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light_stemmer_it.go
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light_stemmer_it.go
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// Copyright (c) 2015 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 it
import (
"bytes"
"github.com/blevesearch/bleve/analysis"
"github.com/blevesearch/bleve/registry"
)
const LightStemmerName = "stemmer_it_light"
type ItalianLightStemmerFilter struct {
}
func NewItalianLightStemmerFilterFilter() *ItalianLightStemmerFilter {
return &ItalianLightStemmerFilter{}
}
func (s *ItalianLightStemmerFilter) 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 {
inputLen := len(input)
if inputLen < 6 {
return input
}
for i := 0; i < inputLen; i++ {
switch input[i] {
case 'à', 'á', 'â', 'ä':
input[i] = 'a'
case 'ò', 'ó', 'ô', 'ö':
input[i] = 'o'
case 'è', 'é', 'ê', 'ë':
input[i] = 'e'
case 'ù', 'ú', 'û', 'ü':
input[i] = 'u'
case 'ì', 'í', 'î', 'ï':
input[i] = 'i'
}
}
switch input[inputLen-1] {
case 'e':
if input[inputLen-2] == 'i' || input[inputLen-2] == 'h' {
return input[0 : inputLen-2]
} else {
return input[0 : inputLen-1]
}
case 'i':
if input[inputLen-2] == 'h' || input[inputLen-2] == 'i' {
return input[0 : inputLen-2]
} else {
return input[0 : inputLen-1]
}
case 'a':
if input[inputLen-2] == 'i' {
return input[0 : inputLen-2]
} else {
return input[0 : inputLen-1]
}
case 'o':
if input[inputLen-2] == 'i' {
return input[0 : inputLen-2]
} else {
return input[0 : inputLen-1]
}
}
return input
}
func ItalianLightStemmerFilterConstructor(config map[string]interface{}, cache *registry.Cache) (analysis.TokenFilter, error) {
return NewItalianLightStemmerFilterFilter(), nil
}
func init() {
registry.RegisterTokenFilter(LightStemmerName, ItalianLightStemmerFilterConstructor)
}