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1   /*
2    * Copyright (C) 2009-2010, Google Inc.
3    * and other copyright owners as documented in the project's IP log.
4    *
5    * This program and the accompanying materials are made available
6    * under the terms of the Eclipse Distribution License v1.0 which
7    * accompanies this distribution, is reproduced below, and is
8    * available at http://www.eclipse.org/org/documents/edl-v10.php
9    *
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13   * without modification, are permitted provided that the following
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15   *
16   * - Redistributions of source code must retain the above copyright
17   *   notice, this list of conditions and the following disclaimer.
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19   * - Redistributions in binary form must reproduce the above
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43  
44  package org.eclipse.jgit.util;
45  
46  import java.text.MessageFormat;
47  import java.util.Collection;
48  
49  import org.eclipse.jgit.internal.JGitText;
50  
51  /** Miscellaneous string comparison utility methods. */
52  public final class StringUtils {
53  	private static final char[] LC;
54  
55  	static {
56  		LC = new char['Z' + 1];
57  		for (char c = 0; c < LC.length; c++)
58  			LC[c] = c;
59  		for (char c = 'A'; c <= 'Z'; c++)
60  			LC[c] = (char) ('a' + (c - 'A'));
61  	}
62  
63  	/**
64  	 * Convert the input to lowercase.
65  	 * <p>
66  	 * This method does not honor the JVM locale, but instead always behaves as
67  	 * though it is in the US-ASCII locale. Only characters in the range 'A'
68  	 * through 'Z' are converted. All other characters are left as-is, even if
69  	 * they otherwise would have a lowercase character equivalent.
70  	 *
71  	 * @param c
72  	 *            the input character.
73  	 * @return lowercase version of the input.
74  	 */
75  	public static char toLowerCase(final char c) {
76  		return c <= 'Z' ? LC[c] : c;
77  	}
78  
79  	/**
80  	 * Convert the input string to lower case, according to the "C" locale.
81  	 * <p>
82  	 * This method does not honor the JVM locale, but instead always behaves as
83  	 * though it is in the US-ASCII locale. Only characters in the range 'A'
84  	 * through 'Z' are converted, all other characters are left as-is, even if
85  	 * they otherwise would have a lowercase character equivalent.
86  	 *
87  	 * @param in
88  	 *            the input string. Must not be null.
89  	 * @return a copy of the input string, after converting characters in the
90  	 *         range 'A'..'Z' to 'a'..'z'.
91  	 */
92  	public static String toLowerCase(final String in) {
93  		final StringBuilder r = new StringBuilder(in.length());
94  		for (int i = 0; i < in.length(); i++)
95  			r.append(toLowerCase(in.charAt(i)));
96  		return r.toString();
97  	}
98  
99  
100 	/**
101 	 * Borrowed from commons-lang <code>StringUtils.capitalize()</code> method.
102 	 *
103 	 * <p>
104 	 * Capitalizes a String changing the first letter to title case as per
105 	 * {@link Character#toTitleCase(char)}. No other letters are changed.
106 	 * </p>
107 	 *
108 	 * A <code>null</code> input String returns <code>null</code>.</p>
109 	 *
110 	 * @param str
111 	 *            the String to capitalize, may be null
112 	 * @return the capitalized String, <code>null</code> if null String input
113 	 * @since 4.0
114 	 */
115 	public static String capitalize(String str) {
116 		int strLen;
117 		if (str == null || (strLen = str.length()) == 0) {
118 			return str;
119 		}
120 		return new StringBuffer(strLen)
121 				.append(Character.toTitleCase(str.charAt(0)))
122 				.append(str.substring(1)).toString();
123 	}
124 
125 	/**
126 	 * Test if two strings are equal, ignoring case.
127 	 * <p>
128 	 * This method does not honor the JVM locale, but instead always behaves as
129 	 * though it is in the US-ASCII locale.
130 	 *
131 	 * @param a
132 	 *            first string to compare.
133 	 * @param b
134 	 *            second string to compare.
135 	 * @return true if a equals b
136 	 */
137 	public static boolean equalsIgnoreCase(final String a, final String b) {
138 		if (a == b)
139 			return true;
140 		if (a.length() != b.length())
141 			return false;
142 		for (int i = 0; i < a.length(); i++) {
143 			if (toLowerCase(a.charAt(i)) != toLowerCase(b.charAt(i)))
144 				return false;
145 		}
146 		return true;
147 	}
148 
149 	/**
150 	 * Compare two strings, ignoring case.
151 	 * <p>
152 	 * This method does not honor the JVM locale, but instead always behaves as
153 	 * though it is in the US-ASCII locale.
154 	 *
155 	 * @param a
156 	 *            first string to compare.
157 	 * @param b
158 	 *            second string to compare.
159 	 * @return negative, zero or positive if a sorts before, is equal to, or
160 	 *         sorts after b.
161 	 * @since 2.0
162 	 */
163 	public static int compareIgnoreCase(String a, String b) {
164 		for (int i = 0; i < a.length() && i < b.length(); i++) {
165 			int d = toLowerCase(a.charAt(i)) - toLowerCase(b.charAt(i));
166 			if (d != 0)
167 				return d;
168 		}
169 		return a.length() - b.length();
170 	}
171 
172 	/**
173 	 * Compare two strings, honoring case.
174 	 * <p>
175 	 * This method does not honor the JVM locale, but instead always behaves as
176 	 * though it is in the US-ASCII locale.
177 	 *
178 	 * @param a
179 	 *            first string to compare.
180 	 * @param b
181 	 *            second string to compare.
182 	 * @return negative, zero or positive if a sorts before, is equal to, or
183 	 *         sorts after b.
184 	 * @since 2.0
185 	 */
186 	public static int compareWithCase(String a, String b) {
187 		for (int i = 0; i < a.length() && i < b.length(); i++) {
188 			int d = a.charAt(i) - b.charAt(i);
189 			if (d != 0)
190 				return d;
191 		}
192 		return a.length() - b.length();
193 	}
194 
195 	/**
196 	 * Parse a string as a standard Git boolean value. See
197 	 * {@link #toBooleanOrNull(String)}.
198 	 *
199 	 * @param stringValue
200 	 *            the string to parse.
201 	 * @return the boolean interpretation of {@code value}.
202 	 * @throws IllegalArgumentException
203 	 *             if {@code value} is not recognized as one of the standard
204 	 *             boolean names.
205 	 */
206 	public static boolean toBoolean(final String stringValue) {
207 		if (stringValue == null)
208 			throw new NullPointerException(JGitText.get().expectedBooleanStringValue);
209 
210 		final Boolean bool = toBooleanOrNull(stringValue);
211 		if (bool == null)
212 			throw new IllegalArgumentException(MessageFormat.format(JGitText.get().notABoolean, stringValue));
213 
214 		return bool.booleanValue();
215 	}
216 
217 	/**
218 	 * Parse a string as a standard Git boolean value.
219 	 * <p>
220 	 * The terms {@code yes}, {@code true}, {@code 1}, {@code on} can all be
221 	 * used to mean {@code true}.
222 	 * <p>
223 	 * The terms {@code no}, {@code false}, {@code 0}, {@code off} can all be
224 	 * used to mean {@code false}.
225 	 * <p>
226 	 * Comparisons ignore case, via {@link #equalsIgnoreCase(String, String)}.
227 	 *
228 	 * @param stringValue
229 	 *            the string to parse.
230 	 * @return the boolean interpretation of {@code value} or null in case the
231 	 *         string does not represent a boolean value
232 	 */
233 	public static Boolean toBooleanOrNull(final String stringValue) {
234 		if (stringValue == null)
235 			return null;
236 
237 		if (equalsIgnoreCase("yes", stringValue) //$NON-NLS-1$
238 				|| equalsIgnoreCase("true", stringValue) //$NON-NLS-1$
239 				|| equalsIgnoreCase("1", stringValue) //$NON-NLS-1$
240 				|| equalsIgnoreCase("on", stringValue)) //$NON-NLS-1$
241 			return Boolean.TRUE;
242 		else if (equalsIgnoreCase("no", stringValue) //$NON-NLS-1$
243 				|| equalsIgnoreCase("false", stringValue) //$NON-NLS-1$
244 				|| equalsIgnoreCase("0", stringValue) //$NON-NLS-1$
245 				|| equalsIgnoreCase("off", stringValue)) //$NON-NLS-1$
246 			return Boolean.FALSE;
247 		else
248 			return null;
249 	}
250 
251 	/**
252 	 * Join a collection of Strings together using the specified separator.
253 	 *
254 	 * @param parts
255 	 *            Strings to join
256 	 * @param separator
257 	 *            used to join
258 	 * @return a String with all the joined parts
259 	 */
260 	public static String join(Collection<String> parts, String separator) {
261 		return StringUtils.join(parts, separator, separator);
262 	}
263 
264 	/**
265 	 * Join a collection of Strings together using the specified separator and a
266 	 * lastSeparator which is used for joining the second last and the last
267 	 * part.
268 	 *
269 	 * @param parts
270 	 *            Strings to join
271 	 * @param separator
272 	 *            separator used to join all but the two last elements
273 	 * @param lastSeparator
274 	 *            separator to use for joining the last two elements
275 	 * @return a String with all the joined parts
276 	 */
277 	public static String join(Collection<String> parts, String separator,
278 			String lastSeparator) {
279 		StringBuilder sb = new StringBuilder();
280 		int i = 0;
281 		int lastIndex = parts.size() - 1;
282 		for (String part : parts) {
283 			sb.append(part);
284 			if (i == lastIndex - 1) {
285 				sb.append(lastSeparator);
286 			} else if (i != lastIndex) {
287 				sb.append(separator);
288 			}
289 			i++;
290 		}
291 		return sb.toString();
292 	}
293 
294 	private StringUtils() {
295 		// Do not create instances
296 	}
297 
298 	/**
299 	 * Test if a string is empty or null.
300 	 *
301 	 * @param stringValue
302 	 *            the string to check
303 	 * @return <code>true</code> if the string is <code>null</code> or empty
304 	 */
305 	public static boolean isEmptyOrNull(String stringValue) {
306 		return stringValue == null || stringValue.length() == 0;
307 	}
308 
309 	/**
310 	 * Replace CRLF, CR or LF with a single space.
311 	 *
312 	 * @param in
313 	 *            A string with line breaks
314 	 * @return in without line breaks
315 	 * @since 3.1
316 	 */
317 	public static String replaceLineBreaksWithSpace(String in) {
318 		char[] buf = new char[in.length()];
319 		int o = 0;
320 		for (int i = 0; i < buf.length; ++i) {
321 			char ch = in.charAt(i);
322 			if (ch == '\r') {
323 				if (i + 1 < buf.length && in.charAt(i + 1) == '\n') {
324 					buf[o++] = ' ';
325 					++i;
326 				} else
327 					buf[o++] = ' ';
328 			} else if (ch == '\n')
329 				buf[o++] = ' ';
330 			else
331 				buf[o++] = ch;
332 		}
333 		return new String(buf, 0, o);
334 	}
335 }