Reduce repo indexer disk usage (#3452)

vendor/github.com/blevesearch/bleve/analysis/token/unique/unique.go

@@ -0,0 +1,53 @@
+//  Copyright (c) 2018 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 unique
+
+import (
+	"github.com/blevesearch/bleve/analysis"
+	"github.com/blevesearch/bleve/registry"
+)
+
+const Name = "unique"
+
+// UniqueTermFilter retains only the tokens which mark the first occurence of
+// a term. Tokens whose term appears in a preceding token are dropped.
+type UniqueTermFilter struct{}
+
+func NewUniqueTermFilter() *UniqueTermFilter {
+	return &UniqueTermFilter{}
+}
+
+func (f *UniqueTermFilter) Filter(input analysis.TokenStream) analysis.TokenStream {
+	encounteredTerms := make(map[string]struct{}, len(input)/4)
+	j := 0
+	for _, token := range input {
+		term := string(token.Term)
+		if _, ok := encounteredTerms[term]; ok {
+			continue
+		}
+		encounteredTerms[term] = struct{}{}
+		input[j] = token
+		j++
+	}
+	return input[:j]
+}
+
+func UniqueTermFilterConstructor(config map[string]interface{}, cache *registry.Cache) (analysis.TokenFilter, error) {
+	return NewUniqueTermFilter(), nil
+}
+
+func init() {
+	registry.RegisterTokenFilter(Name, UniqueTermFilterConstructor)
+}