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// Copyright (c) 2014 Couchbase, Inc.
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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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package en
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import (
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"unicode/utf8"
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"github.com/blevesearch/bleve/v2/analysis"
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"github.com/blevesearch/bleve/v2/registry"
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)
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// PossessiveName is the name PossessiveFilter is registered as
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// in the bleve registry.
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const PossessiveName = "possessive_en"
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const rightSingleQuotationMark = '’'
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const apostrophe = '\''
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const fullWidthApostrophe = '＇'
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const apostropheChars = rightSingleQuotationMark + apostrophe + fullWidthApostrophe
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// PossessiveFilter implements a TokenFilter which
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// strips the English possessive suffix ('s) from tokens.
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// It handle a variety of apostrophe types, is case-insensitive
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// and doesn't distinguish between possessive and contraction.
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// (ie "She's So Rad" becomes "She So Rad")
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type PossessiveFilter struct {
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}
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func NewPossessiveFilter() *PossessiveFilter {
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return &PossessiveFilter{}
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}
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func (s *PossessiveFilter) Filter(input analysis.TokenStream) analysis.TokenStream {
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for _, token := range input {
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lastRune, lastRuneSize := utf8.DecodeLastRune(token.Term)
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if lastRune == 's' || lastRune == 'S' {
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nextLastRune, nextLastRuneSize := utf8.DecodeLastRune(token.Term[:len(token.Term)-lastRuneSize])
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if nextLastRune == rightSingleQuotationMark ||
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nextLastRune == apostrophe ||
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nextLastRune == fullWidthApostrophe {
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token.Term = token.Term[:len(token.Term)-lastRuneSize-nextLastRuneSize]
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}
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}
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}
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return input
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}
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func PossessiveFilterConstructor(config map[string]interface{}, cache *registry.Cache) (analysis.TokenFilter, error) {
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return NewPossessiveFilter(), nil
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}
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func init() {
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registry.RegisterTokenFilter(PossessiveName, PossessiveFilterConstructor)
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}
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