returns immediately. Also, if @p cb returns #EINA_FALSE,
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* the iteration stops at that point, if @p cb returns #EINA_TRUE
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* the iteration continues.
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*/
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EAPI void eina_iterator_foreach(Eina_Iterator *iterator,
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Eina_Each_Cb callback,
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const void *fdata) EINA_ARG_NONNULL(2);
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/**
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* @brief Lock the container of the iterator.
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*
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* @param iterator The iterator.
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* @return #EINA_TRUE on success, #EINA_FALSE otherwise.
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*
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* If the container of the @p iterator permits it, it will be locked. When a
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* container is locked calling eina_iterator_foreach() on it will return
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* immediately. If @p iterator is @c NULL or if a problem occurred, #EINA_FALSE
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* is returned, otherwise #EINA_TRUE is returned. If the container isn't
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* lockable, it will return #EINA_TRUE.
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*
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* @warning None of the existing eina data structures are lockable.
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*/
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EAPI Eina_Bool eina_iterator_lock(Eina_Iterator *iterator) EINA_ARG_NONNULL(1);
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/**
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* @brief Unlock the container of the iterator.
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*
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* @param iterator The iterator.
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* @return #EINA_TRUE on success, #EINA_FALSE otherwise.
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*
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* If the container of the @p iterator permits it and was previously
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* locked, it will be unlocked. If @p iterator is @c NULL or if a
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* problem occurred, #EINA_FALSE is returned, otherwise #EINA_TRUE
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* is returned. If the container is not lockable, it will
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* return #EINA_TRUE.
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*
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* @warning None of the existing eina data structures are lockable.
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*/
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EAPI Eina_Bool eina_iterator_unlock(Eina_Iterator *iterator) EINA_ARG_NONNULL(1);
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/**
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* @def EINA_ITERATOR_FOREACH
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* @brief Macro to iterate over all elements easily.
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*
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* @param itr The iterator to use.
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* @param data Where to store * data, must be a pointer support getting
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* its address since * eina_iterator_next() requires a pointer
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* to pointer!
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*
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* This macro is a convenient way to use iterators, very similar to
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* EINA_LIST_FOREACH().
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*
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* This macro can be used for freeing the data of a list, like in the
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* following example. It has the same goal as the one documented in
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* EINA_LIST_FOREACH(), but using iterators:
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*
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* @code
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* Eina_List *list;
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* Eina_Iterator *itr;
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* char *data;
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*
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* // list is already filled,
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* // its elements are just duplicated strings
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*
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* itr = eina_list_iterator_new(list);
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* EINA_ITERATOR_FOREACH(itr, data)
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* free(data);
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* eina_iterator_free(itr);
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* eina_list_free(list);
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* @endcode
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*
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* @note this example is not optimal algorithm to release a list since
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* it will walk the list twice, but it serves as an example. For
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* optimized version use EINA_LIST_FREE()
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*
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* @warning The order in which the elements will be traversed depends on the
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* underlying container and @b shouldn't be relied upon.
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*
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* @warning unless explicitly stated in functions returning iterators,
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* do not modify the iterated object while you walk it, in this
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* example using lists, do not remove list nodes or you might
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* crash! This is not a limitiation of iterators themselves,
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* rather in the iterators implementations to keep them as simple
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* and fast as possible.
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*/
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#define EINA_ITERATOR_FOREACH(itr, \
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data) while (eina_iterator_next((itr), \
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(void **)(void *)&(data)))
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/**
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* @}
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*/
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/**
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* @}
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*/
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#endif
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