faa07ac3a6
the token stream resulting from the removal of stop words must be shorter or the same length as the original, so we just reuse it and truncate it at the end.
66 lines
1.9 KiB
Go
66 lines
1.9 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 stop_tokens_filter implements a TokenFilter removing tokens found in
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// a TokenMap.
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//
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// It constructor takes the following arguments:
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//
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// "stop_token_map" (string): the name of the token map identifying tokens to
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// remove.
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package stop_tokens_filter
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import (
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"fmt"
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"github.com/blevesearch/bleve/analysis"
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"github.com/blevesearch/bleve/registry"
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)
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const Name = "stop_tokens"
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type StopTokensFilter struct {
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stopTokens analysis.TokenMap
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}
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func NewStopTokensFilter(stopTokens analysis.TokenMap) *StopTokensFilter {
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return &StopTokensFilter{
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stopTokens: stopTokens,
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}
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}
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func (f *StopTokensFilter) Filter(input analysis.TokenStream) analysis.TokenStream {
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j := 0
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for _, token := range input {
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_, isStopToken := f.stopTokens[string(token.Term)]
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if !isStopToken {
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input[j] = token
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j++
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}
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}
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return input[:j]
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}
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func StopTokensFilterConstructor(config map[string]interface{}, cache *registry.Cache) (analysis.TokenFilter, error) {
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stopTokenMapName, ok := config["stop_token_map"].(string)
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if !ok {
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return nil, fmt.Errorf("must specify stop_token_map")
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}
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stopTokenMap, err := cache.TokenMapNamed(stopTokenMapName)
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if err != nil {
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return nil, fmt.Errorf("error building stop words filter: %v", err)
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}
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return NewStopTokensFilter(stopTokenMap), nil
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}
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func init() {
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registry.RegisterTokenFilter(Name, StopTokensFilterConstructor)
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}
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