comparison: docs/Writerside/topics/map.h.md
docs/Writerside/topics/map.h.md
- changeset 1274
- 03e9360e98f5
- parent 1250
- 80a1d63ede19
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| 1273:c35be6dc1667 | 1274:03e9360e98f5 |
|---|---|
| 287 The function `cxMapFree()` invokes the [destructor functions](collection.h.md#destructor-functions) for all elements, | 287 The function `cxMapFree()` invokes the [destructor functions](collection.h.md#destructor-functions) for all elements, |
| 288 and then deallocates the entire memory for the map. | 288 and then deallocates the entire memory for the map. |
| 289 | 289 |
| 290 ## Implement own Map Structures | 290 ## Implement own Map Structures |
| 291 | 291 |
| 292 If the UCX [hash map](hash_map.h.md) implementation does not suit your needs, | |
| 293 you can also implement your own map. | |
| 294 To be compatible with the `CxMap` interface, it needs to store key/value pairs of the following form. | |
| 295 | |
| 292 ```C | 296 ```C |
| 293 typedef struct { | 297 typedef struct { |
| 294 const CxHashKey *key; | 298 const CxHashKey *key; |
| 295 void *value; | 299 void *value; |
| 296 } CxMapEntry; | 300 } CxMapEntry; |
| 297 ``` | 301 ``` |
| 298 | 302 |
| 299 <warning> | 303 When you are declaring your map structure, a `CxMap` member must be embedded as first member of this structure. |
| 300 TODO: example | 304 Secondly, you need to implement the `cx_map_class` and assign it when allocating your map. |
| 301 </warning> | 305 |
| 306 ```C | |
| 307 #include <cx/map.h> | |
| 308 | |
| 309 typedef struct { | |
| 310 CxMap base; | |
| 311 // ... data members for storing CxMapEntry elements go here ... | |
| 312 } MyMap; | |
| 313 | |
| 314 // declare the class - implement the functions somewhere | |
| 315 static cx_map_class my_map_class = { | |
| 316 my_map_destructor, | |
| 317 my_map_clear, | |
| 318 my_map_put, | |
| 319 my_map_get, | |
| 320 my_map_remove, | |
| 321 my_map_iterator, | |
| 322 }; | |
| 323 | |
| 324 // this function will create the map | |
| 325 CxMap *myMapCreate(const CxAllocator *allocator, size_t itemsize) { | |
| 326 if (allocator == NULL) { | |
| 327 allocator = cxDefaultAllocator; | |
| 328 } | |
| 329 | |
| 330 // allocate memory | |
| 331 MyMap *map = cxCalloc(allocator, 1, sizeof(MyMap)); | |
| 332 if (map == NULL) return NULL; | |
| 333 | |
| 334 // initialize base members | |
| 335 map->base.cl = &my_map_class; // <--- assign class here | |
| 336 map->base.collection.allocator = allocator; | |
| 337 if (itemsize == CX_STORE_POINTERS) { | |
| 338 map->base.collection.elem_size = sizeof(void *); | |
| 339 map->base.collection.store_pointer = true; | |
| 340 } else { | |
| 341 map->base.collection.elem_size = itemsize; | |
| 342 } | |
| 343 | |
| 344 // ... initialization of data members go here ... | |
| 345 | |
| 346 return (CxMap *) map; | |
| 347 } | |
| 348 ``` | |
| 302 | 349 |
| 303 The required behavior for the implementations is described in the following table. | 350 The required behavior for the implementations is described in the following table. |
| 304 You can always look at the source code of the UCX hash map to get inspiration. | 351 You can always look at the source code of the UCX hash map to get inspiration. |
| 305 | 352 |
| 306 | Function | Description | | 353 | Function | Description | |
