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 * SciJava library for generic type reasoning.
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package org.scijava.types.extract;

import java.lang.reflect.Type;
import java.util.stream.StreamSupport;

import org.scijava.priority.Priority;
import org.scijava.common3.Any;
import org.scijava.common3.Types;

/**
 * {@link TypeExtractor} plugin which operates on {@link Iterable} objects.
 * <p>
 * In an attempt to balance performance and correctness, we examine the first
 * 100 elements of the iteration and obtain the greatest common supertype of
 * each.
 * </p>
 *
 * @author Curtis Rueden
 */
public class IterableTypeExtractor extends SubTypeExtractor<Iterable<?>> {

	@Override
	public double priority() {
		return Priority.VERY_LOW;
	}

	@Override
	public Class<?> baseClass() {
		return Iterable.class;
	}

	@Override
	protected Type[] getTypeParameters(TypeReifier r, Iterable<?> object) {
		// Obtain the element type using the TypeService.
        var typesToCheck = 100;
		// can we make this more efficient (possibly a parallel stream)?
        var types = StreamSupport.stream(object.spliterator(), false) //
			.limit(typesToCheck) //
			.map(r::reify) //
			.toArray(Type[]::new);

        var actual = Types.commonSuperTypeOf(types);
		if (actual == null) actual = new Any();
		return new Type[] { actual };
	}

}
