/*
* Copyright 2016 Adobe.
*
* 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.adobe.acs.commons.functions;
import aQute.bnd.annotation.ConsumerType;
/**
* Created work-alike for functionality not introduced until Java 8
* Represents a function that accepts one argument and produces a result.
*
* @param <T> the type of the input to the function
* @param <R> the type of the result of the function
*/
@ConsumerType
@Deprecated
public abstract class Function<T, R> implements CheckedFunction<T, R> {
/**
* 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 <V> 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(Function)
*/
public <V> Function<V, R> compose(final Function<? super V, ? extends T> before) {
return adapt(compose((CheckedFunction) before));
}
/**
* 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 <V> 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(Function)
*/
public <V> Function<T, V> andThen(final Function<? super R, ? extends V> after) {
return adapt(compose((CheckedFunction) after));
}
/**
* Returns a function that always returns its input argument.
*
* @param <T> the type of the input and output objects to the function
* @return a function that always returns its input argument
*/
public static <T> Function<T, T> identity() {
return adapt(CheckedFunction.identity());
}
public static <X, Y> Function<X, Y> adapt(CheckedFunction<X, Y> delegate) {
return new Adapter<>(delegate);
}
private static class Adapter<T, R> extends Function<T, R> {
final private CheckedFunction<T, R> delegate;
public Adapter(CheckedFunction<T, R> delegate) {
this.delegate = delegate;
}
@Override
public R apply(T t) throws Exception {
return delegate.apply(t);
}
}
}