From 9a3f8a3e9ce4aa73277ed816d2f583adb3cc7c2e Mon Sep 17 00:00:00 2001 From: Stephen Colebourne Date: Sun, 15 Sep 2002 10:25:22 +0000 Subject: [PATCH] Add CompareToBuilder for building compareTo methods git-svn-id: https://svn.apache.org/repos/asf/jakarta/commons/proper/lang/trunk@137022 13f79535-47bb-0310-9956-ffa450edef68 --- .../lang/builder/CompareToBuilder.java | 633 ++++++++++++++++++ 1 file changed, 633 insertions(+) create mode 100644 src/java/org/apache/commons/lang/builder/CompareToBuilder.java diff --git a/src/java/org/apache/commons/lang/builder/CompareToBuilder.java b/src/java/org/apache/commons/lang/builder/CompareToBuilder.java new file mode 100644 index 000000000..2bf9a28a7 --- /dev/null +++ b/src/java/org/apache/commons/lang/builder/CompareToBuilder.java @@ -0,0 +1,633 @@ +/* ==================================================================== + * The Apache Software License, Version 1.1 + * + * Copyright (c) 2002 The Apache Software Foundation. All rights + * reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in + * the documentation and/or other materials provided with the + * distribution. + * + * 3. The end-user documentation included with the redistribution, if + * any, must include the following acknowlegement: + * "This product includes software developed by the + * Apache Software Foundation (http://www.apache.org/)." + * Alternately, this acknowlegement may appear in the software itself, + * if and wherever such third-party acknowlegements normally appear. + * + * 4. The names "The Jakarta Project", "Commons", and "Apache Software + * Foundation" must not be used to endorse or promote products derived + * from this software without prior written permission. For written + * permission, please contact apache@apache.org. + * + * 5. Products derived from this software may not be called "Apache" + * nor may "Apache" appear in their names without prior written + * permission of the Apache Software Foundation. + * + * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED + * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE + * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR + * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, + * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT + * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF + * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND + * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, + * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT + * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + * ==================================================================== + * + * This software consists of voluntary contributions made by many + * individuals on behalf of the Apache Software Foundation. For more + * information on the Apache Software Foundation, please see + * . + */ +package org.apache.commons.lang.builder; + +import java.lang.reflect.Field; +import java.lang.reflect.Modifier; + +import org.apache.commons.lang.NumberUtils; +/** + * CompareTo generation routines. + *

+ * This class provides methods to build a good compareTo() method for any class. + * It is consistent with the equals and hashcode built + * with EqualsBuilder and HashCodeBuilder. + *

+ * Two object that compare equal using equals should compare equals using + * compareTo. + *

+ * All relevant fields should be included in the calculation of the comparison. Derived + * fields may be ignored. The same fields, in the same order, should be used in + * both compareTo and equals. + *

+ * Typical use for the code is as follows: + * + * 

+ *  public int comapareTo(Object o) {
+ *    MyClass rhs = (MyClass) o;
+ *    return new CompareToBuilder()
+ *                 .append(field1, rhs.field1)
+ *                 .append(field2, rhs.field2)
+ *                 .appendb(field3, rhs.field3)
+ *                 .toComparison();
+ *  }
+ *
+ *

+ * Alternatively, there is a method that uses reflection to determine + * the fields to test. Because these fields are usually private, the method, + * reflectionCompare, uses Field.setAccessible to change + * the visibility of the fields. This will fail under a security manager, + * unless the appropriate permissions are set. It is also slower than testing + * explicitly. + *

+ * A typical invocation for this method would look like: + * 

+ * public int compareTo(Object o) {
+ *   return CompareToBuilder.reflectionCompare(this, obj);
+ * }
+ *
+ * @author Steve Downey + * @author Stephen Colebourne + * @version $Id: CompareToBuilder.java,v 1.1 2002/09/15 10:25:22 scolebourne Exp $ + */ +public class CompareToBuilder { + /** + * If the fields tested are equals. + */ + protected int comparison; + + /** + * Constructor for CompareToBuilder. + * Starts off assuming that the objects are equal. + * @see java.lang.Object#Object() + */ + public CompareToBuilder() { + super(); + comparison = 0; + } + + //------------------------------------------------------------------------- + + /** + * This method uses reflection to determine the ordering between two objects. + *

+ * It uses Field.setAccessible to gain access to private fields. This means + * that it will throw a security exception if run under a security manger, if + * the permissions are not set up. + * It is also not as efficient as testing explicitly. + * Transient members will be not be tested, as they are likely derived + * fields, and not part of the value of the object. + * @param lhs - Left Hand Side + * @param rhs - Right Hand Side + * @return int - a negative integer, zero, or a positive integer as this + * object is less than, equal to, or greater than the specified object. + * @throws ClassCastException - if the specified object's type prevents it + * from being compared to this Object. + */ + public static int reflectionCompare(Object lhs, Object rhs) { + return reflectionCompare(lhs, rhs, false); + } + + /** + * This method uses reflection to determine if the two object are equal. + *

+ * It uses Field.setAccessible to gain access to private fields. This means + * that it will throw a security exception if run under a security manger, if + * the permissions are not set up. + * It is also not as efficient as testing explicitly. + * If the TestTransients parameter is set to true, transient members will be + * tested, otherwise they are ignored, as they are likely derived fields, and + * not part of the value of the object. + * + * @param lhs - Left Hand Side + * @param rhs - Right Hand Side + * @param testTransients - whether to include transient fields + * @return int - a negative integer, zero, or a positive integer as this + * object is less than, equal to, or greater than the specified object. + * @throws ClassCastException - if the specified object's type prevents it + * from being compared to this Object. + */ + public static int reflectionCompare(Object lhs, Object rhs, boolean testTransients) { + if (lhs == rhs) { + return 0; + } + if (lhs == null || rhs == null) { + throw new NullPointerException(); + } + Class c1 = lhs.getClass(); + if (!c1.isInstance(rhs)) { + throw new ClassCastException(); + } + Field[] fields = c1.getDeclaredFields(); + Field.setAccessible(fields, true); + CompareToBuilder compareToBuilder = new CompareToBuilder(); + for (int i = 0; i < fields.length && compareToBuilder.comparison == 0; ++i) { + Field f = fields[i]; + if (testTransients || !Modifier.isTransient(f.getModifiers())) { + try { + compareToBuilder.append(f.get(lhs), f.get(rhs)); + } catch (IllegalAccessException e) { + //this can't happen. Would get a Security exception instead + //throw a runtime exception in case the impossible happens. + throw new InternalError("Unexpected IllegalAccessException"); + } + } + } + return compareToBuilder.toComparison(); + } + + //------------------------------------------------------------------------- + + /** Test if two Objects are equal using either the + * compareTo method, or native comparison if the Objects are + * actually arrays. + *

+ * The objects must be Comparable. If they are not, the method + * will throw a ClassCastException. + * @param lhs - Left Hand Side + * @param rhs - Right Hand Side + * @return CompareToBuilder - used to chain calls. + * @throws ClassCastException - if the specified object's type prevents it + * from being compared to this Object. + */ + public CompareToBuilder append(Object lhs, Object rhs) { + if (comparison != 0) { + return this; + } + if (lhs == rhs) { + return this; + } + if (lhs == null || rhs == null) { + throw new NullPointerException(); + } + Class lhsClass = lhs.getClass(); + if (!lhsClass.isArray()) { + //the simple case, not an array, just test the element + comparison = ((Comparable)lhs).compareTo(rhs); + } else { + //'Switch' on type of array, to dispatch to the correct handler + // This handles multi dimensional arrays + if (lhs instanceof long[]) { + append((long[]) lhs, (long[]) rhs); + } else if (lhs instanceof int[]) { + append((int[]) lhs, (int[]) rhs); + } else if (lhs instanceof short[]) { + append((short[]) lhs, (short[]) rhs); + } else if (lhs instanceof char[]) { + append((char[]) lhs, (char[]) rhs); + } else if (lhs instanceof byte[]) { + append((byte[]) lhs, (byte[]) rhs); + } else if (lhs instanceof double[]) { + append((double[]) lhs, (double[]) rhs); + } else if (lhs instanceof float[]) { + append((float[]) lhs, (float[]) rhs); + } else if (lhs instanceof boolean[]) { + append((boolean[]) lhs, (boolean[]) rhs); + } else { + // Not an array of primitives + append((Object[]) lhs, (Object[]) rhs); + } + } + return this; + } + + /** + * Test if two longs are <, > or ==. + * @param lhs - Left Hand Side + * @param rhs - Right Hand Side + * @return CompareToBuilder - used to chain calls. + */ + public CompareToBuilder append(long lhs, long rhs) { + if (comparison != 0) { + return this; + } + comparison = ((lhs < rhs) ? -1 : ((lhs > rhs) ? 1 : 0)); + return this; + } + + /** + * Test if two ints are <, > or ==. + * @param lhs - Left Hand Side + * @param rhs - Right Hand Side + * @return CompareToBuilder - used to chain calls. + */ + public CompareToBuilder append(int lhs, int rhs) { + if (comparison != 0) { + return this; + } + comparison = ((lhs < rhs) ? -1 : ((lhs > rhs) ? 1 : 0)); + return this; + } + + /** + * Test if two shorts are <, > or ==. + * @param lhs - Left Hand Side + * @param rhs - Right Hand Side + * @return CompareToBuilder - used to chain calls. + */ + public CompareToBuilder append(short lhs, short rhs) { + if (comparison != 0) { + return this; + } + comparison = ((lhs < rhs) ? -1 : ((lhs > rhs) ? 1 : 0)); + return this; + } + + /** + * Test if two chars are <, > or ==. + * @param lhs - Left Hand Side + * @param rhs - Right Hand Side + * @return CompareToBuilder - used to chain calls. + */ + public CompareToBuilder append(char lhs, char rhs) { + if (comparison != 0) { + return this; + } + comparison = ((lhs < rhs) ? -1 : ((lhs > rhs) ? 1 : 0)); + return this; + } + + /** + * Test if two bytes are <, > or ==. + * @param lhs - Left Hand Side + * @param rhs - Right Hand Side + * @return CompareToBuilder - used to chain calls. + */ + public CompareToBuilder append(byte lhs, byte rhs) { + if (comparison != 0) { + return this; + } + comparison = ((lhs < rhs) ? -1 : ((lhs > rhs) ? 1 : 0)); + return this; + } + + /** + * Test if two doubles are <, > or ==. This handles NaNs, + * Infinties, and -0.0. It is compatible with the hash code generated by + * HashCodeBuilder. + * @param lhs - Left Hand Side + * @param rhs - Right Hand Side + * @return CompareToBuilder - used to chain calls. + */ + public CompareToBuilder append(double lhs, double rhs) { + if (comparison != 0) { + return this; + } + comparison = NumberUtils.compare(lhs, rhs); + return this; + } + + /** + * Test if two doubles are <, > or ==. This handles NaNs, + * Infinties, and -0.0. It is compatible with the hash code generated by + * HashCodeBuilder. + * @param lhs - Left Hand Side + * @param rhs - Right Hand Side + * @return CompareToBuilder - used to chain calls. + */ + public CompareToBuilder append(float lhs, float rhs) { + if (comparison != 0) { + return this; + } + comparison = NumberUtils.compare(lhs, rhs); + return this; + } + + /** + * Test if two booleanss are <, > or ==. + * @param lhs - Left Hand Side + * @param rhs - Right Hand Side + * @return CompareToBuilder - used to chain calls. + */ + public CompareToBuilder append(boolean lhs, boolean rhs) { + if (comparison != 0) { + return this; + } + if (lhs == rhs) { + return this; + } + if (lhs == false) { + comparison = -1; + } else { + comparison = +1; + } + return this; + } + + /** + * Performs a deep comparison of two object arrays. This also will be + * called for the top level of multi-dimensional, ragged, and multi-typed + * arrays. If two arrays are of different lengths, and all elements of the + * shorter array are equal to the elements in the longer array, the longer + * array is the greater. This is dictionary, or lexical, ordering. + * @param lhs - Left Hand Side + * @param rhs - Right Hand Side + * @return CompareToBuilder - used to chain calls. + * @throws ClassCastException - if the specified object's type prevents it + * from being compared to this Object. + */ + public CompareToBuilder append(Object[] lhs, Object[] rhs) { + if (comparison != 0) { + return this; + } + if (lhs == rhs) { + return this; + } + if (lhs == null || rhs == null) { + throw new NullPointerException(); + } + + int length = (lhs.length < rhs.length) ? lhs.length : rhs.length; + for (int i = 0; i < length && comparison == 0; ++i) { + Class lhsClass = lhs[i].getClass(); + if (!lhsClass.isInstance(rhs[i])) { + throw new ClassCastException(); + } + append(lhs[i], rhs[i]); + } + if (comparison == 0 && lhs.length != rhs.length) { + comparison = (lhs.length < rhs.length) ? -1 : +1; + } + return this; + } + + /** + * Deep comparison of array of long Length and all values + * are compared. The method append(long, long) is used. + * @param lhs - Left Hand Side + * @param rhs - Right Hand Side + * @return CompareToBuilder - used to chain calls. + */ + public CompareToBuilder append(long[] lhs, long[] rhs) { + if (comparison != 0) { + return this; + } + if (lhs == rhs) { + return this; + } + if (lhs == null || rhs == null) { + throw new NullPointerException(); + } + int length = (lhs.length < rhs.length) ? lhs.length : rhs.length; + for (int i = 0; i < length && comparison == 0; ++i) { + append(lhs[i], rhs[i]); + } + if (comparison == 0 && lhs.length != rhs.length) { + comparison = (lhs.length < rhs.length) ? -1 : +1; + } + return this; + } + + /** + * Deep comparison of array of int Length and all values + * are compared. The method append(int, int) is used. + * @param lhs - Left Hand Side + * @param rhs - Right Hand Side + * @return CompareToBuilder - used to chain calls. + */ + public CompareToBuilder append(int[] lhs, int[] rhs) { + if (comparison != 0) { + return this; + } + if (lhs == rhs) { + return this; + } + if (lhs == null || rhs == null) { + throw new NullPointerException(); + } + int length = (lhs.length < rhs.length) ? lhs.length : rhs.length; + for (int i = 0; i < length && comparison == 0; ++i) { + append(lhs[i], rhs[i]); + } + if (comparison == 0 && lhs.length != rhs.length) { + comparison = (lhs.length < rhs.length) ? -1 : +1; + } + return this; + } + + /** + * Deep comparison of array of short Length and all values + * are compared. The method append(short, short) is used. + * @param lhs - Left Hand Side + * @param rhs - Right Hand Side + * @return CompareToBuilder - used to chain calls. + */ + public CompareToBuilder append(short[] lhs, short[] rhs) { + if (comparison != 0) { + return this; + } + if (lhs == rhs) { + return this; + } + if (lhs == null || rhs == null) { + throw new NullPointerException(); + } + int length = (lhs.length < rhs.length) ? lhs.length : rhs.length; + for (int i = 0; i < length && comparison == 0; ++i) { + append(lhs[i], rhs[i]); + } + if (comparison == 0 && lhs.length != rhs.length) { + comparison = (lhs.length < rhs.length) ? -1 : +1; + } + return this; + } + + /** + * Deep comparison of array of char Length and all values + * are compared. The method append(char, char) is used. + * @param lhs - Left Hand Side + * @param rhs - Right Hand Side + * @return CompareToBuilder - used to chain calls. + */ + public CompareToBuilder append(char[] lhs, char[] rhs) { + if (comparison != 0) { + return this; + } + if (lhs == rhs) { + return this; + } + if (lhs == null || rhs == null) { + throw new NullPointerException(); + } + int length = (lhs.length < rhs.length) ? lhs.length : rhs.length; + for (int i = 0; i < length && comparison == 0; ++i) { + append(lhs[i], rhs[i]); + } + if (comparison == 0 && lhs.length != rhs.length) { + comparison = (lhs.length < rhs.length) ? -1 : +1; + } + return this; + } + + /** + * Deep comparison of array of byte Length and all values + * are compared. The method append(byte, byte) is used. + * @param lhs - Left Hand Side + * @param rhs - Right Hand Side + * @return CompareToBuilder - used to chain calls. + */ + public CompareToBuilder append(byte[] lhs, byte[] rhs) { + if (comparison != 0) { + return this; + } + if (lhs == rhs) { + return this; + } + if (lhs == null || rhs == null) { + throw new NullPointerException(); + } + int length = (lhs.length < rhs.length) ? lhs.length : rhs.length; + for (int i = 0; i < length && comparison == 0; ++i) { + append(lhs[i], rhs[i]); + } + if (comparison == 0 && lhs.length != rhs.length) { + comparison = (lhs.length < rhs.length) ? -1 : +1; + } + return this; + } + + /** + * Deep comparison of array of double Length and all values + * are compared. The method append(double, double) is used. + * @param lhs - Left Hand Side + * @param rhs - Right Hand Side + * @return CompareToBuilder - used to chain calls. + */ + public CompareToBuilder append(double[] lhs, double[] rhs) { + if (comparison != 0) { + return this; + } + if (lhs == rhs) { + return this; + } + if (lhs == null || rhs == null) { + throw new NullPointerException(); + } + int length = (lhs.length < rhs.length) ? lhs.length : rhs.length; + for (int i = 0; i < length && comparison == 0; ++i) { + append(lhs[i], rhs[i]); + } + if (comparison == 0 && lhs.length != rhs.length) { + comparison = (lhs.length < rhs.length) ? -1 : +1; + } + return this; + } + + /** + * Deep comparison of array of float Length and all values + * are compared. The method append(float, float) is used. + * @param lhs - Left Hand Side + * @param rhs - Right Hand Side + * @return CompareToBuilder - used to chain calls. + */ + public CompareToBuilder append(float[] lhs, float[] rhs) { + if (comparison != 0) { + return this; + } + if (lhs == rhs) { + return this; + } + if (lhs == null || rhs == null) { + throw new NullPointerException(); + } + int length = (lhs.length < rhs.length) ? lhs.length : rhs.length; + for (int i = 0; i < length && comparison == 0; ++i) { + append(lhs[i], rhs[i]); + } + if (comparison == 0 && lhs.length != rhs.length) { + comparison = (lhs.length < rhs.length) ? -1 : +1; + } + return this; + } + + /** + * Deep comparison of array of boolean Length and all values + * are compared. The method append(boolean, boolean) is used. + * @param lhs - Left Hand Side + * @param rhs - Right Hand Side + * @return CompareToBuilder - used to chain calls. + */ + public CompareToBuilder append(boolean[] lhs, boolean[] rhs) { + if (comparison != 0) { + return this; + } + if (lhs == rhs) { + return this; + } + if (lhs == null || rhs == null) { + throw new NullPointerException(); + } + int length = (lhs.length < rhs.length) ? lhs.length : rhs.length; + for (int i = 0; i < length && comparison == 0; ++i) { + append(lhs[i], rhs[i]); + } + if (comparison == 0 && lhs.length != rhs.length) { + comparison = (lhs.length < rhs.length) ? -1 : +1; + } + return this; + } + + /** + * Return a negative integer if the object is less than, a positive + * integer if the object is greater than, or 0 if the object is equal. + * + * @return int - a negative integer, zero, or a positive integer as this + * object is less than, equal to, or greater than the specified object. + */ + public int toComparison() { + return comparison; + } + +} +