Move stringSet to util.StringSet

pkg/util/set.go

@@ -0,0 +1,40 @@
+/*
+Copyright 2014 Google Inc. All rights reserved.
+
+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 util
+
+type empty struct{}
+
+// A set of strings, implemented via map[string]struct{} for minimal memory consumption.
+type StringSet map[string]empty
+
+// Insert adds items to the set.
+func (s StringSet) Insert(items ...string) {
+	for _, item := range items {
+		s[item] = empty{}
+	}
+}
+
+// Delete removes item from the set.
+func (s StringSet) Delete(item string) {
+	delete(s, item)
+}
+
+// Has returns true iff item is contained in the set.
+func (s StringSet) Has(item string) bool {
+	_, contained := s[item]
+	return contained
+}