82 lines
2.0 KiB
Go
82 lines
2.0 KiB
Go
// Copyright (c) 2014 Couchbase, Inc.
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// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file
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// except in compliance with the License. You may obtain a copy of the License at
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// http://www.apache.org/licenses/LICENSE-2.0
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// Unless required by applicable law or agreed to in writing, software distributed under the
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// License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
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// either express or implied. See the License for the specific language governing permissions
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// and limitations under the License.
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package ar
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import (
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"bytes"
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"github.com/blevesearch/bleve/analysis"
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"github.com/blevesearch/bleve/registry"
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)
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const StemmerName = "stemmer_ar"
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// These were obtained from org.apache.lucene.analysis.ar.ArabicStemmer
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var prefixes = [][]byte{
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[]byte("ال"),
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[]byte("وال"),
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[]byte("بال"),
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[]byte("كال"),
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[]byte("فال"),
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[]byte("لل"),
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[]byte("و"),
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}
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var suffixes = [][]byte{
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[]byte("ها"),
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[]byte("ان"),
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[]byte("ات"),
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[]byte("ون"),
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[]byte("ين"),
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[]byte("يه"),
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[]byte("ية"),
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[]byte("ه"),
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[]byte("ة"),
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[]byte("ي"),
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}
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type ArabicStemmerFilter struct{}
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func NewArabicStemmerFilter() *ArabicStemmerFilter {
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return &ArabicStemmerFilter{}
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}
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func (s *ArabicStemmerFilter) Filter(input analysis.TokenStream) analysis.TokenStream {
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for _, token := range input {
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term := stem(token.Term)
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token.Term = term
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}
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return input
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}
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func stem(input []byte) []byte {
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// Strip a single prefix.
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for _, p := range prefixes {
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if bytes.HasPrefix(input, p) {
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input = input[len(p):]
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break
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}
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}
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// Strip off multiple suffixes, in their order in the suffixes array.
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for _, s := range suffixes {
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if bytes.HasSuffix(input, s) {
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input = input[:len(input)-len(s)]
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}
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}
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return input
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}
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func StemmerFilterConstructor(config map[string]interface{}, cache *registry.Cache) (analysis.TokenFilter, error) {
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return NewArabicStemmerFilter(), nil
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}
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func init() {
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registry.RegisterTokenFilter(StemmerName, StemmerFilterConstructor)
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}
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