dlib.memory.allocator source code

1 /*
2 Copyright (c) 2016-2021 Eugene Wissner
3 
4 Boost Software License - Version 1.0 - August 17th, 2003
5 
6 Permission is hereby granted, free of charge, to any person or organization
7 obtaining a copy of the software and accompanying documentation covered by
8 this license (the "Software") to use, reproduce, display, distribute,
9 execute, and transmit the Software, and to prepare derivative works of the
10 Software, and to permit third-parties to whom the Software is furnished to
11 do so, all subject to the following:
12 
13 The copyright notices in the Software and this entire statement, including
14 the above license grant, this restriction and the following disclaimer,
15 must be included in all copies of the Software, in whole or in part, and
16 all derivative works of the Software, unless such copies or derivative
17 works are solely in the form of machine-executable object code generated by
18 a source language processor.
19 
20 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
21 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
22 FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
23 SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
24 FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
25 ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
26 DEALINGS IN THE SOFTWARE.
27 */
28 
29 /**
30  * Abstract allocator interface
31  *
32  * Copyright: Eugene Wissner 2016-2021.
33  * License: $(LINK2 boost.org/LICENSE_1_0.txt, Boost License 1.0).
34  * Authors: Eugene Wissner
35  */
36 module dlib.memory.allocator;
37 
38 version (unittest)
39 {
40     import dlib.memory : defaultAllocator;
41 }
42 
43 /**
44  * Allocator interface.
45  */
46 interface Allocator
47 {
48     /**
49      * Allocates $(D_PARAM size) bytes of memory.
50      *
51      * Params:
52      *     size = Amount of memory to allocate.
53      *
54      * Returns: The pointer to the new allocated memory.
55      */
56     void[] allocate(size_t size);
57 
58     /**
59      * Deallocates a memory block.
60      *
61      * Params:
62      *     p = A pointer to the memory block to be freed.
63      *
64      * Returns: Whether the deallocation was successful.
65      */
66     bool deallocate(void[] p);
67 
68     /**
69      * Increases or decreases the size of a memory block.
70      *
71      * Params:
72      *     p    = A pointer to the memory block.
73      *     size = Size of the reallocated block.
74      *
75      * Returns: Whether the reallocation was successful.
76      */
77     bool reallocate(ref void[] p, size_t size);
78 
79     /**
80      * Returns: The alignment offered.
81      */
82     @property immutable(uint) alignment() const @safe pure nothrow;
83 }
84 
85 /**
86  * Params:
87  *     T         = Element type of the array being created.
88  *     allocator = The allocator used for getting memory.
89  *     array     = A reference to the array being changed.
90  *     length    = New array length.
91  *
92  * Returns: $(D_KEYWORD true) upon success, $(D_KEYWORD false) if memory could
93  *          not be reallocated. In the latter
94  */
95 bool resizeArray(T)(Allocator allocator,
96                     ref T[] array,
97                     in size_t length)
98 {
99     void[] buf = array;
100 
101     if (!allocator.reallocate(buf, length * T.sizeof))
102     {
103         return false;
104     }
105     array = cast(T[]) buf;
106 
107     return true;
108 }
109 
110 ///
111 unittest
112 {
113     int[] p;
114 
115     defaultAllocator.resizeArray(p, 20);
116     assert(p.length == 20);
117 
118     defaultAllocator.resizeArray(p, 30);
119     assert(p.length == 30);
120 
121     defaultAllocator.resizeArray(p, 10);
122     assert(p.length == 10);
123 
124     defaultAllocator.resizeArray(p, 0);
125     assert(p is null);
126 }
127 
128 enum bool isFinalizable(T) =
129     is(T == class) ||
130     is(T == interface) ||
131     hasElaborateDestructor!T ||
132     isDynamicArray!T;