Add operation checking to admission control handlers

Adds a new method to the handler interface that returns true only if the
admission control handler handles that operation.

pkg/admission/handler.go

@@ -0,0 +1,44 @@
+/*
+Copyright 2015 The Kubernetes Authors 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 admission
+
+import (
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/util"
+)
+
+// Handler is a base for admission control handlers that
+// support a predefined set of operations
+type Handler struct {
+	operations util.StringSet
+}
+
+// Handles returns true for methods that this handler supports
+func (h *Handler) Handles(operation Operation) bool {
+	return h.operations.Has(string(operation))
+}
+
+// NewHandler creates a new base handler that handles the passed
+// in operations
+func NewHandler(ops ...Operation) *Handler {
+	operations := util.NewStringSet()
+	for _, op := range ops {
+		operations.Insert(string(op))
+	}
+	return &Handler{
+		operations: operations,
+	}
+}