# list_update_policy.hpp

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    00001 // -*- C++ -*-
    00002
    00003 // Copyright (C) 2005, 2006 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 2, 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 // You should have received a copy of the GNU General Public License
    00017 // along with this library; see the file COPYING.  If not, write to
    00018 // the Free Software Foundation, 59 Temple Place - Suite 330, Boston,
    00019 // MA 02111-1307, USA.
    00020
    00021 // As a special exception, you may use this file as part of a free
    00022 // software library without restriction.  Specifically, if other files
    00023 // instantiate templates or use macros or inline functions from this
    00024 // file, or you compile this file and link it with other files to
    00025 // produce an executable, this file does not by itself cause the
    00026 // resulting executable to be covered by the GNU General Public
    00027 // License.  This exception does not however invalidate any other
    00028 // reasons why the executable file might be covered by the GNU General
    00029 // Public License.
    00030
    00031 // Copyright (C) 2004 Ami Tavory and Vladimir Dreizin, IBM-HRL.
    00032
    00033 // Permission to use, copy, modify, sell, and distribute this software
    00034 // is hereby granted without fee, provided that the above copyright
    00035 // notice appears in all copies, and that both that copyright notice
    00036 // and this permission notice appear in supporting documentation. None
    00037 // of the above authors, nor IBM Haifa Research Laboratories, make any
    00038 // representation about the suitability of this software for any
    00039 // purpose. It is provided "as is" without express or implied
    00040 // warranty.
    00041
    00042 /**
    00043  * @file list_update_policy.hpp
    00044  * Contains policies for list update containers.
    00045  */
    00046
    00047 #ifndef PB_DS_LU_POLICY_HPP
    00048 #define PB_DS_LU_POLICY_HPP
    00049
    00050 #include <ext/pb_ds/detail/list_update_policy/counter_lu_metadata.hpp>
    00051
    00052 namespace pb_ds
    00053 {
    00054   // A null type that means that each link in a list-based container
    00055   // does not actually need metadata.
    00056   struct null_lu_metadata
    00057   { };
    00058
    00059 #define PB_DS_CLASS_T_DEC template<typename Allocator>
    00060 #define PB_DS_CLASS_C_DEC move_to_front_lu_policy<Allocator>
    00061
    00062   // A list-update policy that unconditionally moves elements to the
    00063   // front of the list.
    00064   template<typename Allocator = std::allocator<char> >
    00065   class move_to_front_lu_policy
    00066   {
    00067   public:
    00068     typedef Allocator allocator;
    00069
    00070     // Metadata on which this functor operates.
    00071     typedef null_lu_metadata metadata_type;
    00072
    00073     // Reference to metadata on which this functor operates.
    00074     typedef typename allocator::template rebind<metadata_type>::other metadata_rebind;
    00075     typedef typename metadata_rebind::reference metadata_reference;
    00076
    00077     // Creates a metadata object.
    00078     metadata_type
    00079     operator()() const;
    00080
    00081     // Decides whether a metadata object should be moved to the front
    00082     // of the list.
    00083     inline bool
    00084     operator()(metadata_reference r_metadata) const;
    00085
    00086   private:
    00087     static null_lu_metadata s_metadata;
    00088   };
    00089
    00090 #include <ext/pb_ds/detail/list_update_policy/mtf_lu_policy_imp.hpp>
    00091
    00092 #undef PB_DS_CLASS_T_DEC
    00093 #undef PB_DS_CLASS_C_DEC
    00094
    00095 #define PB_DS_CLASS_T_DEC template<size_t Max_Count, class Allocator>
    00096 #define PB_DS_CLASS_C_DEC counter_lu_policy<Max_Count, Allocator>
    00097
    00098   // A list-update policy that moves elements to the front of the list
    00099   // based on the counter algorithm.
    00100   template<size_t Max_Count = 5, typename Allocator = std::allocator<char> >
    00101   class counter_lu_policy
    00102   : private detail::counter_lu_policy_base<typename Allocator::size_type>
    00103   {
    00104   public:
    00105     typedef Allocator allocator;
    00106
    00107     enum
    00108       {
    00109     max_count = Max_Count
    00110       };
    00111
    00112     typedef typename allocator::size_type size_type;
    00113
    00114     // Metadata on which this functor operates.
    00115     typedef detail::counter_lu_metadata<size_type> metadata_type;
    00116
    00117     // Reference to metadata on which this functor operates.
    00118     typedef typename Allocator::template rebind<metadata_type>::other metadata_rebind;
    00119     typedef typename metadata_rebind::reference metadata_reference;
    00120
    00121     // Creates a metadata object.
    00122     metadata_type
    00123     operator()() const;
    00124
    00125     // Decides whether a metadata object should be moved to the front
    00126     // of the list.
    00127     bool
    00128     operator()(metadata_reference r_metadata) const;
    00129
    00130   private:
    00131     typedef detail::counter_lu_policy_base<typename Allocator::size_type> base_type;
    00132   };
    00133
    00134 #include <ext/pb_ds/detail/list_update_policy/counter_lu_policy_imp.hpp>
    00135
    00136 #undef PB_DS_CLASS_T_DEC
    00137 #undef PB_DS_CLASS_C_DEC
    00138
    00139 } // namespace pb_ds
    00140
    00141 #endif