Functions.java
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 org.apache.commons.lang3;
import java.io.IOException;
import java.io.UncheckedIOException;
import java.lang.reflect.UndeclaredThrowableException;
import java.util.Arrays;
import java.util.Collection;
import java.util.Objects;
import java.util.concurrent.Callable;
import java.util.function.BiConsumer;
import java.util.function.BiFunction;
import java.util.function.BiPredicate;
import java.util.function.Consumer;
import java.util.function.Function;
import java.util.function.Predicate;
import java.util.function.Supplier;
import java.util.stream.Stream;
import org.apache.commons.lang3.Streams.FailableStream;
import org.apache.commons.lang3.exception.ExceptionUtils;
import org.apache.commons.lang3.function.Failable;
import org.apache.commons.lang3.function.FailableBooleanSupplier;
/**
* This class provides utility functions, and classes for working with the {@code java.util.function} package, or more
* generally, with Java 8 lambdas. More specifically, it attempts to address the fact that lambdas are supposed not to
* throw Exceptions, at least not checked Exceptions, AKA instances of {@link Exception}. This enforces the use of
* constructs like:
*
* <pre>
* {@code
* Consumer<java.lang.reflect.Method> consumer = m -> {
* try {
* m.invoke(o, args);
* } catch (Throwable t) {
* throw Functions.rethrow(t);
* }
* };
* }</pre>
*
* <p>
* By replacing a {@link java.util.function.Consumer Consumer<O>} with a {@link FailableConsumer
* FailableConsumer<O,? extends Throwable>}, this can be written like follows:
* </p>
*
* <pre>
* {@code
* Functions.accept((m) -> m.invoke(o,args));
* }</pre>
*
* <p>
* Obviously, the second version is much more concise and the spirit of Lambda expressions is met better than the second
* version.
* </p>
* @since 3.9
* @deprecated Use {@link org.apache.commons.lang3.function.Failable}.
*/
@Deprecated
public class Functions {
/**
* A functional interface like {@link BiConsumer} that declares a {@link Throwable}.
*
* <p>TODO for 4.0: Move to org.apache.commons.lang3.function.</p>
*
* @param <O1> Consumed type 1.
* @param <O2> Consumed type 2.
* @param <T> Thrown exception.
* @deprecated Use {@link org.apache.commons.lang3.function.FailableBiConsumer}.
*/
@Deprecated
@FunctionalInterface
public interface FailableBiConsumer<O1, O2, T extends Throwable> {
/**
* Accepts the consumer.
*
* @param object1 the first parameter for the consumable to accept
* @param object2 the second parameter for the consumable to accept
* @throws T Thrown when the consumer fails.
*/
void accept(O1 object1, O2 object2) throws T;
}
/**
* A functional interface like {@link BiFunction} that declares a {@link Throwable}.
*
* <p>TODO for 4.0: Move to org.apache.commons.lang3.function.</p>
*
* @param <O1> Input type 1.
* @param <O2> Input type 2.
* @param <R> Return type.
* @param <T> Thrown exception.
* @deprecated Use {@link org.apache.commons.lang3.function.FailableBiFunction}.
*/
@Deprecated
@FunctionalInterface
public interface FailableBiFunction<O1, O2, R, T extends Throwable> {
/**
* Applies this function.
*
* @param input1 the first input for the function
* @param input2 the second input for the function
* @return the result of the function
* @throws T Thrown when the function fails.
*/
R apply(O1 input1, O2 input2) throws T;
}
/**
* A functional interface like {@link BiPredicate} that declares a {@link Throwable}.
*
* <p>TODO for 4.0: Move to org.apache.commons.lang3.function.</p>
*
* @param <O1> Predicate type 1.
* @param <O2> Predicate type 2.
* @param <T> Thrown exception.
* @deprecated Use {@link org.apache.commons.lang3.function.FailableBiPredicate}.
*/
@Deprecated
@FunctionalInterface
public interface FailableBiPredicate<O1, O2, T extends Throwable> {
/**
* Tests the predicate.
*
* @param object1 the first object to test the predicate on
* @param object2 the second object to test the predicate on
* @return the predicate's evaluation
* @throws T if the predicate fails
*/
boolean test(O1 object1, O2 object2) throws T;
}
/**
* A functional interface like {@link java.util.concurrent.Callable} that declares a {@link Throwable}.
*
* <p>TODO for 4.0: Move to org.apache.commons.lang3.function.</p>
*
* @param <R> Return type.
* @param <T> Thrown exception.
* @deprecated Use {@link org.apache.commons.lang3.function.FailableCallable}.
*/
@Deprecated
@FunctionalInterface
public interface FailableCallable<R, T extends Throwable> {
/**
* Calls the callable.
*
* @return The value returned from the callable
* @throws T if the callable fails
*/
R call() throws T;
}
/**
* A functional interface like {@link Consumer} that declares a {@link Throwable}.
*
* <p>TODO for 4.0: Move to org.apache.commons.lang3.function.</p>
*
* @param <O> Consumed type 1.
* @param <T> Thrown exception.
* @deprecated Use {@link org.apache.commons.lang3.function.FailableConsumer}.
*/
@Deprecated
@FunctionalInterface
public interface FailableConsumer<O, T extends Throwable> {
/**
* Accepts the consumer.
*
* @param object the parameter for the consumable to accept
* @throws T Thrown when the consumer fails.
*/
void accept(O object) throws T;
}
/**
* A functional interface like {@link Function} that declares a {@link Throwable}.
*
* <p>TODO for 4.0: Move to org.apache.commons.lang3.function.</p>
*
* @param <I> Input type 1.
* @param <R> Return type.
* @param <T> Thrown exception.
* @deprecated Use {@link org.apache.commons.lang3.function.FailableFunction}.
*/
@Deprecated
@FunctionalInterface
public interface FailableFunction<I, R, T extends Throwable> {
/**
* Applies this function.
*
* @param input the input for the function
* @return the result of the function
* @throws T Thrown when the function fails.
*/
R apply(I input) throws T;
}
/**
* A functional interface like {@link Predicate} that declares a {@link Throwable}.
*
* <p>TODO for 4.0: Move to org.apache.commons.lang3.function.</p>
*
* @param <I> Predicate type 1.
* @param <T> Thrown exception.
* @deprecated Use {@link org.apache.commons.lang3.function.FailablePredicate}.
*/
@Deprecated
@FunctionalInterface
public interface FailablePredicate<I, T extends Throwable> {
/**
* Tests the predicate.
*
* @param object the object to test the predicate on
* @return the predicate's evaluation
* @throws T if the predicate fails
*/
boolean test(I object) throws T;
}
/**
* A functional interface like {@link Runnable} that declares a {@link Throwable}.
*
* <p>TODO for 4.0: Move to org.apache.commons.lang3.function.</p>
*
* @param <T> Thrown exception.
* @deprecated Use {@link org.apache.commons.lang3.function.FailableRunnable}.
*/
@Deprecated
@FunctionalInterface
public interface FailableRunnable<T extends Throwable> {
/**
* Runs the function.
*
* @throws T Thrown when the function fails.
*/
void run() throws T;
}
/**
* A functional interface like {@link Supplier} that declares a {@link Throwable}.
*
* <p>TODO for 4.0: Move to org.apache.commons.lang3.function.</p>
*
* @param <R> Return type.
* @param <T> Thrown exception.
* @deprecated Use {@link org.apache.commons.lang3.function.FailableSupplier}.
*/
@Deprecated
@FunctionalInterface
public interface FailableSupplier<R, T extends Throwable> {
/**
* Supplies an object
*
* @return a result
* @throws T if the supplier fails
*/
R get() throws T;
}
/**
* Consumes a consumer and rethrows any exception as a {@link RuntimeException}.
*
* @param consumer the consumer to consume
* @param object1 the first object to consume by {@code consumer}
* @param object2 the second object to consume by {@code consumer}
* @param <O1> the type of the first argument the consumer accepts
* @param <O2> the type of the second argument the consumer accepts
* @param <T> the type of checked exception the consumer may throw
*/
public static <O1, O2, T extends Throwable> void accept(final FailableBiConsumer<O1, O2, T> consumer,
final O1 object1, final O2 object2) {
run(() -> consumer.accept(object1, object2));
}
/**
* Consumes a consumer and rethrows any exception as a {@link RuntimeException}.
*
* @param consumer the consumer to consume
* @param object the object to consume by {@code consumer}
* @param <O> the type the consumer accepts
* @param <T> the type of checked exception the consumer may throw
*/
public static <O, T extends Throwable> void accept(final FailableConsumer<O, T> consumer, final O object) {
run(() -> consumer.accept(object));
}
/**
* Applies a function and rethrows any exception as a {@link RuntimeException}.
*
* @param function the function to apply
* @param input1 the first input to apply {@code function} on
* @param input2 the second input to apply {@code function} on
* @param <O1> the type of the first argument the function accepts
* @param <O2> the type of the second argument the function accepts
* @param <O> the return type of the function
* @param <T> the type of checked exception the function may throw
* @return the value returned from the function
*/
public static <O1, O2, O, T extends Throwable> O apply(final FailableBiFunction<O1, O2, O, T> function,
final O1 input1, final O2 input2) {
return get(() -> function.apply(input1, input2));
}
/**
* Applies a function and rethrows any exception as a {@link RuntimeException}.
*
* @param function the function to apply
* @param input the input to apply {@code function} on
* @param <I> the type of the argument the function accepts
* @param <O> the return type of the function
* @param <T> the type of checked exception the function may throw
* @return the value returned from the function
*/
public static <I, O, T extends Throwable> O apply(final FailableFunction<I, O, T> function, final I input) {
return get(() -> function.apply(input));
}
/**
* Converts the given {@link FailableBiConsumer} into a standard {@link BiConsumer}.
*
* @param <O1> the type of the first argument of the consumers
* @param <O2> the type of the second argument of the consumers
* @param consumer a failable {@link BiConsumer}
* @return a standard {@link BiConsumer}
* @since 3.10
*/
public static <O1, O2> BiConsumer<O1, O2> asBiConsumer(final FailableBiConsumer<O1, O2, ?> consumer) {
return (input1, input2) -> accept(consumer, input1, input2);
}
/**
* Converts the given {@link FailableBiFunction} into a standard {@link BiFunction}.
*
* @param <O1> the type of the first argument of the input of the functions
* @param <O2> the type of the second argument of the input of the functions
* @param <O> the type of the output of the functions
* @param function a {@link FailableBiFunction}
* @return a standard {@link BiFunction}
* @since 3.10
*/
public static <O1, O2, O> BiFunction<O1, O2, O> asBiFunction(final FailableBiFunction<O1, O2, O, ?> function) {
return (input1, input2) -> apply(function, input1, input2);
}
/**
* Converts the given {@link FailableBiPredicate} into a standard {@link BiPredicate}.
*
* @param <O1> the type of the first argument used by the predicates
* @param <O2> the type of the second argument used by the predicates
* @param predicate a {@link FailableBiPredicate}
* @return a standard {@link BiPredicate}
* @since 3.10
*/
public static <O1, O2> BiPredicate<O1, O2> asBiPredicate(final FailableBiPredicate<O1, O2, ?> predicate) {
return (input1, input2) -> test(predicate, input1, input2);
}
/**
* Converts the given {@link FailableCallable} into a standard {@link Callable}.
*
* @param <O> the type used by the callables
* @param callable a {@link FailableCallable}
* @return a standard {@link Callable}
* @since 3.10
*/
public static <O> Callable<O> asCallable(final FailableCallable<O, ?> callable) {
return () -> call(callable);
}
/**
* Converts the given {@link FailableConsumer} into a standard {@link Consumer}.
*
* @param <I> the type used by the consumers
* @param consumer a {@link FailableConsumer}
* @return a standard {@link Consumer}
* @since 3.10
*/
public static <I> Consumer<I> asConsumer(final FailableConsumer<I, ?> consumer) {
return input -> accept(consumer, input);
}
/**
* Converts the given {@link FailableFunction} into a standard {@link Function}.
*
* @param <I> the type of the input of the functions
* @param <O> the type of the output of the functions
* @param function a {code FailableFunction}
* @return a standard {@link Function}
* @since 3.10
*/
public static <I, O> Function<I, O> asFunction(final FailableFunction<I, O, ?> function) {
return input -> apply(function, input);
}
/**
* Converts the given {@link FailablePredicate} into a standard {@link Predicate}.
*
* @param <I> the type used by the predicates
* @param predicate a {@link FailablePredicate}
* @return a standard {@link Predicate}
* @since 3.10
*/
public static <I> Predicate<I> asPredicate(final FailablePredicate<I, ?> predicate) {
return input -> test(predicate, input);
}
/**
* Converts the given {@link FailableRunnable} into a standard {@link Runnable}.
*
* @param runnable a {@link FailableRunnable}
* @return a standard {@link Runnable}
* @since 3.10
*/
public static Runnable asRunnable(final FailableRunnable<?> runnable) {
return () -> run(runnable);
}
/**
* Converts the given {@link FailableSupplier} into a standard {@link Supplier}.
*
* @param <O> the type supplied by the suppliers
* @param supplier a {@link FailableSupplier}
* @return a standard {@link Supplier}
* @since 3.10
*/
public static <O> Supplier<O> asSupplier(final FailableSupplier<O, ?> supplier) {
return () -> get(supplier);
}
/**
* Calls a callable and rethrows any exception as a {@link RuntimeException}.
*
* @param callable the callable to call
* @param <O> the return type of the callable
* @param <T> the type of checked exception the callable may throw
* @return the value returned from the callable
*/
public static <O, T extends Throwable> O call(final FailableCallable<O, T> callable) {
return get(callable::call);
}
/**
* Invokes a supplier, and returns the result.
*
* @param supplier The supplier to invoke.
* @param <O> The suppliers output type.
* @param <T> The type of checked exception, which the supplier can throw.
* @return The object, which has been created by the supplier
* @since 3.10
*/
public static <O, T extends Throwable> O get(final FailableSupplier<O, T> supplier) {
try {
return supplier.get();
} catch (final Throwable t) {
throw rethrow(t);
}
}
/**
* Invokes a boolean supplier, and returns the result.
*
* @param supplier The boolean supplier to invoke.
* @param <T> The type of checked exception, which the supplier can throw.
* @return The boolean, which has been created by the supplier
*/
private static <T extends Throwable> boolean getAsBoolean(final FailableBooleanSupplier<T> supplier) {
try {
return supplier.getAsBoolean();
} catch (final Throwable t) {
throw rethrow(t);
}
}
/**
* Rethrows a {@link Throwable} as an unchecked exception. If the argument is already unchecked, namely a
* {@link RuntimeException} or {@link Error} then the argument will be rethrown without modification. If the
* exception is {@link IOException} then it will be wrapped into a {@link UncheckedIOException}. In every other
* cases the exception will be wrapped into a {@code
* UndeclaredThrowableException}
*
* <p>
* Note that there is a declared return type for this method, even though it never returns. The reason for that is
* to support the usual pattern:
* </p>
*
* <pre>
* throw rethrow(myUncheckedException);</pre>
*
* <p>
* instead of just calling the method. This pattern may help the Java compiler to recognize that at that point an
* exception will be thrown and the code flow analysis will not demand otherwise mandatory commands that could
* follow the method call, like a {@code return} statement from a value returning method.
* </p>
*
* @param throwable The throwable to rethrow possibly wrapped into an unchecked exception
* @return Never returns anything, this method never terminates normally.
*/
public static RuntimeException rethrow(final Throwable throwable) {
Objects.requireNonNull(throwable, "throwable");
ExceptionUtils.throwUnchecked(throwable);
if (throwable instanceof IOException) {
throw new UncheckedIOException((IOException) throwable);
}
throw new UndeclaredThrowableException(throwable);
}
/**
* Runs a runnable and rethrows any exception as a {@link RuntimeException}.
*
* @param runnable The runnable to run
* @param <T> the type of checked exception the runnable may throw
*/
public static <T extends Throwable> void run(final FailableRunnable<T> runnable) {
try {
runnable.run();
} catch (final Throwable t) {
throw rethrow(t);
}
}
/**
* Converts the given collection into a {@link FailableStream}. The {@link FailableStream} consists of the
* collections elements. Shortcut for
*
* <pre>
* Functions.stream(collection.stream());</pre>
*
* @param collection The collection, which is being converted into a {@link FailableStream}.
* @param <O> The collections element type. (In turn, the result streams element type.)
* @return The created {@link FailableStream}.
* @since 3.10
*/
public static <O> FailableStream<O> stream(final Collection<O> collection) {
return new FailableStream<>(collection.stream());
}
/**
* Converts the given stream into a {@link FailableStream}. The {@link FailableStream} consists of the same
* elements, than the input stream. However, failable lambdas, like {@link FailablePredicate},
* {@link FailableFunction}, and {@link FailableConsumer} may be applied, rather than {@link Predicate},
* {@link Function}, {@link Consumer}, etc.
*
* @param stream The stream, which is being converted into a {@link FailableStream}.
* @param <O> The streams element type.
* @return The created {@link FailableStream}.
* @since 3.10
*/
public static <O> FailableStream<O> stream(final Stream<O> stream) {
return new FailableStream<>(stream);
}
/**
* Tests a predicate and rethrows any exception as a {@link RuntimeException}.
*
* @param predicate the predicate to test
* @param object1 the first input to test by {@code predicate}
* @param object2 the second input to test by {@code predicate}
* @param <O1> the type of the first argument the predicate tests
* @param <O2> the type of the second argument the predicate tests
* @param <T> the type of checked exception the predicate may throw
* @return the boolean value returned by the predicate
*/
public static <O1, O2, T extends Throwable> boolean test(final FailableBiPredicate<O1, O2, T> predicate,
final O1 object1, final O2 object2) {
return getAsBoolean(() -> predicate.test(object1, object2));
}
/**
* Tests a predicate and rethrows any exception as a {@link RuntimeException}.
*
* @param predicate the predicate to test
* @param object the input to test by {@code predicate}
* @param <O> the type of argument the predicate tests
* @param <T> the type of checked exception the predicate may throw
* @return the boolean value returned by the predicate
*/
public static <O, T extends Throwable> boolean test(final FailablePredicate<O, T> predicate, final O object) {
return getAsBoolean(() -> predicate.test(object));
}
/**
* A simple try-with-resources implementation, that can be used, if your objects do not implement the
* {@link AutoCloseable} interface. The method executes the {@code action}. The method guarantees, that <em>all</em>
* the {@code resources} are being executed, in the given order, afterwards, and regardless of success, or failure.
* If either the original action, or any of the resource action fails, then the <em>first</em> failure (AKA
* {@link Throwable}) is rethrown. Example use:
*
* <pre>
* {@code
* final FileInputStream fis = new FileInputStream("my.file");
* Functions.tryWithResources(useInputStream(fis), null, () -> fis.close());
* }</pre>
*
* @param action The action to execute. This object <em>will</em> always be invoked.
* @param errorHandler An optional error handler, which will be invoked finally, if any error occurred. The error
* handler will receive the first error, AKA {@link Throwable}.
* @param resources The resource actions to execute. <em>All</em> resource actions will be invoked, in the given
* order. A resource action is an instance of {@link FailableRunnable}, which will be executed.
* @see #tryWithResources(FailableRunnable, FailableRunnable...)
*/
@SafeVarargs
public static void tryWithResources(final FailableRunnable<? extends Throwable> action,
final FailableConsumer<Throwable, ? extends Throwable> errorHandler,
final FailableRunnable<? extends Throwable>... resources) {
final org.apache.commons.lang3.function.FailableRunnable<?>[] fr = new org.apache.commons.lang3.function.FailableRunnable[resources.length];
Arrays.setAll(fr, i -> () -> resources[i].run());
Failable.tryWithResources(action::run, errorHandler != null ? errorHandler::accept : null, fr);
}
/**
* A simple try-with-resources implementation, that can be used, if your objects do not implement the
* {@link AutoCloseable} interface. The method executes the {@code action}. The method guarantees, that <em>all</em>
* the {@code resources} are being executed, in the given order, afterwards, and regardless of success, or failure.
* If either the original action, or any of the resource action fails, then the <em>first</em> failure (AKA
* {@link Throwable}) is rethrown. Example use:
*
* <pre>
* {@code
* final FileInputStream fis = new FileInputStream("my.file");
* Functions.tryWithResources(useInputStream(fis), () -> fis.close());
* }</pre>
*
* @param action The action to execute. This object <em>will</em> always be invoked.
* @param resources The resource actions to execute. <em>All</em> resource actions will be invoked, in the given
* order. A resource action is an instance of {@link FailableRunnable}, which will be executed.
* @see #tryWithResources(FailableRunnable, FailableConsumer, FailableRunnable...)
*/
@SafeVarargs
public static void tryWithResources(final FailableRunnable<? extends Throwable> action,
final FailableRunnable<? extends Throwable>... resources) {
tryWithResources(action, null, resources);
}
/**
* Constructs a new instance.
*/
public Functions() {
// empty
}
}