Refactoring of Delta.IDs & horizon functionality with a PrimaryKey type, needed for implementing UUID based primary keys for backends such as the appengine datastore \n Tests: at top level and if available per backend, if not then just visual

graph/primarykey.go

@@ -0,0 +1,28 @@
+// Copyright 2014 The Cayley 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 graph
+
+// Defines the PrimaryKey interface, this abstracts the generation of IDs
+
+type PrimaryKey interface {
+	// Returns a new unique primary key
+	Next() PrimaryKey
+
+	// Get the integer format if possible, otherwise logs an error and returns -1
+	Int() int64
+
+	// Get the string format
+	String() string
+}