manifold.ext.rt.api.IndexedFunction Maven / Gradle / Ivy
/*
* Copyright (c) 2020 - Manifold Systems LLC
*
* 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 manifold.ext.rt.api;
import java.util.Objects;
/**
* Represents a function that accepts an argument and an index for the argument and produces a result.
*
* This is a functional interface
* whose functional method is {@link #apply(int, Object)}.
*
* @param the type of the input to the function
* @param the type of the result of the function
*
*/
@FunctionalInterface
public interface IndexedFunction {
/**
* Applies this function to the given argument.
*
* @param index the index of [t]
* @param t the function argument
* @return the function result
*/
R apply(int index, T t);
/**
* Returns a composed function that first applies the {@code before}
* function to its input, and then applies this function to the result.
* If evaluation of either function throws an exception, it is relayed to
* the caller of the composed function.
*
* @param the type of input to the {@code before} function, and to the
* composed function
* @param before the function to apply before this function is applied
* @return a composed function that first applies the {@code before}
* function and then applies this function
* @throws NullPointerException if before is null
*
* @see #andThen(IndexedFunction)
*/
default IndexedFunction compose( IndexedFunction before) {
Objects.requireNonNull( before);
return (int index, V v) -> apply(index, before.apply(index, v));
}
/**
* Returns a composed function that first applies this function to
* its input, and then applies the {@code after} function to the result.
* If evaluation of either function throws an exception, it is relayed to
* the caller of the composed function.
*
* @param the type of output of the {@code after} function, and of the
* composed function
* @param after the function to apply after this function is applied
* @return a composed function that first applies this function and then
* applies the {@code after} function
* @throws NullPointerException if after is null
*
* @see #compose(IndexedFunction)
*/
default IndexedFunction andThen( IndexedFunction after) {
Objects.requireNonNull(after);
return (int index, T t) -> after.apply(index, apply(index, t));
}
/**
* Returns a function that always returns its input argument.
*
* @param the type of the input and output objects to the function
* @return a function that always returns its input argument
*/
static IndexedFunction identity() {
return (i, t) -> t;
}
}