jgit/org.eclipse.jgit.test/tst/org/eclipse/jgit/diff/DiffTestDataGenerator.java

/*
 * Copyright (C) 2009, Christian Halstrick <christian.halstrick@sap.com>
 * and other copyright owners as documented in the project's IP log.
 *
 * This program and the accompanying materials are made available
 * under the terms of the Eclipse Distribution License v1.0 which
 * accompanies this distribution, is reproduced below, and is
 * available at http://www.eclipse.org/org/documents/edl-v10.php
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or
 * without modification, are permitted provided that the following
 * conditions are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 *
 * - Redistributions in binary form must reproduce the above
 *   copyright notice, this list of conditions and the following
 *   disclaimer in the documentation and/or other materials provided
 *   with the distribution.
 *
 * - Neither the name of the Eclipse Foundation, Inc. nor the
 *   names of its contributors may be used to endorse or promote
 *   products derived from this software without specific prior
 *   written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
 * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
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 */

package org.eclipse.jgit.diff;

public class DiffTestDataGenerator {
	/**
	 * Generate sequence of characters in ascending order. The first character
	 * is a space. All subsequent characters have an ASCII code one greater then
	 * the ASCII code of the preceding character. On exception: the character
	 * following which follows '~' is again a ' '.
	 *
	 * @param len
	 *            length of the String to be returned
	 * @return the sequence of characters as String
	 */
	public static String generateSequence(int len) {
		return generateSequence(len, 0, 0);
	}

	/**
	 * Generate sequence of characters similar to the one returned by
	 * {@link #generateSequence(int)}. But this time in each chunk of
	 * <skipPeriod> characters the last <skipLength> characters are left out. By
	 * calling this method twice with two different prime skipPeriod values and
	 * short skipLength values you create test data which is similar to what
	 * programmers do to their source code - huge files with only few
	 * insertions/deletions/changes.
	 *
	 * @param len
	 *            length of the String to be returned
	 * @param skipPeriod
	 * @param skipLength
	 * @return the sequence of characters as String
	 */
	public static String generateSequence(int len, int skipPeriod,
			int skipLength) {
		StringBuilder text = new StringBuilder(len);
		int skipStart = skipPeriod - skipLength;
		int skippedChars = 0;
		for (int i = 0; i - skippedChars < len; ++i) {
			if (skipPeriod == 0 || i % skipPeriod < skipStart) {
				text.append((char) (32 + i % 95));
			} else {
				skippedChars++;
			}
		}
		return text.toString();
	}
}