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/*
 * Copyright (C) 2003-2017 Paolo Boldi and Sebastiano Vigna
 *
 * 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 PACKAGE;

#if KEYS_REFERENCE
import java.util.Comparator;
#endif

/** A class providing static methods and objects that do useful things with comparators.
 */

public class COMPARATORS {

	private COMPARATORS() {}

	/** A type-specific comparator mimicking the natural order. */
#if KEYS_REFERENCE
	SUPPRESS_WARNINGS_KEY_UNCHECKED_RAWTYPES
	protected static class NaturalImplicitComparator implements Comparator, java.io.Serializable {
#else
	protected static class NaturalImplicitComparator extends KEY_ABSTRACT_COMPARATOR KEY_GENERIC implements java.io.Serializable {
#endif
		private static final long serialVersionUID = 1L;

		@Override
		public final int compare(final KEY_TYPE a, final KEY_TYPE b) {
#if KEYS_PRIMITIVE
			return KEY_CMP(a, b);
#else
			return ((Comparable)a).compareTo(b);
#endif
		}
		private Object readResolve() { return NATURAL_COMPARATOR; }
	};

	SUPPRESS_WARNINGS_KEY_RAWTYPES
	public static final KEY_COMPARATOR NATURAL_COMPARATOR = new NaturalImplicitComparator();

	/** A type-specific comparator mimicking the opposite of the natural order. */
#if KEYS_REFERENCE
	SUPPRESS_WARNINGS_KEY_UNCHECKED_RAWTYPES
	protected static class OppositeImplicitComparator implements Comparator, java.io.Serializable {
#else
	protected static class OppositeImplicitComparator extends KEY_ABSTRACT_COMPARATOR KEY_GENERIC implements java.io.Serializable {
#endif
		private static final long serialVersionUID = 1L;

		@Override
		public final int compare(final KEY_TYPE a, final KEY_TYPE b) {
#if KEYS_PRIMITIVE
			return - KEY_CMP(a, b);
#else
			return ((Comparable)b).compareTo(a);
#endif
		}
		private Object readResolve() { return OPPOSITE_COMPARATOR; }
	};

	SUPPRESS_WARNINGS_KEY_RAWTYPES
	public static final KEY_COMPARATOR OPPOSITE_COMPARATOR = new OppositeImplicitComparator();


#if KEYS_REFERENCE
	protected static class OppositeComparator KEY_GENERIC implements Comparator KEY_GENERIC, java.io.Serializable {
#else
	protected static class OppositeComparator KEY_GENERIC extends KEY_ABSTRACT_COMPARATOR KEY_GENERIC implements java.io.Serializable {
#endif
		private static final long serialVersionUID = 1L;

		private final KEY_COMPARATOR KEY_GENERIC comparator;

		protected OppositeComparator(final KEY_COMPARATOR KEY_GENERIC c) {
			comparator = c;
		}

		@Override
		public final int compare(final KEY_GENERIC_TYPE a, final KEY_GENERIC_TYPE b) {
			return comparator.compare(b, a);
		}
	};

	/** Returns a comparator representing the opposite order of the given comparator.
	 *
	 * @param c a comparator.
	 * @return a comparator representing the opposite order of c.
	 */
	public static KEY_GENERIC KEY_COMPARATOR KEY_GENERIC oppositeComparator(final KEY_COMPARATOR KEY_GENERIC c) {
		return new OppositeComparator KEY_GENERIC (c);
	}
}