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Engine API: Engine API module, suitable as a compile-time dependency for most queries
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//
// Copyright (c) 2016-2024 Deephaven Data Labs and Patent Pending
//
package io.deephaven.engine.table.iterators;

import io.deephaven.engine.primitive.function.CharToIntFunction;
import io.deephaven.engine.primitive.iterator.CloseablePrimitiveIteratorOfChar;
import io.deephaven.util.QueryConstants;
import io.deephaven.util.annotations.FinalDefault;
import io.deephaven.util.type.TypeUtils;
import org.jetbrains.annotations.NotNull;

import java.util.PrimitiveIterator;
import java.util.Spliterator;
import java.util.Spliterators;
import java.util.function.Consumer;
import java.util.stream.IntStream;
import java.util.stream.Stream;
import java.util.stream.StreamSupport;

/**
 * {@link ColumnIterator} implementation for columns of primitive chars.
 */
public interface CharacterColumnIterator extends ColumnIterator, CloseablePrimitiveIteratorOfChar {

    @Override
    @FinalDefault
    default Character next() {
        return TypeUtils.box(nextChar());
    }

    @Override
    @FinalDefault
    default void forEachRemaining(@NotNull final Consumer action) {
        forEachRemaining((final char element) -> action.accept(TypeUtils.box(element)));
    }

    /**
     * Create a {@link IntStream} over the remaining elements of this ChunkedCharacterColumnIterator by applying
     * {@code adapter} to each element. The result must be {@link java.util.stream.BaseStream#close() closed}
     * in order to ensure resources are released. A try-with-resources block is strongly encouraged.
     *
     * @return A {@link IntStream} over the remaining contents of this iterator. Must be {@link Stream#close() closed}.
     */
    @Override
    @FinalDefault
    default IntStream streamAsInt(@NotNull final CharToIntFunction adapter) {
        final PrimitiveIterator.OfInt adapted = adaptToOfInt(adapter);
        return StreamSupport.intStream(
                Spliterators.spliterator(
                        adapted,
                        remaining(),
                        Spliterator.IMMUTABLE | Spliterator.ORDERED),
                false)
                .onClose(this::close);
    }

    /**
     * Create an unboxed {@link IntStream} over the remaining elements of this ChunkedCharacterColumnIterator by casting
     * each element to {@code int} with the appropriate adjustment of {@link io.deephaven.util.QueryConstants#NULL_CHAR
     * NULL_CHAR} to {@link io.deephaven.util.QueryConstants#NULL_INT NULL_INT}. The result must be
     * {@link java.util.stream.BaseStream#close() closed} in order to ensure resources are released. A
     * try-with-resources block is strongly encouraged.
     *
     * @return An unboxed {@link IntStream} over the remaining contents of this iterator. Must be {@link Stream#close()
     *         closed}.
     */
    @Override
    @FinalDefault
    default IntStream streamAsInt() {
        return streamAsInt(
                (final char value) -> value == QueryConstants.NULL_CHAR ? QueryConstants.NULL_INT : (int) value);
    }

    /**
     * Create a boxed {@link Stream} over the remaining elements of this CharColumnIterator. The result must be
     * {@link java.util.stream.BaseStream#close() closed} in order to ensure resources are released. A
     * try-with-resources block is strongly encouraged.
     *
     * @return A boxed {@link Stream} over the remaining contents of this iterator. Must be {@link Stream#close()
     *         closed}.
     */
    @Override
    @FinalDefault
    default Stream stream() {
        return StreamSupport.stream(
                Spliterators.spliterator(
                        this,
                        remaining(),
                        Spliterator.IMMUTABLE | Spliterator.ORDERED),
                false)
                .onClose(this::close);
    }
}