1// -*- C++ -*-
2
3// Copyright (C) 2005, 2006 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 2, 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// You should have received a copy of the GNU General Public License
17// along with this library; see the file COPYING.  If not, write to
18// the Free Software Foundation, 59 Temple Place - Suite 330, Boston,
19// MA 02111-1307, USA.
20
21// As a special exception, you may use this file as part of a free
22// software library without restriction.  Specifically, if other files
23// instantiate templates or use macros or inline functions from this
24// file, or you compile this file and link it with other files to
25// produce an executable, this file does not by itself cause the
26// resulting executable to be covered by the GNU General Public
27// License.  This exception does not however invalidate any other
28// reasons why the executable file might be covered by the GNU General
29// Public License.
30
31// Copyright (C) 2004 Ami Tavory and Vladimir Dreizin, IBM-HRL.
32
33// Permission to use, copy, modify, sell, and distribute this software
34// is hereby granted without fee, provided that the above copyright
35// notice appears in all copies, and that both that copyright notice
36// and this permission notice appear in supporting documentation. None
37// of the above authors, nor IBM Haifa Research Laboratories, make any
38// representation about the suitability of this software for any
39// purpose. It is provided "as is" without express or implied
40// warranty.
41
42/**
43 * @file trie_policy_base.hpp
44 * Contains an implementation of trie_policy_base.
45 */
46
47#ifndef PB_DS_TRIE_POLICY_BASE_HPP
48#define PB_DS_TRIE_POLICY_BASE_HPP
49
50#include <ext/pb_ds/detail/basic_tree_policy/basic_tree_policy_base.hpp>
51
52namespace pb_ds
53{
54  namespace detail
55  {
56
57#define PB_DS_CLASS_T_DEC						\
58    template<								\
59						class Const_Node_Iterator, \
60						class Node_Iterator,	\
61						class E_Access_Traits,	\
62						typename Allocator>
63
64#define PB_DS_CLASS_C_DEC						\
65    trie_policy_base<							\
66						Const_Node_Iterator,	\
67						Node_Iterator,		\
68						E_Access_Traits,	\
69						Allocator>
70
71#define PB_DS_BASE_C_DEC						\
72    basic_tree_policy_base<				\
73								Const_Node_Iterator, \
74								Node_Iterator, \
75								Allocator>
76
77    template<typename Const_Node_Iterator,
78	     class Node_Iterator,
79	     class E_Access_Traits,
80	     class Allocator>
81    class trie_policy_base : public PB_DS_BASE_C_DEC
82    {
83
84    public:
85
86      typedef E_Access_Traits e_access_traits;
87
88      typedef Allocator allocator;
89
90      typedef typename allocator::size_type size_type;
91
92      typedef null_node_metadata metadata_type;
93
94      typedef Const_Node_Iterator const_node_iterator;
95
96      typedef Node_Iterator node_iterator;
97
98      typedef typename const_node_iterator::value_type const_iterator;
99
100      typedef typename node_iterator::value_type iterator;
101
102    public:
103
104      typedef typename PB_DS_BASE_C_DEC::key_type key_type;
105
106      typedef
107      typename PB_DS_BASE_C_DEC::const_key_reference
108      const_key_reference;
109
110    protected:
111
112      virtual const_iterator
113      end() const = 0;
114
115      virtual iterator
116      end() = 0;
117
118      virtual const_node_iterator
119      node_begin() const = 0;
120
121      virtual node_iterator
122      node_begin() = 0;
123
124      virtual const_node_iterator
125      node_end() const = 0;
126
127      virtual node_iterator
128      node_end() = 0;
129
130      virtual const e_access_traits&
131      get_e_access_traits() const = 0;
132
133    private:
134      typedef
135      std::pair<
136      typename e_access_traits::const_iterator,
137      typename e_access_traits::const_iterator>
138      prefix_range_t;
139
140      typedef PB_DS_BASE_C_DEC base_type;
141
142    protected:
143      static size_type
144      common_prefix_len(node_iterator nd_it, typename e_access_traits::const_iterator b_r, typename e_access_traits::const_iterator e_r, const e_access_traits& r_traits);
145
146      static iterator
147      leftmost_it(node_iterator nd_it);
148
149      static iterator
150      rightmost_it(node_iterator nd_it);
151
152      static bool
153      less(typename e_access_traits::const_iterator b_l, typename e_access_traits::const_iterator e_l, typename e_access_traits::const_iterator b_r, typename e_access_traits::const_iterator e_r, const e_access_traits& r_traits);
154    };
155
156    PB_DS_CLASS_T_DEC
157    typename PB_DS_CLASS_C_DEC::size_type
158    PB_DS_CLASS_C_DEC::
159    common_prefix_len(node_iterator nd_it, typename e_access_traits::const_iterator b_r, typename e_access_traits::const_iterator e_r, const e_access_traits& r_traits)
160    {
161      prefix_range_t pref_range = nd_it.valid_prefix();
162
163      typename e_access_traits::const_iterator b_l = pref_range.first;
164      typename e_access_traits::const_iterator e_l = pref_range.second;
165
166      const size_type range_length_l =
167	std::distance(b_l, e_l);
168
169      const size_type range_length_r =
170	std::distance(b_r, e_r);
171
172      if (range_length_r < range_length_l)
173	{
174	  std::swap(b_l, b_r);
175
176	  std::swap(e_l, e_r);
177	}
178
179      size_type ret = 0;
180
181      while (b_l != e_l)
182	{
183	  if (r_traits.e_pos(*b_l) != r_traits.e_pos(*b_r))
184	    return (ret);
185
186	  ++ret;
187
188	  ++b_l;
189
190	  ++b_r;
191	}
192
193      return (ret);
194    }
195
196    PB_DS_CLASS_T_DEC
197    typename PB_DS_CLASS_C_DEC::iterator
198    PB_DS_CLASS_C_DEC::
199    leftmost_it(node_iterator nd_it)
200    {
201      if (nd_it.num_children() == 0)
202	return (*nd_it);
203
204      return (leftmost_it(nd_it.get_child(0)));
205    }
206
207    PB_DS_CLASS_T_DEC
208    typename PB_DS_CLASS_C_DEC::iterator
209    PB_DS_CLASS_C_DEC::
210    rightmost_it(node_iterator nd_it)
211    {
212      const size_type num_children = nd_it.num_children();
213
214      if (num_children == 0)
215	return (*nd_it);
216
217      return (rightmost_it(nd_it.get_child(num_children - 1)));
218    }
219
220    PB_DS_CLASS_T_DEC
221    bool
222    PB_DS_CLASS_C_DEC::
223    less(typename e_access_traits::const_iterator b_l, typename e_access_traits::const_iterator e_l, typename e_access_traits::const_iterator b_r, typename e_access_traits::const_iterator e_r, const e_access_traits& r_traits)
224    {
225      while (b_l != e_l)
226	{
227	  if (b_r == e_r)
228	    return (false);
229
230	  size_type l_pos =
231	    r_traits.e_pos(*b_l);
232	  size_type r_pos =
233	    r_traits.e_pos(*b_r);
234
235	  if (l_pos != r_pos)
236	    return (l_pos < r_pos);
237
238	  ++b_l;
239	  ++b_r;
240	}
241
242      return (b_r != e_r);
243    }
244
245#undef PB_DS_CLASS_T_DEC
246
247#undef PB_DS_CLASS_C_DEC
248
249#undef PB_DS_BASE_C_DEC
250
251  } // namespace detail
252} // namespace pb_ds
253
254#endif // #ifndef PB_DS_TRIE_POLICY_BASE_HPP
255
256