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
|
// Copyright (c) 2017 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 de
import (
"bytes"
"github.com/blevesearch/bleve/analysis"
"github.com/blevesearch/bleve/registry"
)
const LightStemmerName = "stemmer_de_light"
type GermanLightStemmerFilter struct {
}
func NewGermanLightStemmerFilter() *GermanLightStemmerFilter {
return &GermanLightStemmerFilter{}
}
func (s *GermanLightStemmerFilter) Filter(input analysis.TokenStream) analysis.TokenStream {
for _, token := range input {
runes := bytes.Runes(token.Term)
runes = stem(runes)
token.Term = analysis.BuildTermFromRunes(runes)
}
return input
}
func stem(input []rune) []rune {
for i, r := range input {
switch r {
case 'ä', 'à', 'á', 'â':
input[i] = 'a'
case 'ö', 'ò', 'ó', 'ô':
input[i] = 'o'
case 'ï', 'ì', 'í', 'î':
input[i] = 'i'
case 'ü', 'ù', 'ú', 'û':
input[i] = 'u'
}
}
input = step1(input)
return step2(input)
}
func stEnding(ch rune) bool {
switch ch {
case 'b', 'd', 'f', 'g', 'h', 'k', 'l', 'm', 'n', 't':
return true
}
return false
}
func step1(s []rune) []rune {
l := len(s)
if l > 5 && s[l-3] == 'e' && s[l-2] == 'r' && s[l-1] == 'n' {
return s[:l-3]
}
if l > 4 && s[l-2] == 'e' {
switch s[l-1] {
case 'm', 'n', 'r', 's':
return s[:l-2]
}
}
if l > 3 && s[l-1] == 'e' {
return s[:l-1]
}
if l > 3 && s[l-1] == 's' && stEnding(s[l-2]) {
return s[:l-1]
}
return s
}
func step2(s []rune) []rune {
l := len(s)
if l > 5 && s[l-3] == 'e' && s[l-2] == 's' && s[l-1] == 't' {
return s[:l-3]
}
if l > 4 && s[l-2] == 'e' && (s[l-1] == 'r' || s[l-1] == 'n') {
return s[:l-2]
}
if l > 4 && s[l-2] == 's' && s[l-1] == 't' && stEnding(s[l-3]) {
return s[:l-2]
}
return s
}
func GermanLightStemmerFilterConstructor(config map[string]interface{}, cache *registry.Cache) (analysis.TokenFilter, error) {
return NewGermanLightStemmerFilter(), nil
}
func init() {
registry.RegisterTokenFilter(LightStemmerName, GermanLightStemmerFilterConstructor)
}
|
