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 java.util.Objects;
020
021import de.cuioss.test.generator.internal.net.java.quickcheck.Generator;
022import de.cuioss.tools.base.Preconditions;
023
024public class SubstringGenerator implements Generator<String> {
025
026    private final String superstring;
027    private final Generator<Integer> sizes;
028
029    public SubstringGenerator(String superstring, int minSize, int maxSize) {
030        Objects.requireNonNull(superstring, "superstring");
031        Preconditions.checkArgument(minSize >= 0);
032        Preconditions.checkArgument(superstring.length() >= maxSize);
033        this.superstring = superstring;
034        this.sizes = new IntegerGenerator(minSize, maxSize);
035    }
036
037    @Override
038    public String next() {
039        int size = sizes.next();
040        int space = superstring.length() - size;
041        assert space >= 0;
042        Integer offset = new IntegerGenerator(0, space).next();
043        String substring = superstring.substring(offset, offset + size);
044        assert substring.length() == size;
045        return substring;
046    }
047}