forked from blevesearch/bleve
-
Notifications
You must be signed in to change notification settings - Fork 0
/
fragmenter_simple.go
138 lines (118 loc) · 3.52 KB
/
fragmenter_simple.go
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
// Copyright (c) 2014 Couchbase, Inc.
// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file
// except in compliance with the License. You may obtain a copy of the License at
// http://www.apache.org/licenses/LICENSE-2.0
// Unless required by applicable law or agreed to in writing, software distributed under the
// License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
// either express or implied. See the License for the specific language governing permissions
// and limitations under the License.
package simple
import (
"unicode/utf8"
"github.com/blevesearch/bleve/registry"
"github.com/blevesearch/bleve/search/highlight"
)
const Name = "simple"
const defaultFragmentSize = 200
type Fragmenter struct {
fragmentSize int
}
func NewFragmenter(fragmentSize int) *Fragmenter {
return &Fragmenter{
fragmentSize: fragmentSize,
}
}
func (s *Fragmenter) Fragment(orig []byte, ot highlight.TermLocations) []*highlight.Fragment {
rv := make([]*highlight.Fragment, 0)
maxbegin := 0
OUTER:
for currTermIndex, termLocation := range ot {
// start with this
// it should be the highest scoring fragment with this term first
start := termLocation.Start
end := start
used := 0
for end < len(orig) && used < s.fragmentSize {
r, size := utf8.DecodeRune(orig[end:])
if r == utf8.RuneError {
continue OUTER // bail
}
end += size
used += 1
}
// if we still have more characters available to us
// push back towards begining
// without cross maxbegin
for start > 0 && used < s.fragmentSize {
r, size := utf8.DecodeLastRune(orig[0:start])
if r == utf8.RuneError {
continue OUTER // bail
}
if start-size >= maxbegin {
start -= size
used += 1
} else {
break
}
}
// however, we'd rather have the tokens centered more in the frag
// lets try to do that as best we can, without affecting the score
// find the end of the last term in this fragment
minend := end
for _, innerTermLocation := range ot[currTermIndex:] {
if innerTermLocation.End > end {
break
}
minend = innerTermLocation.End
}
// find the smaller of the two rooms to move
roomToMove := utf8.RuneCount(orig[minend:end])
roomToMoveStart := 0
if start >= maxbegin {
roomToMoveStart = utf8.RuneCount(orig[maxbegin:start])
}
if roomToMoveStart < roomToMove {
roomToMove = roomToMoveStart
}
offset := roomToMove / 2
for offset > 0 {
r, size := utf8.DecodeLastRune(orig[0:start])
if r == utf8.RuneError {
continue OUTER // bail
}
start -= size
r, size = utf8.DecodeLastRune(orig[0:end])
if r == utf8.RuneError {
continue OUTER // bail
}
end -= size
offset--
}
rv = append(rv, &highlight.Fragment{Orig: orig, Start: start - offset, End: end - offset})
// set maxbegin to the end of the current term location
// so that next one won't back up to include it
maxbegin = termLocation.End
}
if len(ot) == 0 {
// if there were no terms to highlight
// produce a single fragment from the beginning
start := 0
end := start + s.fragmentSize
if end > len(orig) {
end = len(orig)
}
rv = append(rv, &highlight.Fragment{Orig: orig, Start: start, End: end})
}
return rv
}
func Constructor(config map[string]interface{}, cache *registry.Cache) (highlight.Fragmenter, error) {
size := defaultFragmentSize
sizeVal, ok := config["size"].(float64)
if ok {
size = int(sizeVal)
}
return NewFragmenter(size), nil
}
func init() {
registry.RegisterFragmenter(Name, Constructor)
}