/*
* 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.tuple;
import java.io.Serializable;
import org.apache.commons.lang3.ObjectUtils;
import org.apache.commons.lang3.builder.CompareToBuilder;
/**
* <p>A triple consisting of three elements.</p>
*
* <p>This class is an abstract implementation defining the basic API.
* It refers to the elements as 'left', 'middle' and 'right'.</p>
*
* <p>Subclass implementations may be mutable or immutable.
* However, there is no restriction on the type of the stored objects that may be stored.
* If mutable objects are stored in the triple, then the triple itself effectively becomes mutable.</p>
*
* @param <L> the left element type
* @param <M> the middle element type
* @param <R> the right element type
*
* @version $Id: Triple.java 1552635 2013-12-20 13:02:03Z britter $
* @since 3.2
*/
public abstract class Triple<L, M, R> implements Comparable<Triple<L, M, R>>, Serializable {
/** Serialization version */
private static final long serialVersionUID = 1L;
/**
* <p>Obtains an immutable triple of from three objects inferring the generic types.</p>
*
* <p>This factory allows the triple to be created using inference to
* obtain the generic types.</p>
*
* @param <L> the left element type
* @param <M> the middle element type
* @param <R> the right element type
* @param left the left element, may be null
* @param middle the middle element, may be null
* @param right the right element, may be null
* @return a triple formed from the three parameters, not null
*/
public static <L, M, R> Triple<L, M, R> of(final L left, final M middle, final R right) {
return new ImmutableTriple<L, M, R>(left, middle, right);
}
//-----------------------------------------------------------------------
/**
* <p>Gets the left element from this triple.</p>
*
* @return the left element, may be null
*/
public abstract L getLeft();
/**
* <p>Gets the middle element from this triple.</p>
*
* @return the middle element, may be null
*/
public abstract M getMiddle();
/**
* <p>Gets the right element from this triple.</p>
*
* @return the right element, may be null
*/
public abstract R getRight();
//-----------------------------------------------------------------------
/**
* <p>Compares the triple based on the left element, followed by the middle element,
* finally the right element.
* The types must be {@code Comparable}.</p>
*
* @param other the other triple, not null
* @return negative if this is less, zero if equal, positive if greater
*/
@Override
public int compareTo(final Triple<L, M, R> other) {
return new CompareToBuilder().append(getLeft(), other.getLeft())
.append(getMiddle(), other.getMiddle())
.append(getRight(), other.getRight()).toComparison();
}
/**
* <p>Compares this triple to another based on the three elements.</p>
*
* @param obj the object to compare to, null returns false
* @return true if the elements of the triple are equal
*/
@Override
public boolean equals(final Object obj) {
if (obj == this) {
return true;
}
if (obj instanceof Triple<?, ?, ?>) {
final Triple<?, ?, ?> other = (Triple<?, ?, ?>) obj;
return ObjectUtils.equals(getLeft(), other.getLeft())
&& ObjectUtils.equals(getMiddle(), other.getMiddle())
&& ObjectUtils.equals(getRight(), other.getRight());
}
return false;
}
/**
* <p>Returns a suitable hash code.</p>
*
* @return the hash code
*/
@Override
public int hashCode() {
return (getLeft() == null ? 0 : getLeft().hashCode()) ^
(getMiddle() == null ? 0 : getMiddle().hashCode()) ^
(getRight() == null ? 0 : getRight().hashCode());
}
/**
* <p>Returns a String representation of this triple using the format {@code ($left,$middle,$right)}.</p>
*
* @return a string describing this object, not null
*/
@Override
public String toString() {
return new StringBuilder().append('(').append(getLeft()).append(',').append(getMiddle()).append(',')
.append(getRight()).append(')').toString();
}
/**
* <p>Formats the receiver using the given format.</p>
*
* <p>This uses {@link java.util.Formattable} to perform the formatting. Three variables may
* be used to embed the left and right elements. Use {@code %1$s} for the left
* element, {@code %2$s} for the middle and {@code %3$s} for the right element.
* The default format used by {@code toString()} is {@code (%1$s,%2$s,%3$s)}.</p>
*
* @param format the format string, optionally containing {@code %1$s}, {@code %2$s} and {@code %3$s}, not null
* @return the formatted string, not null
*/
public String toString(final String format) {
return String.format(format, getLeft(), getMiddle(), getRight());
}
}