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/*
* Copyright (C) 2002-2022 Sebastiano Vigna
*
* 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 it.unimi.dsi.fastutil.longs;
import java.lang.Iterable;
import java.util.Objects;
import java.util.function.Consumer;
/** A type-specific {@link Iterable} that strengthens that specification of {@link #iterator()} and {@link #forEach(Consumer)}.
*
* Note that whenever there exist a primitive consumer in {@link java.util.function} (e.g., {@link java.util.function.IntConsumer}),
* trying to access any version of {@link #forEach(Consumer)} using a lambda expression with untyped arguments
* will generate an ambiguous method error. This can be easily solved by specifying the type of the argument, as in
*
* intIterable.forEach((int x) -> { // Do something with x });
*
* The same problem plagues, for example, {@link java.util.PrimitiveIterator.OfInt#forEachRemaining(java.util.function.IntConsumer)}.
*
*
Warning: Java will let you write “colon” {@code for} statements with primitive-type
* loop variables; however, what is (unfortunately) really happening is that at each iteration an
* unboxing (and, in the case of {@code fastutil} type-specific data structures, a boxing) will be performed. Watch out.
*
* @see Iterable
*/
public interface LongIterable extends Iterable {
/** Returns a type-specific iterator.
*
* @apiNote Note that this specification strengthens the one given in {@link Iterable#iterator()}.
*
* @return a type-specific iterator.
* @see Iterable#iterator()
*/
@Override
LongIterator iterator();
/** Returns a primitive iterator on the elements of this iterable.
*
* This method is identical to {@link #iterator()}, as the type-specific
* iterator is already compatible with the JDK's primitive iterators.
* It only exists for compatibility with the other primitive types' {@code Iterable}s
* that have use for widened iterators.
*
* @return a primitive iterator on the elements of this iterable.
* @since 8.5.0
*/
default LongIterator longIterator() { return iterator(); }
// If you change these default spliterator methods, you will likely need to update Collection, List, Set, and SortedSet too.
/** Returns a type-specific spliterator on the elements of this iterable.
*
* @apiNote Note that this specification strengthens the one given in
* {@link java.lang.Iterable#spliterator()}.
*
* @return a type-specific spliterator on the elements of this iterable.
* @since 8.5.0
*/
@Override
default LongSpliterator spliterator() {
return LongSpliterators.asSpliteratorUnknownSize(iterator(), 0);
}
/** Returns a primitive spliterator on the elements of this iterable.
*
* This method is identical to {@link #spliterator()}, as the type-specific
* spliterator is already compatible with the JDK's primitive spliterators.
* It only exists for compatibility with the other primitive types' {@code Iterable}s
* that have use for widened spliterators.
*
* @return a primitive spliterator on the elements of this collection.
* @since 8.5.0
*/
default LongSpliterator longSpliterator() { return spliterator(); }
/**
* Performs the given action for each element of this type-specific {@link java.lang.Iterable}
* until all elements have been processed or the action throws an
* exception.
*
* @param action the action to be performed for each element.
* @see java.lang.Iterable#forEach(java.util.function.Consumer)
* @since 8.0.0
* @apiNote Implementing classes should generally override this method, and take the default
* implementation of the other overloads which will delegate to this method (after proper
* conversions).
*/
default void forEach(final java.util.function.LongConsumer action) {
Objects.requireNonNull(action);
iterator().forEachRemaining(action);
}
// Because our primitive Consumer interface extends both the JDK's primitive
// and object Consumer interfaces, calling this method with it would be ambiguous.
// This overload exists to pass it to the proper primitive overload.
/**
* Performs the given action for each element of this type-specific {@link java.lang.Iterable}
* until all elements have been processed or the action throws an exception.
*
*
WARNING: Overriding this method is almost always a mistake, as this
* overload only exists to disambiguate. Instead, override the {@code forEach()} overload
* that uses the JDK's primitive consumer type (e.g. {@link java.util.function.IntConsumer}).
*
*
If Java supported final default methods, this would be one, but sadly it does not.
*
*
If you checked and are overriding the version with {@code java.util.function.XConsumer}, and
* still see this warning, then your IDE is incorrectly conflating this method with the proper
* method to override, and you can safely ignore this message.
*
* @param action the action to be performed for each element.
* @see java.lang.Iterable#forEach(java.util.function.Consumer)
* @since 8.5.0
*/
default void forEach(final LongConsumer action) {
forEach((java.util.function.LongConsumer) action);
}
/** {@inheritDoc}
* @deprecated Please use the corresponding type-specific method instead. */
@Deprecated
@Override
default void forEach(final Consumer action) {
Objects.requireNonNull(action);
// The instanceof and cast is required for performance. Without it, calls routed through this
// overload using a primitive consumer would go through the slow lambda.
forEach(action instanceof java.util.function.LongConsumer ? (java.util.function.LongConsumer)action : (java.util.function.LongConsumer) action::accept);
}
}