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    * and other copyright owners as documented in the project's IP log.
    *
    * This program and the accompanying materials are made available
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    * available at http://www.eclipse.org/org/documents/edl-v10.php
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  package org.eclipse.jgit.util;
  
  import java.text.MessageFormat;
  import java.util.Collection;
  
  import org.eclipse.jgit.internal.JGitText;
  
  /** Miscellaneous string comparison utility methods. */
  public final class StringUtils {
  	private static final char[] LC;
  
  	static {
  		LC = new char['Z' + 1];
  		for (char c = 0; c < LC.length; c++)
  			LC[c] = c;
  		for (char c = 'A'; c <= 'Z'; c++)
  			LC[c] = (char) ('a' + (c - 'A'));
  	}
  
  	/**
  	 * Convert the input to lowercase.
  	 * <p>
  	 * This method does not honor the JVM locale, but instead always behaves as
  	 * though it is in the US-ASCII locale. Only characters in the range 'A'
  	 * through 'Z' are converted. All other characters are left as-is, even if
  	 * they otherwise would have a lowercase character equivalent.
  	 *
  	 * @param c
  	 *            the input character.
  	 * @return lowercase version of the input.
  	 */
  	public static char toLowerCase(final char c) {
  		return c <= 'Z' ? LC[c] : c;
  	}
  
  	/**
  	 * Convert the input string to lower case, according to the "C" locale.
  	 * <p>
  	 * This method does not honor the JVM locale, but instead always behaves as
  	 * though it is in the US-ASCII locale. Only characters in the range 'A'
  	 * through 'Z' are converted, all other characters are left as-is, even if
  	 * they otherwise would have a lowercase character equivalent.
  	 *
  	 * @param in
  	 *            the input string. Must not be null.
  	 * @return a copy of the input string, after converting characters in the
  	 *         range 'A'..'Z' to 'a'..'z'.
  	 */
  	public static String toLowerCase(final String in) {
  		final StringBuilder r = new StringBuilder(in.length());
  		for (int i = 0; i < in.length(); i++)
  			r.append(toLowerCase(in.charAt(i)));
  		return r.toString();
  	}
  
  
 	/**
 	 * Borrowed from commons-lang <code>StringUtils.capitalize()</code> method.
 	 *
 	 * <p>
 	 * Capitalizes a String changing the first letter to title case as per
 	 * {@link Character#toTitleCase(char)}. No other letters are changed.
 	 * </p>
 	 *
 	 * A <code>null</code> input String returns <code>null</code>.</p>
 	 *
 	 * @param str
 	 *            the String to capitalize, may be null
 	 * @return the capitalized String, <code>null</code> if null String input
 	 * @since 4.0
 	 */
 	public static String capitalize(String str) {
 		int strLen;
 		if (str == null || (strLen = str.length()) == 0) {
 			return str;
 		}
 		return new StringBuffer(strLen)
 				.append(Character.toTitleCase(str.charAt(0)))
 				.append(str.substring(1)).toString();
 	}
 
 	/**
 	 * Test if two strings are equal, ignoring case.
 	 * <p>
 	 * This method does not honor the JVM locale, but instead always behaves as
 	 * though it is in the US-ASCII locale.
 	 *
 	 * @param a
 	 *            first string to compare.
 	 * @param b
 	 *            second string to compare.
 	 * @return true if a equals b
 	 */
 	public static boolean equalsIgnoreCase(final String a, final String b) {
 		if (a == b)
 			return true;
 		if (a.length() != b.length())
 			return false;
 		for (int i = 0; i < a.length(); i++) {
 			if (toLowerCase(a.charAt(i)) != toLowerCase(b.charAt(i)))
 				return false;
 		}
 		return true;
 	}
 
 	/**
 	 * Compare two strings, ignoring case.
 	 * <p>
 	 * This method does not honor the JVM locale, but instead always behaves as
 	 * though it is in the US-ASCII locale.
 	 *
 	 * @param a
 	 *            first string to compare.
 	 * @param b
 	 *            second string to compare.
 	 * @return negative, zero or positive if a sorts before, is equal to, or
 	 *         sorts after b.
 	 * @since 2.0
 	 */
 	public static int compareIgnoreCase(String a, String b) {
 		for (int i = 0; i < a.length() && i < b.length(); i++) {
 			int d = toLowerCase(a.charAt(i)) - toLowerCase(b.charAt(i));
 			if (d != 0)
 				return d;
 		}
 		return a.length() - b.length();
 	}
 
 	/**
 	 * Compare two strings, honoring case.
 	 * <p>
 	 * This method does not honor the JVM locale, but instead always behaves as
 	 * though it is in the US-ASCII locale.
 	 *
 	 * @param a
 	 *            first string to compare.
 	 * @param b
 	 *            second string to compare.
 	 * @return negative, zero or positive if a sorts before, is equal to, or
 	 *         sorts after b.
 	 * @since 2.0
 	 */
 	public static int compareWithCase(String a, String b) {
 		for (int i = 0; i < a.length() && i < b.length(); i++) {
 			int d = a.charAt(i) - b.charAt(i);
 			if (d != 0)
 				return d;
 		}
 		return a.length() - b.length();
 	}
 
 	/**
 	 * Parse a string as a standard Git boolean value. See
 	 * {@link #toBooleanOrNull(String)}.
 	 *
 	 * @param stringValue
 	 *            the string to parse.
 	 * @return the boolean interpretation of {@code value}.
 	 * @throws IllegalArgumentException
 	 *             if {@code value} is not recognized as one of the standard
 	 *             boolean names.
 	 */
 	public static boolean toBoolean(final String stringValue) {
 		if (stringValue == null)
 			throw new NullPointerException(JGitText.get().expectedBooleanStringValue);
 
 		final Boolean bool = toBooleanOrNull(stringValue);
 		if (bool == null)
 			throw new IllegalArgumentException(MessageFormat.format(JGitText.get().notABoolean, stringValue));
 
 		return bool.booleanValue();
 	}
 
 	/**
 	 * Parse a string as a standard Git boolean value.
 	 * <p>
 	 * The terms {@code yes}, {@code true}, {@code 1}, {@code on} can all be
 	 * used to mean {@code true}.
 	 * <p>
 	 * The terms {@code no}, {@code false}, {@code 0}, {@code off} can all be
 	 * used to mean {@code false}.
 	 * <p>
 	 * Comparisons ignore case, via {@link #equalsIgnoreCase(String, String)}.
 	 *
 	 * @param stringValue
 	 *            the string to parse.
 	 * @return the boolean interpretation of {@code value} or null in case the
 	 *         string does not represent a boolean value
 	 */
 	public static Boolean toBooleanOrNull(final String stringValue) {
 		if (stringValue == null)
 			return null;
 
 		if (equalsIgnoreCase("yes", stringValue) //$NON-NLS-1$
 				|| equalsIgnoreCase("true", stringValue) //$NON-NLS-1$
 				|| equalsIgnoreCase("1", stringValue) //$NON-NLS-1$
 				|| equalsIgnoreCase("on", stringValue)) //$NON-NLS-1$
 			return Boolean.TRUE;
 		else if (equalsIgnoreCase("no", stringValue) //$NON-NLS-1$
 				|| equalsIgnoreCase("false", stringValue) //$NON-NLS-1$
 				|| equalsIgnoreCase("0", stringValue) //$NON-NLS-1$
 				|| equalsIgnoreCase("off", stringValue)) //$NON-NLS-1$
 			return Boolean.FALSE;
 		else
 			return null;
 	}
 
 	/**
 	 * Join a collection of Strings together using the specified separator.
 	 *
 	 * @param parts
 	 *            Strings to join
 	 * @param separator
 	 *            used to join
 	 * @return a String with all the joined parts
 	 */
 	public static String join(Collection<String> parts, String separator) {
 		return StringUtils.join(parts, separator, separator);
 	}
 
 	/**
 	 * Join a collection of Strings together using the specified separator and a
 	 * lastSeparator which is used for joining the second last and the last
 	 * part.
 	 *
 	 * @param parts
 	 *            Strings to join
 	 * @param separator
 	 *            separator used to join all but the two last elements
 	 * @param lastSeparator
 	 *            separator to use for joining the last two elements
 	 * @return a String with all the joined parts
 	 */
 	public static String join(Collection<String> parts, String separator,
 			String lastSeparator) {
 		StringBuilder sb = new StringBuilder();
 		int i = 0;
 		int lastIndex = parts.size() - 1;
 		for (String part : parts) {
 			sb.append(part);
 			if (i == lastIndex - 1) {
 				sb.append(lastSeparator);
 			} else if (i != lastIndex) {
 				sb.append(separator);
 			}
 			i++;
 		}
 		return sb.toString();
 	}
 
 	private StringUtils() {
 		// Do not create instances
 	}
 
 	/**
 	 * Test if a string is empty or null.
 	 *
 	 * @param stringValue
 	 *            the string to check
 	 * @return <code>true</code> if the string is <code>null</code> or empty
 	 */
 	public static boolean isEmptyOrNull(String stringValue) {
 		return stringValue == null || stringValue.length() == 0;
 	}
 
 	/**
 	 * Replace CRLF, CR or LF with a single space.
 	 *
 	 * @param in
 	 *            A string with line breaks
 	 * @return in without line breaks
 	 * @since 3.1
 	 */
 	public static String replaceLineBreaksWithSpace(String in) {
 		char[] buf = new char[in.length()];
 		int o = 0;
 		for (int i = 0; i < buf.length; ++i) {
 			char ch = in.charAt(i);
 			if (ch == '\r') {
 				if (i + 1 < buf.length && in.charAt(i + 1) == '\n') {
 					buf[o++] = ' ';
 					++i;
 				} else
 					buf[o++] = ' ';
 			} else if (ch == '\n')
 				buf[o++] = ' ';
 			else
 				buf[o++] = ch;
 		}
 		return new String(buf, 0, o);
 	}
 }