libstdc++-v3/include/ext/pb_ds/detail/trie_policy/trie_policy_base.hpp

   1 // -*- C++ -*-
   2
   3 // Copyright (C) 2005-2016 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 trie_policy/trie_policy_base.hpp
  38  * Contains an implementation of trie_policy_base.
  39  */
  40
  41 #ifndef PB_DS_TRIE_POLICY_BASE_HPP
  42 #define PB_DS_TRIE_POLICY_BASE_HPP
  43
  44 #include <ext/pb_ds/detail/branch_policy/branch_policy.hpp>
  45
  46 namespace __gnu_pbds
  47 {
  48   namespace detail
  49   {
  50     /// Base class for trie policies.
  51     template<typename Node_CItr, typename Node_Itr,
  52              typename _ATraits, typename _Alloc>
  53     class trie_policy_base
  54     : public branch_policy<Node_CItr, Node_Itr, _Alloc>
  55     {
  56       typedef branch_policy<Node_CItr, Node_Itr, _Alloc> base_type;
  57
  58     public:
  59       typedef _ATraits                          access_traits;
  60       typedef _Alloc                                    allocator_type;
  61       typedef typename allocator_type::size_type        size_type;
  62       typedef null_type                                 metadata_type;
  63       typedef Node_CItr                                 node_const_iterator;
  64       typedef Node_Itr                                  node_iterator;
  65       typedef typename node_const_iterator::value_type  const_iterator;
  66       typedef typename node_iterator::value_type        iterator;
  67       typedef typename base_type::key_type              key_type;
  68       typedef typename base_type::key_const_reference   key_const_reference;
  69
  70     protected:
  71       virtual const_iterator
  72       end() const = 0;
  73
  74       virtual iterator
  75       end() = 0;
  76
  77       virtual node_const_iterator
  78       node_begin() const = 0;
  79
  80       virtual node_iterator
  81       node_begin() = 0;
  82
  83       virtual node_const_iterator
  84       node_end() const = 0;
  85
  86       virtual node_iterator
  87       node_end() = 0;
  88
  89       virtual const access_traits&
  90       get_access_traits() const = 0;
  91
  92     private:
  93       typedef typename access_traits::const_iterator    e_const_iterator;
  94       typedef std::pair<e_const_iterator, e_const_iterator> prefix_range_t;
  95
  96     protected:
  97       static size_type
  98       common_prefix_len(node_iterator, e_const_iterator,
  99                         e_const_iterator, const access_traits&);
 100
 101       static iterator
 102       leftmost_it(node_iterator);
 103
 104       static iterator
 105       rightmost_it(node_iterator);
 106
 107       static bool
 108       less(e_const_iterator, e_const_iterator, e_const_iterator,
 109            e_const_iterator, const access_traits&);
 110     };
 111
 112
 113 #define PB_DS_CLASS_T_DEC \
 114     template<typename Node_CItr, typename Node_Itr, \
 115              typename _ATraits, typename _Alloc>
 116
 117 #define PB_DS_CLASS_C_DEC \
 118     trie_policy_base<Node_CItr, Node_Itr, _ATraits, _Alloc>
 119
 120     PB_DS_CLASS_T_DEC
 121     typename PB_DS_CLASS_C_DEC::size_type
 122     PB_DS_CLASS_C_DEC::
 123     common_prefix_len(node_iterator nd_it, e_const_iterator b_r,
 124                       e_const_iterator e_r, const access_traits& r_traits)
 125     {
 126       prefix_range_t pref_range = nd_it.valid_prefix();
 127
 128       e_const_iterator b_l = pref_range.first;
 129       e_const_iterator e_l = pref_range.second;
 130
 131       const size_type range_length_l = std::distance(b_l, e_l);
 132       const size_type range_length_r = std::distance(b_r, e_r);
 133
 134       if (range_length_r < range_length_l)
 135         {
 136           std::swap(b_l, b_r);
 137           std::swap(e_l, e_r);
 138         }
 139
 140       size_type ret = 0;
 141       while (b_l != e_l)
 142         {
 143           if (r_traits.e_pos(*b_l) != r_traits.e_pos(*b_r))
 144             return ret;
 145
 146           ++ret;
 147           ++b_l;
 148           ++b_r;
 149         }
 150
 151       return ret;
 152     }
 153
 154     PB_DS_CLASS_T_DEC
 155     typename PB_DS_CLASS_C_DEC::iterator
 156     PB_DS_CLASS_C_DEC::
 157     leftmost_it(node_iterator nd_it)
 158     {
 159       if (nd_it.num_children() == 0)
 160         return *nd_it;
 161
 162       return leftmost_it(nd_it.get_child(0));
 163     }
 164
 165     PB_DS_CLASS_T_DEC
 166     typename PB_DS_CLASS_C_DEC::iterator
 167     PB_DS_CLASS_C_DEC::
 168     rightmost_it(node_iterator nd_it)
 169     {
 170       const size_type num_children = nd_it.num_children();
 171
 172       if (num_children == 0)
 173         return *nd_it;
 174
 175       return rightmost_it(nd_it.get_child(num_children - 1));
 176     }
 177
 178     PB_DS_CLASS_T_DEC
 179     bool
 180     PB_DS_CLASS_C_DEC::
 181     less(e_const_iterator b_l, e_const_iterator e_l,
 182          e_const_iterator b_r, e_const_iterator e_r,
 183          const access_traits& r_traits)
 184     {
 185       while (b_l != e_l)
 186         {
 187           if (b_r == e_r)
 188             return false;
 189
 190           size_type l_pos = r_traits.e_pos(*b_l);
 191           size_type r_pos = r_traits.e_pos(*b_r);
 192           if (l_pos != r_pos)
 193             return (l_pos < r_pos);
 194
 195           ++b_l;
 196           ++b_r;
 197         }
 198       return b_r != e_r;
 199     }
 200
 201 #undef PB_DS_CLASS_T_DEC
 202 #undef PB_DS_CLASS_C_DEC
 203
 204   } // namespace detail
 205 } // namespace __gnu_pbds
 206
 207 #endif // #ifndef PB_DS_TRIE_POLICY_BASE_HPP