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
|
/* -*- c-basic-offset: 2 -*- */
/* Copyright(C) 2011 Brazil
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License version 2.1 as published by the Free Software Foundation.
This library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335 USA
*/
#include "prefix-cursor.hpp"
#include <algorithm>
#include "trie.hpp"
namespace grn {
namespace dat {
PrefixCursor::PrefixCursor()
: trie_(NULL),
offset_(0),
limit_(MAX_UINT32),
flags_(PREFIX_CURSOR),
buf_(),
cur_(0),
end_(0) {}
PrefixCursor::~PrefixCursor() = default;
void PrefixCursor::open(const Trie &trie,
const String &str,
UInt32 min_length,
UInt32 offset,
UInt32 limit,
UInt32 flags) {
GRN_DAT_THROW_IF(PARAM_ERROR, (str.ptr() == NULL) && (str.length() != 0));
GRN_DAT_THROW_IF(PARAM_ERROR, min_length > str.length());
flags = fix_flags(flags);
PrefixCursor new_cursor(trie, offset, limit, flags);
new_cursor.init(str, min_length);
new_cursor.swap(this);
}
void PrefixCursor::close() {
PrefixCursor new_cursor;
new_cursor.swap(this);
}
const Key &PrefixCursor::next() {
if (cur_ == end_) {
return Key::invalid_key();
}
if ((flags_ & ASCENDING_CURSOR) == ASCENDING_CURSOR) {
return trie_->get_key(buf_[cur_++]);
} else {
return trie_->get_key(buf_[--cur_]);
}
}
PrefixCursor::PrefixCursor(const Trie &trie,
UInt32 offset, UInt32 limit, UInt32 flags)
: trie_(&trie),
offset_(offset),
limit_(limit),
flags_(flags),
buf_(),
cur_(0),
end_(0) {}
UInt32 PrefixCursor::fix_flags(UInt32 flags) const {
const UInt32 cursor_type = flags & CURSOR_TYPE_MASK;
GRN_DAT_THROW_IF(PARAM_ERROR, (cursor_type != 0) &&
(cursor_type != PREFIX_CURSOR));
flags |= PREFIX_CURSOR;
const UInt32 cursor_order = flags & CURSOR_ORDER_MASK;
GRN_DAT_THROW_IF(PARAM_ERROR, (cursor_order != 0) &&
(cursor_order != ASCENDING_CURSOR) &&
(cursor_order != DESCENDING_CURSOR));
if (cursor_order == 0) {
flags |= ASCENDING_CURSOR;
}
const UInt32 cursor_options = flags & CURSOR_OPTIONS_MASK;
GRN_DAT_THROW_IF(PARAM_ERROR, cursor_options & ~EXCEPT_EXACT_MATCH);
return flags;
}
void PrefixCursor::init(const String &str, UInt32 min_length) {
if ((limit_ == 0) || (offset_ > (str.length() - min_length))) {
return;
}
UInt32 node_id = ROOT_NODE_ID;
UInt32 i;
for (i = 0; i < str.length(); ++i) {
const Base base = trie_->ith_node(node_id).base();
if (base.is_linker()) {
const Key &key = trie_->get_key(base.key_pos());
if ((key.length() >= min_length) && (key.length() <= str.length()) &&
(str.substr(0, key.length()).compare(key.str(), i) == 0) &&
((key.length() < str.length()) ||
((flags_ & EXCEPT_EXACT_MATCH) != EXCEPT_EXACT_MATCH))) {
buf_.push_back(base.key_pos());
}
break;
}
if ((i >= min_length) &&
(trie_->ith_node(node_id).child() == TERMINAL_LABEL)) {
const Base linker_base =
trie_->ith_node(base.offset() ^ TERMINAL_LABEL).base();
if (linker_base.is_linker()) {
buf_.push_back(linker_base.key_pos());
}
}
node_id = base.offset() ^ str[i];
if (trie_->ith_node(node_id).label() != str[i]) {
break;
}
}
if ((i == str.length()) &&
((flags_ & EXCEPT_EXACT_MATCH) != EXCEPT_EXACT_MATCH)) {
const Base base = trie_->ith_node(node_id).base();
if (base.is_linker()) {
const Key &key = trie_->get_key(base.key_pos());
if ((key.length() >= min_length) && (key.length() <= str.length())) {
buf_.push_back(base.key_pos());
}
} else if (trie_->ith_node(node_id).child() == TERMINAL_LABEL) {
const Base linker_base =
trie_->ith_node(base.offset() ^ TERMINAL_LABEL).base();
if (linker_base.is_linker()) {
buf_.push_back(linker_base.key_pos());
}
}
}
if (buf_.size() <= offset_) {
return;
}
if ((flags_ & ASCENDING_CURSOR) == ASCENDING_CURSOR) {
cur_ = offset_;
end_ = (limit_ < (buf_.size() - cur_)) ? (cur_ + limit_) : buf_.size();
} else {
cur_ = buf_.size() - offset_;
end_ = (limit_ < cur_) ? (cur_ - limit_) : 0;
}
}
void PrefixCursor::swap(PrefixCursor *cursor) {
std::swap(trie_, cursor->trie_);
std::swap(offset_, cursor->offset_);
std::swap(limit_, cursor->limit_);
std::swap(flags_, cursor->flags_);
buf_.swap(&cursor->buf_);
std::swap(cur_, cursor->cur_);
std::swap(end_, cursor->end_);
}
} // namespace dat
} // namespace grn
|
