1/*
2 Copyright (c) 2010 Volker Krause <vkrause@kde.org>
3
4 This library is free software; you can redistribute it and/or modify it
5 under the terms of the GNU Library General Public License as published by
6 the Free Software Foundation; either version 2 of the License, or (at your
7 option) any later version.
8
9 This library is distributed in the hope that it will be useful, but WITHOUT
10 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public
12 License for more details.
13
14 You should have received a copy of the GNU Library General Public License
15 along with this library; see the file COPYING.LIB. If not, write to the
16 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
17 02110-1301, USA.
18*/
19
20#ifndef AKONADI_SHAREDVALUEPOOL_P_H
21#define AKONADI_SHAREDVALUEPOOL_P_H
22
23#include <boost/utility/enable_if.hpp>
24#include <algorithm>
25
26namespace Akonadi {
27namespace Internal {
28
29/*template <typename T> class container_traits
30{
31 private:
32 typedef char sizeOne;
33 typedef struct
34 {
35 char a[2];
36 } sizeTwo;
37 template <typename C> static sizeOne testForKeyType( typename C::key_type const* );
38 template <typename C> static sizeTwo testForKeyType( ... );
39 public:
40 enum {
41 isAssociative=sizeof(container_traits<T>::testForKeyType<T>(0))==1
42 };
43};*/
44
45/**
46 * Pool of implicitly shared values, use for optimizing memory use
47 * when having a large amount of copies from a small set of different values.
48 */
49template <typename T, template <typename> class Container>
50class SharedValuePool
51{
52public:
53 /** Returns the shared value equal to @p value .*/
54 /*template <typename C>
55 typename boost::enable_if_c<container_traits<Container<C> >::isAssociative, C>::type sharedValue( const C &value, const int * = 0 )
56 {
57 typename Container<T>::const_iterator it = m_pool.constFind( value );
58 if ( it != m_pool.constEnd() )
59 return *it;
60 m_pool.insert( value );
61 return value;
62 }
63
64 template <typename C>
65 typename boost::disable_if_c<container_traits<Container<C> >::isAssociative, C>::type sharedValue( const C &value )*/
66 T sharedValue(const T &value)
67 {
68 // for small pool sizes this is actually faster than using lower_bound and a sorted vector
69 typename Container<T>::const_iterator it = std::find(m_pool.constBegin(), m_pool.constEnd(), value);
70 if (it != m_pool.constEnd()) {
71 return *it;
72 }
73 m_pool.push_back(value);
74 return value;
75 }
76
77private:
78 Container<T> m_pool;
79};
80
81}
82}
83
84#endif
85