Add new java.util.Comparator implementation supporting Object identity comparisons.

Add new java.util.Comparator implementation supporting Object identity hash code comparisons.

Add new java.util.Comparator implementation supporting (Serializable Object to) byte array comparisons.

spring-data-geode-test/src/main/java/org/springframework/data/gemfire/tests/util/ByteArrayComparator.java

@@ -0,0 +1,65 @@
+/*
+ *  Copyright 2018 the original author or authors.
+ *
+ *  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 org.springframework.data.gemfire.tests.util;
+
+import java.util.Comparator;
+
+import org.apache.shiro.util.Assert;
+
+/**
+ * The ByteArrayComparator class...
+ *
+ * @author John Blum
+ * @since 1.0.0
+ */
+public class ByteArrayComparator implements Comparator<byte[]> {
+
+	public static final ByteArrayComparator INSTANCE = new ByteArrayComparator();
+
+	@Override
+	public int compare(byte[] bytesOne, byte[] bytesTwo) {
+
+		int bytesOneLength = bytesOne.length;
+		int bytesTwoLength = bytesTwo.length;
+
+		// Cannot use subtraction; Must be careful of overflow/underflow.
+		return bytesOneLength < bytesTwoLength ? -1
+			: bytesOneLength > bytesTwoLength ? 1
+			: compareByteByByte(bytesOne, bytesTwo);
+	}
+
+	private int compareByteByByte(byte[] bytesOne, byte[] bytesTwo) {
+
+		String errorMessage =
+			"The length of the byte arrays do no match; byte array 1 is [%d] and byte array 2 is [%d]";
+
+		Assert.isTrue(bytesOne.length == bytesTwo.length,
+			String.format(errorMessage, bytesOne.length, bytesTwo.length));
+
+		for (int index = 0; index < bytesOne.length; index++) {
+
+			// Subtraction is OK here since a byte cannot cause an int to either overflow or underflow.
+			int diff = (int) bytesOne[index] - (int) bytesTwo[index];
+
+			if (diff != 0) {
+				return diff;
+			}
+		}
+
+		return 0;
+	}
+}

spring-data-geode-test/src/main/java/org/springframework/data/gemfire/tests/util/IdentityComparator.java

@@ -0,0 +1,36 @@
+/*
+ *  Copyright 2018 the original author or authors.
+ *
+ *  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 org.springframework.data.gemfire.tests.util;
+
+import java.util.Comparator;
+
+/**
+ * The IdentityComparator class...
+ *
+ * @author John Blum
+ * @since 1.0.0
+ */
+@SuppressWarnings("unused")
+public class IdentityComparator implements Comparator<Object> {
+
+	public static final IdentityComparator INSTANCE = new IdentityComparator();
+
+	@Override
+	public int compare(Object objectOne, Object objectTwo) {
+		return objectOne == objectTwo ? 0 : ObjectToByteArrayComparator.INSTANCE.compare(objectOne, objectTwo);
+	}
+}

spring-data-geode-test/src/main/java/org/springframework/data/gemfire/tests/util/IdentityHashCodeComparator.java

@@ -0,0 +1,41 @@
+/*
+ *  Copyright 2018 the original author or authors.
+ *
+ *  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 org.springframework.data.gemfire.tests.util;
+
+import java.util.Comparator;
+
+/**
+ * The IdentityHashCodeComparator class...
+ *
+ * @author John Blum
+ * @since 1.0.0
+ */
+@SuppressWarnings("unused")
+public class IdentityHashCodeComparator implements Comparator<Object> {
+
+	@Override
+	public int compare(Object objectOne, Object objectTwo) {
+
+		int objectOneHashCode = System.identityHashCode(objectOne);
+		int objectTwoHashCode = System.identityHashCode(objectTwo);
+
+		// Cannot use subtraction; Must be careful of overflow/underflow.
+		return objectOneHashCode < objectTwoHashCode ? -1
+			: objectOneHashCode > objectTwoHashCode ? 1
+			: 0;
+	}
+}

spring-data-geode-test/src/main/java/org/springframework/data/gemfire/tests/util/ObjectToByteArrayComparator.java

@@ -0,0 +1,64 @@
+/*
+ *  Copyright 2018 the original author or authors.
+ *
+ *  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 org.springframework.data.gemfire.tests.util;
+
+import static org.springframework.data.gemfire.util.RuntimeExceptionFactory.newIllegalArgumentException;
+
+import java.io.IOException;
+import java.io.Serializable;
+import java.util.Comparator;
+
+import org.apache.shiro.util.Assert;
+
+/**
+ * The ObjectToByteArrayComparator class...
+ *
+ * @author John Blum
+ * @since 1.0.0
+ */
+public class ObjectToByteArrayComparator implements Comparator<Object> {
+
+	public static final ObjectToByteArrayComparator INSTANCE = new ObjectToByteArrayComparator();
+
+	@Override
+	public int compare(Object objectOne, Object objectTwo) {
+
+		return ByteArrayComparator.INSTANCE
+			.compare(fromSerializableToByteArray(objectOne), fromSerializableToByteArray(objectTwo));
+	}
+
+	private Serializable assertSerializable(Object target) {
+
+		Assert.isInstanceOf(Serializable.class, target);
+
+		return (Serializable) target;
+	}
+
+	private byte[] fromSerializableToByteArray(Object target) {
+		return toByteArray(assertSerializable(target));
+	}
+
+	private byte[] toByteArray(Object target) {
+
+		try {
+			return IOUtils.serializeObject(assertSerializable(target));
+		}
+		catch (IOException cause) {
+			throw newIllegalArgumentException(cause, "Object [%s] could not be serialized", target);
+		}
+	}
+}