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/*
* Copyright (C) Posten Norge AS
*
* 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 no.digipost;
import no.digipost.function.ThrowingConsumer;
import no.digipost.util.AutoClosed;
import no.digipost.util.ThrowingAutoClosed;
import java.util.ArrayDeque;
import java.util.Deque;
import java.util.Objects;
import java.util.Optional;
import java.util.function.Consumer;
import java.util.function.Function;
import java.util.function.Supplier;
import java.util.stream.Stream;
import static java.util.Spliterator.ORDERED;
import static java.util.Spliterators.spliterator;
import static java.util.stream.Collectors.joining;
import static java.util.stream.StreamSupport.stream;
/**
* Party people, turn up tha...
*
* –– {@link DiggBase} ––
*
* This class contains basic utilities. Basically.
*/
public final class DiggBase {
/**
* Not allow {@code null}-references.
*
* @param description A small description of the reference. Will be used in the exception message if
* the reference is {@code null}
* @param t the reference
* @return the same instance given as argument.
* @throws NullPointerException if {@code t} is {@code null}.
*/
public static T nonNull(String description, T t) {
return nonNull(description, d -> t);
}
/**
* Not allow {@code null}-references.
*
* @param description A small description of the reference. Will be used in the exception message if
* the reference is {@code null}
* @param t the reference
* @param throwIfNull Construct the exception to be thrown if the reference is {@code null}.
* @return the same instance given as argument.
* @throws X if {@code t} is {@code null}.
*/
public static T nonNull(String description, T t, Function throwIfNull) throws X {
return nonNull(t, () -> throwIfNull.apply(description + " can not be null"));
}
/**
* Not allow {@code null}-references.
*
* @param t the reference
* @param throwIfNull the exception to throw if {@code t} is {@code null}
* @return the same instance given as argument.
* @throws X if {@code t} is {@code null}.
*/
public static T nonNull(T t, Supplier throwIfNull) throws X {
return nonNull("a reference", s -> t, s -> throwIfNull.get());
}
/**
* Not allow {@code null}-references. This is a convenience method for when a descriptive refKey
* can be used to resolve the reference, for instance to resolve resources
* on classpath with {@link Class#getResourceAsStream(String) .class::getResourceAsStream}.
* The refKey will appear in the exception message if the resolved reference is {@code null}.
*
* @param descriptiveRefKey the key used to resolve the reference
* @param refResolver the function the will resolve the non-null result based on the description.
* @return the reference resolved by {@code refResolver}, never {@code null}
*/
public static T nonNull(String descriptiveRefKey, Function refResolver) {
return nonNull(descriptiveRefKey, refResolver, d -> new NullPointerException("Tried to resolve " + d + ", but got null!"));
}
/**
* Not allow {@code null}-references.
*
* @param descriptiveRefKey the key used to resolve the reference
* @param refResolver the function the will resolve the non-null result based on the description.
* @param throwIfNull the function to construct the exception if the {@code refResolver} yields {@code null}.
* @return the reference resolved by {@code refResolver}, never {@code null}
* @throws X if {@code refResolver} yields {@code null}
*/
public static T nonNull(String descriptiveRefKey, Function refResolver, Function throwIfNull) throws X {
T ref = refResolver.apply(descriptiveRefKey);
if (ref != null) {
return ref;
} else {
throw throwIfNull.apply(descriptiveRefKey);
}
}
/**
* The "friendly name" of a class is defined as its {@link Class#getSimpleName() simple name}, with
* all enclosing classes prepended and joined with a '.' delimiter. This name is typically
* useful for logging, naming based on classes, where the fully qualified name would be too verbose
* and the simple name is not specific enough.
*
* Given the following class model:
*
* class Base {
* class Nested {}
* }
*
* The friendly name for the {@code Nested} class is "Base.Nested".
*
* @param clazz the clazz to get the friendly name of
* @return the friendly name
*/
public static String friendlyName(Class clazz) {
Deque> classes = new ArrayDeque<>();
classes.add(clazz);
for (Class enclosing = clazz.getEnclosingClass(); enclosing != null; enclosing = enclosing.getEnclosingClass()) {
classes.add(enclosing);
}
return stream(spliterator(classes.descendingIterator(), classes.size(), ORDERED), false)
.map(Class::getSimpleName)
.collect(joining("."));
}
/**
* Extract (derive) multiple values from one given object.
*
* @param object the object to extract values from.
* @param extractors each function that will extract a value from the given object. The resulting
* value must not be {@code null}. Use {@link #extract(Object, Function...)}
* if the extractors may yield non-existing values.
*
* @return a stream of the extracted values. The resulting stream will have the same size as the amount of
* given extractors.
*
* @param The type of the object to extract from.
* @param The resulting most common type of the extracted values. Typically, the extractors
* should yield the same type.
*/
@SafeVarargs
public static final Stream extract(T object, Function ... extractors) {
return Stream.of(extractors).map(e -> e.apply(object));
}
/**
* Extract (derive) multiple values from one given object. This will only include the "present"
* values yielded from the given extractors, and is a shorthand for:
*
* {@code {@link #extract(Object, Function...) extract(object, extractors...)}{@link Stream#filter(java.util.function.Predicate) .filter(}{@link Optional#isPresent() Optional::isPresent)}{@link Stream#map(Function) .map(}{@link Optional#get() Optional::get)}}
*
*
* @param object the object to extract values from.
* @param extractors each function that will extract a value from the given object.
*
* @return a stream of values to be extracted. The resulting stream will have either the same size as
* or less than the amount of given extractors.
*
*
* @param The type of the object to extract from.
* @param The resulting most common type of the extracted values. Typically, the extractors
* should yield the same type.
*/
@SafeVarargs
public static final Stream extractIfPresent(T object, Function> ... extractors) {
return extract(object, extractors).filter(Optional::isPresent).map(Optional::get);
}
/**
* Create a stream which will yield the exceptions from closing several {@link AutoCloseable closeables}.
* Consuming the stream will ensure that all closeables are attempted
* {@link AutoCloseable#close() closed}, and any exceptions happening will be available
* through the returned stream.
*
* To further collapse the possibly multiple exceptions into one throwable exception,
* use either
* {@link DiggCollectors#toSingleExceptionWithSuppressed() .collect(toSingleExceptionWithSuppressed())}
* or {@link DiggCollectors#asSuppressedExceptionsOf(Throwable) .collect(asSuppressedExceptionsOf(..))}
* in {@code DiggCollectors}.
*
* If you have non-AutoCloseable related actions that need to be performed as well, this can be achieved
* by using Stream.concat(close(..),
* {@link #forceOnAll(ThrowingConsumer, Object...) forceOnAll(T::action, T ... instances)})
*
*
* @param closeables The {@code AutoCloseable} instances to close.
*
* @return the Stream with exceptions, if any, from closing the closeables
*
* @see DiggCollectors#toSingleExceptionWithSuppressed()
* @see DiggCollectors#asSuppressedExceptionsOf(Throwable)
*/
public static Stream close(AutoCloseable ... closeables) {
return forceOnAll(AutoCloseable::close, closeables);
}
/**
* Create a stream which will yield the exceptions (if any) from invoking an {@link ThrowingConsumer action} on
* several {@code instances}. Consuming the stream will ensure that all instances will have
* the action invoked on them, and any exceptions happening will be available through the returned stream.
*
* @param action the action to execute for each provided instance
* @param instances the instances to act on with the provided {@code action}.
*
* @return the Stream with exceptions, if any
*/
@SafeVarargs
public static Stream forceOnAll(ThrowingConsumer action, T ... instances) {
return forceOnAll(action, Stream.of(instances));
}
/**
* Create a stream which will yield the exceptions (if any) from invoking an {@link ThrowingConsumer action} on
* several {@code instances}. Consuming the stream will ensure that all instances will have
* the action invoked on them, and any exceptions happening will be available through the returned stream.
*
* @param action the action to execute for each provided instance
* @param instances the instances to act on with the provided {@code action}.
*
* @return the Stream with exceptions, if any
*/
public static Stream forceOnAll(ThrowingConsumer action, Stream instances) {
return instances.filter(Objects::nonNull).flatMap(instance -> {
try {
action.accept(instance);
} catch (Exception exception) {
return Stream.of(exception);
}
return Stream.empty();
});
}
/**
* Wrap an arbitrary object to an {@link AutoCloseable} container, and assign an operation to be
* performed on the wrapped object when calling {@link AutoCloseable#close()}. This can be
* used for legacy classes which does not implement {@code AutoCloseable} to be used with the
* {@code try-with-resources} construct. It should not be used (although it can) for
* objects already implementing {@code AutoCloseable}.
*
* @param object the object to be managed with {@code try-with-resources}.
* @param closeOperation the operation to invoke on {@code object} to close it.
*
* @return The wrapper which is {@link AutoCloseable}. Assign this with {@code try-with-resources} to
* have it properly closed.
*
*
* @param The type of the wrapped/managed object.
* @param The exception which may be throwed when closing by {@link AutoCloseable#close()}.
*
* @see #autoClose(Object, Consumer)
*/
public static ThrowingAutoClosed throwingAutoClose(T object, ThrowingConsumer closeOperation) {
return new ThrowingAutoClosed(object, closeOperation);
}
/**
* Wrap an arbitrary object to an {@link AutoCloseable} container, and assign an operation to be
* performed on the wrapped object when calling {@link AutoCloseable#close()}. This can be
* used for legacy classes which does not implement {@code AutoCloseable} to be used with the
* {@code try-with-resources} construct. It should not be used (although it can) for
* objects already implementing {@code AutoCloseable}.
*
* @param object the object to be managed with {@code try-with-resources}.
* @param closeOperation the operation to invoke on {@code object} to close it. If the operation
* can throw a checked exception, use {@link #throwingAutoClose(Object, ThrowingConsumer)}
* instead.
*
* @return The wrapper which is {@link AutoCloseable}. Assign this with {@code try-with-resources} to
* have it properly closed.
*
*
* @param The type of the wrapped/managed object.
*
* @see #throwingAutoClose(Object, ThrowingConsumer)
*/
public static AutoClosed autoClose(T object, Consumer closeOperation) {
return new AutoClosed(object, closeOperation);
}
private DiggBase() {}
}