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1: /* BreakIterator.java -- Breaks text into elements 2: Copyright (C) 1998, 1999, 2001, 2004, 2005 Free Software Foundation, Inc. 3: 4: This file is part of GNU Classpath. 5: 6: GNU Classpath is free software; you can redistribute it and/or modify 7: it under the terms of the GNU General Public License as published by 8: the Free Software Foundation; either version 2, or (at your option) 9: any later version. 10: 11: GNU Classpath is distributed in the hope that it will be useful, but 12: WITHOUT ANY WARRANTY; without even the implied warranty of 13: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14: General Public License for more details. 15: 16: You should have received a copy of the GNU General Public License 17: along with GNU Classpath; see the file COPYING. If not, write to the 18: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 19: 02110-1301 USA. 20: 21: Linking this library statically or dynamically with other modules is 22: making a combined work based on this library. Thus, the terms and 23: conditions of the GNU General Public License cover the whole 24: combination. 25: 26: As a special exception, the copyright holders of this library give you 27: permission to link this library with independent modules to produce an 28: executable, regardless of the license terms of these independent 29: modules, and to copy and distribute the resulting executable under 30: terms of your choice, provided that you also meet, for each linked 31: independent module, the terms and conditions of the license of that 32: module. An independent module is a module which is not derived from 33: or based on this library. If you modify this library, you may extend 34: this exception to your version of the library, but you are not 35: obligated to do so. If you do not wish to do so, delete this 36: exception statement from your version. */ 37: 38: 39: package java.text; 40: 41: import java.util.Locale; 42: import java.util.MissingResourceException; 43: import java.util.ResourceBundle; 44: 45: /** 46: * This class iterates over text elements such as words, lines, sentences, 47: * and characters. It can only iterate over one of these text elements at 48: * a time. An instance of this class configured for the desired iteration 49: * type is created by calling one of the static factory methods, not 50: * by directly calling a constructor. 51: * 52: * The standard iterators created by the factory methods in this 53: * class will be valid upon creation. That is, their methods will 54: * not cause exceptions if called before you call setText(). 55: * 56: * @author Tom Tromey (tromey@cygnus.com) 57: * @author Aaron M. Renn (arenn@urbanophile.com) 58: * @date March 19, 1999 59: */ 60: /* Written using "Java Class Libraries", 2nd edition, plus online 61: * API docs for JDK 1.2 beta from http://www.javasoft.com. 62: * Status: Believed complete and correct to 1.1. 63: */ 64: public abstract class BreakIterator implements Cloneable 65: { 66: /** 67: * This value is returned by the <code>next()</code> and 68: * <code>previous</code> in order to indicate that the end of the 69: * text has been reached. 70: */ 71: // The value was discovered by writing a test program. 72: public static final int DONE = -1; 73: 74: /** 75: * This method initializes a new instance of <code>BreakIterator</code>. 76: * This protected constructor is available to subclasses as a default 77: * no-arg superclass constructor. 78: */ 79: protected BreakIterator () 80: { 81: } 82: 83: /** 84: * Create a clone of this object. 85: */ 86: public Object clone () 87: { 88: try 89: { 90: return super.clone(); 91: } 92: catch (CloneNotSupportedException e) 93: { 94: return null; 95: } 96: } 97: 98: /** 99: * This method returns the index of the current text element boundary. 100: * 101: * @return The current text boundary. 102: */ 103: public abstract int current (); 104: 105: /** 106: * This method returns the first text element boundary in the text being 107: * iterated over. 108: * 109: * @return The first text boundary. 110: */ 111: public abstract int first (); 112: 113: /** 114: * This methdod returns the offset of the text element boundary following 115: * the specified offset. 116: * 117: * @param pos The text index from which to find the next text boundary. 118: * 119: * @return The next text boundary following the specified index. 120: */ 121: public abstract int following (int pos); 122: 123: /** 124: * This method returns a list of locales for which instances of 125: * <code>BreakIterator</code> are available. 126: * 127: * @return A list of available locales 128: */ 129: public static synchronized Locale[] getAvailableLocales () 130: { 131: Locale[] l = new Locale[1]; 132: l[0] = Locale.US; 133: return l; 134: } 135: 136: private static BreakIterator getInstance (String type, Locale loc) 137: { 138: String className; 139: try 140: { 141: ResourceBundle res 142: = ResourceBundle.getBundle("gnu.java.locale.LocaleInformation", 143: loc, ClassLoader.getSystemClassLoader()); 144: className = res.getString(type); 145: } 146: catch (MissingResourceException x) 147: { 148: return null; 149: } 150: try 151: { 152: Class k = Class.forName(className); 153: return (BreakIterator) k.newInstance(); 154: } 155: catch (ClassNotFoundException x1) 156: { 157: return null; 158: } 159: catch (InstantiationException x2) 160: { 161: return null; 162: } 163: catch (IllegalAccessException x3) 164: { 165: return null; 166: } 167: } 168: 169: /** 170: * This method returns an instance of <code>BreakIterator</code> that will 171: * iterate over characters as defined in the default locale. 172: * 173: * @return A <code>BreakIterator</code> instance for the default locale. 174: */ 175: public static BreakIterator getCharacterInstance () 176: { 177: return getCharacterInstance (Locale.getDefault()); 178: } 179: 180: /** 181: * This method returns an instance of <code>BreakIterator</code> that will 182: * iterate over characters as defined in the specified locale. If the 183: * desired locale is not available, the default locale is used. 184: * 185: * @param locale The desired locale. 186: * 187: * @return A <code>BreakIterator</code> instance for the default locale. 188: */ 189: public static BreakIterator getCharacterInstance (Locale locale) 190: { 191: BreakIterator r = getInstance ("CharacterIterator", locale); 192: if (r == null) 193: r = new gnu.java.text.CharacterBreakIterator (); 194: return r; 195: } 196: 197: /** 198: * This method returns an instance of <code>BreakIterator</code> that will 199: * iterate over line breaks as defined in the default locale. 200: * 201: * @return A <code>BreakIterator</code> instance for the default locale. 202: */ 203: public static BreakIterator getLineInstance () 204: { 205: return getLineInstance (Locale.getDefault()); 206: } 207: 208: /** 209: * This method returns an instance of <code>BreakIterator</code> that will 210: * iterate over line breaks as defined in the specified locale. If the 211: * desired locale is not available, the default locale is used. 212: * 213: * @param locale The desired locale. 214: * 215: * @return A <code>BreakIterator</code> instance for the default locale. 216: */ 217: public static BreakIterator getLineInstance (Locale locale) 218: { 219: BreakIterator r = getInstance ("LineIterator", locale); 220: if (r == null) 221: r = new gnu.java.text.LineBreakIterator (); 222: return r; 223: } 224: 225: /** 226: * This method returns an instance of <code>BreakIterator</code> that will 227: * iterate over sentences as defined in the default locale. 228: * 229: * @return A <code>BreakIterator</code> instance for the default locale. 230: */ 231: public static BreakIterator getSentenceInstance () 232: { 233: return getSentenceInstance (Locale.getDefault()); 234: } 235: 236: /** 237: * This method returns an instance of <code>BreakIterator</code> that will 238: * iterate over sentences as defined in the specified locale. If the 239: * desired locale is not available, the default locale is used. 240: * 241: * @param locale The desired locale. 242: * 243: * @return A <code>BreakIterator</code> instance for the default locale. 244: */ 245: public static BreakIterator getSentenceInstance (Locale locale) 246: { 247: BreakIterator r = getInstance ("SentenceIterator", locale); 248: if (r == null) 249: r = new gnu.java.text.SentenceBreakIterator (); 250: return r; 251: } 252: 253: /** 254: * This method returns the text this object is iterating over as a 255: * <code>CharacterIterator</code>. 256: * 257: * @return The text being iterated over. 258: */ 259: public abstract CharacterIterator getText (); 260: 261: /** 262: * This method returns an instance of <code>BreakIterator</code> that will 263: * iterate over words as defined in the default locale. 264: * 265: * @return A <code>BreakIterator</code> instance for the default locale. 266: */ 267: public static BreakIterator getWordInstance () 268: { 269: return getWordInstance (Locale.getDefault()); 270: } 271: 272: /** 273: * This method returns an instance of <code>BreakIterator</code> that will 274: * iterate over words as defined in the specified locale. If the 275: * desired locale is not available, the default locale is used. 276: * 277: * @param locale The desired locale. 278: * 279: * @return A <code>BreakIterator</code> instance for the default locale. 280: */ 281: public static BreakIterator getWordInstance (Locale locale) 282: { 283: BreakIterator r = getInstance ("WordIterator", locale); 284: if (r == null) 285: r = new gnu.java.text.WordBreakIterator (); 286: return r; 287: } 288: 289: /** 290: * This method tests whether or not the specified position is a text 291: * element boundary. 292: * 293: * @param pos The text position to test. 294: * 295: * @return <code>true</code> if the position is a boundary, 296: * <code>false</code> otherwise. 297: */ 298: public boolean isBoundary (int pos) 299: { 300: if (pos == 0) 301: return true; 302: return following (pos - 1) == pos; 303: } 304: 305: /** 306: * This method returns the last text element boundary in the text being 307: * iterated over. 308: * 309: * @return The last text boundary. 310: */ 311: public abstract int last (); 312: 313: /** 314: * This method returns the text element boundary following the current 315: * text position. 316: * 317: * @return The next text boundary. 318: */ 319: public abstract int next (); 320: 321: /** 322: * This method returns the n'th text element boundary following the current 323: * text position. 324: * 325: * @param n The number of text element boundaries to skip. 326: * 327: * @return The next text boundary. 328: */ 329: public abstract int next (int n); 330: 331: /** 332: * This methdod returns the offset of the text element boundary preceding 333: * the specified offset. 334: * 335: * @param pos The text index from which to find the preceding text boundary. 336: * 337: * @returns The next text boundary preceding the specified index. 338: */ 339: public int preceding (int pos) 340: { 341: if (following (pos) == DONE) 342: last (); 343: while (previous () >= pos) 344: ; 345: return current (); 346: } 347: 348: /** 349: * This method returns the text element boundary preceding the current 350: * text position. 351: * 352: * @return The previous text boundary. 353: */ 354: public abstract int previous (); 355: 356: /** 357: * This method sets the text string to iterate over. 358: * 359: * @param newText The <code>String</code> to iterate over. 360: */ 361: public void setText (String newText) 362: { 363: setText (new StringCharacterIterator (newText)); 364: } 365: 366: /** 367: * This method sets the text to iterate over from the specified 368: * <code>CharacterIterator</code>. 369: * 370: * @param newText The desired <code>CharacterIterator</code>. 371: */ 372: public abstract void setText (CharacterIterator newText); 373: }
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