libstdc++
list_update_policy.hpp
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26 // Copyright (C) 2004 Ami Tavory and Vladimir Dreizin, IBM-HRL.
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36 
37 /**
38  * @file list_update_policy.hpp
39  * Contains policies for list update containers.
40  */
41 
42 #ifndef PB_DS_LU_POLICY_HPP
43 #define PB_DS_LU_POLICY_HPP
44 
45 #include <bits/c++config.h>
46 #include <cstdlib>
47 #include <ext/pb_ds/detail/list_update_policy/counter_lu_metadata.hpp>
48 
49 namespace __gnu_pbds
50 {
51  // A null type that means that each link in a list-based container
52  // does not actually need metadata.
53  struct null_lu_metadata
54  { };
55 
56 #define PB_DS_CLASS_T_DEC template<typename Allocator>
57 #define PB_DS_CLASS_C_DEC move_to_front_lu_policy<Allocator>
58 
59  // A list-update policy that unconditionally moves elements to the
60  // front of the list.
61  template<typename Allocator = std::allocator<char> >
62  class move_to_front_lu_policy
63  {
64  public:
65  typedef Allocator allocator_type;
66 
67  // Metadata on which this functor operates.
68  typedef null_lu_metadata metadata_type;
69 
70  // Reference to metadata on which this functor operates.
71  typedef typename allocator_type::template rebind<metadata_type>::other metadata_rebind;
72  typedef typename metadata_rebind::reference metadata_reference;
73 
74  // Creates a metadata object.
75  metadata_type
76  operator()() const;
77 
78  // Decides whether a metadata object should be moved to the front
79  // of the list.
80  inline bool
81  operator()(metadata_reference r_metadata) const;
82 
83  private:
84  static null_lu_metadata s_metadata;
85  };
86 
87 #include <ext/pb_ds/detail/list_update_policy/mtf_lu_policy_imp.hpp>
88 
89 #undef PB_DS_CLASS_T_DEC
90 #undef PB_DS_CLASS_C_DEC
91 
92 #define PB_DS_CLASS_T_DEC template<std::size_t Max_Count, class Allocator>
93 #define PB_DS_CLASS_C_DEC counter_lu_policy<Max_Count, Allocator>
94 
95  // A list-update policy that moves elements to the front of the list
96  // based on the counter algorithm.
97  template<std::size_t Max_Count = 5,
98  typename Allocator = std::allocator<char> >
99  class counter_lu_policy
100  : private detail::counter_lu_policy_base<typename Allocator::size_type>
101  {
102  public:
103  typedef Allocator allocator_type;
104 
105  enum
106  {
107  max_count = Max_Count
108  };
109 
110  typedef typename allocator_type::size_type size_type;
111 
112  // Metadata on which this functor operates.
113  typedef detail::counter_lu_metadata<size_type> metadata_type;
114 
115  // Reference to metadata on which this functor operates.
116  typedef typename Allocator::template rebind<metadata_type>::other metadata_rebind;
117  typedef typename metadata_rebind::reference metadata_reference;
118 
119  // Creates a metadata object.
120  metadata_type
121  operator()() const;
122 
123  // Decides whether a metadata object should be moved to the front
124  // of the list.
125  bool
126  operator()(metadata_reference r_metadata) const;
127 
128  private:
129  typedef detail::counter_lu_policy_base<typename Allocator::size_type> base_type;
130  };
131 
132 #include <ext/pb_ds/detail/list_update_policy/counter_lu_policy_imp.hpp>
133 
134 #undef PB_DS_CLASS_T_DEC
135 #undef PB_DS_CLASS_C_DEC
136 
137 } // namespace __gnu_pbds
138 
139 #endif
The standard allocator, as per [20.4].Further details: http://gcc.gnu.org/onlinedocs/libstdc++/manual...
Definition: allocator.h:66