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From bay...@apache.org
Subject svn commit: r1161605 - /commons/proper/lang/trunk/src/main/java/org/apache/commons/lang3/compare/ComparatorUtils.java
Date Thu, 25 Aug 2011 15:27:40 GMT
Author: bayard
Date: Thu Aug 25 15:27:39 2011
New Revision: 1161605

URL: http://svn.apache.org/viewvc?rev=1161605&view=rev
Log:
Rolling back r1161378. NullComparator and ReverseComparator need the NATURAL_COMPARATOR field
and the ComparableComparator.INSTANCE field is not a straight replacement

Added:
    commons/proper/lang/trunk/src/main/java/org/apache/commons/lang3/compare/ComparatorUtils.java
  (with props)

Added: commons/proper/lang/trunk/src/main/java/org/apache/commons/lang3/compare/ComparatorUtils.java
URL: http://svn.apache.org/viewvc/commons/proper/lang/trunk/src/main/java/org/apache/commons/lang3/compare/ComparatorUtils.java?rev=1161605&view=auto
==============================================================================
--- commons/proper/lang/trunk/src/main/java/org/apache/commons/lang3/compare/ComparatorUtils.java
(added)
+++ commons/proper/lang/trunk/src/main/java/org/apache/commons/lang3/compare/ComparatorUtils.java
Thu Aug 25 15:27:39 2011
@@ -0,0 +1,201 @@
+/*
+ * 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.commons.lang3.compare;
+
+import java.util.Collection;
+import java.util.Comparator;
+
+/**
+ * Provides convenient static utility methods for <Code>Comparator</Code>
+ * objects.
+ * <p>
+ * Most of the functionality in this class can also be found in the 
+ * <code>comparators</code> package. This class merely provides a 
+ * convenient central place if you have use for more than one class
+ * in the <code>comparators</code> subpackage.
+ *
+ * @since Commons Collections 2.1
+ * @version $Revision$ $Date$
+ */
+public class ComparatorUtils {
+
+    /**
+     * ComparatorUtils should not normally be instantiated.
+     */
+    public ComparatorUtils() {
+    }
+
+    /**
+     * Comparator for natural sort order.
+     *
+     * @see ComparableComparator#getInstance
+     */
+    @SuppressWarnings("unchecked")
+    public static final Comparator NATURAL_COMPARATOR = ComparableComparator.<Comparable>comparableComparator();
+
+    /**
+     * Gets a comparator that uses the natural order of the objects.
+     *
+     * @return  a comparator which uses natural order
+     */
+    @SuppressWarnings("unchecked")
+    public static <E extends Comparable<? super E>> Comparator<E> naturalComparator()
{
+        return NATURAL_COMPARATOR;
+    }
+
+    /**
+     * Gets a comparator that compares using two {@link Comparator}s.
+     * <p>
+     * The second comparator is used if the first comparator returns equal.
+     *
+     * @param comparator1  the first comparator to use, not null
+     * @param comparator2  the first comparator to use, not null
+     * @return a {@link ComparatorChain} formed from the two comparators
+     * @throws NullPointerException if either comparator is null
+     * @see ComparatorChain
+     */
+    @SuppressWarnings("unchecked")
+    public static <E extends Comparable<? super E>> Comparator<E> chainedComparator(Comparator<E>
comparator1, Comparator<E> comparator2) {
+        return chainedComparator(new Comparator[] {comparator1, comparator2});
+    }
+
+    /**
+     * Gets a comparator that compares using an array of {@link Comparator}s, applied
+     * in sequence until one returns not equal or the array is exhausted.
+     *
+     * @param comparators  the comparators to use, not null or empty or containing nulls
+     * @return a {@link ComparatorChain} formed from the input comparators
+     * @throws NullPointerException if comparators array is null or contains a null
+     * @see ComparatorChain
+     */
+    public static <E extends Comparable<? super E>> Comparator<E> chainedComparator(Comparator<E>[]
comparators) {
+        ComparatorChain<E> chain = new ComparatorChain<E>();
+        for (int i = 0; i < comparators.length; i++) {
+            if (comparators[i] == null) {
+                throw new NullPointerException("Comparator cannot be null");
+            }
+            chain.addComparator(comparators[i]);
+        }
+        return chain;
+    }
+
+    /**
+     * Gets a comparator that compares using a collection of {@link Comparator}s,
+     * applied in (default iterator) sequence until one returns not equal or the 
+     * collection is exhausted.
+     *
+     * @param comparators  the comparators to use, not null or empty or containing nulls
+     * @return a {@link ComparatorChain} formed from the input comparators
+     * @throws NullPointerException if comparators collection is null or contains a null
+     * @throws ClassCastException if the comparators collection contains the wrong object
type
+     * @see ComparatorChain
+     */
+    @SuppressWarnings("unchecked")
+    public static <E extends Comparable<? super E>> Comparator<E> chainedComparator(Collection<Comparator<E>>
comparators) {
+        return chainedComparator(
+            (Comparator<E>[]) comparators.toArray(new Comparator[comparators.size()])
+        );
+    }
+
+    /**
+     * Gets a comparator that reverses the order of the given comparator.
+     *
+     * @param comparator  the comparator to reverse
+     * @return  a comparator that reverses the order of the input comparator
+     * @see ReverseComparator
+     */
+    public static <E> Comparator<E> reversedComparator(Comparator<E> comparator)
{
+        return new ReverseComparator<E>(comparator);
+    }
+
+    /**
+     * Gets a Comparator that controls the comparison of <code>null</code> values.
+     * <p>
+     * The returned comparator will consider a null value to be less than
+     * any nonnull value, and equal to any other null value.  Two nonnull
+     * values will be evaluated with the given comparator.
+     *
+     * @param comparator the comparator that wants to allow nulls
+     * @return  a version of that comparator that allows nulls
+     * @see NullComparator
+     */
+    @SuppressWarnings("unchecked")
+    public static <E> Comparator<E> nullLowComparator(Comparator<E> comparator)
{
+        if (comparator == null) {
+            comparator = NATURAL_COMPARATOR;
+        }
+        return new NullComparator<E>(comparator, false);
+    }
+
+    /**
+     * Gets a Comparator that controls the comparison of <code>null</code> values.
+     * <p>
+     * The returned comparator will consider a null value to be greater than
+     * any nonnull value, and equal to any other null value.  Two nonnull
+     * values will be evaluated with the given comparator.
+     *
+     * @param comparator the comparator that wants to allow nulls
+     * @return  a version of that comparator that allows nulls
+     * @see NullComparator
+     */
+    @SuppressWarnings("unchecked")
+    public static <E> Comparator<E> nullHighComparator(Comparator<E> comparator)
{
+        if (comparator == null) {
+            comparator = NATURAL_COMPARATOR;
+        }
+        return new NullComparator<E>(comparator, true);
+    }
+
+    /**
+     *  Returns the smaller of the given objects according to the given 
+     *  comparator, returning the second object if the comparator
+     *  returns equal.
+     * 
+     *  @param o1  the first object to compare
+     *  @param o2  the second object to compare
+     *  @param comparator  the sort order to use
+     *  @return  the smaller of the two objects
+     */
+    @SuppressWarnings("unchecked")
+    public static <E> E min(E o1, E o2, Comparator<E> comparator) {
+        if (comparator == null) {
+            comparator = NATURAL_COMPARATOR;
+        }
+        int c = comparator.compare(o1, o2);
+        return (c < 0) ? o1 : o2;
+    }
+
+    /**
+     *  Returns the larger of the given objects according to the given 
+     *  comparator, returning the second object if the comparator 
+     *  returns equal.
+     * 
+     *  @param o1  the first object to compare
+     *  @param o2  the second object to compare
+     *  @param comparator  the sort order to use
+     *  @return  the larger of the two objects
+     */
+    @SuppressWarnings("unchecked")
+    public static <E> E max(E o1, E o2, Comparator<E> comparator) {
+        if (comparator == null) {
+            comparator = NATURAL_COMPARATOR;
+        }
+        int c = comparator.compare(o1, o2);
+        return (c > 0) ? o1 : o2;
+    }
+    
+}

Propchange: commons/proper/lang/trunk/src/main/java/org/apache/commons/lang3/compare/ComparatorUtils.java
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    svn:eol-style = native



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