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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.commons.lang3.tuple;
import java.io.Serializable;
import java.util.Objects;
import org.apache.commons.lang3.builder.CompareToBuilder;
/**
* A triple consisting of three elements.
*
* This class is an abstract implementation defining the basic API.
* It refers to the elements as 'left', 'middle' and 'right'.
*
* 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.
*
* @param the left element type
* @param the middle element type
* @param the right element type
*
* @since 3.2
*/
public abstract class Triple implements Comparable>, Serializable {
private static final class TripleAdapter extends Triple {
private static final long serialVersionUID = 1L;
@Override
public L getLeft() {
return null;
}
@Override
public M getMiddle() {
return null;
}
@Override
public R getRight() {
return null;
}
}
/** Serialization version */
private static final long serialVersionUID = 1L;
/**
* An empty array.
*
* Consider using {@link #emptyArray()} to avoid generics warnings.
*
*
* @since 3.10.
*/
public static final Triple[] EMPTY_ARRAY = new TripleAdapter[0];
/**
* Returns the empty array singleton that can be assigned without compiler warning.
*
* @param the left element type
* @param the middle element type
* @param the right element type
* @return the empty array singleton that can be assigned without compiler warning.
*
* @since 3.10.
*/
@SuppressWarnings("unchecked")
public static Triple[] emptyArray() {
return (Triple[]) EMPTY_ARRAY;
}
/**
* Obtains an immutable triple of three objects inferring the generic types.
*
* This factory allows the triple to be created using inference to
* obtain the generic types.
*
* @param the left element type
* @param the middle element type
* @param 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 Triple of(final L left, final M middle, final R right) {
return new ImmutableTriple<>(left, middle, right);
}
//-----------------------------------------------------------------------
/**
* Compares the triple based on the left element, followed by the middle element,
* finally the right element.
* The types must be {@code Comparable}.
*
* @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 other) {
return new CompareToBuilder().append(getLeft(), other.getLeft())
.append(getMiddle(), other.getMiddle())
.append(getRight(), other.getRight()).toComparison();
}
/**
* Compares this triple to another based on the three elements.
*
* @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 Objects.equals(getLeft(), other.getLeft())
&& Objects.equals(getMiddle(), other.getMiddle())
&& Objects.equals(getRight(), other.getRight());
}
return false;
}
//-----------------------------------------------------------------------
/**
* Gets the left element from this triple.
*
* @return the left element, may be null
*/
public abstract L getLeft();
/**
* Gets the middle element from this triple.
*
* @return the middle element, may be null
*/
public abstract M getMiddle();
/**
* Gets the right element from this triple.
*
* @return the right element, may be null
*/
public abstract R getRight();
/**
* Returns a suitable hash code.
*
* @return the hash code
*/
@Override
public int hashCode() {
return Objects.hashCode(getLeft()) ^ Objects.hashCode(getMiddle()) ^ Objects.hashCode(getRight());
}
/**
* Returns a String representation of this triple using the format {@code ($left,$middle,$right)}.
*
* @return a string describing this object, not null
*/
@Override
public String toString() {
return "(" + getLeft() + "," + getMiddle() + "," + getRight() + ")";
}
/**
* Formats the receiver using the given format.
*
* This uses {@link java.util.Formattable} to perform the formatting. Three variables may
* be used to embed the left and right elements. Use {@code %1$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$s)}.
*
* @param format the format string, optionally containing {@code %1$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());
}
}