GOSSIP-53 CRDT types

src/main/java/org/apache/gossip/crdt/CrdtBiFunctionMerge.java

@@ -0,0 +1,55 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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 org.apache.gossip.crdt;
+
+import java.util.function.BiFunction;
+
+@SuppressWarnings("rawtypes")
+public class CrdtBiFunctionMerge implements BiFunction<Crdt,Crdt,Crdt> {
+
+  @SuppressWarnings("unchecked")
+  @Override
+  public Crdt apply(Crdt t, Crdt u) {
+    if (t == null && u == null){
+      return null;
+    } else if (t == null){
+      return u;
+    } else if (u == null){
+      return t;
+    }
+    if (! u.getClass().equals(t.getClass())){
+      throw new IllegalArgumentException( "Can not merge " + t.getClass() + " "+ u.getClass());
+    }
+    return t.merge(u);
+  }
+
+  @SuppressWarnings("unchecked")
+  public static Crdt applyStatic(Crdt t, Crdt u){
+    if (t == null && u == null){
+      return null;
+    } else if (t == null){
+      return u;
+    } else if (u == null){
+      return t;
+    }
+    if (! u.getClass().equals(t.getClass())){
+      throw new IllegalArgumentException( "Can not merge " + t.getClass() + " "+ u.getClass());
+    }
+    return t.merge(u);
+  }
+}