/src/libreoffice/include/o3tl/vector_pool.hxx
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1 | | /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */ |
2 | | /* |
3 | | * This file is part of the LibreOffice project. |
4 | | * |
5 | | * This Source Code Form is subject to the terms of the Mozilla Public |
6 | | * License, v. 2.0. If a copy of the MPL was not distributed with this |
7 | | * file, You can obtain one at http://mozilla.org/MPL/2.0/. |
8 | | * |
9 | | * This file incorporates work covered by the following license notice: |
10 | | * |
11 | | * Licensed to the Apache Software Foundation (ASF) under one or more |
12 | | * contributor license agreements. See the NOTICE file distributed |
13 | | * with this work for additional information regarding copyright |
14 | | * ownership. The ASF licenses this file to you under the Apache |
15 | | * License, Version 2.0 (the "License"); you may not use this file |
16 | | * except in compliance with the License. You may obtain a copy of |
17 | | * the License at http://www.apache.org/licenses/LICENSE-2.0 . |
18 | | */ |
19 | | |
20 | | #ifndef INCLUDED_O3TL_VECTOR_POOL_HXX |
21 | | #define INCLUDED_O3TL_VECTOR_POOL_HXX |
22 | | |
23 | | #include <utility> |
24 | | #include <vector> |
25 | | |
26 | | namespace o3tl |
27 | | { |
28 | | namespace detail |
29 | | { |
30 | | template<typename ValueType, class Container> class simple_pool_impl : |
31 | | public Container |
32 | | { |
33 | | typedef typename Container::value_type value_type; |
34 | | std::ptrdiff_t mnFirstFreeIndex; |
35 | | |
36 | | public: |
37 | | simple_pool_impl() : |
38 | 0 | mnFirstFreeIndex(-1) |
39 | 0 | {} |
40 | | |
41 | | std::ptrdiff_t alloc() |
42 | 0 | { |
43 | 0 | return store(ValueType()); |
44 | 0 | } |
45 | | |
46 | | std::ptrdiff_t store(const ValueType& rCopy) |
47 | 0 | { |
48 | 0 | if( mnFirstFreeIndex != -1 ) |
49 | 0 | { |
50 | 0 | std::ptrdiff_t nIdx=mnFirstFreeIndex; |
51 | 0 | mnFirstFreeIndex = this->at(mnFirstFreeIndex).nextFree; |
52 | 0 | this->at(nIdx).value = rCopy; |
53 | 0 | this->at(nIdx).nextFree = -1; |
54 | |
|
55 | 0 | return nIdx; |
56 | 0 | } |
57 | 0 | else |
58 | 0 | { |
59 | 0 | this->push_back(value_type(rCopy)); |
60 | 0 | return this->size()-1; |
61 | 0 | } |
62 | 0 | } |
63 | | |
64 | | void free( std::ptrdiff_t nIdx ) |
65 | 0 | { |
66 | 0 | this->at(nIdx).nextFree = mnFirstFreeIndex; |
67 | 0 | mnFirstFreeIndex = nIdx; |
68 | 0 | } |
69 | | |
70 | | const ValueType& get( std::ptrdiff_t nIdx ) const |
71 | | { |
72 | | return this->operator[](nIdx).value; |
73 | | } |
74 | | ValueType& get( std::ptrdiff_t nIdx ) |
75 | 0 | { |
76 | 0 | return this->operator[](nIdx).value; |
77 | 0 | } |
78 | | }; |
79 | | |
80 | | template< typename ValueType > struct struct_from_value |
81 | | { |
82 | | struct type |
83 | | { |
84 | | type() : |
85 | | value(), |
86 | | nextFree(-1) |
87 | | {} |
88 | | explicit type( ValueType val ) : |
89 | 0 | value(std::move(val)), |
90 | 0 | nextFree(-1) |
91 | 0 | {} |
92 | | |
93 | | ValueType value; |
94 | | std::ptrdiff_t nextFree; |
95 | | }; |
96 | | }; |
97 | | } |
98 | | |
99 | | /** Simple vector-based memory pool allocator |
100 | | |
101 | | This template can be used to provide simple pooled memory |
102 | | allocation from a container class that adheres to the stl |
103 | | random access container concept. Note that alloc/free works |
104 | | with _indices_ into the container! |
105 | | |
106 | | @example |
107 | | <pre> |
108 | | vector_pool<type> myPool; |
109 | | int nIdx=myPool.alloc(); |
110 | | myPool[nIdx] = myVal; |
111 | | ... do stuff ... |
112 | | myPool.free(nIdx); |
113 | | </pre> |
114 | | */ |
115 | | template<typename ValueType> struct vector_pool : |
116 | | public detail::simple_pool_impl<ValueType, |
117 | | std::vector<typename detail::struct_from_value<ValueType>::type > > |
118 | | {}; |
119 | | } |
120 | | |
121 | | #endif /* INCLUDED_O3TL_VECTOR_POOL_HXX */ |
122 | | |
123 | | /* vim:set shiftwidth=4 softtabstop=4 expandtab: */ |