libstdc++-v3/include/ext/pb_ds/detail/list_update_policy/sample_update_policy.hpp

   1 // -*- C++ -*-
   2
   3 // Copyright (C) 2005-2023 Free Software Foundation, Inc.
   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
   8 // Foundation; either version 3, or (at your option) any later
   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
  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.
  19
  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/>.
  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 sample_update_policy.hpp
  38  * Contains a sample policy for list update containers.
  39  */
  40
  41 #ifndef PB_DS_SAMPLE_UPDATE_POLICY_HPP
  42 #define PB_DS_SAMPLE_UPDATE_POLICY_HPP
  43
  44 namespace __gnu_pbds
  45 {
  46   /// A sample list-update policy.
  47   struct sample_update_policy
  48   {
  49     /// Default constructor.
  50     sample_update_policy();
  51
  52     /// Copy constructor.
  53     sample_update_policy(const sample_update_policy&);
  54
  55     /// Swaps content.
  56     inline void
  57     swap(sample_update_policy& other);
  58
  59   protected:
  60     /// Metadata on which this functor operates.
  61     typedef some_metadata_type metadata_type;
  62
  63     /// Creates a metadata object.
  64     metadata_type
  65     operator()() const;
  66
  67     /// Decides whether a metadata object should be moved to the front
  68     /// of the list. A list-update based containers object will call
  69     /// this method to decide whether to move a node to the front of
  70     /// the list. The method shoule return true if the node should be
  71     /// moved to the front of the list.
  72     bool
  73     operator()(metadata_reference) const;
  74   };
  75 }
  76 #endif