forked from blevesearch/bleve
/
stop.go
70 lines (60 loc) · 1.89 KB
/
stop.go
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// 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 stop implements a TokenFilter removing tokens found in
// a TokenMap.
//
// It constructor takes the following arguments:
//
// "stop_token_map" (string): the name of the token map identifying tokens to
// remove.
package stop
import (
"fmt"
"github.com/qri-io/bleve/analysis"
"github.com/qri-io/bleve/registry"
)
const Name = "stop_tokens"
type StopTokensFilter struct {
stopTokens analysis.TokenMap
}
func NewStopTokensFilter(stopTokens analysis.TokenMap) *StopTokensFilter {
return &StopTokensFilter{
stopTokens: stopTokens,
}
}
func (f *StopTokensFilter) Filter(input analysis.TokenStream) analysis.TokenStream {
j := 0
for _, token := range input {
_, isStopToken := f.stopTokens[string(token.Term)]
if !isStopToken {
input[j] = token
j++
}
}
return input[:j]
}
func StopTokensFilterConstructor(config map[string]interface{}, cache *registry.Cache) (analysis.TokenFilter, error) {
stopTokenMapName, ok := config["stop_token_map"].(string)
if !ok {
return nil, fmt.Errorf("must specify stop_token_map")
}
stopTokenMap, err := cache.TokenMapNamed(stopTokenMapName)
if err != nil {
return nil, fmt.Errorf("error building stop words filter: %v", err)
}
return NewStopTokensFilter(stopTokenMap), nil
}
func init() {
registry.RegisterTokenFilter(Name, StopTokensFilterConstructor)
}