1 /* EINA - EFL data type library 2 * Copyright (C) 2008 Cedric Bail 3 * 4 * This library is free software; you can redistribute it and/or 5 * modify it under the terms of the GNU Lesser General Public 6 * License as published by the Free Software Foundation; either 7 * version 2.1 of the License, or (at your option) any later version. 8 * 9 * This library is distributed in the hope that it will be useful, 10 * but WITHOUT ANY WARRANTY; without even the implied warranty of 11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 12 * Lesser General Public License for more details. 13 * 14 * You should have received a copy of the GNU Lesser General Public 15 * License along with this library; 16 * if not, see <http://www.gnu.org/licenses/>. 17 */ 18 19 #ifndef EINA_ITERATOR_H__ 20 #define EINA_ITERATOR_H__ 21 22 #include "eina_config.h" 23 24 #include "eina_types.h" 25 #include "eina_magic.h" 26 27 /** 28 * @page eina_iterator_example_page Eina_Iterator usage 29 * @dontinclude eina_iterator_01.c 30 * 31 * As always when using eina we need to include it: 32 * @skip #include 33 * @until Eina.h 34 * 35 * Here we a declare an unimpressive @ref Eina_Each_Cb "function" that prints 36 * some data: 37 * @until } 38 * @note Returning EINA_TRUE is important so we don't stop iterating over the 39 * container. 40 * 41 * And here's a more interesting function, it uses an iterator to print the 42 * contents of a container. What's interesting about it is that it doesn't care 43 * the type of container, it works for anything that can provide an iterator: 44 * @until } 45 * 46 * And on to our main function were we declare some variables and initialize 47 * eina, nothing too special: 48 * @until eina_init 49 * 50 * Next we populate both an array and a list with our strings, for more details 51 * see @ref eina_list_01_example_page and @ref eina_array_01_example_page : 52 * @until } 53 * 54 * And now we create an array and because the first element of the container 55 * doesn't interest us we skip it: 56 * @until iterator_next 57 * 58 * Having our iterator now pointing to interesting data we go ahead and print: 59 * @until print_eina_container 60 * 61 * As always once data with a structure we free it, but just because we can we 62 * do it by asking the iterator for it's container, and then of course free the 63 * iterator itself: 64 * @until eina_iterator_free 65 * 66 * But so far you're not impressed in @ref eina_array_01_example_page an array is 67 * also printed, so now we go to the cool stuff and use an iterator to do same 68 * stuff to a list: 69 * @until eina_iterator_free 70 * @note The only significant difference to the block above is in the 71 * function used to create the iterator. 72 * 73 * And now we free the list and shut eina down: 74 * @until } 75 */ 76 77 /** 78 * @page eina_iterator_01_c Eina_Iterator usage 79 * @page eina_iterator_01_c Eina_Iterator usage 80 * 81 * @include eina_iterator_01.c 82 * @example eina_iterator_01.c 83 */ 84 85 /** 86 * @addtogroup Eina_Iterator_Group Iterator Functions 87 * 88 * @brief These functions manage iterators on containers. 89 * 90 * These functions allow accessing elements of a container in a 91 * generic way, without knowing which container is used (a bit like 92 * iterators in the C++ STL). Iterators only allow sequential access 93 * (that is, from one element to the next one). For random access, see 94 * @ref Eina_Accessor_Group. 95 * 96 * Getting an iterator to access elements of a given container is done through 97 * the functions of that particular container. There is no function to create 98 * a generic iterator as iterators absolutely depend on the container. This 99 * means you won't find an iterator creation function here, those can be found with 100 * the documentation of the container type you're using. Though created with 101 * container specific functions iterators are always deleted with the same 102 * function: eina_iterator_free(). 103 * 104 * To get the data and iterate, use eina_iterator_next(). To call a function on 105 * all the elements of a container, use eina_iterator_foreach(). 106 * 107 * Here an @ref eina_iterator_example_page "example" 108 */ 109 110 /** 111 * @addtogroup Eina_Content_Access_Group Content Access 112 * 113 * @{ 114 */ 115 116 /** 117 * @defgroup Eina_Iterator_Group Iterator Functions 118 * 119 * @{ 120 */ 121 122 /** 123 * @typedef Eina_Iterator 124 * Abstract type for iterators. 125 */ 126 typedef struct _Eina_Iterator Eina_Iterator; 127 128 /** 129 * @typedef Eina_Iterator_Next_Callback 130 * Type for a callback that returns the next element in a container. 131 */ 132 typedef Eina_Bool (*Eina_Iterator_Next_Callback)(Eina_Iterator *it, void **data); 133 134 /** 135 * @typedef Eina_Iterator_Get_Container_Callback 136 * Type for a callback that returns the container. 137 */ 138 typedef void *(*Eina_Iterator_Get_Container_Callback)(Eina_Iterator *it); 139 140 /** 141 * @typedef Eina_Iterator_Free_Callback 142 * Type for a callback that frees the container. 143 */ 144 typedef void (*Eina_Iterator_Free_Callback)(Eina_Iterator *it); 145 146 /** 147 * @typedef Eina_Iterator_Lock_Callback 148 * Type for a callback that lock the container. 149 */ 150 typedef Eina_Bool (*Eina_Iterator_Lock_Callback)(Eina_Iterator *it); 151 152 /** 153 * @struct _Eina_Iterator 154 * structure of an iterator 155 * 156 * If creating an iterator remember to set the type using @ref EINA_MAGIC_SET. 157 */ 158 struct _Eina_Iterator 159 { 160 #define EINA_ITERATOR_VERSION 1 161 int version; /**< Version of the Iterator API. */ 162 163 Eina_Iterator_Next_Callback next EINA_ARG_NONNULL(1, 2) EINA_WARN_UNUSED_RESULT; /**< Callback called when a next element is requested. */ 164 Eina_Iterator_Get_Container_Callback get_container EINA_ARG_NONNULL(1) EINA_WARN_UNUSED_RESULT; /**< Callback called when the container is requested. */ 165 Eina_Iterator_Free_Callback free EINA_ARG_NONNULL(1); /**< Callback called when the container is freed. */ 166 167 Eina_Iterator_Lock_Callback lock EINA_WARN_UNUSED_RESULT; /**< Callback called when the container is locked. */ 168 Eina_Iterator_Lock_Callback unlock EINA_WARN_UNUSED_RESULT; /**< Callback called when the container is unlocked. */ 169 170 #define EINA_MAGIC_ITERATOR 0x98761233 171 EINA_MAGIC 172 }; 173 174 /** 175 * @def FUNC_ITERATOR_NEXT(Function) 176 * Helper macro to cast @p Function to a Eina_Iterator_Next_Callback. 177 */ 178 #define FUNC_ITERATOR_NEXT(Function) ((Eina_Iterator_Next_Callback)Function) 179 180 /** 181 * @def FUNC_ITERATOR_GET_CONTAINER(Function) 182 * Helper macro to cast @p Function to a Eina_Iterator_Get_Container_Callback. 183 */ 184 #define FUNC_ITERATOR_GET_CONTAINER(Function) ((Eina_Iterator_Get_Container_Callback)Function) 185 186 /** 187 * @def FUNC_ITERATOR_FREE(Function) 188 * Helper macro to cast @p Function to a Eina_Iterator_Free_Callback. 189 */ 190 #define FUNC_ITERATOR_FREE(Function) ((Eina_Iterator_Free_Callback)Function) 191 192 /** 193 * @def FUNC_ITERATOR_LOCK(Function) 194 * Helper macro to cast @p Function to a Eina_Iterator_Lock_Callback. 195 */ 196 #define FUNC_ITERATOR_LOCK(Function) ((Eina_Iterator_Lock_Callback)Function) 197 198 199 /** 200 * @brief Frees an iterator. 201 * 202 * @param[in,out] iterator The iterator to free. 203 * 204 * This function frees @p iterator if it is not @c NULL; 205 */ 206 EAPI void eina_iterator_free(Eina_Iterator *iterator); 207 208 209 /** 210 * @brief Returns the container of an iterator. 211 * 212 * @param[in] iterator The iterator. 213 * @return The container which created the iterator. 214 * 215 * This function returns the container which created @p iterator. If 216 * @p iterator is @c NULL, this function returns @c NULL. 217 */ 218 EAPI void *eina_iterator_container_get(Eina_Iterator *iterator) EINA_ARG_NONNULL(1) EINA_PURE; 219 220 /** 221 * @brief Returns the value of the current element and go to the next one. 222 * 223 * @param[in,out] iterator The iterator. 224 * @param[out] data The data of the element. 225 * @return #EINA_TRUE on success, #EINA_FALSE otherwise. 226 * 227 * This function returns the value of the current element pointed by 228 * @p iterator in @p data, then goes to the next element. If @p 229 * iterator is @c NULL or if a problem occurred, #EINA_FALSE is 230 * returned, otherwise #EINA_TRUE is returned. 231 */ 232 EAPI Eina_Bool eina_iterator_next(Eina_Iterator *iterator, 233 void **data) EINA_ARG_NONNULL(2) EINA_WARN_UNUSED_RESULT; 234 235 236 /** 237 * @brief Iterates over the container and execute a callback on each element. 238 * 239 * @param[in,out] iterator The iterator. 240 * @param[in] callback The callback called on each iteration. 241 * @param[in] fdata The data passed to the callback. 242 * 243 * This function iterates over the elements pointed by @p iterator, 244 * beginning with the current element. For each element, the callback 245 * @p cb is called with the data @p fdata. If @p iterator is @c NULL, 246 * the function returns immediately. Also, if @p cb returns #EINA_FALSE, 247 * the iteration stops at that point, if @p cb returns #EINA_TRUE 248 * the iteration continues. 249 */ 250 EAPI void eina_iterator_foreach(Eina_Iterator *iterator, 251 Eina_Each_Cb callback, 252 const void *fdata) EINA_ARG_NONNULL(2); 253 254 255 /** 256 * @brief Locks the container of the iterator. 257 * 258 * @param[in,out] iterator The iterator. 259 * @return #EINA_TRUE on success, #EINA_FALSE otherwise. 260 * 261 * If the container of the @p iterator permits it, it will be locked. When a 262 * container is locked calling eina_iterator_foreach() on it will return 263 * immediately. If @p iterator is @c NULL or if a problem occurred, #EINA_FALSE 264 * is returned, otherwise #EINA_TRUE is returned. If the container isn't 265 * lockable, it will return #EINA_TRUE. 266 * 267 * @warning None of the existing eina data structures are lockable. 268 */ 269 EAPI Eina_Bool eina_iterator_lock(Eina_Iterator *iterator) EINA_ARG_NONNULL(1); 270 271 /** 272 * @brief Unlocks the container of the iterator. 273 * 274 * @param[in,out] iterator The iterator. 275 * @return #EINA_TRUE on success, #EINA_FALSE otherwise. 276 * 277 * If the container of the @p iterator permits it and was previously 278 * locked, it will be unlocked. If @p iterator is @c NULL or if a 279 * problem occurred, #EINA_FALSE is returned, otherwise #EINA_TRUE 280 * is returned. If the container is not lockable, it will 281 * return #EINA_TRUE. 282 * 283 * @warning None of the existing eina data structures are lockable. 284 */ 285 EAPI Eina_Bool eina_iterator_unlock(Eina_Iterator *iterator) EINA_ARG_NONNULL(1); 286 287 /** 288 * @brief Creates an Eina_Iterator that iterates through a 289 * NUL-terminated C array. 290 * 291 * @param[in] array The NUL-terminated array 292 * @return The iterator that will walk over the array. 293 * 294 * You can create it like this: 295 * int array[] = {1, 2, 3, 4}; 296 * int* array2[] = {&array[0], &array[1], &array[2], &array[3], NULL}; 297 * 298 * Eina_Iterator* iterator = eina_carray_iterator_new((void**)array2); 299 * 300 * @since 1.18 301 */ 302 EAPI Eina_Iterator *eina_carray_iterator_new(void** array) EINA_ARG_NONNULL(1) EINA_WARN_UNUSED_RESULT; 303 304 /** 305 * @brief Creates an Eina_Iterator that iterates through a 306 * C array of specified size. 307 * 308 * @param[in] array The array 309 * @return The iterator that will walk over the array. 310 * 311 * You can create it like this: 312 * int array[] = {1, 2, 3, 4}; 313 * 314 * Eina_Iterator* iterator = eina_carray_length_iterator_new((void**)array, sizeof (array[0]), (EINA_C_ARRAY_LENGTH(array)); 315 * 316 * @since 1.22 317 */ 318 EAPI Eina_Iterator *eina_carray_length_iterator_new(void** array, unsigned int step, unsigned int length) EINA_ARG_NONNULL(1) EINA_WARN_UNUSED_RESULT; 319 320 /** 321 * @def EINA_C_ARRAY_ITERATOR_NEW 322 * @brief Creates an Eina_Iterator that iterates through a 323 * NUL-terminated C array. 324 * 325 * @param[in] Array The NUL-terminated array 326 * @return The iterator that will walk over the array. 327 * 328 * You can create it like this: 329 * int array[] = {1, 2, 3, 4}; 330 * 331 * Eina_Iterator* iterator = EINA_C_ARRAY_ITERATOR_NEW(array); 332 * 333 * @since 1.22 334 */ 335 #define EINA_C_ARRAY_ITERATOR_NEW(Array) eina_carray_length_iterator_new((void**) Array, sizeof (Array[0]), EINA_C_ARRAY_LENGTH(Array)) 336 337 /** 338 * @brief Creates a new iterator which which iterates through all elements with are accepted by the filter callback 339 * 340 * @param[in] original the iterator the use as original set 341 * @param[in] filter if the callback returns true the element from the original set is taken into the the new set. 342 * @param[in] free_cb when the iterator is gone this callback will be called with data as argument 343 * @param[in] data the data which is passed to the filter callback 344 * 345 * The iterator is filtered while it is being iterated. 346 * The original iterator you pass in here is is then owned and will be freed once the the new iterator is freed. 347 * 348 * @since 1.19 349 */ 350 EAPI Eina_Iterator* eina_iterator_filter_new(Eina_Iterator *original, Eina_Each_Cb filter, Eina_Free_Cb free_cb, void *data) EINA_ARG_NONNULL(1) EINA_WARN_UNUSED_RESULT; 351 352 /** 353 * @brief Creates an Eina_Iterator that iterates through a series 354 * of Eina_Iterator. 355 * 356 * @param[in] it The first Eina_Iterator to iterate over 357 * @return The iterator that will walk all the other iterator 358 * 359 * Eina_Iterator* iterator = eina_multi_iterator_new(it1, it2, it3, NULL); 360 * 361 * @note The returned array will destroy iterator given to it once they are not 362 * necessary anymore. Taking ownership of those iterator. 363 * 364 * @since 1.22 365 */ 366 EAPI Eina_Iterator *eina_multi_iterator_internal_new(Eina_Iterator *it, ...) EINA_ARG_NONNULL(1) EINA_WARN_UNUSED_RESULT; 367 368 369 /** 370 * @brief Calls the process method on each node of iterator, producing new "processed" 371 * nodes and returning a new iterator which contains them. 372 * 373 * @param[in] iterator Iterator containing the nodes to process. 374 * @param[in] process Method to call on each node. 375 * @param[in] free_cb Method called when all nodes have been processed. It receives "data" as a parameter. 376 * @param[in] fdata Additional data passed to the process method. 377 * 378 * Processes every node in the input iterator and returns a new iterator containing 379 * the processed nodes. This is akin to a Map function: 380 * https://en.wikipedia.org/wiki/Map_(higher-order_function) 381 * 382 * @since 1.24 383 */ 384 EAPI Eina_Iterator* eina_iterator_processed_new(Eina_Iterator *iterator, Eina_Process_Cb process, Eina_Free_Cb free_cb, void *fdata) EINA_WARN_UNUSED_RESULT; 385 386 /** 387 * @def eina_multi_iterator_new 388 * @brief Creates an Eina_Iterator that iterates through a series 389 * of Eina_Iterator. 390 * 391 * @param[in] It The first Eina_Iterator to iterate over 392 * @return The iterator that will walk all the other iterator 393 * 394 * Eina_Iterator* iterator = eina_multi_iterator_new(it1, it2, it3); 395 * 396 * @note The returned array will destroy iterator given to it once they are not 397 * necessary anymore. Taking ownership of those iterator. 398 * 399 * @since 1.22 400 */ 401 #define eina_multi_iterator_new(It, ...) eina_multi_iterator_internal_new(It, ##__VA_ARGS__, NULL) 402 403 /** 404 * @def EINA_ITERATOR_FOREACH 405 * @brief Definition for the macro to iterate over all elements easily. 406 * 407 * @param[in,out] itr The iterator to use. 408 * @param[out] data Where to store * data, must be a pointer support getting 409 * its address since * eina_iterator_next() requires a pointer 410 * to pointer! 411 * 412 * This macro is a convenient way to use iterators, very similar to 413 * EINA_LIST_FOREACH(). 414 * 415 * This macro can be used for freeing the data of a list, like in the 416 * following example. It has the same goal as the one documented in 417 * EINA_LIST_FOREACH(), but using iterators: 418 * 419 * @code 420 * Eina_List *list; 421 * Eina_Iterator *itr; 422 * char *data; 423 * 424 * // list is already filled, 425 * // its elements are just duplicated strings 426 * 427 * itr = eina_list_iterator_new(list); 428 * EINA_ITERATOR_FOREACH(itr, data) 429 * free(data); 430 * eina_iterator_free(itr); 431 * eina_list_free(list); 432 * @endcode 433 * 434 * @note This example is not optimal algorithm to release a list since 435 * it will walk the list twice, but it serves as an example. For 436 * optimized version use EINA_LIST_FREE() 437 * 438 * @warning The order in which the elements will be traversed depends on the 439 * underlying container and @b shouldn't be relied upon. 440 * 441 * @warning unless explicitly stated in functions returning iterators, 442 * do not modify the iterated object while you walk it, in this 443 * example using lists, do not remove list nodes or you might 444 * crash! This is not a limitation of iterators themselves, 445 * rather in the iterators implementations to keep them as simple 446 * and fast as possible. 447 */ 448 #define EINA_ITERATOR_FOREACH(itr, \ 449 data) while (eina_iterator_next((itr), \ 450 (void **)(void *)&(data))) 451 452 /** 453 * @} 454 */ 455 456 /** 457 * @} 458 */ 459 460 #endif 461