2014-08-04 01:17:35 +02:00
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// Copyright (c) 2014 Couchbase, Inc.
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2016-10-02 16:13:14 +02:00
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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2014-09-02 16:54:50 +02:00
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2016-09-30 17:18:39 +02:00
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package elision
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2014-08-04 01:17:35 +02:00
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import (
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2014-08-14 03:14:47 +02:00
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"fmt"
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2015-11-04 10:59:10 +01:00
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"unicode/utf8"
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2014-08-04 01:17:35 +02:00
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2014-08-28 21:38:57 +02:00
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"github.com/blevesearch/bleve/analysis"
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"github.com/blevesearch/bleve/registry"
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2014-08-04 01:17:35 +02:00
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)
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2014-08-14 03:14:47 +02:00
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const Name = "elision"
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2015-11-04 10:59:10 +01:00
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const RightSingleQuotationMark = '’'
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const Apostrophe = '\''
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2014-08-04 01:17:35 +02:00
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type ElisionFilter struct {
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2014-08-14 03:14:47 +02:00
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articles analysis.TokenMap
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2014-08-04 01:17:35 +02:00
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}
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2014-08-14 03:14:47 +02:00
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func NewElisionFilter(articles analysis.TokenMap) *ElisionFilter {
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2014-08-04 01:17:35 +02:00
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return &ElisionFilter{
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articles: articles,
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}
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}
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func (s *ElisionFilter) Filter(input analysis.TokenStream) analysis.TokenStream {
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for _, token := range input {
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2015-11-04 10:59:10 +01:00
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term := token.Term
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for i := 0; i < len(term); {
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r, size := utf8.DecodeRune(term[i:])
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if r == Apostrophe || r == RightSingleQuotationMark {
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// see if the prefix matches one of the articles
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prefix := term[0:i]
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_, articleMatch := s.articles[string(prefix)]
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if articleMatch {
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token.Term = term[i+size:]
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break
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}
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}
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2015-11-04 10:59:10 +01:00
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i += size
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2014-08-04 01:17:35 +02:00
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}
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}
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2014-09-24 00:41:32 +02:00
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return input
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2014-08-04 01:17:35 +02:00
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}
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2014-08-14 03:14:47 +02:00
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func ElisionFilterConstructor(config map[string]interface{}, cache *registry.Cache) (analysis.TokenFilter, error) {
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articlesTokenMapName, ok := config["articles_token_map"].(string)
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if !ok {
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return nil, fmt.Errorf("must specify articles_token_map")
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}
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articlesTokenMap, err := cache.TokenMapNamed(articlesTokenMapName)
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if err != nil {
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return nil, fmt.Errorf("error building elision filter: %v", err)
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}
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return NewElisionFilter(articlesTokenMap), nil
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}
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func init() {
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registry.RegisterTokenFilter(Name, ElisionFilterConstructor)
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}
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