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
027/**
028 * A {@link ValueGenerator} which generates a sequence of long values. By default, the sequence starts at 1 and
029 * increments by 1, but this can be customized. Instances of this class are created using
030 * {@link ValueGenerators#sequence()}.
031 * @author JB Nizet
032 */
033public final class SequenceValueGenerator implements ValueGenerator<Long> {
034
035    private long next = 1L;
036    private int increment = 1;
037
038    SequenceValueGenerator() {
039        this(1, 1);
040    }
041
042    private SequenceValueGenerator(long start, int increment) {
043        this.next = start;
044        this.increment = increment;
045    }
046
047    /**
048     * Restarts the sequence at the given value
049     * @param start the starting value of the created generator
050     * @return this instance, for chaining
051     */
052    public SequenceValueGenerator startingAt(long start) {
053        this.next = start;
054        return this;
055    }
056
057    /**
058     * Increments the value by the given increment.
059     * @return this instance, for chaining
060     */
061    public SequenceValueGenerator incrementingBy(int increment) {
062        this.increment = increment;
063        return this;
064    }
065
066    @Override
067    public Long nextValue() {
068        long result = next;
069        next += increment;
070        return result;
071    }
072
073    @Override
074    public String toString() {
075        return "SequenceValueGenerator["
076               + "next="
077               + next
078               + ", increment="
079               + increment
080               + "]";
081    }
082}