ce901a8870
this introduces new German light stemmer and moves the other pure Go german analysis components back in from the blevex package the libstemmer version of the stemmer will remain in blevex
96 lines
2.1 KiB
Go
96 lines
2.1 KiB
Go
// 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 NormalizeName = "normalize_de"
|
|
|
|
const (
|
|
N = 0 /* ordinary state */
|
|
V = 1 /* stops 'u' from entering umlaut state */
|
|
U = 2 /* umlaut state, allows e-deletion */
|
|
)
|
|
|
|
type GermanNormalizeFilter struct {
|
|
}
|
|
|
|
func NewGermanNormalizeFilter() *GermanNormalizeFilter {
|
|
return &GermanNormalizeFilter{}
|
|
}
|
|
|
|
func (s *GermanNormalizeFilter) Filter(input analysis.TokenStream) analysis.TokenStream {
|
|
for _, token := range input {
|
|
term := normalize(token.Term)
|
|
token.Term = term
|
|
}
|
|
return input
|
|
}
|
|
|
|
func normalize(input []byte) []byte {
|
|
state := N
|
|
runes := bytes.Runes(input)
|
|
for i := 0; i < len(runes); i++ {
|
|
switch runes[i] {
|
|
case 'a', 'o':
|
|
state = U
|
|
case 'u':
|
|
if state == N {
|
|
state = U
|
|
} else {
|
|
state = V
|
|
}
|
|
case 'e':
|
|
if state == U {
|
|
runes = analysis.DeleteRune(runes, i)
|
|
i--
|
|
}
|
|
state = V
|
|
case 'i', 'q', 'y':
|
|
state = V
|
|
case 'ä':
|
|
runes[i] = 'a'
|
|
state = V
|
|
case 'ö':
|
|
runes[i] = 'o'
|
|
state = V
|
|
case 'ü':
|
|
runes[i] = 'u'
|
|
state = V
|
|
case 'ß':
|
|
runes[i] = 's'
|
|
i++
|
|
runes = analysis.InsertRune(runes, i, 's')
|
|
state = N
|
|
default:
|
|
state = N
|
|
}
|
|
}
|
|
return analysis.BuildTermFromRunes(runes)
|
|
}
|
|
|
|
func NormalizerFilterConstructor(config map[string]interface{}, cache *registry.Cache) (analysis.TokenFilter, error) {
|
|
return NewGermanNormalizeFilter(), nil
|
|
}
|
|
|
|
func init() {
|
|
registry.RegisterTokenFilter(NormalizeName, NormalizerFilterConstructor)
|
|
}
|