com.indeed.util.core.Pair Maven / Gradle / Ivy
package com.indeed.util.core;
import com.google.common.base.Function;
import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import java.io.Serializable;
import java.util.Comparator;
/**
* @author ahudson
*/
public class Pair implements Serializable {
private static final long serialVersionUID = -7675178028057823346L;
private final A a;
private final B b;
public Pair(A a, B b) {
this.a = a;
this.b = b;
}
public A getFirst() {
return a;
}
public B getSecond() {
return b;
}
@Override
public boolean equals(Object obj) {
if (obj instanceof Pair) {
Pair p = (Pair)obj;
Object a = p.getFirst();
Object b = p.getSecond();
return (a == null ? this.a == null : a.equals(this.a))
&& (b == null ? this.b == null : b.equals(this.b));
}
return false;
}
@Override
public int hashCode() {
int result;
result = (a != null ? a.hashCode() : 0);
result = 31 * result + (b != null ? b.hashCode() : 0);
return result;
}
@Override
public String toString() {
return "("+a+", "+b+")";
}
public static Pair of(T1 first, T2 second) {
return new Pair(first, second);
}
public static class FullPairComparator implements Comparator {
public int compare(Pair o1, Pair o2) {
int ret = ((Comparable)o1.a).compareTo(o2.a);
if (ret == 0) return ((Comparable)o1.b).compareTo(o2.b);
return ret;
}
}
public static class HalfPairComparator implements Comparator {
public int compare(Pair o1, Pair o2) {
return ((Comparable)o1.a).compareTo(o2.a);
}
}
/**
* Makes grabbing the first value out of a collection of Pairs a bit easier, e.g.
* given an iterable over Pair.of(String, ?) objects:
*
* ... = Iterables.transform(iterable, Pair.fst(String.class))
*
* @return a Function that returns null or the first value of the Pair, which also may be null
* @deprecated use {@link #fst()}.
*/
@Nonnull
@SuppressWarnings("UnusedParameters")
@Deprecated
public static Function, ? extends T1> fst(@Nonnull final Class clazz) {
return new First();
}
private static final class First implements Function, T1> {
@Nullable
@Override
public T1 apply(@Nullable Pair input) {
return input == null ? null : input.getFirst();
}
}
/**
* Makes grabbing the first value out of a collection of Pairs a bit easier, e.g.
* given an iterable over Pair.of(String, ?) objects:
*
* ... = Iterables.transform(iterable, Pair.fst())
*
* @return a Function that returns null or the first value of the Pair, which also may be null
*/
@Nonnull
public static Function, ? extends T> fst() {
return new Function, T>() {
@Nullable
@Override
public T apply(@Nullable Pair input) {
return input == null ? null : input.getFirst();
}
};
}
/**
* Makes grabbing the second value out of a collection of Pairs a bit easier, e.g.
* given an iterable over Pair.of(?, String) objects:
*
* ... = Iterables.transform(iterable, Pair.snd(String.class))
*
* @return a Function that returns null or the second value of the Pair, which also may be null
*/
@Nonnull
@SuppressWarnings("UnusedParameters")
@Deprecated
public static Function, ? extends T2> snd(@Nonnull final Class clazz) {
return new Second();
}
private static final class Second implements Function, T2> {
@Nullable
@Override
public T2 apply(@Nullable Pair input) {
return input == null ? null : input.getSecond();
}
}
/**
* Makes grabbing the second value out of a collection of Pairs a bit easier, e.g.
* given an iterable over Pair.of(?, String) objects:
*
* ... = Iterables.transform(iterable, Pair.snd())
*
* @return a Function that returns null or the second value of the Pair, which also may be null
*/
@Nonnull
public static Function, ? extends T> snd() {
return new Function, T>() {
@Nullable
@Override
public T apply(@Nullable Pair input) {
return input == null ? null : input.getSecond();
}
};
}
}