comparison: docs/Writerside/topics/collection.h.md
docs/Writerside/topics/collection.h.md
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| 1 # Collections | |
| 2 | |
| 3 UCX defines common attributes for collections. | |
| 4 If you want to implement an own collection data type that uses the same features, you can use the | |
| 5 `CX_COLLECTION_BASE` macro at the beginning of your struct to roll out all members a usual UCX collection has. | |
| 6 | |
| 7 This macro will embed a structure in your collection that can be accessed with the member name `collection`. | |
| 8 | |
| 9 ```c | |
| 10 struct my_fancy_collection_s { | |
| 11 CX_COLLECTION_BASE; // adds a member named 'collection' | |
| 12 struct my_collection_data_s *data; | |
| 13 }; | |
| 14 ``` | |
| 15 | |
| 16 > You can always look at the UCX list and map implementations if you need some inspiration. | |
| 17 | |
| 18 ## Base Attributes of a Collection | |
| 19 | |
| 20 The following attributes are declared by the `CX_COLLECTION_BASE` macro: | |
| 21 | |
| 22 | Attribute | Description | | |
| 23 |-----------------------|----------------------------------------------------------------------------------------------------------------| | |
| 24 | `allocator` | The [allocator](allocator.h.md) that shall be used for the collection data. | | |
| 25 | `cmpfunc` | A function to [compare](compare.h.md) two elements. | | |
| 26 | `elem_size` | The size of one element in bytes. | | |
| 27 | `size` | The size, meaning the number of elements, currently stored. | | |
| 28 | `simple_destructor` | An optional simple [destructor function](allocator.h.md#destructor-functions). | | |
| 29 | `advanced_destructor` | An optional advanced destructor function. | | |
| 30 | `destructor_data` | A pointer to the custom data that shall be passed to the advanced destructor. | | |
| 31 | `store_pointer` | A `bool` indicating whether this collection stores pointers instead of the element's data. | | |
| 32 | `sorted` | A `bool` indicating whether the elements are currently guaranteed sorted with respect to the compare function. | | |
| 33 | |
| 34 The attributes can be accessed directly via the `collection` member of your struct, or with the following convenience macros. | |
| 35 | |
| 36 ```C | |
| 37 cxCollectionSize(c) | |
| 38 cxCollectionElementSize(c) | |
| 39 cxCollectionStoresPointers(c) | |
| 40 cxCollectionSorted(c) | |
| 41 ``` | |
| 42 | |
| 43 In each case the argument `c` is a pointer to your collection. The macro will then access the base data with `c->collection`. | |
| 44 | |
| 45 For working with destructors, the following macros are defined: | |
| 46 | |
| 47 ```C | |
| 48 cxDefineDestructor(c, destr) | |
| 49 cxDefineAdvancedDestructor(c, destr, data) | |
| 50 | |
| 51 // use in your collection's implementation | |
| 52 cx_invoke_destructor(c, elem) | |
| 53 | |
| 54 // the following two should not be used | |
| 55 cx_invoke_simple_destructor(c, elem) | |
| 56 cx_invoke_advanced_destructor(c, elem) | |
| 57 ``` | |
| 58 | |
| 59 With `cxDefineDestructor()` you can assign a simple [destructor function](allocator.h.md#destructor-functions) | |
| 60 to an _instance_ of your collection. | |
| 61 Similarly, you can assign an advanced destructor with custom `data` by using `cxDefineAdvancedDestructor`. | |
| 62 | |
| 63 Your collection _should_ be supporting destructors by invoking `cx_invoke_destructor()` whenever an element | |
| 64 is removed from your collection _without_ being returned to the caller. | |
| 65 This macro will invoke a simple destructor, if one is assigned, first, and then the advanced destructor (again, if assigned). | |
| 66 | |
| 67 > Destructor functions are always invoked with a pointer to the element in your collection. | |
| 68 > If your collection is storing pointers (i.e. `cxCollectionStorePointers()` returns `true`) | |
| 69 > the `cx_invoke_destructor()` will make sure that the pointer to the element is dereferenced first, | |
| 70 > so that the destructor functions are _always_ invoked with pointer to the actual element. | |
| 71 {style="note"} | |
| 72 | |
| 73 <seealso> | |
| 74 <category ref="apidoc"> | |
| 75 <a href="https://ucx.sourceforge.io/api/collection_8h.html">collection.h</a> | |
| 76 </category> | |
| 77 </seealso> |
