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1 | // -*- C++ -*- |
2 | ||
818ab71a | 3 | // Copyright (C) 2005-2016 Free Software Foundation, Inc. |
4569a895 AT |
4 | // |
5 | // This file is part of the GNU ISO C++ Library. This library is free | |
6 | // software; you can redistribute it and/or modify it under the terms | |
7 | // of the GNU General Public License as published by the Free Software | |
748086b7 | 8 | // Foundation; either version 3, or (at your option) any later |
4569a895 AT |
9 | // version. |
10 | ||
11 | // This library is distributed in the hope that it will be useful, but | |
12 | // WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
14 | // General Public License for more details. | |
15 | ||
748086b7 JJ |
16 | // Under Section 7 of GPL version 3, you are granted additional |
17 | // permissions described in the GCC Runtime Library Exception, version | |
18 | // 3.1, as published by the Free Software Foundation. | |
4569a895 | 19 | |
748086b7 JJ |
20 | // You should have received a copy of the GNU General Public License and |
21 | // a copy of the GCC Runtime Library Exception along with this program; | |
22 | // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see | |
23 | // <http://www.gnu.org/licenses/>. | |
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24 | |
25 | // Copyright (C) 2004 Ami Tavory and Vladimir Dreizin, IBM-HRL. | |
26 | ||
27 | // Permission to use, copy, modify, sell, and distribute this software | |
28 | // is hereby granted without fee, provided that the above copyright | |
29 | // notice appears in all copies, and that both that copyright notice | |
30 | // and this permission notice appear in supporting documentation. None | |
31 | // of the above authors, nor IBM Haifa Research Laboratories, make any | |
32 | // representation about the suitability of this software for any | |
33 | // purpose. It is provided "as is" without express or implied | |
34 | // warranty. | |
35 | ||
36 | /** | |
37 | * @file list_update_policy.hpp | |
38 | * Contains policies for list update containers. | |
39 | */ | |
40 | ||
41 | #ifndef PB_DS_LU_POLICY_HPP | |
42 | #define PB_DS_LU_POLICY_HPP | |
43 | ||
8fc81078 | 44 | #include <bits/c++config.h> |
4ba851b5 | 45 | #include <cstdlib> |
a345e45d BK |
46 | #include <ext/pb_ds/detail/list_update_policy/lu_counter_metadata.hpp> |
47 | #include <ext/pb_ds/tag_and_trait.hpp> | |
4569a895 | 48 | |
5e11f978 | 49 | namespace __gnu_pbds |
4569a895 | 50 | { |
a345e45d BK |
51 | /** |
52 | * A list-update policy that unconditionally moves elements to the | |
53 | * front of the list. A null type means that each link in a | |
54 | * list-based container does not actually need metadata. | |
55 | */ | |
56 | template<typename _Alloc = std::allocator<char> > | |
57 | class lu_move_to_front_policy | |
58 | { | |
59 | public: | |
60 | typedef _Alloc allocator_type; | |
61 | ||
30a96b3b | 62 | /// Metadata on which this functor operates. |
a345e45d BK |
63 | typedef null_type metadata_type; |
64 | ||
65 | private: | |
66 | typedef typename _Alloc::template rebind<metadata_type> __rebind_m; | |
67 | ||
68 | public: | |
30a96b3b | 69 | /// Reference to metadata on which this functor operates. |
a345e45d BK |
70 | typedef typename __rebind_m::other::reference metadata_reference; |
71 | ||
30a96b3b | 72 | /// Creates a metadata object. |
a345e45d BK |
73 | metadata_type |
74 | operator()() const | |
75 | { return s_metadata; } | |
76 | ||
30a96b3b BK |
77 | /// Decides whether a metadata object should be moved to the front |
78 | /// of the list. | |
a345e45d BK |
79 | inline bool |
80 | operator()(metadata_reference r_metadata) const | |
81 | { return true; } | |
82 | ||
83 | private: | |
84 | static null_type s_metadata; | |
85 | }; | |
86 | ||
87 | /** | |
88 | * A list-update policy that moves elements to the front of the | |
89 | * list based on the counter algorithm. | |
90 | */ | |
91 | template<std::size_t Max_Count = 5, typename _Alloc = std::allocator<char> > | |
92 | class lu_counter_policy | |
93 | : private detail::lu_counter_policy_base<typename _Alloc::size_type> | |
94 | { | |
95 | public: | |
96 | typedef _Alloc allocator_type; | |
97 | typedef typename allocator_type::size_type size_type; | |
98 | ||
99 | enum | |
100 | { | |
30a96b3b BK |
101 | /// When some element is accessed this number of times, it |
102 | /// will be moved to the front of the list. | |
a345e45d BK |
103 | max_count = Max_Count |
104 | }; | |
105 | ||
30a96b3b | 106 | /// Metadata on which this functor operates. |
a345e45d BK |
107 | typedef detail::lu_counter_metadata<size_type> metadata_type; |
108 | ||
109 | private: | |
110 | typedef detail::lu_counter_policy_base<size_type> base_type; | |
111 | typedef typename _Alloc::template rebind<metadata_type> __rebind_m; | |
112 | ||
113 | public: | |
30a96b3b | 114 | /// Reference to metadata on which this functor operates. |
a345e45d BK |
115 | typedef typename __rebind_m::other::reference metadata_reference; |
116 | ||
30a96b3b | 117 | /// Creates a metadata object. |
a345e45d BK |
118 | metadata_type |
119 | operator()() const | |
120 | { return base_type::operator()(max_count); } | |
121 | ||
30a96b3b BK |
122 | /// Decides whether a metadata object should be moved to the front |
123 | /// of the list. | |
a345e45d BK |
124 | bool |
125 | operator()(metadata_reference r_data) const | |
126 | { return base_type::operator()(r_data, max_count); } | |
127 | }; | |
5e11f978 | 128 | } // namespace __gnu_pbds |
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129 | |
130 | #endif |