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-rw-r--r--src/jogl/classes/org/apache/harmony/misc/HashCode.java203
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+/*
+ * 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.harmony.misc;
+
+/**
+ * This class is a convenience method to sequentially calculate hash code of the
+ * object based on the field values. The result depends on the order of elements
+ * appended. The exact formula is the same as for
+ * <code>java.util.List.hashCode</code>.
+ *
+ * If you need order independent hash code just summate, multiply or XOR all
+ * elements.
+ *
+ * <p>
+ * Suppose we have class:
+ *
+ * <pre><code>
+ * class Thing {
+ * long id;
+ * String name;
+ * float weight;
+ * }
+ * </code></pre>
+ *
+ * The hash code calculation can be expressed in 2 forms.
+ *
+ * <p>
+ * For maximum performance:
+ *
+ * <pre><code>
+ * public int hashCode() {
+ * int hashCode = HashCode.EMPTY_HASH_CODE;
+ * hashCode = HashCode.combine(hashCode, id);
+ * hashCode = HashCode.combine(hashCode, name);
+ * hashCode = HashCode.combine(hashCode, weight);
+ * return hashCode;
+ * }
+ * </code></pre>
+ *
+ * <p>
+ * For convenience: <code><pre>
+ * public int hashCode() {
+ * return new HashCode().append(id).append(name).append(weight).hashCode();
+ * }
+ * </code></pre>
+ *
+ * @see java.util.List#hashCode()
+ */
+public final class HashCode {
+ /**
+ * The hashCode value before any data is appended, equals to 1.
+ * @see java.util.List#hashCode()
+ */
+ public static final int EMPTY_HASH_CODE = 1;
+
+ private int hashCode = EMPTY_HASH_CODE;
+
+ /**
+ * Returns accumulated hashCode
+ */
+ public final int hashCode() {
+ return hashCode;
+ }
+
+ /**
+ * Combines hashCode of previous elements sequence and value's hashCode.
+ * @param hashCode previous hashCode value
+ * @param value new element
+ * @return combined hashCode
+ */
+ public static int combine(int hashCode, boolean value) {
+ int v = value ? 1231 : 1237;
+ return combine(hashCode, v);
+ }
+
+ /**
+ * Combines hashCode of previous elements sequence and value's hashCode.
+ * @param hashCode previous hashCode value
+ * @param value new element
+ * @return combined hashCode
+ */
+ public static int combine(int hashCode, long value) {
+ int v = (int) (value ^ (value >>> 32));
+ return combine(hashCode, v);
+ }
+
+ /**
+ * Combines hashCode of previous elements sequence and value's hashCode.
+ * @param hashCode previous hashCode value
+ * @param value new element
+ * @return combined hashCode
+ */
+ public static int combine(int hashCode, float value) {
+ int v = Float.floatToIntBits(value);
+ return combine(hashCode, v);
+ }
+
+ /**
+ * Combines hashCode of previous elements sequence and value's hashCode.
+ * @param hashCode previous hashCode value
+ * @param value new element
+ * @return combined hashCode
+ */
+ public static int combine(int hashCode, double value) {
+ long v = Double.doubleToLongBits(value);
+ return combine(hashCode, v);
+ }
+
+ /**
+ * Combines hashCode of previous elements sequence and value's hashCode.
+ * @param hashCode previous hashCode value
+ * @param value new element
+ * @return combined hashCode
+ */
+ public static int combine(int hashCode, Object value) {
+ return combine(hashCode, value.hashCode());
+ }
+
+ /**
+ * Combines hashCode of previous elements sequence and value's hashCode.
+ * @param hashCode previous hashCode value
+ * @param value new element
+ * @return combined hashCode
+ */
+ public static int combine(int hashCode, int value) {
+ return 31 * hashCode + value;
+ }
+
+ /**
+ * Appends value's hashCode to the current hashCode.
+ * @param value new element
+ * @return this
+ */
+ public final HashCode append(int value) {
+ hashCode = combine(hashCode, value);
+ return this;
+ }
+
+ /**
+ * Appends value's hashCode to the current hashCode.
+ * @param value new element
+ * @return this
+ */
+ public final HashCode append(long value) {
+ hashCode = combine(hashCode, value);
+ return this;
+ }
+
+ /**
+ * Appends value's hashCode to the current hashCode.
+ * @param value new element
+ * @return this
+ */
+ public final HashCode append(float value) {
+ hashCode = combine(hashCode, value);
+ return this;
+ }
+
+ /**
+ * Appends value's hashCode to the current hashCode.
+ * @param value new element
+ * @return this
+ */
+ public final HashCode append(double value) {
+ hashCode = combine(hashCode, value);
+ return this;
+ }
+
+ /**
+ * Appends value's hashCode to the current hashCode.
+ * @param value new element
+ * @return this
+ */
+ public final HashCode append(boolean value) {
+ hashCode = combine(hashCode, value);
+ return this;
+ }
+
+ /**
+ * Appends value's hashCode to the current hashCode.
+ * @param value new element
+ * @return this
+ */
+ public final HashCode append(Object value) {
+ hashCode = combine(hashCode, value);
+ return this;
+ }
+}