001/*
002 * The MIT License
003 *
004 * Copyright (c) 2013, Ninja Squad
005 *
006 * Permission is hereby granted, free of charge, to any person obtaining a copy
007 * of this software and associated documentation files (the "Software"), to deal
008 * in the Software without restriction, including without limitation the rights
009 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
010 * copies of the Software, and to permit persons to whom the Software is
011 * furnished to do so, subject to the following conditions:
012 *
013 * The above copyright notice and this permission notice shall be included in
014 * all copies or substantial portions of the Software.
015 *
016 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
017 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
018 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
019 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
020 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
021 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
022 * THE SOFTWARE.
023 */
024
025package com.ninja_squad.dbsetup.generator;
026
027import com.ninja_squad.dbsetup.util.Preconditions;
028
029import javax.annotation.Nonnull;
030import javax.annotation.Nullable;
031
032/**
033 * Utility class containing factory methods for {@link ValueGenerator}
034 * @author JB Nizet
035 */
036public final class ValueGenerators {
037    private ValueGenerators() {
038    }
039
040    /**
041     * Returns a value generator which generates a sequence of long values starting with 1, with an increment of 1.
042     * The starting value and increment can be customized using
043     * <pre>
044     *     ValueGenerators.increment().startingAt(1000).incrementingBy(5)
045     * </pre>
046     */
047    public static SequenceValueGenerator sequence() {
048        return new SequenceValueGenerator();
049    }
050
051    /**
052     * Returns a value generator which always returns the same, given value.
053     */
054    public static <T> ValueGenerator<T> constant(@Nullable final T constant) {
055        return new ValueGenerator<T>() {
056            @Override
057            public T nextValue() {
058                return constant;
059            }
060
061            @Override
062            public String toString() {
063                return "ValueGenerators.constant(" + constant + ")";
064            }
065        };
066    }
067
068    /**
069     * Returns a value generator that returns a string prefix followed by a sequence number, optionally left-padded
070     * with 0 to ensure a correct ordering (for example: CODE_001, CODE_002, etc.). The returned generator starts the
071     * sequence at 1 and increments by 1, and doesn't pad the numbers.
072     * @param prefix the prefix before the generated number (for example: <code>"CODE_"</code>).
073     */
074    public static StringSequenceValueGenerator stringSequence(@Nonnull String prefix) {
075        Preconditions.checkNotNull(prefix, "prefix may not be null");
076        return new StringSequenceValueGenerator(prefix);
077    }
078
079    /**
080     * Returns a value generator that returns a sequence of dates, starting at a given date and incremented by a given
081     * time, specified as an increment and a calendar field. The returned generator starts today at 00:00:00
082     * and increments by 1 day by default.
083     */
084    public static DateSequenceValueGenerator dateSequence() {
085        return new DateSequenceValueGenerator();
086    }
087}