75 lines
2.0 KiB
Go
75 lines
2.0 KiB
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 elision
|
||
|
||
import (
|
||
"fmt"
|
||
"unicode/utf8"
|
||
|
||
"github.com/blevesearch/bleve/analysis"
|
||
"github.com/blevesearch/bleve/registry"
|
||
)
|
||
|
||
const Name = "elision"
|
||
|
||
const RightSingleQuotationMark = '’'
|
||
const Apostrophe = '\''
|
||
|
||
type ElisionFilter struct {
|
||
articles analysis.TokenMap
|
||
}
|
||
|
||
func NewElisionFilter(articles analysis.TokenMap) *ElisionFilter {
|
||
return &ElisionFilter{
|
||
articles: articles,
|
||
}
|
||
}
|
||
|
||
func (s *ElisionFilter) Filter(input analysis.TokenStream) analysis.TokenStream {
|
||
for _, token := range input {
|
||
term := token.Term
|
||
for i := 0; i < len(term); {
|
||
r, size := utf8.DecodeRune(term[i:])
|
||
if r == Apostrophe || r == RightSingleQuotationMark {
|
||
// see if the prefix matches one of the articles
|
||
prefix := term[0:i]
|
||
_, articleMatch := s.articles[string(prefix)]
|
||
if articleMatch {
|
||
token.Term = term[i+size:]
|
||
break
|
||
}
|
||
}
|
||
i += size
|
||
}
|
||
}
|
||
return input
|
||
}
|
||
|
||
func ElisionFilterConstructor(config map[string]interface{}, cache *registry.Cache) (analysis.TokenFilter, error) {
|
||
articlesTokenMapName, ok := config["articles_token_map"].(string)
|
||
if !ok {
|
||
return nil, fmt.Errorf("must specify articles_token_map")
|
||
}
|
||
articlesTokenMap, err := cache.TokenMapNamed(articlesTokenMapName)
|
||
if err != nil {
|
||
return nil, fmt.Errorf("error building elision filter: %v", err)
|
||
}
|
||
return NewElisionFilter(articlesTokenMap), nil
|
||
}
|
||
|
||
func init() {
|
||
registry.RegisterTokenFilter(Name, ElisionFilterConstructor)
|
||
}
|