dk.cloudcreate.essentials.shared.functional.tuple.Pair Maven / Gradle / Ivy
/*
* Copyright 2021-2024 the original author or authors.
*
* 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
*
* https://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 dk.cloudcreate.essentials.shared.functional.tuple;
import java.util.*;
import java.util.function.*;
import static dk.cloudcreate.essentials.shared.FailFast.requireNonNull;
/**
* Represents a {@link Tuple} with two elements.
* Note: {@link Pair} supports {@link #equals(Object)} comparison using subclasses, e.g.:
* {@code
* public class LeftAndRightSide extends Pair {
*
* public LeftAndRightSide(String leftSide, String rightSide) {
* super(leftSide, rightSide);
* }
* }
* }
*
* @param the first element type
* @param the second element type
*/
public class Pair implements Tuple> {
/**
* The first element in this tuple
*/
public final T1 _1;
/**
* The second element in this tuple
*/
public final T2 _2;
/**
* Construct a new {@link Tuple} with 2 elements
*
* @param t1 the first element
* @param t2 the second element
*/
public Pair(T1 t1, T2 t2) {
this._1 = t1;
this._2 = t2;
}
/**
* Create a new {@link Tuple} with 2 elements
*
* @param t1 the first element
* @param t2 the second element
*/
public static Pair of(T1 t1, T2 t2) {
return new Pair<>(t1, t2);
}
@Override
public int arity() {
return 2;
}
@Override
public List toList() {
return List.of(_1, _2);
}
/**
* The first element in this tuple
*
* @return The first element in this tuple
*/
public T1 _1() {
return _1;
}
/**
* The second element in this tuple
*
* @return The second element in this tuple
*/
public T2 _2() {
return _2;
}
/**
* Swap the elements of this {@link Pair}
*
* @return A new {@link Pair} where the first element is the second element of this {@link Pair} AND
* where the second element is the first element of this {@link Pair}
*/
public Pair swap() {
return Tuple.of(_2, _1);
}
/**
* Converts the {@link Pair} to a {@link Map} {@link java.util.Map.Entry}
*
* @return a {@link java.util.Map.Entry} where the key is the first element of this {@link Pair}
* and the value is the second element of this {@link Pair}
*/
public Map.Entry toEntry() {
return new AbstractMap.SimpleEntry<>(_1, _2);
}
/**
* Maps the elements of this {@link Pair} using the mapping function
*
* @param mappingFunction the mapping function
* @param result type for first element of the {@link Pair} after applying the mapping function
* @param result type for second element of the {@link Pair} after applying the mapping function
* @return a new {@link Pair} with the result of applying the mapping function to this {@link Pair}
*/
public Pair map(BiFunction> mappingFunction) {
requireNonNull(mappingFunction, "You must supply a mapping function");
return mappingFunction.apply(_1, _2);
}
/**
* Maps the elements of this {@link Pair} using two distinct mapping functions
*
* @param mappingFunction1 the mapping function for element number 1
* @param mappingFunction2 the mapping function for element number 2
* @param result type for first element of the {@link Pair} after applying the mapping function
* @param result type for second element of the {@link Pair} after applying the mapping function
* @return a new {@link Pair} with the result of applying the mapping function to this {@link Pair}
*/
@SuppressWarnings("unchecked")
public Pair map(Function mappingFunction1,
Function mappingFunction2) {
requireNonNull(mappingFunction1, "You must supply a mappingFunction1");
requireNonNull(mappingFunction2, "You must supply a mappingFunction2");
R1 r1 = (R1) mappingFunction1.apply(_1);
R2 r2 = (R2) mappingFunction2.apply(_2);
return Tuple.of(r1,
r2);
}
/**
* Map the first element of this {@link Pair} using the mapping function
*
* @param mappingFunction1 the mapping function for element number 1
* @param result type for first element of the {@link Pair} after applying the mapping function
* @return a new {@link Pair} with the result of applying the mapping function to the first element of this {@link Pair}
*/
@SuppressWarnings("unchecked")
public Pair map1(Function mappingFunction1) {
requireNonNull(mappingFunction1, "You must supply a mappingFunction1");
R1 r1 = (R1) mappingFunction1.apply(_1);
return Tuple.of(r1,
_2);
}
/**
* Map the second element of this {@link Pair} using the mapping function
*
* @param mappingFunction2 the mapping function for element number 2
* @param result type for second element of the {@link Pair} after applying the mapping function
* @return a new {@link Pair} with the result of applying the mapping function to the second element of this {@link Pair}
*/
@SuppressWarnings("unchecked")
public Pair map2(Function mappingFunction2) {
requireNonNull(mappingFunction2, "You must supply a mappingFunction2");
R2 r2 = (R2) mappingFunction2.apply(_2);
return Tuple.of(_1,
r2);
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (!(o instanceof Pair)) return false;
var pair = (Pair) o;
return Objects.equals(_1, pair._1) && Objects.equals(_2, pair._2);
}
@Override
public int hashCode() {
return Objects.hash(_1, _2);
}
@Override
public String toString() {
return "(" + _1 + ", " + _2 + ")";
}
}
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