001/*
002 * Licensed to the author under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package de.cuioss.test.generator.internal.net.java.quickcheck.generator.support;
018
019import static de.cuioss.tools.base.Preconditions.checkArgument;
020import static de.cuioss.tools.collect.CollectionLiterals.mutableList;
021import static java.util.Objects.requireNonNull;
022
023import java.util.Collection;
024import java.util.Collections;
025import java.util.HashSet;
026import java.util.List;
027import java.util.Set;
028
029import de.cuioss.test.generator.internal.net.java.quickcheck.Generator;
030
031public class SubsetGenerator<T> implements Generator<Set<T>> {
032
033    private final List<T> superset;
034    private final Generator<Integer> sizes;
035
036    public SubsetGenerator(Iterable<T> superset, Generator<Integer> size) {
037        requireNonNull(superset, "superset");
038        requireNonNull(size, "size");
039        this.superset = mutableList(superset);
040        this.sizes = size;
041    }
042
043    public SubsetGenerator(Iterable<T> superset) {
044        this(superset, new IntegerGenerator(0, mutableList(superset).size()));
045    }
046
047    @Override
048    public Set<T> next() {
049        Collections.shuffle(superset);
050        int size = sizes.next();
051        checkArgument(0 <= size);
052        checkArgument(maxSize(superset) >= size);
053        return new HashSet<>(superset.subList(0, size));
054    }
055
056    private static <T> int maxSize(Collection<T> superset) {
057        return superset.size();
058    }
059
060}