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1: /* Collator.java -- Perform locale dependent String comparisons. 2: Copyright (C) 1998, 1999, 2000, 2001, 2004, 2005, 2007 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.text.spi.CollatorProvider; 42: 43: import java.util.Comparator; 44: import java.util.Locale; 45: import java.util.MissingResourceException; 46: import java.util.ResourceBundle; 47: import java.util.ServiceLoader; 48: 49: /** 50: * This class is the abstract superclass of classes which perform 51: * locale dependent <code>String</code> comparisons. A caller requests 52: * an instance of <code>Collator</code> for a particular locale using 53: * the <code>getInstance()</code> static method in this class. That method 54: * will return a locale specific subclass of <code>Collator</code> which 55: * can be used to perform <code>String</code> comparisons for that locale. 56: * If a subclass of <code>Collator</code> cannot be located for a particular 57: * locale, a default instance for the current locale will be returned. 58: * 59: * In addition to setting the correct locale, there are two additional 60: * settings that can be adjusted to affect <code>String</code> comparisons: 61: * strength and decomposition. The strength value determines the level 62: * of signficance of character differences required for them to sort 63: * differently. (For example, whether or not capital letters are considered 64: * different from lower case letters). The decomposition value affects how 65: * variants of the same character are treated for sorting purposes. (For 66: * example, whether or not an accent is signficant or not). These settings 67: * are described in detail in the documentation for the methods and values 68: * that are related to them. 69: * 70: * @author Tom Tromey (tromey@cygnus.com) 71: * @author Aaron M. Renn (arenn@urbanophile.com) 72: * @date March 18, 1999 73: */ 74: public abstract class Collator implements Comparator<Object>, Cloneable 75: { 76: /** 77: * This constant is a strength value which indicates that only primary 78: * differences between characters will be considered signficant. As an 79: * example, two completely different English letters such as 'a' and 'b' 80: * are considered to have a primary difference. 81: */ 82: public static final int PRIMARY = 0; 83: 84: /** 85: * This constant is a strength value which indicates that only secondary 86: * or primary differences between characters will be considered 87: * significant. An example of a secondary difference between characters 88: * are instances of the same letter with different accented forms. 89: */ 90: public static final int SECONDARY = 1; 91: 92: /** 93: * This constant is a strength value which indicates that tertiary, 94: * secondary, and primary differences will be considered during sorting. 95: * An example of a tertiary difference is capitalization of a given letter. 96: * This is the default value for the strength setting. 97: */ 98: public static final int TERTIARY = 2; 99: 100: /** 101: * This constant is a strength value which indicates that any difference 102: * at all between character values are considered significant. 103: */ 104: public static final int IDENTICAL = 3; 105: 106: /** 107: * This constant indicates that accented characters won't be decomposed 108: * when performing comparisons. This will yield the fastest results, but 109: * will only work correctly in call cases for languages which do not 110: * use accents such as English. 111: */ 112: public static final int NO_DECOMPOSITION = 0; 113: 114: /** 115: * This constant indicates that only characters which are canonical variants 116: * in Unicode 2.0 will be decomposed prior to performing comparisons. This 117: * will cause accented languages to be sorted correctly. This is the 118: * default decomposition value. 119: */ 120: public static final int CANONICAL_DECOMPOSITION = 1; 121: 122: /** 123: * This constant indicates that both canonical variants and compatibility 124: * variants in Unicode 2.0 will be decomposed prior to performing 125: * comparisons. This is the slowest mode, but is required to get the 126: * correct sorting for certain languages with certain special formats. 127: */ 128: public static final int FULL_DECOMPOSITION = 2; 129: 130: /** 131: * This method initializes a new instance of <code>Collator</code> to have 132: * the default strength (TERTIARY) and decomposition 133: * (CANONICAL_DECOMPOSITION) settings. This constructor is protected and 134: * is for use by subclasses only. Non-subclass callers should use the 135: * static <code>getInstance()</code> methods of this class to instantiate 136: * <code>Collation</code> objects for the desired locale. 137: */ 138: protected Collator () 139: { 140: strength = TERTIARY; 141: decmp = CANONICAL_DECOMPOSITION; 142: } 143: 144: /** 145: * This method compares the two <code>String</code>'s and returns an 146: * integer indicating whether or not the first argument is less than, 147: * equal to, or greater than the second argument. The comparison is 148: * performed according to the rules of the locale for this 149: * <code>Collator</code> and the strength and decomposition rules in 150: * effect. 151: * 152: * @param source The first object to compare 153: * @param target The second object to compare 154: * 155: * @return A negative integer if str1 < str2, 0 if str1 == str2, or 156: * a positive integer if str1 > str2. 157: */ 158: public abstract int compare (String source, String target); 159: 160: /** 161: * This method compares the two <code>Object</code>'s and returns an 162: * integer indicating whether or not the first argument is less than, 163: * equal to, or greater than the second argument. These two objects 164: * must be <code>String</code>'s or an exception will be thrown. 165: * 166: * @param o1 The first object to compare 167: * @param o2 The second object to compare 168: * 169: * @return A negative integer if obj1 < obj2, 0 if obj1 == obj2, or 170: * a positive integer if obj1 > obj2. 171: * 172: * @exception ClassCastException If the arguments are not instances 173: * of <code>String</code>. 174: */ 175: public int compare (Object o1, Object o2) 176: { 177: return compare ((String) o1, (String) o2); 178: } 179: 180: /** 181: * This method tests the specified object for equality against this 182: * object. This will be true if and only if the following conditions are 183: * met: 184: * <ul> 185: * <li>The specified object is not <code>null</code>.</li> 186: * <li>The specified object is an instance of <code>Collator</code>.</li> 187: * <li>The specified object has the same strength and decomposition 188: * settings as this object.</li> 189: * </ul> 190: * 191: * @param obj The <code>Object</code> to test for equality against 192: * this object. 193: * 194: * @return <code>true</code> if the specified object is equal to 195: * this one, <code>false</code> otherwise. 196: */ 197: public boolean equals (Object obj) 198: { 199: if (! (obj instanceof Collator)) 200: return false; 201: Collator c = (Collator) obj; 202: return decmp == c.decmp && strength == c.strength; 203: } 204: 205: /** 206: * This method tests whether the specified <code>String</code>'s are equal 207: * according to the collation rules for the locale of this object and 208: * the current strength and decomposition settings. 209: * 210: * @param source The first <code>String</code> to compare 211: * @param target The second <code>String</code> to compare 212: * 213: * @return <code>true</code> if the two strings are equal, 214: * <code>false</code> otherwise. 215: */ 216: public boolean equals (String source, String target) 217: { 218: return compare (source, target) == 0; 219: } 220: 221: /** 222: * This method returns a copy of this <code>Collator</code> object. 223: * 224: * @return A duplicate of this object. 225: */ 226: public Object clone () 227: { 228: try 229: { 230: return super.clone (); 231: } 232: catch (CloneNotSupportedException _) 233: { 234: return null; 235: } 236: } 237: 238: /** 239: * This method returns an array of <code>Locale</code> objects which is 240: * the list of locales for which <code>Collator</code> objects exist. 241: * 242: * @return The list of locales for which <code>Collator</code>'s exist. 243: */ 244: public static synchronized Locale[] getAvailableLocales () 245: { 246: // FIXME 247: Locale[] l = new Locale[1]; 248: l[0] = Locale.US; 249: return l; 250: } 251: 252: /** 253: * This method transforms the specified <code>String</code> into a 254: * <code>CollationKey</code> for faster comparisons. This is useful when 255: * comparisons against a string might be performed multiple times, such 256: * as during a sort operation. 257: * 258: * @param source The <code>String</code> to convert. 259: * 260: * @return A <code>CollationKey</code> for the specified <code>String</code>. 261: */ 262: public abstract CollationKey getCollationKey (String source); 263: 264: /** 265: * This method returns the current decomposition setting for this 266: * object. This * will be one of NO_DECOMPOSITION, 267: * CANONICAL_DECOMPOSITION, or * FULL_DECOMPOSITION. See the 268: * documentation for those constants for an * explanation of this 269: * setting. 270: * 271: * @return The current decomposition setting. 272: */ 273: public synchronized int getDecomposition () 274: { 275: return decmp; 276: } 277: 278: /** 279: * This method returns an instance of <code>Collator</code> for the 280: * default locale. 281: * 282: * @return A <code>Collator</code> for the default locale. 283: */ 284: public static Collator getInstance () 285: { 286: return getInstance (Locale.getDefault()); 287: } 288: 289: /** 290: * This method returns an instance of <code>Collator</code> for the 291: * specified locale. If no <code>Collator</code> exists for the desired 292: * locale, the fallback procedure described in 293: * {@link java.util.spi.LocaleServiceProvider} is invoked. 294: * 295: * @param loc The desired locale to load a <code>Collator</code> for. 296: * 297: * @return A <code>Collator</code> for the requested locale 298: */ 299: public static Collator getInstance (Locale loc) 300: { 301: String pattern; 302: try 303: { 304: ResourceBundle res = 305: ResourceBundle.getBundle("gnu.java.locale.LocaleInformation", 306: loc, ClassLoader.getSystemClassLoader()); 307: return new RuleBasedCollator(res.getString("collation_rules")); 308: } 309: catch (MissingResourceException x) 310: { 311: /* This means runtime support for the locale 312: * is not available, so we check providers. */ 313: } 314: catch (ParseException x) 315: { 316: throw (InternalError)new InternalError().initCause(x); 317: } 318: for (CollatorProvider p : ServiceLoader.load(CollatorProvider.class)) 319: { 320: for (Locale l : p.getAvailableLocales()) 321: { 322: if (l.equals(loc)) 323: { 324: Collator c = p.getInstance(loc); 325: if (c != null) 326: return c; 327: break; 328: } 329: } 330: } 331: if (loc.equals(Locale.ROOT)) 332: { 333: try 334: { 335: return new RuleBasedCollator("<0<1<2<3<4<5<6<7<8<9<A,a<b,B<c," + 336: "C<d,D<e,E<f,F<g,G<h,H<i,I<j,J<k,K" + 337: "<l,L<m,M<n,N<o,O<p,P<q,Q<r,R<s,S<t,"+ 338: "T<u,U<v,V<w,W<x,X<y,Y<z,Z"); 339: } 340: catch (ParseException x) 341: { 342: throw (InternalError)new InternalError().initCause(x); 343: } 344: } 345: // FIXME 346: return getInstance(Locale.US); 347: } 348: 349: /** 350: * This method returns the current strength setting for this object. This 351: * will be one of PRIMARY, SECONDARY, TERTIARY, or IDENTICAL. See the 352: * documentation for those constants for an explanation of this setting. 353: * 354: * @return The current strength setting. 355: */ 356: public synchronized int getStrength () 357: { 358: return strength; 359: } 360: 361: /** 362: * This method returns a hash code value for this object. 363: * 364: * @return A hash value for this object. 365: */ 366: public abstract int hashCode (); 367: 368: /** 369: * This method sets the decomposition setting for this object to the 370: * specified value. This must be one of NO_DECOMPOSITION, 371: * CANONICAL_DECOMPOSITION, or FULL_DECOMPOSITION. Otherwise an 372: * exception will be thrown. See the documentation for those 373: * contants for an explanation of this setting. 374: * 375: * @param mode The new decomposition setting. 376: * 377: * @exception IllegalArgumentException If the requested 378: * decomposition setting is not valid. 379: */ 380: public synchronized void setDecomposition (int mode) 381: { 382: if (mode != NO_DECOMPOSITION 383: && mode != CANONICAL_DECOMPOSITION 384: && mode != FULL_DECOMPOSITION) 385: throw new IllegalArgumentException (); 386: decmp = mode; 387: } 388: 389: /** 390: * This method sets the strength setting for this object to the specified 391: * value. This must be one of PRIMARY, SECONDARY, TERTIARY, or IDENTICAL. 392: * Otherwise an exception is thrown. See the documentation for these 393: * constants for an explanation of this setting. 394: * 395: * @param strength The new strength setting. 396: * 397: * @exception IllegalArgumentException If the requested strength 398: * setting value is not valid. 399: */ 400: public synchronized void setStrength (int strength) 401: { 402: if (strength != PRIMARY && strength != SECONDARY 403: && strength != TERTIARY && strength != IDENTICAL) 404: throw new IllegalArgumentException (); 405: this.strength = strength; 406: } 407: 408: // Decompose a single character and append results to the buffer. 409: native final void decomposeCharacter (char c, StringBuffer buf); 410: 411: /** 412: * This is the current collation decomposition setting. 413: */ 414: int decmp; 415: 416: /** 417: * This is the current collation strength setting. 418: */ 419: int strength; 420: }