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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.util.Objects;
/**
* An immutable triple consisting of three {@link Object} elements.
*
* <p>Although the implementation is immutable, there is no restriction on the objects
* that may be stored. If mutable objects are stored in the triple, then the triple
* itself effectively becomes mutable. The class is also {@code final}, so a subclass
* can not add undesirable behavior.</p>
*
* <p>#ThreadSafe# if all three objects are thread-safe</p>
*
* @param <L> the left element type
* @param <M> the middle element type
* @param <R> the right element type
*
* @since 3.2
*/
public class ImmutableTriple<L, M, R> extends Triple<L, M, R> {
/**
* An empty array.
* <p>
* Consider using {@link #emptyArray()} to avoid generics warnings.
* </p>
*
* @since 3.10.
*/
public static final ImmutableTriple<?, ?, ?>[] EMPTY_ARRAY = {};
/**
* An immutable triple of nulls.
*/
// This is not defined with generics to avoid warnings in call sites.
@SuppressWarnings("rawtypes")
private static final ImmutableTriple NULL = new ImmutableTriple<>(null, null, null);
/** Serialization version */
private static final long serialVersionUID = 1L;
/**
* Returns the empty array singleton that can be assigned without compiler warning.
*
* @param <L> the left element type
* @param <M> the middle element type
* @param <R> the right element type
* @return the empty array singleton that can be assigned without compiler warning.
*
* @since 3.10.
*/
@SuppressWarnings("unchecked")
public static <L, M, R> ImmutableTriple<L, M, R>[] emptyArray() {
return (ImmutableTriple<L, M, R>[]) EMPTY_ARRAY;
}
/**
* Returns an immutable triple of nulls.
*
* @param <L> the left element of this triple. Value is {@code null}.
* @param <M> the middle element of this triple. Value is {@code null}.
* @param <R> the right element of this triple. Value is {@code null}.
* @return an immutable triple of nulls.
* @since 3.6
*/
public static <L, M, R> ImmutableTriple<L, M, R> nullTriple() {
return NULL;
}
/**
* Obtains an immutable triple of three objects inferring the generic types.
*
* <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> ImmutableTriple<L, M, R> of(final L left, final M middle, final R right) {
return left != null | middle != null || right != null ? new ImmutableTriple<>(left, middle, right) : nullTriple();
}
/**
* Obtains an immutable triple of three non-null objects inferring the generic types.
*
* <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 not be null
* @param middle the middle element, may not be null
* @param right the right element, may not be null
* @return a triple formed from the three parameters, not null
* @throws NullPointerException if any input is null
* @since 3.13.0
*/
public static <L, M, R> ImmutableTriple<L, M, R> ofNonNull(final L left, final M middle, final R right) {
return of(Objects.requireNonNull(left, "left"), Objects.requireNonNull(middle, "middle"), Objects.requireNonNull(right, "right"));
}
/** Left object */
public final L left;
/** Middle object */
public final M middle;
/** Right object */
public final R right;
/**
* Create a new triple instance.
*
* @param left the left value, may be null
* @param middle the middle value, may be null
* @param right the right value, may be null
*/
public ImmutableTriple(final L left, final M middle, final R right) {
this.left = left;
this.middle = middle;
this.right = right;
}
/**
* {@inheritDoc}
*/
@Override
public L getLeft() {
return left;
}
/**
* {@inheritDoc}
*/
@Override
public M getMiddle() {
return middle;
}
/**
* {@inheritDoc}
*/
@Override
public R getRight() {
return right;
}
}
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