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
|
/** @file vectortermlist.h
* @brief A vector-like container of terms which can be iterated.
*/
/* Copyright (C) 2011,2012 Olly Betts
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef XAPIAN_INCLUDED_VECTORTERMLIST_H
#define XAPIAN_INCLUDED_VECTORTERMLIST_H
#include "xapian/types.h"
#include "net/length.h"
#include "termlist.h"
/** This class stores a list of terms.
*
* To be memory efficient, we store the terms in a single string using a
* suitable simple encoding. This way the number of bytes needed will
* usually be the sum of the lengths of all the terms plus the number of
* terms. If we used std::vector<std::string> here like we used to, that
* would need something like an additional 30 bytes per term (30 calculated
* for GCC 4.x on x86_64).
*/
class VectorTermList : public TermList {
/// The encoded terms.
std::string data;
/// Pointer to the next term's data, or NULL if we are at end.
const char * p;
/// The number of terms in the list.
Xapian::termcount num_terms;
/// The current term.
std::string current_term;
public:
template<typename I>
VectorTermList(I begin, I end) : num_terms(0)
{
// First calculate how much space we'll need so we can reserve it.
size_t total_size = 0;
I i;
for (i = begin; i != end; ++i) {
++num_terms;
const std::string & s = *i;
total_size += s.size() + 1;
if (s.size() >= 255) {
// Not a common case, so just assume the worst case rather than
// trying to carefully calculate the exact size.
total_size += 5;
}
}
data.reserve(total_size);
// Now encode all the terms into data.
for (i = begin; i != end; ++i) {
const std::string & s = *i;
data += encode_length(s.size());
data += s;
}
p = data.data();
}
Xapian::termcount get_approx_size() const;
std::string get_termname() const;
Xapian::termcount get_wdf() const;
Xapian::doccount get_termfreq() const;
TermList * next();
TermList * skip_to(const std::string &);
bool at_end() const;
Xapian::termcount positionlist_count() const;
Xapian::PositionIterator positionlist_begin() const;
};
#endif // XAPIAN_INCLUDED_VECTORTERMLIST_H
|
