bleve/analysis/token/porter/porter.go

//  Copyright (c) 2014 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 porter

import (
	"bytes"

	"github.com/blevesearch/bleve/analysis"
	"github.com/blevesearch/bleve/registry"

	"github.com/blevesearch/go-porterstemmer"
)

const Name = "stemmer_porter"

type PorterStemmer struct {
}

func NewPorterStemmer() *PorterStemmer {
	return &PorterStemmer{}
}

func (s *PorterStemmer) Filter(input analysis.TokenStream) analysis.TokenStream {
	for _, token := range input {
		// if it is not a protected keyword, stem it
		if !token.KeyWord {
			termRunes := bytes.Runes(token.Term)
			stemmedRunes := porterstemmer.StemWithoutLowerCasing(termRunes)
			token.Term = analysis.BuildTermFromRunes(stemmedRunes)
		}
	}
	return input
}

func PorterStemmerConstructor(config map[string]interface{}, cache *registry.Cache) (analysis.TokenFilter, error) {
	return NewPorterStemmer(), nil
}

func init() {
	registry.RegisterTokenFilter(Name, PorterStemmerConstructor)
}