comparison: docs/Writerside/topics/map.h.md
docs/Writerside/topics/map.h.md
- changeset 1474
- 84de0ba791af
- parent 1465
- dc886f1a6155
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| 1473:944f02992369 | 1474:84de0ba791af |
|---|---|
| 322 int cxMapListIntersection(CxMap *dst, | 322 int cxMapListIntersection(CxMap *dst, |
| 323 const CxMap *src, const CxList *keys, | 323 const CxMap *src, const CxList *keys, |
| 324 cx_clone_func clone_func, | 324 cx_clone_func clone_func, |
| 325 const CxAllocator *clone_allocator, | 325 const CxAllocator *clone_allocator, |
| 326 void *data); | 326 void *data); |
| 327 | |
| 328 int cxMapUnion(CxMap *dst, const CxMap *src, | |
| 329 cx_clone_func clone_func, | |
| 330 const CxAllocator *clone_allocator, | |
| 331 void *data); | |
| 327 ``` | 332 ``` |
| 328 | 333 |
| 329 With `cxMapClone()` you can create deep copies of the values in one map and insert them into another map. | 334 With `cxMapClone()` you can create deep copies of the values in one map and insert them into another map. |
| 330 The destination map does not need to be empty. | 335 The destination map does not need to be empty. |
| 331 But when a key already exists in the destination map, the value is overwritten with the clone from the source map. | 336 But when a key already exists in the destination map, the value is overwritten with the clone from the source map. |
| 335 except that they only clone an element from the source map, when the key is _not_ contained in the | 340 except that they only clone an element from the source map, when the key is _not_ contained in the |
| 336 other map (or list, respectively). | 341 other map (or list, respectively). |
| 337 This is equivalent to computing the set difference for the set of keys. | 342 This is equivalent to computing the set difference for the set of keys. |
| 338 Likewise, `cxMapIntersection()` and `cxMapListIntersection()` only clone an element from the source map, | 343 Likewise, `cxMapIntersection()` and `cxMapListIntersection()` only clone an element from the source map, |
| 339 when the key is contained in _both_ collections. | 344 when the key is contained in _both_ collections. |
| 345 The function `cxMapUnion()` only clones elements from `src` to `dst` when their key is not present in `dst`. | |
| 346 | |
| 347 > The function `cxMapUnion()` does not operate on three maps for the sake of simplicity. | |
| 348 > If you want to combine two maps without modifying either of them, you can first use `cxMapClone()` | |
| 349 > to clone the first map into a new, empty, map, and then use `cxMapUnion()`. | |
| 340 | 350 |
| 341 Refer to the documentation of the [clone-function callback](allocator.h.md#clone-function) to learn how to implement it. | 351 Refer to the documentation of the [clone-function callback](allocator.h.md#clone-function) to learn how to implement it. |
| 342 | 352 |
| 343 The functions return zero if and only if all clone operations were successful. | 353 The functions return zero if and only if all clone operations were successful. |
| 344 | 354 |
