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 * Copyright (c) 2013, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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 */
package java.util;

import java.util.function.Consumer;
import java.util.function.DoubleConsumer;
import java.util.function.IntConsumer;
import java.util.function.LongConsumer;

/**
 * A base type for primitive specializations of {@code Iterator}. Specialized
 * subtypes are provided for {@link OfInt int}, {@link OfLong long}, and
 * {@link OfDouble double} values.
 *
 * <p>The specialized subtype default implementations of {@link Iterator#next}
 * and {@link Iterator#forEachRemaining(java.util.function.Consumer)} box
 * primitive values to instances of their corresponding wrapper class. Such
 * boxing may offset any advantages gained when using the primitive
 * specializations. To avoid boxing, the corresponding primitive-based methods
 * should be used. For example, {@link PrimitiveIterator.OfInt#nextInt()} and
 * {@link PrimitiveIterator.OfInt#forEachRemaining(java.util.function.IntConsumer)}
 * should be used in preference to {@link PrimitiveIterator.OfInt#next()} and
 * {@link PrimitiveIterator.OfInt#forEachRemaining(java.util.function.Consumer)}.
 *
 * <p>Iteration of primitive values using boxing-based methods
 * {@link Iterator#next next()} and
 * {@link Iterator#forEachRemaining(java.util.function.Consumer) forEachRemaining()},
 * does not affect the order in which the values, transformed to boxed values,
 * are encountered.
 *
 * @implNote
 * If the boolean system property {@code org.openjdk.java.util.stream.tripwire}
 * is set to {@code true} then diagnostic warnings are reported if boxing of
 * primitive values occur when operating on primitive subtype specializations.
 *
 * @param <T> the type of elements returned by this PrimitiveIterator. The
 * type must be a wrapper type for a primitive type, such as
 * {@code Integer} for the primitive {@code int} type.
 * @param <T_CONS> the type of primitive consumer. The type must be a
 * primitive specialization of {@link java.util.function.Consumer} for
 * {@code T}, such as {@link java.util.function.IntConsumer} for
 * {@code Integer}.
 *
 * @since 1.8
 */
public interface PrimitiveIterator<T, T_CONS> extends Iterator<T> {

 /**
 * Performs the given action for each remaining element, in the order
 * elements occur when iterating, until all elements have been processed
 * or the action throws an exception. Errors or runtime exceptions
 * thrown by the action are relayed to the caller.
 *
 * @param action The action to be performed for each element
 * @throws NullPointerException if the specified action is null
 */
 @SuppressWarnings("overloads")
 void forEachRemaining(T_CONS action);

 /**
 * An Iterator specialized for {@code int} values.
 * @since 1.8
 */
 public static interface OfInt extends PrimitiveIterator<Integer, IntConsumer> {

 /**
 * Returns the next {@code int} element in the iteration.
 *
 * @return the next {@code int} element in the iteration
 * @throws NoSuchElementException if the iteration has no more elements
 */
 int nextInt();

 /**
 * Performs the given action for each remaining element until all elements
 * have been processed or the action throws an exception. Actions are
 * performed in the order of iteration, if that order is specified.
 * Exceptions thrown by the action are relayed to the caller.
 *
 * @implSpec
 * <p>The default implementation behaves as if:
 * <pre>{@code
 * while (hasNext())
 * action.accept(nextInt());
 * }</pre>
 *
 * @param action The action to be performed for each element
 * @throws NullPointerException if the specified action is null
 */
 default void forEachRemaining(IntConsumer action) {
 Objects.requireNonNull(action);
 while (hasNext())
 action.accept(nextInt());
 }

 /**
 * {@inheritDoc}
 * @implSpec
 * The default implementation boxes the result of calling
 * {@link #nextInt()}, and returns that boxed result.
 */
 @Override
 default Integer next() {
 if (Tripwire.ENABLED)
 Tripwire.trip(getClass(), "{0} calling PrimitiveIterator.OfInt.nextInt()");
 return nextInt();
 }

 /**
 * {@inheritDoc}
 * @implSpec
 * If the action is an instance of {@code IntConsumer} then it is cast
 * to {@code IntConsumer} and passed to {@link #forEachRemaining};
 * otherwise the action is adapted to an instance of
 * {@code IntConsumer}, by boxing the argument of {@code IntConsumer},
 * and then passed to {@link #forEachRemaining}.
 */
 @Override
 default void forEachRemaining(Consumer<? super Integer> action) {
 if (action instanceof IntConsumer) {
 forEachRemaining((IntConsumer) action);
 }
 else {
 // The method reference action::accept is never null
 Objects.requireNonNull(action);
 if (Tripwire.ENABLED)
 Tripwire.trip(getClass(), "{0} calling PrimitiveIterator.OfInt.forEachRemainingInt(action::accept)");
 forEachRemaining((IntConsumer) action::accept);
 }
 }

 }

 /**
 * An Iterator specialized for {@code long} values.
 * @since 1.8
 */
 public static interface OfLong extends PrimitiveIterator<Long, LongConsumer> {

 /**
 * Returns the next {@code long} element in the iteration.
 *
 * @return the next {@code long} element in the iteration
 * @throws NoSuchElementException if the iteration has no more elements
 */
 long nextLong();

 /**
 * Performs the given action for each remaining element until all elements
 * have been processed or the action throws an exception. Actions are
 * performed in the order of iteration, if that order is specified.
 * Exceptions thrown by the action are relayed to the caller.
 *
 * @implSpec
 * <p>The default implementation behaves as if:
 * <pre>{@code
 * while (hasNext())
 * action.accept(nextLong());
 * }</pre>
 *
 * @param action The action to be performed for each element
 * @throws NullPointerException if the specified action is null
 */
 default void forEachRemaining(LongConsumer action) {
 Objects.requireNonNull(action);
 while (hasNext())
 action.accept(nextLong());
 }

 /**
 * {@inheritDoc}
 * @implSpec
 * The default implementation boxes the result of calling
 * {@link #nextLong()}, and returns that boxed result.
 */
 @Override
 default Long next() {
 if (Tripwire.ENABLED)
 Tripwire.trip(getClass(), "{0} calling PrimitiveIterator.OfLong.nextLong()");
 return nextLong();
 }

 /**
 * {@inheritDoc}
 * @implSpec
 * If the action is an instance of {@code LongConsumer} then it is cast
 * to {@code LongConsumer} and passed to {@link #forEachRemaining};
 * otherwise the action is adapted to an instance of
 * {@code LongConsumer}, by boxing the argument of {@code LongConsumer},
 * and then passed to {@link #forEachRemaining}.
 */
 @Override
 default void forEachRemaining(Consumer<? super Long> action) {
 if (action instanceof LongConsumer) {
 forEachRemaining((LongConsumer) action);
 }
 else {
 // The method reference action::accept is never null
 Objects.requireNonNull(action);
 if (Tripwire.ENABLED)
 Tripwire.trip(getClass(), "{0} calling PrimitiveIterator.OfLong.forEachRemainingLong(action::accept)");
 forEachRemaining((LongConsumer) action::accept);
 }
 }
 }

 /**
 * An Iterator specialized for {@code double} values.
 * @since 1.8
 */
 public static interface OfDouble extends PrimitiveIterator<Double, DoubleConsumer> {

 /**
 * Returns the next {@code double} element in the iteration.
 *
 * @return the next {@code double} element in the iteration
 * @throws NoSuchElementException if the iteration has no more elements
 */
 double nextDouble();

 /**
 * Performs the given action for each remaining element until all elements
 * have been processed or the action throws an exception. Actions are
 * performed in the order of iteration, if that order is specified.
 * Exceptions thrown by the action are relayed to the caller.
 *
 * @implSpec
 * <p>The default implementation behaves as if:
 * <pre>{@code
 * while (hasNext())
 * action.accept(nextDouble());
 * }</pre>
 *
 * @param action The action to be performed for each element
 * @throws NullPointerException if the specified action is null
 */
 default void forEachRemaining(DoubleConsumer action) {
 Objects.requireNonNull(action);
 while (hasNext())
 action.accept(nextDouble());
 }

 /**
 * {@inheritDoc}
 * @implSpec
 * The default implementation boxes the result of calling
 * {@link #nextDouble()}, and returns that boxed result.
 */
 @Override
 default Double next() {
 if (Tripwire.ENABLED)
 Tripwire.trip(getClass(), "{0} calling PrimitiveIterator.OfDouble.nextLong()");
 return nextDouble();
 }

 /**
 * {@inheritDoc}
 * @implSpec
 * If the action is an instance of {@code DoubleConsumer} then it is
 * cast to {@code DoubleConsumer} and passed to
 * {@link #forEachRemaining}; otherwise the action is adapted to
 * an instance of {@code DoubleConsumer}, by boxing the argument of
 * {@code DoubleConsumer}, and then passed to
 * {@link #forEachRemaining}.
 */
 @Override
 default void forEachRemaining(Consumer<? super Double> action) {
 if (action instanceof DoubleConsumer) {
 forEachRemaining((DoubleConsumer) action);
 }
 else {
 // The method reference action::accept is never null
 Objects.requireNonNull(action);
 if (Tripwire.ENABLED)
 Tripwire.trip(getClass(), "{0} calling PrimitiveIterator.OfDouble.forEachRemainingDouble(action::accept)");
 forEachRemaining((DoubleConsumer) action::accept);
 }
 }
 }
}