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/*
* (c) Copyright 2018 Palantir Technologies Inc. All rights reserved.
*
* 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 com.palantir.util;
import com.google.common.base.Function;
import com.google.common.collect.Ordering;
import com.palantir.common.annotation.LongTermSerialized;
import java.io.Serializable;
import java.util.Comparator;
import javax.annotation.concurrent.Immutable;
/**
* A generic class for handling pairs of things.
* @author cfreeland
* In general, it is good practice to make a usefully named class that holds the two
* things you care about. Typically, you'll find soon after you use this class that you
* really need to put 3 things in this "pair" anyways.
*/
@Immutable
@LongTermSerialized
public final class Pair implements Serializable {
private static final long serialVersionUID = 1L;
/**
* The left-hand side, or first, object
* in the Pair.
* @see #getLhSide()
*/
public final V lhSide;
/**
* The right-hand side, or second, object
* in the Pair.
*/
public final W rhSide;
/**
* Creates a new instance of Pair
* with the left and right side set to the provided objects.
* @param lh the object that will be the lhSide object.
* @param rh the object that will be the rhSide object.
*/
public Pair(V lh, W rh) {
lhSide = lh;
rhSide = rh;
}
/**
* Creates a new instance of Pair
* with both sides of the pair set to null.
*/
public Pair() {
this(null, null);
}
/**
* Returns the left-hand side, or first, object
* of the pair.
*/
public V getLhSide() {
return lhSide;
}
/**
* Returns the right-hand side, or second, object
* of the pair.
*/
public W getRhSide() {
return rhSide;
}
/**
* Returns a pair with the left and right reversed.
*/
public Pair getReversed() {
return create(rhSide, lhSide);
}
/**
* Returns a String representation of
* both items in the pair, left side first.
*/
@Override
public String toString() {
StringBuilder out = new StringBuilder("Pair(");
out.append(lhSide).append(", ").append(rhSide).append(")");
return out.toString();
}
/**
* Returns a hash code of the Pair's values.
*/
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + ((lhSide == null) ? 0 : lhSide.hashCode());
result = prime * result + ((rhSide == null) ? 0 : rhSide.hashCode());
return result;
}
/**
* Returns true if this Pair
* is equal to the given object.
*/
@Override
public boolean equals(Object obj) {
if (this == obj) {
return true;
}
if (obj == null) {
return false;
}
if (getClass() != obj.getClass()) {
return false;
}
Pair other = (Pair) obj;
if (lhSide == null) {
if (other.lhSide != null) {
return false;
}
} else if (!lhSide.equals(other.lhSide)) {
return false;
}
if (rhSide == null) {
if (other.rhSide != null) {
return false;
}
} else if (!rhSide.equals(other.rhSide)) {
return false;
}
return true;
}
/**
* Returns a new Pair instance
* with the given left-side and right-side objects.
*/
public static Pair create(V v, W w) {
return new Pair(v, w);
}
/**
* Return a new Pair with the left hand side set to the passed value.
*/
public Pair withLhSide(T newLhSide) {
return Pair.create(newLhSide, rhSide);
}
/**
* Returns a new Pair with the right hand side set to the passed value.
*/
public Pair withRhSide(T newRhSide) {
return Pair.create(lhSide, newRhSide);
}
/**
* Returns a Comparator for the
* left-hand side object of the Pair.
*/
public static , V> Ordering> compareLhSide() {
return new Ordering>() {
@Override
public int compare(Pair o1, Pair o2) {
return o1.lhSide.compareTo(o2.lhSide);
}
};
}
/**
* Returns a Comparator for the
* right-hand side object of the Pair.
*/
public static > Ordering> compareRhSide() {
return new Ordering>() {
@Override
public int compare(Pair o1, Pair o2) {
return o1.rhSide.compareTo(o2.rhSide);
}
};
}
/**
* Returns a Comparator for the
* left-hand side object of the Pair.
*/
public static Ordering> compareLhSide(final Comparator comp) {
return new Ordering>() {
@Override
public int compare(Pair o1, Pair o2) {
return comp.compare(o1.lhSide, o2.lhSide);
}
};
}
/**
* Returns a Comparator for the
* right-hand side object of the Pair.
*/
public static Ordering> compareRhSide(final Comparator comp) {
return new Ordering>() {
@Override
public int compare(Pair o1, Pair o2) {
return comp.compare(o1.rhSide, o2.rhSide);
}
};
}
public static Function, L> getLeftFunc() {
return from -> from.lhSide;
}
public static Function, R> getRightFunc() {
return from -> from.rhSide;
}
}