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| 1 | +/* | |
| 2 | + * Copyright (c) 1994, 2004, Oracle and/or its affiliates. All rights reserved. | |
| 3 | + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. | |
| 4 | + * | |
| 5 | + * This code is free software; you can redistribute it and/or modify it | |
| 6 | + * under the terms of the GNU General Public License version 2 only, as | |
| 7 | + * published by the Free Software Foundation. Oracle designates this | |
| 8 | + * particular file as subject to the "Classpath" exception as provided | |
| 9 | + * by Oracle in the LICENSE file that accompanied this code. | |
| 10 | + * | |
| 11 | + * This code is distributed in the hope that it will be useful, but WITHOUT | |
| 12 | + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
| 13 | + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
| 14 | + * version 2 for more details (a copy is included in the LICENSE file that | |
| 15 | + * accompanied this code). | |
| 16 | + * | |
| 17 | + * You should have received a copy of the GNU General Public License version | |
| 18 | + * 2 along with this work; if not, write to the Free Software Foundation, | |
| 19 | + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | |
| 20 | + * | |
| 21 | + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA | |
| 22 | + * or visit www.oracle.com if you need additional information or have any | |
| 23 | + * questions. | |
| 24 | + */ | |
| 25 | + | |
| 26 | +package java.util; | |
| 27 | + | |
| 28 | +import java.lang.*; | |
| 29 | + | |
| 30 | +/** | |
| 31 | + * The string tokenizer class allows an application to break a | |
| 32 | + * string into tokens. The tokenization method is much simpler than | |
| 33 | + * the one used by the <code>StreamTokenizer</code> class. The | |
| 34 | + * <code>StringTokenizer</code> methods do not distinguish among | |
| 35 | + * identifiers, numbers, and quoted strings, nor do they recognize | |
| 36 | + * and skip comments. | |
| 37 | + * <p> | |
| 38 | + * The set of delimiters (the characters that separate tokens) may | |
| 39 | + * be specified either at creation time or on a per-token basis. | |
| 40 | + * <p> | |
| 41 | + * An instance of <code>StringTokenizer</code> behaves in one of two | |
| 42 | + * ways, depending on whether it was created with the | |
| 43 | + * <code>returnDelims</code> flag having the value <code>true</code> | |
| 44 | + * or <code>false</code>: | |
| 45 | + * <ul> | |
| 46 | + * <li>If the flag is <code>false</code>, delimiter characters serve to | |
| 47 | + * separate tokens. A token is a maximal sequence of consecutive | |
| 48 | + * characters that are not delimiters. | |
| 49 | + * <li>If the flag is <code>true</code>, delimiter characters are themselves | |
| 50 | + * considered to be tokens. A token is thus either one delimiter | |
| 51 | + * character, or a maximal sequence of consecutive characters that are | |
| 52 | + * not delimiters. | |
| 53 | + * </ul><p> | |
| 54 | + * A <tt>StringTokenizer</tt> object internally maintains a current | |
| 55 | + * position within the string to be tokenized. Some operations advance this | |
| 56 | + * current position past the characters processed.<p> | |
| 57 | + * A token is returned by taking a substring of the string that was used to | |
| 58 | + * create the <tt>StringTokenizer</tt> object. | |
| 59 | + * <p> | |
| 60 | + * The following is one example of the use of the tokenizer. The code: | |
| 61 | + * <blockquote><pre> | |
| 62 | + * StringTokenizer st = new StringTokenizer("this is a test"); | |
| 63 | + * while (st.hasMoreTokens()) { | |
| 64 | + * System.out.println(st.nextToken()); | |
| 65 | + * } | |
| 66 | + * </pre></blockquote> | |
| 67 | + * <p> | |
| 68 | + * prints the following output: | |
| 69 | + * <blockquote><pre> | |
| 70 | + * this | |
| 71 | + * is | |
| 72 | + * a | |
| 73 | + * test | |
| 74 | + * </pre></blockquote> | |
| 75 | + * | |
| 76 | + * <p> | |
| 77 | + * <tt>StringTokenizer</tt> is a legacy class that is retained for | |
| 78 | + * compatibility reasons although its use is discouraged in new code. It is | |
| 79 | + * recommended that anyone seeking this functionality use the <tt>split</tt> | |
| 80 | + * method of <tt>String</tt> or the java.util.regex package instead. | |
| 81 | + * <p> | |
| 82 | + * The following example illustrates how the <tt>String.split</tt> | |
| 83 | + * method can be used to break up a string into its basic tokens: | |
| 84 | + * <blockquote><pre> | |
| 85 | + * String[] result = "this is a test".split("\\s"); | |
| 86 | + * for (int x=0; x<result.length; x++) | |
| 87 | + * System.out.println(result[x]); | |
| 88 | + * </pre></blockquote> | |
| 89 | + * <p> | |
| 90 | + * prints the following output: | |
| 91 | + * <blockquote><pre> | |
| 92 | + * this | |
| 93 | + * is | |
| 94 | + * a | |
| 95 | + * test | |
| 96 | + * </pre></blockquote> | |
| 97 | + * | |
| 98 | + * @author unascribed | |
| 99 | + * @see java.io.StreamTokenizer | |
| 100 | + * @since JDK1.0 | |
| 101 | + */ | |
| 102 | +public | |
| 103 | +class StringTokenizer implements Enumeration<Object> { | |
| 104 | + private int currentPosition; | |
| 105 | + private int newPosition; | |
| 106 | + private int maxPosition; | |
| 107 | + private String str; | |
| 108 | + private String delimiters; | |
| 109 | + private boolean retDelims; | |
| 110 | + private boolean delimsChanged; | |
| 111 | + | |
| 112 | + /** | |
| 113 | + * maxDelimCodePoint stores the value of the delimiter character with the | |
| 114 | + * highest value. It is used to optimize the detection of delimiter | |
| 115 | + * characters. | |
| 116 | + * | |
| 117 | + * It is unlikely to provide any optimization benefit in the | |
| 118 | + * hasSurrogates case because most string characters will be | |
| 119 | + * smaller than the limit, but we keep it so that the two code | |
| 120 | + * paths remain similar. | |
| 121 | + */ | |
| 122 | + private int maxDelimCodePoint; | |
| 123 | + | |
| 124 | + /** | |
| 125 | + * If delimiters include any surrogates (including surrogate | |
| 126 | + * pairs), hasSurrogates is true and the tokenizer uses the | |
| 127 | + * different code path. This is because String.indexOf(int) | |
| 128 | + * doesn't handle unpaired surrogates as a single character. | |
| 129 | + */ | |
| 130 | + private boolean hasSurrogates = false; | |
| 131 | + | |
| 132 | + /** | |
| 133 | + * When hasSurrogates is true, delimiters are converted to code | |
| 134 | + * points and isDelimiter(int) is used to determine if the given | |
| 135 | + * codepoint is a delimiter. | |
| 136 | + */ | |
| 137 | + private int[] delimiterCodePoints; | |
| 138 | + | |
| 139 | + /** | |
| 140 | + * Set maxDelimCodePoint to the highest char in the delimiter set. | |
| 141 | + */ | |
| 142 | + private void setMaxDelimCodePoint() { | |
| 143 | + if (delimiters == null) { | |
| 144 | + maxDelimCodePoint = 0; | |
| 145 | + return; | |
| 146 | + } | |
| 147 | + | |
| 148 | + int m = 0; | |
| 149 | + int c; | |
| 150 | + int count = 0; | |
| 151 | + for (int i = 0; i < delimiters.length(); i += Character.charCount(c)) { | |
| 152 | + c = delimiters.charAt(i); | |
| 153 | + if (c >= Character.MIN_HIGH_SURROGATE && c <= Character.MAX_LOW_SURROGATE) { | |
| 154 | + c = delimiters.codePointAt(i); | |
| 155 | + hasSurrogates = true; | |
| 156 | + } | |
| 157 | + if (m < c) | |
| 158 | + m = c; | |
| 159 | + count++; | |
| 160 | + } | |
| 161 | + maxDelimCodePoint = m; | |
| 162 | + | |
| 163 | + if (hasSurrogates) { | |
| 164 | + delimiterCodePoints = new int[count]; | |
| 165 | + for (int i = 0, j = 0; i < count; i++, j += Character.charCount(c)) { | |
| 166 | + c = delimiters.codePointAt(j); | |
| 167 | + delimiterCodePoints[i] = c; | |
| 168 | + } | |
| 169 | + } | |
| 170 | + } | |
| 171 | + | |
| 172 | + /** | |
| 173 | + * Constructs a string tokenizer for the specified string. All | |
| 174 | + * characters in the <code>delim</code> argument are the delimiters | |
| 175 | + * for separating tokens. | |
| 176 | + * <p> | |
| 177 | + * If the <code>returnDelims</code> flag is <code>true</code>, then | |
| 178 | + * the delimiter characters are also returned as tokens. Each | |
| 179 | + * delimiter is returned as a string of length one. If the flag is | |
| 180 | + * <code>false</code>, the delimiter characters are skipped and only | |
| 181 | + * serve as separators between tokens. | |
| 182 | + * <p> | |
| 183 | + * Note that if <tt>delim</tt> is <tt>null</tt>, this constructor does | |
| 184 | + * not throw an exception. However, trying to invoke other methods on the | |
| 185 | + * resulting <tt>StringTokenizer</tt> may result in a | |
| 186 | + * <tt>NullPointerException</tt>. | |
| 187 | + * | |
| 188 | + * @param str a string to be parsed. | |
| 189 | + * @param delim the delimiters. | |
| 190 | + * @param returnDelims flag indicating whether to return the delimiters | |
| 191 | + * as tokens. | |
| 192 | + * @exception NullPointerException if str is <CODE>null</CODE> | |
| 193 | + */ | |
| 194 | + public StringTokenizer(String str, String delim, boolean returnDelims) { | |
| 195 | + currentPosition = 0; | |
| 196 | + newPosition = -1; | |
| 197 | + delimsChanged = false; | |
| 198 | + this.str = str; | |
| 199 | + maxPosition = str.length(); | |
| 200 | + delimiters = delim; | |
| 201 | + retDelims = returnDelims; | |
| 202 | + setMaxDelimCodePoint(); | |
| 203 | + } | |
| 204 | + | |
| 205 | + /** | |
| 206 | + * Constructs a string tokenizer for the specified string. The | |
| 207 | + * characters in the <code>delim</code> argument are the delimiters | |
| 208 | + * for separating tokens. Delimiter characters themselves will not | |
| 209 | + * be treated as tokens. | |
| 210 | + * <p> | |
| 211 | + * Note that if <tt>delim</tt> is <tt>null</tt>, this constructor does | |
| 212 | + * not throw an exception. However, trying to invoke other methods on the | |
| 213 | + * resulting <tt>StringTokenizer</tt> may result in a | |
| 214 | + * <tt>NullPointerException</tt>. | |
| 215 | + * | |
| 216 | + * @param str a string to be parsed. | |
| 217 | + * @param delim the delimiters. | |
| 218 | + * @exception NullPointerException if str is <CODE>null</CODE> | |
| 219 | + */ | |
| 220 | + public StringTokenizer(String str, String delim) { | |
| 221 | + this(str, delim, false); | |
| 222 | + } | |
| 223 | + | |
| 224 | + /** | |
| 225 | + * Constructs a string tokenizer for the specified string. The | |
| 226 | + * tokenizer uses the default delimiter set, which is | |
| 227 | + * <code>" \t\n\r\f"</code>: the space character, | |
| 228 | + * the tab character, the newline character, the carriage-return character, | |
| 229 | + * and the form-feed character. Delimiter characters themselves will | |
| 230 | + * not be treated as tokens. | |
| 231 | + * | |
| 232 | + * @param str a string to be parsed. | |
| 233 | + * @exception NullPointerException if str is <CODE>null</CODE> | |
| 234 | + */ | |
| 235 | + public StringTokenizer(String str) { | |
| 236 | + this(str, " \t\n\r\f", false); | |
| 237 | + } | |
| 238 | + | |
| 239 | + /** | |
| 240 | + * Skips delimiters starting from the specified position. If retDelims | |
| 241 | + * is false, returns the index of the first non-delimiter character at or | |
| 242 | + * after startPos. If retDelims is true, startPos is returned. | |
| 243 | + */ | |
| 244 | + private int skipDelimiters(int startPos) { | |
| 245 | + if (delimiters == null) | |
| 246 | + throw new NullPointerException(); | |
| 247 | + | |
| 248 | + int position = startPos; | |
| 249 | + while (!retDelims && position < maxPosition) { | |
| 250 | + if (!hasSurrogates) { | |
| 251 | + char c = str.charAt(position); | |
| 252 | + if ((c > maxDelimCodePoint) || (delimiters.indexOf(c) < 0)) | |
| 253 | + break; | |
| 254 | + position++; | |
| 255 | + } else { | |
| 256 | + int c = str.codePointAt(position); | |
| 257 | + if ((c > maxDelimCodePoint) || !isDelimiter(c)) { | |
| 258 | + break; | |
| 259 | + } | |
| 260 | + position += Character.charCount(c); | |
| 261 | + } | |
| 262 | + } | |
| 263 | + return position; | |
| 264 | + } | |
| 265 | + | |
| 266 | + /** | |
| 267 | + * Skips ahead from startPos and returns the index of the next delimiter | |
| 268 | + * character encountered, or maxPosition if no such delimiter is found. | |
| 269 | + */ | |
| 270 | + private int scanToken(int startPos) { | |
| 271 | + int position = startPos; | |
| 272 | + while (position < maxPosition) { | |
| 273 | + if (!hasSurrogates) { | |
| 274 | + char c = str.charAt(position); | |
| 275 | + if ((c <= maxDelimCodePoint) && (delimiters.indexOf(c) >= 0)) | |
| 276 | + break; | |
| 277 | + position++; | |
| 278 | + } else { | |
| 279 | + int c = str.codePointAt(position); | |
| 280 | + if ((c <= maxDelimCodePoint) && isDelimiter(c)) | |
| 281 | + break; | |
| 282 | + position += Character.charCount(c); | |
| 283 | + } | |
| 284 | + } | |
| 285 | + if (retDelims && (startPos == position)) { | |
| 286 | + if (!hasSurrogates) { | |
| 287 | + char c = str.charAt(position); | |
| 288 | + if ((c <= maxDelimCodePoint) && (delimiters.indexOf(c) >= 0)) | |
| 289 | + position++; | |
| 290 | + } else { | |
| 291 | + int c = str.codePointAt(position); | |
| 292 | + if ((c <= maxDelimCodePoint) && isDelimiter(c)) | |
| 293 | + position += Character.charCount(c); | |
| 294 | + } | |
| 295 | + } | |
| 296 | + return position; | |
| 297 | + } | |
| 298 | + | |
| 299 | + private boolean isDelimiter(int codePoint) { | |
| 300 | + for (int i = 0; i < delimiterCodePoints.length; i++) { | |
| 301 | + if (delimiterCodePoints[i] == codePoint) { | |
| 302 | + return true; | |
| 303 | + } | |
| 304 | + } | |
| 305 | + return false; | |
| 306 | + } | |
| 307 | + | |
| 308 | + /** | |
| 309 | + * Tests if there are more tokens available from this tokenizer's string. | |
| 310 | + * If this method returns <tt>true</tt>, then a subsequent call to | |
| 311 | + * <tt>nextToken</tt> with no argument will successfully return a token. | |
| 312 | + * | |
| 313 | + * @return <code>true</code> if and only if there is at least one token | |
| 314 | + * in the string after the current position; <code>false</code> | |
| 315 | + * otherwise. | |
| 316 | + */ | |
| 317 | + public boolean hasMoreTokens() { | |
| 318 | + /* | |
| 319 | + * Temporarily store this position and use it in the following | |
| 320 | + * nextToken() method only if the delimiters haven't been changed in | |
| 321 | + * that nextToken() invocation. | |
| 322 | + */ | |
| 323 | + newPosition = skipDelimiters(currentPosition); | |
| 324 | + return (newPosition < maxPosition); | |
| 325 | + } | |
| 326 | + | |
| 327 | + /** | |
| 328 | + * Returns the next token from this string tokenizer. | |
| 329 | + * | |
| 330 | + * @return the next token from this string tokenizer. | |
| 331 | + * @exception NoSuchElementException if there are no more tokens in this | |
| 332 | + * tokenizer's string. | |
| 333 | + */ | |
| 334 | + public String nextToken() { | |
| 335 | + /* | |
| 336 | + * If next position already computed in hasMoreElements() and | |
| 337 | + * delimiters have changed between the computation and this invocation, | |
| 338 | + * then use the computed value. | |
| 339 | + */ | |
| 340 | + | |
| 341 | + currentPosition = (newPosition >= 0 && !delimsChanged) ? | |
| 342 | + newPosition : skipDelimiters(currentPosition); | |
| 343 | + | |
| 344 | + /* Reset these anyway */ | |
| 345 | + delimsChanged = false; | |
| 346 | + newPosition = -1; | |
| 347 | + | |
| 348 | + if (currentPosition >= maxPosition) | |
| 349 | + throw new NoSuchElementException(); | |
| 350 | + int start = currentPosition; | |
| 351 | + currentPosition = scanToken(currentPosition); | |
| 352 | + return str.substring(start, currentPosition); | |
| 353 | + } | |
| 354 | + | |
| 355 | + /** | |
| 356 | + * Returns the next token in this string tokenizer's string. First, | |
| 357 | + * the set of characters considered to be delimiters by this | |
| 358 | + * <tt>StringTokenizer</tt> object is changed to be the characters in | |
| 359 | + * the string <tt>delim</tt>. Then the next token in the string | |
| 360 | + * after the current position is returned. The current position is | |
| 361 | + * advanced beyond the recognized token. The new delimiter set | |
| 362 | + * remains the default after this call. | |
| 363 | + * | |
| 364 | + * @param delim the new delimiters. | |
| 365 | + * @return the next token, after switching to the new delimiter set. | |
| 366 | + * @exception NoSuchElementException if there are no more tokens in this | |
| 367 | + * tokenizer's string. | |
| 368 | + * @exception NullPointerException if delim is <CODE>null</CODE> | |
| 369 | + */ | |
| 370 | + public String nextToken(String delim) { | |
| 371 | + delimiters = delim; | |
| 372 | + | |
| 373 | + /* delimiter string specified, so set the appropriate flag. */ | |
| 374 | + delimsChanged = true; | |
| 375 | + | |
| 376 | + setMaxDelimCodePoint(); | |
| 377 | + return nextToken(); | |
| 378 | + } | |
| 379 | + | |
| 380 | + /** | |
| 381 | + * Returns the same value as the <code>hasMoreTokens</code> | |
| 382 | + * method. It exists so that this class can implement the | |
| 383 | + * <code>Enumeration</code> interface. | |
| 384 | + * | |
| 385 | + * @return <code>true</code> if there are more tokens; | |
| 386 | + * <code>false</code> otherwise. | |
| 387 | + * @see java.util.Enumeration | |
| 388 | + * @see java.util.StringTokenizer#hasMoreTokens() | |
| 389 | + */ | |
| 390 | + public boolean hasMoreElements() { | |
| 391 | + return hasMoreTokens(); | |
| 392 | + } | |
| 393 | + | |
| 394 | + /** | |
| 395 | + * Returns the same value as the <code>nextToken</code> method, | |
| 396 | + * except that its declared return value is <code>Object</code> rather than | |
| 397 | + * <code>String</code>. It exists so that this class can implement the | |
| 398 | + * <code>Enumeration</code> interface. | |
| 399 | + * | |
| 400 | + * @return the next token in the string. | |
| 401 | + * @exception NoSuchElementException if there are no more tokens in this | |
| 402 | + * tokenizer's string. | |
| 403 | + * @see java.util.Enumeration | |
| 404 | + * @see java.util.StringTokenizer#nextToken() | |
| 405 | + */ | |
| 406 | + public Object nextElement() { | |
| 407 | + return nextToken(); | |
| 408 | + } | |
| 409 | + | |
| 410 | + /** | |
| 411 | + * Calculates the number of times that this tokenizer's | |
| 412 | + * <code>nextToken</code> method can be called before it generates an | |
| 413 | + * exception. The current position is not advanced. | |
| 414 | + * | |
| 415 | + * @return the number of tokens remaining in the string using the current | |
| 416 | + * delimiter set. | |
| 417 | + * @see java.util.StringTokenizer#nextToken() | |
| 418 | + */ | |
| 419 | + public int countTokens() { | |
| 420 | + int count = 0; | |
| 421 | + int currpos = currentPosition; | |
| 422 | + while (currpos < maxPosition) { | |
| 423 | + currpos = skipDelimiters(currpos); | |
| 424 | + if (currpos >= maxPosition) | |
| 425 | + break; | |
| 426 | + currpos = scanToken(currpos); | |
| 427 | + count++; | |
| 428 | + } | |
| 429 | + return count; | |
| 430 | + } | |
| 431 | +} | |