symbols.hpp
6.23 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
/*=============================================================================
Copyright (c) 2001-2003 Joel de Guzman
Copyright (c) 2011 Daniel James
http://spirit.sourceforge.net/
Use, modification and distribution is subject to the Boost Software
License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
http://www.boost.org/LICENSE_1_0.txt)
=============================================================================*/
#ifndef QUICKBOOK_SYMBOLS_IPP
#define QUICKBOOK_SYMBOLS_IPP
///////////////////////////////////////////////////////////////////////////////
#include <boost/intrusive_ptr.hpp>
#include <boost/scoped_ptr.hpp>
#include <boost/spirit/home/classic/symbols.hpp>
///////////////////////////////////////////////////////////////////////////////
namespace quickbook
{
///////////////////////////////////////////////////////////////////////////////
//
// tst class
//
// This it the Ternary Search Tree from
// <boost/spirit/home/classic/symbols/impl/tst.ipp> adapted to be cheap
// to copy.
//
// Ternary Search Tree implementation. The data structure is faster
// than
// hashing for many typical search problems especially when the search
// interface is iterator based. Searching for a string of length k in a
// ternary search tree with n strings will require at most O(log n+k)
// character comparisons. TSTs are many times faster than hash tables
// for unsuccessful searches since mismatches are discovered earlier
// after examining only a few characters. Hash tables always examine an
// entire key when searching.
//
// For details see http://www.cs.princeton.edu/~rs/strings/.
//
// *** This is a low level class and is
// not meant for public consumption ***
//
///////////////////////////////////////////////////////////////////////////////
template <typename T, typename CharT> struct tst_node
{
tst_node(CharT value_)
: reference_count(0)
, left()
, middle()
, right()
, data()
, value(value_)
{
}
tst_node(tst_node const& other)
: reference_count(0)
, left(other.left)
, middle(other.middle)
, right(other.right)
, data(other.data ? new T(*other.data) : 0)
, value(other.value)
{
}
// If you fancy a slight improvement in memory use,
// reference_count + value could probably be packed
// in the space for a single int.
int reference_count;
boost::intrusive_ptr<tst_node> left;
boost::intrusive_ptr<tst_node> middle;
boost::intrusive_ptr<tst_node> right;
boost::scoped_ptr<T> data;
CharT value;
private:
tst_node& operator=(tst_node const&);
};
template <typename T, typename CharT>
void intrusive_ptr_add_ref(tst_node<T, CharT>* ptr)
{
++ptr->reference_count;
}
template <typename T, typename CharT>
void intrusive_ptr_release(tst_node<T, CharT>* ptr)
{
if (--ptr->reference_count == 0) delete ptr;
}
///////////////////////////////////////////////////////////////////////////
template <typename T, typename CharT> class tst
{
typedef tst_node<T, CharT> node_t;
typedef boost::intrusive_ptr<node_t> node_ptr;
node_ptr root;
public:
struct search_info
{
T* data;
std::size_t length;
};
void swap(tst& other) { root.swap(other.root); }
// Adds symbol to ternary search tree.
// If it already exists, then replace it with new value.
//
// pre: first != last
template <typename IteratorT>
T* add(IteratorT first, IteratorT const& last, T const& data)
{
assert(first != last);
node_ptr* np = &root;
CharT ch = *first;
for (;;) {
if (!*np) {
*np = new node_t(ch);
}
else if ((*np)->reference_count > 1) {
*np = new node_t(**np);
}
if (ch < (*np)->value) {
np = &(*np)->left;
}
else if (ch == (*np)->value) {
++first;
if (first == last) break;
ch = *first;
np = &(*np)->middle;
}
else {
np = &(*np)->right;
}
}
boost::scoped_ptr<T> new_data(new T(data));
boost::swap((*np)->data, new_data);
return (*np)->data.get();
}
template <typename ScannerT>
search_info find(ScannerT const& scan) const
{
search_info result = {0, 0};
if (scan.at_end()) {
return result;
}
typedef typename ScannerT::iterator_t iterator_t;
node_ptr np = root;
CharT ch = *scan;
iterator_t latest = scan.first;
std::size_t length = 0;
while (np) {
if (ch < np->value) // => go left!
{
np = np->left;
}
else if (ch == np->value) // => go middle!
{
++scan;
++length;
// Found a potential match.
if (np->data.get()) {
result.data = np->data.get();
result.length = length;
latest = scan.first;
}
if (scan.at_end()) break;
ch = *scan;
np = np->middle;
}
else // (ch > np->value) => go right!
{
np = np->right;
}
}
scan.first = latest;
return result;
}
};
typedef boost::spirit::classic::
symbols<std::string, char, quickbook::tst<std::string, char> >
string_symbols;
} // namespace quickbook
#endif