net.jqwik.engine.properties.arbitraries.exhaustive.UniqueExhaustiveGenerator Maven / Gradle / Ivy

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Jqwik Engine module

There is a newer version: 1.9.1

package net.jqwik.engine.properties.arbitraries.exhaustive;

import java.util.*;
import java.util.concurrent.*;

import net.jqwik.api.*;

public class UniqueExhaustiveGenerator implements ExhaustiveGenerator {
	private static final long MAX_MISSES = 10000;
	private final ExhaustiveGenerator base;

	public UniqueExhaustiveGenerator(ExhaustiveGenerator base) {
		this.base = base;
	}

	@Override
	public boolean isUnique() {
		return true;
	}

	@Override
	public long maxCount() {
		return base.maxCount();
	}

	@Override
	public Iterator iterator() {
		final Iterator mappedIterator = base.iterator();
		final Set usedValues = ConcurrentHashMap.newKeySet();

		return new Iterator() {

			T next = findNext();

			@Override
			public boolean hasNext() {
				return next != null;
			}

			@Override
			public T next() {
				if (next == null) {
					throw new NoSuchElementException();
				}
				T result = next;
				next = findNext();
				return result;
			}

			private T findNext() {
				long count = 0;
				while (true) {
					if (!mappedIterator.hasNext()) {
						return null;
					}
					T next = mappedIterator.next();
					if (!usedValues.contains(next)) {
						usedValues.add(next);
						return next;
					} else {
						if (++count > MAX_MISSES) {
							String message =
								String.format("Uniqueness filter missed more than %s times.", MAX_MISSES);
							throw new TooManyFilterMissesException(message);
						}
					}

				}
			}

		};
	}

}