# list_update_policy.hpp

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    00001 // -*- C++ -*-
    00002
    00003 // Copyright (C) 2005, 2006, 2007, 2009 Free Software Foundation, Inc.
    00004 //
    00005 // This file is part of the GNU ISO C++ Library.  This library is free
    00006 // software; you can redistribute it and/or modify it under the terms
    00007 // of the GNU General Public License as published by the Free Software
    00008 // Foundation; either version 3, or (at your option) any later
    00009 // version.
    00010
    00011 // This library is distributed in the hope that it will be useful, but
    00012 // WITHOUT ANY WARRANTY; without even the implied warranty of
    00013 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    00014 // General Public License for more details.
    00015
    00016 // Under Section 7 of GPL version 3, you are granted additional
    00017 // permissions described in the GCC Runtime Library Exception, version
    00018 // 3.1, as published by the Free Software Foundation.
    00019
    00020 // You should have received a copy of the GNU General Public License and
    00021 // a copy of the GCC Runtime Library Exception along with this program;
    00022 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
    00023 // <http://www.gnu.org/licenses/>.
    00024
    00025 // Copyright (C) 2004 Ami Tavory and Vladimir Dreizin, IBM-HRL.
    00026
    00027 // Permission to use, copy, modify, sell, and distribute this software
    00028 // is hereby granted without fee, provided that the above copyright
    00029 // notice appears in all copies, and that both that copyright notice
    00030 // and this permission notice appear in supporting documentation. None
    00031 // of the above authors, nor IBM Haifa Research Laboratories, make any
    00032 // representation about the suitability of this software for any
    00033 // purpose. It is provided "as is" without express or implied
    00034 // warranty.
    00035
    00036 /**
    00037  * @file list_update_policy.hpp
    00038  * Contains policies for list update containers.
    00039  */
    00040
    00041 #ifndef PB_DS_LU_POLICY_HPP
    00042 #define PB_DS_LU_POLICY_HPP
    00043
    00044 #include <cstdlib>
    00045 #include <ext/pb_ds/detail/list_update_policy/counter_lu_metadata.hpp>
    00046
    00047 namespace __gnu_pbds
    00048 {
    00049   // A null type that means that each link in a list-based container
    00050   // does not actually need metadata.
    00051   struct null_lu_metadata
    00052   { };
    00053
    00054 #define PB_DS_CLASS_T_DEC template<typename Allocator>
    00055 #define PB_DS_CLASS_C_DEC move_to_front_lu_policy<Allocator>
    00056
    00057   // A list-update policy that unconditionally moves elements to the
    00058   // front of the list.
    00059   template<typename Allocator = std::allocator<char> >
    00060   class move_to_front_lu_policy
    00061   {
    00062   public:
    00063     typedef Allocator allocator_type;
    00064
    00065     // Metadata on which this functor operates.
    00066     typedef null_lu_metadata metadata_type;
    00067
    00068     // Reference to metadata on which this functor operates.
    00069     typedef typename allocator_type::template rebind<metadata_type>::other metadata_rebind;
    00070     typedef typename metadata_rebind::reference metadata_reference;
    00071
    00072     // Creates a metadata object.
    00073     metadata_type
    00074     operator()() const;
    00075
    00076     // Decides whether a metadata object should be moved to the front
    00077     // of the list.
    00078     inline bool
    00079     operator()(metadata_reference r_metadata) const;
    00080
    00081   private:
    00082     static null_lu_metadata s_metadata;
    00083   };
    00084
    00085 #include <ext/pb_ds/detail/list_update_policy/mtf_lu_policy_imp.hpp>
    00086
    00087 #undef PB_DS_CLASS_T_DEC
    00088 #undef PB_DS_CLASS_C_DEC
    00089
    00090 #define PB_DS_CLASS_T_DEC template<size_t Max_Count, class Allocator>
    00091 #define PB_DS_CLASS_C_DEC counter_lu_policy<Max_Count, Allocator>
    00092
    00093   // A list-update policy that moves elements to the front of the list
    00094   // based on the counter algorithm.
    00095   template<size_t Max_Count = 5, typename Allocator = std::allocator<char> >
    00096   class counter_lu_policy
    00097   : private detail::counter_lu_policy_base<typename Allocator::size_type>
    00098   {
    00099   public:
    00100     typedef Allocator allocator_type;
    00101
    00102     enum
    00103       {
    00104     max_count = Max_Count
    00105       };
    00106
    00107     typedef typename allocator_type::size_type size_type;
    00108
    00109     // Metadata on which this functor operates.
    00110     typedef detail::counter_lu_metadata<size_type> metadata_type;
    00111
    00112     // Reference to metadata on which this functor operates.
    00113     typedef typename Allocator::template rebind<metadata_type>::other metadata_rebind;
    00114     typedef typename metadata_rebind::reference metadata_reference;
    00115
    00116     // Creates a metadata object.
    00117     metadata_type
    00118     operator()() const;
    00119
    00120     // Decides whether a metadata object should be moved to the front
    00121     // of the list.
    00122     bool
    00123     operator()(metadata_reference r_metadata) const;
    00124
    00125   private:
    00126     typedef detail::counter_lu_policy_base<typename Allocator::size_type> base_type;
    00127   };
    00128
    00129 #include <ext/pb_ds/detail/list_update_policy/counter_lu_policy_imp.hpp>
    00130
    00131 #undef PB_DS_CLASS_T_DEC
    00132 #undef PB_DS_CLASS_C_DEC
    00133
    00134 } // namespace __gnu_pbds
    00135
    00136 #endif