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/**
* Copyright 2015 Peter Nerg
*
* 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 javascalautils.concurrent;
import javascalautils.*;
/**
* Acts as a Scala type companion object for {@link Future}.
* The primary purpose is to get the Scala feel of instantiating classes.
* In Scala you can define a companion object for a class, acting as a static reference/singleton
* for that class allowing you do define factory methods.
* One use case is to define methods with the same name as the class and let these methods invoke
* the constructor thus creating a nice way to create instances without using the word "new".
* This can be achieved in java by statically importing a method and then using it.
* The limitation is that classes may not have method with the same name as the class itself hence
* new companion classes have to be created.
* To be able to use it in a neat concise way one needs to statically import the method.
*
*
*
*
* import static javascalautils.FutureCompanion.Future;
*
* Future<Integer> resultSuccess = Future(() -> 9 / 3); // The Future will at some point contain: Success(3)
* Future<Integer> resultFailure = Future(() -> 9 / 0); // The Future will at some point contain: Failure(ArithmeticException)
*
* //code that performs a side effect but has not return type can be written like this
* Future<Unit> f = Future(() -> {
* database.delete(someId);
* });
*
*
*
*
* @author Peter Nerg
* @since 1.3
*/
public final class FutureCompanion {
private FutureCompanion() {}
/**
* Allows for easy creation of asynchronous computations that will be executed in the future.
* The purpose is to allow the user to invoke a side-effecting function that may succeed/fail but
* has now return type.
* E.g. deleting something from a database may not have an interesting return type. One is only
* interested of the outcome, {@link Success}/{@link Failure}.
* The method relays the execution to {@link Future#apply(ThrowableFunction0)}.
* Best used in conjunction with statically importing this method.
*
*
*
*
* import static javascalautils.concurrent.FutureCompanion.Future;
*
* Future<Unit> t = Future(() -> {
* database.delete(someId);
* });
*
*
*
*
* @param function The function to render either the value T or raise an exception.
* @return The future that will hold either {@link Unit} or an exception.
* @since 1.9
* @see Future#apply(ThrowableFunction0)
*/
public static Future Future(VoidFunction0 function) {
return Future(
() -> {
function.apply();
return Unit.Instance;
});
}
/**
* Allows for easy creation of asynchronous computations that will be executed in the future.
* The purpose is to allow the user to invoke a side-effecting function that may succeed/fail but
* has now return type.
* E.g. deleting something from a database may not have an interesting return type. One is only
* interested of the outcome, {@link Success}/{@link Failure}.
* The method relays the execution to {@link Future#apply(ThrowableFunction0)}.
* Best used in conjunction with statically importing this method.
*
*
*
*
* import static javascalautils.concurrent.FutureCompanion.Future;
*
* Future<Unit> t = Future(() -> {
* database.delete(someId);
* }, someExecutor);
*
*
*
*
* @param function The function to render either the value T or raise an exception.
* @param executor The executor to use to compute/execute the Future holding the provided function
* @return The future that will hold either {@link Unit} or an exception.
* @since 1.9
* @see Future#apply(ThrowableFunction0)
*/
public static Future Future(VoidFunction0 function, Executor executor) {
return Future(
() -> {
function.apply();
return Unit.Instance;
},
executor);
}
/**
* Allows for easy creation of asynchronous computations that will be executed in the future.
* The method relays the execution to {@link Future#apply(ThrowableFunction0)}.
* Best used in conjunction with statically importing this method.
*
*
*
*
* import static javascalautils.concurrent.FutureCompanion.Future;
*
* Future<Integer> resultSuccess = Future(() -> 9 / 3); // The Future will at some point contain: Success(3)
* Future<Integer> resultFailure = Future(() -> 9 / 0); // The Future will at some point contain: Failure(ArithmeticException)
*
*
*
*
* @param The type for the Future
* @param function The function to render either the value T or raise an exception.
* @return The future that will hold the result provided by the function
* @since 1.3
* @see Future#apply(ThrowableFunction0)
*/
public static Future Future(ThrowableFunction0 function) {
return Future.apply(function);
}
/**
* Allows for easy creation of asynchronous computations that will be executed in the future.
* The method relays the execution to {@link Future#apply(ThrowableFunction0)}.
* Best used in conjunction with statically importing this method.
*
*
*
*
* import static javascalautils.concurrent.FutureCompanion.Future;
*
* Future<Integer> resultSuccess = Future(() -> 9 / 3, someExecutor); // The Future will at some point contain: Success(3)
* Future<Integer> resultFailure = Future(() -> 9 / 0, someExecutor); // The Future will at some point contain: Failure(ArithmeticException)
*
*
*
*
* @param The type for the Future
* @param function The function to render either the value T or raise an exception.
* @param executor The executor to use to compute/execute the Future holding the provided function
* @return The future that will hold the result provided by the function
* @since 1.4
* @see Future#apply(ThrowableFunction0, Executor)
*/
public static Future Future(ThrowableFunction0 function, Executor executor) {
return Future.apply(function, executor);
}
/**
* Allows for converting a blocking JDK {@link java.util.concurrent.Future Future} into a
* non-blocking future.
* This will use the default executor to wait/block on the provided future.
*
* @param The type for the Future
* @param future The blocking future
* @return The future that will hold the result provided by the future
* @since 1.5
*/
public static Future Future(java.util.concurrent.Future future) {
return Future.apply(() -> future.get());
}
/**
* Allows for converting a blocking JDK {@link java.util.concurrent.Future Future} into a
* non-blocking future.
*
* @param The type for the Future
* @param future The blocking future
* @param executor The executor to use to compute/execute the Future holding the provided function
* @return The future that will hold the result provided by the future
* @since 1.5
*/
public static Future Future(java.util.concurrent.Future future, Executor executor) {
return Future.apply(() -> future.get(), executor);
}
}