libstdc++: trie_policy_base.hpp Source File

libstdc++

trie_policy_base.hpp
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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
44#include <ext/pb_ds/detail/branch_policy/branch_policy.hpp>
45
46namespace __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
branch_policy.hpp
std::distance
constexpr iterator_traits< _InputIterator >::difference_type distance(_InputIterator __first, _InputIterator __last)
A generalization of pointer arithmetic.
Definition stl_iterator_base_funcs.h:178
__gnu_pbds
GNU extensions for policy-based data structures for public use.
Definition assoc_container.hpp:52
std::pair
Struct holding two objects (or references) of arbitrary type.
Definition stl_pair.h:307
__gnu_pbds::null_type
Represents no type, or absence of type, for template tricks.
Definition tag_and_trait.hpp:210
__gnu_pbds::detail::size_type
__gnu_pbds::detail::branch_policy
Primary template, base class for branch structure policies.
Definition branch_policy.hpp:54
__gnu_pbds::detail::trie_policy_base
Base class for trie policies.
Definition trie_policy_base.hpp:55