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/*
* Copyright (C) 2019 The Android Open Source Project
*
* 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.android.testutils;
import java.util.function.Supplier;
/**
* A class grouping some utilities to deal with exceptions.
*/
public class FunctionalUtils {
/**
* Like a Consumer, but declared to throw an exception.
* @param <T>
*/
@FunctionalInterface
public interface ThrowingConsumer<T> {
/** @see java.util.function.Consumer */
void accept(T t) throws Exception;
}
/**
* Like a Supplier, but declared to throw an exception.
* @param <T>
*/
@FunctionalInterface
public interface ThrowingSupplier<T> {
/** @see java.util.function.Supplier */
T get() throws Exception;
}
/**
* Like a Runnable, but declared to throw an exception.
*/
@FunctionalInterface
public interface ThrowingRunnable {
/** @see java.lang.Runnable */
void run() throws Exception;
}
/**
* Convert a supplier that throws into one that doesn't.
*
* The returned supplier returns null in cases where the source throws.
*/
public static <T> Supplier<T> ignoreExceptions(ThrowingSupplier<T> func) {
return () -> {
try {
return func.get();
} catch (Exception e) {
return null;
}
};
}
/**
* Convert a runnable that throws into one that doesn't.
*
* All exceptions are ignored by the returned Runnable.
*/
public static Runnable ignoreExceptions(ThrowingRunnable r) {
return () -> {
try {
r.run();
} catch (Exception e) {
}
};
}
// Java has Function<T, R> and BiFunction<T, U, V> but nothing for higher-arity functions.
// Function3 is what Kotlin and Scala use (they also have higher-arity variants, with
// FunctionN taking N arguments, as the JVM does not have variadic formal parameters)
/**
* A function with three arguments.
* @param <TArg1> Type of the first argument
* @param <TArg2> Type of the second argument
* @param <TArg3> Type of the third argument
* @param <TResult> Type of the return value
*/
public interface Function3<TArg1, TArg2, TArg3, TResult> {
/**
* Apply the function to the arguments
*/
TResult apply(TArg1 a1, TArg2 a2, TArg3 a3);
}
}
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