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Primitives: Expanding upon java.util.PrimitiveIterator and java.util.function.* for {byte, char, float, short}
package io.deephaven.engine.primitive.iterator;
import io.deephaven.util.SafeCloseableArray;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;
import java.util.NoSuchElementException;
import java.util.Objects;
import java.util.PrimitiveIterator;
import java.util.Spliterator;
import java.util.Spliterators;
import java.util.function.IntConsumer;
import java.util.stream.IntStream;
import java.util.stream.StreamSupport;
/**
* {@link CloseablePrimitiveIterator Closeable primitive iterator} over elements of type {@code int}.
*/
public interface CloseablePrimitiveIteratorOfInt
extends PrimitiveIterator.OfInt, CloseablePrimitiveIterator {
/**
* Create a {@link IntStream} over the remaining elements of this CloseablePrimitiveIteratorOfInt. Closing the
* result will close this CloseablePrimitiveIteratorOfInt.
*
* @return A {@link IntStream} over the remaining contents of this iterator
*/
default IntStream intStream() {
return StreamSupport.intStream(
Spliterators.spliteratorUnknownSize(
this,
Spliterator.IMMUTABLE | Spliterator.ORDERED),
false)
.onClose(this::close);
}
/**
* A re-usable, immutable CloseablePrimitiveIteratorOfInt with no elements.
*/
CloseablePrimitiveIteratorOfInt EMPTY = new CloseablePrimitiveIteratorOfInt() {
@Override
public int nextInt() {
throw new NoSuchElementException();
}
@Override
public boolean hasNext() {
return false;
}
};
/**
* Get a CloseablePrimitiveIteratorOfInt with no elements. The result does not need to be {@link #close() closed}.
*
* @return A CloseablePrimitiveIteratorOfInt with no elements
*/
static CloseablePrimitiveIteratorOfInt empty() {
return EMPTY;
}
/**
* Create a CloseablePrimitiveIteratorOfInt over an array of {@code int}. The result does not need to be
* {@link #close() closed}.
*
* @param values The elements to iterate
* @return A CloseablePrimitiveIteratorOfInt of {@code values}
*/
static CloseablePrimitiveIteratorOfInt of(@NotNull final int... values) {
Objects.requireNonNull(values);
return new CloseablePrimitiveIteratorOfInt() {
private int valueIndex;
@Override
public int nextInt() {
return values[valueIndex++];
}
@Override
public boolean hasNext() {
return valueIndex < values.length;
}
};
}
/**
* Create a CloseablePrimitiveIteratorOfInt that repeats {@code value}, {@code repeatCount} times. The result does
* not need to be {@link #close() closed}.
*
* @param value The value to repeat
* @param repeatCount The number of repetitions
* @return A CloseablePrimitiveIteratorOfInt that repeats {@code value}, {@code repeatCount} times
*/
static CloseablePrimitiveIteratorOfInt repeat(final int value, final long repeatCount) {
return new CloseablePrimitiveIteratorOfInt() {
private long repeatIndex;
@Override
public int nextInt() {
if (repeatIndex < repeatCount) {
++repeatIndex;
return value;
}
throw new NoSuchElementException();
}
@Override
public boolean hasNext() {
return repeatIndex < repeatCount;
}
};
}
/**
* Create a CloseablePrimitiveIteratorOfInt that concatenates an array of non-{@code null} {@code subIterators}. The
* result only needs to be {@link #close() closed} if any of the {@code subIterators} require it.
*
* @param subIterators The iterators to concatenate, none of which should be {@code null}. If directly passing an
* array, ensure that this iterator has full ownership.
* @return A CloseablePrimitiveIteratorOfInt concatenating all elements from {@code subIterators}
*/
static CloseablePrimitiveIteratorOfInt concat(@NotNull final CloseablePrimitiveIteratorOfInt... subIterators) {
Objects.requireNonNull(subIterators);
if (subIterators.length == 0) {
return empty();
}
if (subIterators.length == 1) {
return subIterators[0];
}
return new CloseablePrimitiveIteratorOfInt() {
private boolean hasNextChecked;
private int subIteratorIndex;
@Override
public int nextInt() {
if (hasNext()) {
hasNextChecked = false;
return subIterators[subIteratorIndex].nextInt();
}
throw new NoSuchElementException();
}
@Override
public boolean hasNext() {
if (hasNextChecked) {
return true;
}
for (; subIteratorIndex < subIterators.length; ++subIteratorIndex) {
if (subIterators[subIteratorIndex].hasNext()) {
return hasNextChecked = true;
}
}
return false;
}
@Override
public void close() {
SafeCloseableArray.close(subIterators);
}
};
}
/**
* Return a CloseablePrimitiveIteratorOfInt that concatenates the contents of any non-{@code null}
* CloseablePrimitiveIteratorOfInt found amongst {@code first}, {@code second}, and {@code third}.
*
* @param first The first iterator to consider concatenating
* @param second The second iterator to consider concatenating
* @param third The third iterator to consider concatenating
* @return A CloseablePrimitiveIteratorOfInt that concatenates all elements as specified
*/
static CloseablePrimitiveIteratorOfInt maybeConcat(
@Nullable final CloseablePrimitiveIteratorOfInt first,
@Nullable final CloseablePrimitiveIteratorOfInt second,
@Nullable final CloseablePrimitiveIteratorOfInt third) {
if (first != null) {
if (second != null) {
if (third != null) {
return concat(first, second, third);
}
return concat(first, second);
}
if (third != null) {
return concat(first, third);
}
return first;
}
if (second != null) {
if (third != null) {
return concat(second, third);
}
return second;
}
if (third != null) {
return third;
}
return empty();
}
}