libstdc++
trie_policy_base.hpp
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1 // -*- C++ -*-
2 
3 // Copyright (C) 2005, 2006, 2009 Free Software Foundation, Inc.
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16 // Under Section 7 of GPL version 3, you are granted additional
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18 // 3.1, as published by the Free Software Foundation.
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25 // Copyright (C) 2004 Ami Tavory and Vladimir Dreizin, IBM-HRL.
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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 
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>
54  : public branch_policy<Node_CItr, Node_Itr, _Alloc>
55  {
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;
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