DoubleFunctionWithException.java
/**
* Powerunit - A JDK1.8 test framework
* Copyright (C) 2014 Mathieu Boretti.
*
* This file is part of Powerunit
*
* Powerunit is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* Powerunit is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with Powerunit. If not, see <http://www.gnu.org/licenses/>.
*/
package ch.powerunit.extensions.exceptions;
import static ch.powerunit.extensions.exceptions.Constants.verifyExceptionMapper;
import static ch.powerunit.extensions.exceptions.Constants.verifyFunction;
import java.util.Optional;
import java.util.concurrent.CompletionStage;
import java.util.function.DoubleFunction;
import java.util.function.Function;
import java.util.function.Supplier;
/**
* Represents a function that accepts a double-valued argument, may throw
* exception and produces a result. This is the {@code double}-consuming
* primitive specialization for {@link FunctionWithException}.
* <h3>General contract</h3>
* <ul>
* <li><b>{@link #apply(double) R apply(double value) throws
* E}</b> - The functional method.</li>
* <li><b>uncheck</b> - Return a {@code DoubleFunction<R>}</li>
* <li><b>lift</b> - Return a {@code DoubleFunction<Optional<R>>}</li>
* <li><b>ignore</b> - Return a {@code DoubleFunction<R>}</li>
* </ul>
*
* @see DoubleFunction
* @param <R>
* the type of the result of the function
* @param <E>
* the type of the potential exception of the function
*/
@FunctionalInterface
public interface DoubleFunctionWithException<R, E extends Exception> extends
ObjectReturnExceptionHandlerSupport<DoubleFunction<R>, DoubleFunction<Optional<R>>, DoubleFunction<CompletionStage<R>>, R, DoubleFunctionWithException<R, E>> {
/**
* Applies this function to the given argument.
*
* @param value
* the function argument
* @return the function result
* @throws E
* any exception
* @see DoubleFunction#apply(double)
*/
R apply(double value) throws E;
/**
* Converts this {@code DoubleFunctionWithException} to a {@code DoubleFunction}
* that wraps to {@code RuntimeException}.
*
* @return the unchecked function
* @see #unchecked(DoubleFunctionWithException)
* @see #unchecked(DoubleFunctionWithException, Function)
*/
@Override
default DoubleFunction<R> uncheck() {
return t -> ObjectReturnExceptionHandlerSupport.unchecked(() -> apply(t), throwingHandler());
}
/**
* Converts this {@code DoubleFunctionWithException} to a lifted
* {@code DoubleFunction} using {@code Optional} as return value.
*
* @return the lifted function
* @see #lifted(DoubleFunctionWithException)
*/
@Override
default DoubleFunction<Optional<R>> lift() {
return t -> ObjectReturnExceptionHandlerSupport.unchecked(() -> Optional.ofNullable(apply(t)),
notThrowingHandler());
}
/**
* Converts this {@code DoubleFunctionWithException} to a lifted
* {@code DoubleFunction} returning {@code null} (or the value redefined by the
* method {@link #defaultValue()}) in case of exception.
*
* @return the function that ignore error
* @see #ignored(DoubleFunctionWithException)
*/
@Override
default DoubleFunction<R> ignore() {
return t -> ObjectReturnExceptionHandlerSupport.unchecked(() -> apply(t), e -> defaultValue());
}
/**
* Convert this {@code DoubleFunctionWithException} to a lifted
* {@code DoubleFunction} returning {@code CompletionStage} as return value.
*
* @return the lifted function
* @see #staged(DoubleFunctionWithException)
*/
@Override
default DoubleFunction<CompletionStage<R>> stage() {
return t -> ObjectReturnExceptionHandlerSupport.staged(() -> apply(t));
}
/**
* Returns a function that always throw exception.
*
* @param exceptionBuilder
* the supplier to create the exception
* @param <R>
* the type of the result of the function
* @param <E>
* the type of the exception
* @return a function that always throw exception
*/
static <R, E extends Exception> DoubleFunctionWithException<R, E> failing(Supplier<E> exceptionBuilder) {
return t -> {
throw exceptionBuilder.get();
};
}
/**
* Converts a {@code DoubleFunctionWithException} to a {@code DoubleFunction}
* that wraps to {@code RuntimeException}.
*
* @param function
* to be unchecked
* @param <R>
* the type of the result of the function
* @param <E>
* the type of the potential exception
* @return the unchecked exception
* @see #uncheck()
* @see #unchecked(DoubleFunctionWithException, Function)
* @throws NullPointerException
* if function is null
*/
static <R, E extends Exception> DoubleFunction<R> unchecked(DoubleFunctionWithException<R, E> function) {
return verifyFunction(function).uncheck();
}
/**
* Converts a {@code DoubleFunctionWithException} to a {@code DoubleFunction}
* that wraps to {@code RuntimeException} by using the provided mapping
* function.
*
* @param function
* the be unchecked
* @param exceptionMapper
* a function to convert the exception to the runtime exception.
* @param <R>
* the type of the result of the function
* @param <E>
* the type of the potential exception
* @return the unchecked function
* @see #uncheck()
* @see #unchecked(DoubleFunctionWithException)
* @throws NullPointerException
* if function or exceptionMapper is null
*/
static <R, E extends Exception> DoubleFunction<R> unchecked(DoubleFunctionWithException<R, E> function,
Function<Exception, RuntimeException> exceptionMapper) {
verifyFunction(function);
verifyExceptionMapper(exceptionMapper);
return new DoubleFunctionWithException<R, E>() {
@Override
public R apply(double value) throws E {
return function.apply(value);
}
@Override
public Function<Exception, RuntimeException> exceptionMapper() {
return exceptionMapper;
}
}.uncheck();
}
/**
* Converts a {@code DoubleFunctionWithException} to a lifted
* {@code DoubleFunction} using {@code Optional} as return value.
*
* @param function
* to be lifted
* @param <R>
* the type of the result of the function
* @param <E>
* the type of the potential exception
* @return the lifted function
* @see #lift()
* @throws NullPointerException
* if function is null
*/
static <R, E extends Exception> DoubleFunction<Optional<R>> lifted(DoubleFunctionWithException<R, E> function) {
return verifyFunction(function).lift();
}
/**
* Converts a {@code DoubleFunctionWithException} to a lifted
* {@code DoubleFunction} returning {@code null} in case of exception.
*
* @param function
* to be lifted
* @param <R>
* the type of the result of the function
* @param <E>
* the type of the potential exception
* @return the lifted function
* @see #ignore()
* @throws NullPointerException
* if function is null
*/
static <R, E extends Exception> DoubleFunction<R> ignored(DoubleFunctionWithException<R, E> function) {
return verifyFunction(function).ignore();
}
/**
* Converts a {@code DoubleFunctionWithException} to a lifted
* {@code DoubleFunction} returning a default value in case of exception.
*
* @param function
* to be lifted
* @param defaultValue
* the default value in case of error.
* @param <R>
* the type of the result of the function
* @param <E>
* the type of the potential exception
* @return the lifted function
* @see #ignore()
* @see #ignored(DoubleFunctionWithException)
* @throws NullPointerException
* if function is null
* @since 3.0.0
*/
static <R, E extends Exception> DoubleFunction<R> ignored(DoubleFunctionWithException<R, E> function,
R defaultValue) {
verifyFunction(function);
return new DoubleFunctionWithException<R, E>() {
@Override
public R apply(double value) throws E {
return function.apply(value);
}
@Override
public R defaultValue() {
return defaultValue;
}
}.ignore();
}
/**
* Convert this {@code DoubleFunctionWithException} to a lifted
* {@code DoubleFunction} return {@code CompletionStage} as return value.
*
* @param function
* to be lifted
* @param <R>
* the type of the result of the function
* @param <E>
* the type of the potential exception
* @return the lifted function
* @see #stage()
* @throws NullPointerException
* if function is null
*/
static <R, E extends Exception> DoubleFunction<CompletionStage<R>> staged(
DoubleFunctionWithException<R, E> function) {
return verifyFunction(function).stage();
}
}