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1: /* Collator.java -- Perform locale dependent String comparisons. 2: Copyright (C) 1998, 1999, 2000, 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.Comparator; 42: import java.util.Locale; 43: import java.util.MissingResourceException; 44: import java.util.ResourceBundle; 45: 46: /** 47: * This class is the abstract superclass of classes which perform 48: * locale dependent <code>String</code> comparisons. A caller requests 49: * an instance of <code>Collator</code> for a particular locale using 50: * the <code>getInstance()</code> static method in this class. That method 51: * will return a locale specific subclass of <code>Collator</code> which 52: * can be used to perform <code>String</code> comparisons for that locale. 53: * If a subclass of <code>Collator</code> cannot be located for a particular 54: * locale, a default instance for the current locale will be returned. 55: * 56: * In addition to setting the correct locale, there are two additional 57: * settings that can be adjusted to affect <code>String</code> comparisons: 58: * strength and decomposition. The strength value determines the level 59: * of signficance of character differences required for them to sort 60: * differently. (For example, whether or not capital letters are considered 61: * different from lower case letters). The decomposition value affects how 62: * variants of the same character are treated for sorting purposes. (For 63: * example, whether or not an accent is signficant or not). These settings 64: * are described in detail in the documentation for the methods and values 65: * that are related to them. 66: * 67: * @author Tom Tromey (tromey@cygnus.com) 68: * @author Aaron M. Renn (arenn@urbanophile.com) 69: * @date March 18, 1999 70: */ 71: /* Written using "Java Class Libraries", 2nd edition, plus online 72: * API docs for JDK 1.2 from http://www.javasoft.com. 73: * Status: Mostly complete, but parts stubbed out. Look for FIXME. 74: */ 75: public abstract class Collator implements Comparator, Cloneable 76: { 77: /** 78: * This constant is a strength value which indicates that only primary 79: * differences between characters will be considered signficant. As an 80: * example, two completely different English letters such as 'a' and 'b' 81: * are considered to have a primary difference. 82: */ 83: public static final int PRIMARY = 0; 84: 85: /** 86: * This constant is a strength value which indicates that only secondary 87: * or primary differences between characters will be considered 88: * significant. An example of a secondary difference between characters 89: * are instances of the same letter with different accented forms. 90: */ 91: public static final int SECONDARY = 1; 92: 93: /** 94: * This constant is a strength value which indicates that tertiary, 95: * secondary, and primary differences will be considered during sorting. 96: * An example of a tertiary difference is capitalization of a given letter. 97: * This is the default value for the strength setting. 98: */ 99: public static final int TERTIARY = 2; 100: 101: /** 102: * This constant is a strength value which indicates that any difference 103: * at all between character values are considered significant. 104: */ 105: public static final int IDENTICAL = 3; 106: 107: /** 108: * This constant indicates that accented characters won't be decomposed 109: * when performing comparisons. This will yield the fastest results, but 110: * will only work correctly in call cases for languages which do not 111: * use accents such as English. 112: */ 113: public static final int NO_DECOMPOSITION = 0; 114: 115: /** 116: * This constant indicates that only characters which are canonical variants 117: * in Unicode 2.0 will be decomposed prior to performing comparisons. This 118: * will cause accented languages to be sorted correctly. This is the 119: * default decomposition value. 120: */ 121: public static final int CANONICAL_DECOMPOSITION = 1; 122: 123: /** 124: * This constant indicates that both canonical variants and compatibility 125: * variants in Unicode 2.0 will be decomposed prior to performing 126: * comparisons. This is the slowest mode, but is required to get the 127: * correct sorting for certain languages with certain special formats. 128: */ 129: public static final int FULL_DECOMPOSITION = 2; 130: 131: /** 132: * This method initializes a new instance of <code>Collator</code> to have 133: * the default strength (TERTIARY) and decomposition 134: * (CANONICAL_DECOMPOSITION) settings. This constructor is protected and 135: * is for use by subclasses only. Non-subclass callers should use the 136: * static <code>getInstance()</code> methods of this class to instantiate 137: * <code>Collation</code> objects for the desired locale. 138: */ 139: protected Collator () 140: { 141: strength = TERTIARY; 142: decmp = CANONICAL_DECOMPOSITION; 143: } 144: 145: /** 146: * This method compares the two <code>String</code>'s and returns an 147: * integer indicating whether or not the first argument is less than, 148: * equal to, or greater than the second argument. The comparison is 149: * performed according to the rules of the locale for this 150: * <code>Collator</code> and the strength and decomposition rules in 151: * effect. 152: * 153: * @param source The first object to compare 154: * @param target The second object to compare 155: * 156: * @return A negative integer if str1 < str2, 0 if str1 == str2, or 157: * a positive integer if str1 > str2. 158: */ 159: public abstract int compare (String source, String target); 160: 161: /** 162: * This method compares the two <code>Object</code>'s and returns an 163: * integer indicating whether or not the first argument is less than, 164: * equal to, or greater than the second argument. These two objects 165: * must be <code>String</code>'s or an exception will be thrown. 166: * 167: * @param o1 The first object to compare 168: * @param o2 The second object to compare 169: * 170: * @return A negative integer if obj1 < obj2, 0 if obj1 == obj2, or 171: * a positive integer if obj1 > obj2. 172: * 173: * @exception ClassCastException If the arguments are not instances 174: * of <code>String</code>. 175: */ 176: public int compare (Object o1, Object o2) 177: { 178: return compare ((String) o1, (String) o2); 179: } 180: 181: /** 182: * This method tests the specified object for equality against this 183: * object. This will be true if and only if the following conditions are 184: * met: 185: * <ul> 186: * <li>The specified object is not <code>null</code>.</li> 187: * <li>The specified object is an instance of <code>Collator</code>.</li> 188: * <li>The specified object has the same strength and decomposition 189: * settings as this object.</li> 190: * </ul> 191: * 192: * @param obj The <code>Object</code> to test for equality against 193: * this object. 194: * 195: * @return <code>true</code> if the specified object is equal to 196: * this one, <code>false</code> otherwise. 197: */ 198: public boolean equals (Object obj) 199: { 200: if (! (obj instanceof Collator)) 201: return false; 202: Collator c = (Collator) obj; 203: return decmp == c.decmp && strength == c.strength; 204: } 205: 206: /** 207: * This method tests whether the specified <code>String</code>'s are equal 208: * according to the collation rules for the locale of this object and 209: * the current strength and decomposition settings. 210: * 211: * @param source The first <code>String</code> to compare 212: * @param target The second <code>String</code> to compare 213: * 214: * @return <code>true</code> if the two strings are equal, 215: * <code>false</code> otherwise. 216: */ 217: public boolean equals (String source, String target) 218: { 219: return compare (source, target) == 0; 220: } 221: 222: /** 223: * This method returns a copy of this <code>Collator</code> object. 224: * 225: * @return A duplicate of this object. 226: */ 227: public Object clone () 228: { 229: try 230: { 231: return super.clone (); 232: } 233: catch (CloneNotSupportedException _) 234: { 235: return null; 236: } 237: } 238: 239: /** 240: * This method returns an array of <code>Locale</code> objects which is 241: * the list of locales for which <code>Collator</code> objects exist. 242: * 243: * @return The list of locales for which <code>Collator</code>'s exist. 244: */ 245: public static synchronized Locale[] getAvailableLocales () 246: { 247: // FIXME 248: Locale[] l = new Locale[1]; 249: l[0] = Locale.US; 250: return l; 251: } 252: 253: /** 254: * This method transforms the specified <code>String</code> into a 255: * <code>CollationKey</code> for faster comparisons. This is useful when 256: * comparisons against a string might be performed multiple times, such 257: * as during a sort operation. 258: * 259: * @param source The <code>String</code> to convert. 260: * 261: * @return A <code>CollationKey</code> for the specified <code>String</code>. 262: */ 263: public abstract CollationKey getCollationKey (String source); 264: 265: /** 266: * This method returns the current decomposition setting for this 267: * object. This * will be one of NO_DECOMPOSITION, 268: * CANONICAL_DECOMPOSITION, or * FULL_DECOMPOSITION. See the 269: * documentation for those constants for an * explanation of this 270: * setting. 271: * 272: * @return The current decomposition setting. 273: */ 274: public synchronized int getDecomposition () 275: { 276: return decmp; 277: } 278: 279: /** 280: * This method returns an instance of <code>Collator</code> for the 281: * default locale. 282: * 283: * @return A <code>Collator</code> for the default locale. 284: */ 285: public static Collator getInstance () 286: { 287: return getInstance (Locale.getDefault()); 288: } 289: 290: /** 291: * This method returns an instance of <code>Collator</code> for the 292: * specified locale. If no <code>Collator</code> exists for the desired 293: * locale, a <code>Collator</code> for the default locale will be returned. 294: * 295: * @param loc The desired localed 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: ResourceBundle res; 302: String pattern; 303: try 304: { 305: res = ResourceBundle.getBundle("gnu.java.locale.LocaleInformation", 306: loc, ClassLoader.getSystemClassLoader()); 307: pattern = res.getString("collation_rules"); 308: } 309: catch (MissingResourceException x) 310: { 311: pattern = "<0<1<2<3<4<5<6<7<8<9<A,a<b,B<c,C<d,D<e,E<f,F<g,G<h,H<i,I<j,J<k,K" + 312: "<l,L<m,M<n,N<o,O<p,P<q,Q<r,R<s,S<t,T<u,U<v,V<w,W<x,X<y,Y<z,Z"; 313: } 314: try 315: { 316: return new RuleBasedCollator (pattern); 317: } 318: catch (ParseException x) 319: { 320: throw (InternalError)new InternalError().initCause(x); 321: } 322: } 323: 324: /** 325: * This method returns the current strength setting for this object. This 326: * will be one of PRIMARY, SECONDARY, TERTIARY, or IDENTICAL. See the 327: * documentation for those constants for an explanation of this setting. 328: * 329: * @return The current strength setting. 330: */ 331: public synchronized int getStrength () 332: { 333: return strength; 334: } 335: 336: /** 337: * This method returns a hash code value for this object. 338: * 339: * @return A hash value for this object. 340: */ 341: public abstract int hashCode (); 342: 343: /** 344: * This method sets the decomposition setting for this object to the 345: * specified value. This must be one of NO_DECOMPOSITION, 346: * CANONICAL_DECOMPOSITION, or FULL_DECOMPOSITION. Otherwise an 347: * exception will be thrown. See the documentation for those 348: * contants for an explanation of this setting. 349: * 350: * @param mode The new decomposition setting. 351: * 352: * @exception IllegalArgumentException If the requested 353: * decomposition setting is not valid. 354: */ 355: public synchronized void setDecomposition (int mode) 356: { 357: if (mode != NO_DECOMPOSITION 358: && mode != CANONICAL_DECOMPOSITION 359: && mode != FULL_DECOMPOSITION) 360: throw new IllegalArgumentException (); 361: decmp = mode; 362: } 363: 364: /** 365: * This method sets the strength setting for this object to the specified 366: * value. This must be one of PRIMARY, SECONDARY, TERTIARY, or IDENTICAL. 367: * Otherwise an exception is thrown. See the documentation for these 368: * constants for an explanation of this setting. 369: * 370: * @param strength The new strength setting. 371: * 372: * @exception IllegalArgumentException If the requested strength 373: * setting value is not valid. 374: */ 375: public synchronized void setStrength (int strength) 376: { 377: if (strength != PRIMARY && strength != SECONDARY 378: && strength != TERTIARY && strength != IDENTICAL) 379: throw new IllegalArgumentException (); 380: this.strength = strength; 381: } 382: 383: // Decompose a single character and append results to the buffer. 384: native final void decomposeCharacter (char c, StringBuffer buf); 385: 386: /** 387: * This is the current collation decomposition setting. 388: */ 389: int decmp; 390: 391: /** 392: * This is the current collation strength setting. 393: */ 394: int strength; 395: }