44ff6ced8a
1. porter stemmer offers method to NOT do lowercasing, however to use this we must convert to runes first ourself, so we did this 2. now we can invoke the version that skips lowercasing, we already do this ourselves before stemming through separate filter due to the fact that the stemmer modifies the runes in place we have no way to know if there were changes, thus we must always encode back into the term byte slice added unit test which catches the problem found NOTE this uses analysis.BuildTermFromRunes so perf gain is only visible with other PR also merged future gains are possible if we udpate the stemmer to let us know if changes were made, thus skipping re-encoding to []byte when no changes were actually made
49 lines
1.4 KiB
Go
49 lines
1.4 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 porter
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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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"github.com/blevesearch/go-porterstemmer"
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)
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const Name = "stemmer_porter"
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type PorterStemmer struct {
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}
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func NewPorterStemmer() *PorterStemmer {
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return &PorterStemmer{}
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}
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func (s *PorterStemmer) Filter(input analysis.TokenStream) analysis.TokenStream {
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for _, token := range input {
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// if it is not a protected keyword, stem it
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if !token.KeyWord {
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termRunes := bytes.Runes(token.Term)
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stemmedRunes := porterstemmer.StemWithoutLowerCasing(termRunes)
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token.Term = analysis.BuildTermFromRunes(stemmedRunes)
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}
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}
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return input
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}
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func PorterStemmerConstructor(config map[string]interface{}, cache *registry.Cache) (analysis.TokenFilter, error) {
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return NewPorterStemmer(), nil
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}
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func init() {
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registry.RegisterTokenFilter(Name, PorterStemmerConstructor)
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}
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