UnaryOperatorWithException.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.function.Function;
import java.util.function.Supplier;
import java.util.function.UnaryOperator;
/**
* Represents an operation on a single operand that produces a result of the
* same type as its operand. This is a specialization of
* {@code FunctionWithException} for the case where the operand and result are
* of the same type.
* <p>
* As this interface must return the same type of the input, a lifted version
* which returns {@code Optional} is not possible.
* <h3>General contract</h3>
* <ul>
* <li><b>{@link #apply(Object) T apply(T t) throws E}</b> - The
* functional method.</li>
* <li><b>uncheck</b> - Return a {@code UnaryOperator<T>}</li>
* <li><b>lift</b> - Return a {@code Function<T,Optional<T>}</li>
* <li><b>ignore</b> - Return a {@code UnaryOperator<T>}</li>
* </ul>
*
* @see FunctionWithException
* @see UnaryOperator
* @param <T>
* the type of the operand and result of the operator
*/
@FunctionalInterface
public interface UnaryOperatorWithException<T, E extends Exception> extends FunctionWithException<T, T, E> {
/**
* Converts this {@code UnaryOperatorWithException} to a {@code UnaryOperator}
* that wraps exception to {@code RuntimeException}.
*
* @return the unchecked function
* @see #unchecked(FunctionWithException)
* @see #unchecked(FunctionWithException, Function)
*/
@Override
default UnaryOperator<T> uncheck() {
return t -> ObjectReturnExceptionHandlerSupport.unchecked(() -> apply(t), throwingHandler());
}
/**
* Converts this {@code UnaryOperatorWithException} to a lifted
* {@code UnaryOperator} returning {@code null} in case of exception.
*
* @return the function that ignore error
* @see #ignored(FunctionWithException)
*/
@Override
default UnaryOperator<T> ignore() {
return t -> ObjectReturnExceptionHandlerSupport.unchecked(() -> apply(t), e -> null);
}
@Override
default UnaryOperatorWithException<T, E> documented(Supplier<String> toString) {
return (UnaryOperatorWithException<T, E>) FunctionWithException.super.documented(toString);
}
/**
* Returns a unary operator that always returns its input argument.
*
* @param <T>
* the type of the input and output of the operator
* @param <E>
* the type of the potential exception
* @return a unary operator that always returns its input argument
* @see Function#identity()
*/
static <T, E extends Exception> UnaryOperatorWithException<T, E> identity() {
return t -> t;
}
/**
* Returns a unary operator that always throw exception.
*
* @param exceptionBuilder
* the supplier to create the exception
* @param <T>
* the type of the input and output of the operator
* @param <E>
* the type of the exception
* @return a function that always throw exception
*/
static <T, E extends Exception> UnaryOperatorWithException<T, E> failing(Supplier<E> exceptionBuilder) {
return t -> {
throw exceptionBuilder.get();
};
}
/**
* Converts a {@code UnaryOperatorWithException} to a {@code UnaryOperator} that
* wraps exception to {@code RuntimeException}.
*
* @param function
* to be unchecked
* @param <T>
* the type of the input and output of the operator
* @param <E>
* the type of the potential exception
* @return the unchecked exception
* @see #uncheck()
* @see #unchecked(UnaryOperatorWithException, Function)
* @throws NullPointerException
* if function is null
*/
static <T, E extends Exception> UnaryOperator<T> unchecked(UnaryOperatorWithException<T, E> function) {
return verifyFunction(function).uncheck();
}
/**
* Converts a {@code UnaryOperatorWithException} to a {@code UnaryOperator} that
* wraps exception 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 <T>
* the type of the input and output of the operator
* @param <E>
* the type of the potential exception
* @return the unchecked exception
* @see #uncheck()
* @see #unchecked(UnaryOperatorWithException)
* @throws NullPointerException
* if function or exceptionMapper is null
*/
static <T, E extends Exception> UnaryOperator<T> unchecked(UnaryOperatorWithException<T, E> function,
Function<Exception, RuntimeException> exceptionMapper) {
verifyFunction(function);
verifyExceptionMapper(exceptionMapper);
return new UnaryOperatorWithException<T, E>() {
@Override
public T apply(T t) throws E {
return function.apply(t);
}
@Override
public Function<Exception, RuntimeException> exceptionMapper() {
return exceptionMapper;
}
}.uncheck();
}
/**
* Converts a {@code UnaryOperatorWithException} to a lifted {@code Function}
* returning {@code Optional}.
*
* @param function
* to be lifted
* @param <T>
* the type of the input and output of the operator
* @param <E>
* the type of the potential exception
* @return the lifted function
* @see #ignore()
* @throws NullPointerException
* if function is null
*/
static <T, E extends Exception> Function<T, Optional<T>> lifted(UnaryOperatorWithException<T, E> function) {
return verifyFunction(function).lift();
}
/**
* Converts a {@code UnaryOperatorWithException} to a lifted
* {@code UnaryOperator} returning {@code null} in case of exception.
*
* @param function
* to be lifted
* @param <T>
* the type of the input and output of the operator
* @param <E>
* the type of the potential exception
* @return the lifted function
* @see #ignore()
* @throws NullPointerException
* if function is null
*/
static <T, E extends Exception> UnaryOperator<T> ignored(UnaryOperatorWithException<T, E> function) {
return verifyFunction(function).ignore();
}
}