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intl/icu/source/i18n/rbt.h
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| 1 /* | |
| 2 ********************************************************************** | |
| 3 * Copyright (C) 1999-2007, International Business Machines | |
| 4 * Corporation and others. All Rights Reserved. | |
| 5 ********************************************************************** | |
| 6 * Date Name Description | |
| 7 * 11/17/99 aliu Creation. | |
| 8 ********************************************************************** | |
| 9 */ | |
| 10 #ifndef RBT_H | |
| 11 #define RBT_H | |
| 12 | |
| 13 #include "unicode/utypes.h" | |
| 14 | |
| 15 #if !UCONFIG_NO_TRANSLITERATION | |
| 16 | |
| 17 #include "unicode/translit.h" | |
| 18 #include "unicode/utypes.h" | |
| 19 #include "unicode/parseerr.h" | |
| 20 #include "unicode/udata.h" | |
| 21 | |
| 22 #define U_ICUDATA_TRANSLIT U_ICUDATA_NAME U_TREE_SEPARATOR_STRING "translit" | |
| 23 | |
| 24 U_NAMESPACE_BEGIN | |
| 25 | |
| 26 class TransliterationRuleData; | |
| 27 | |
| 28 /** | |
| 29 * <code>RuleBasedTransliterator</code> is a transliterator | |
| 30 * that reads a set of rules in order to determine how to perform | |
| 31 * translations. Rule sets are stored in resource bundles indexed by | |
| 32 * name. Rules within a rule set are separated by semicolons (';'). | |
| 33 * To include a literal semicolon, prefix it with a backslash ('\'). | |
| 34 * Whitespace, as defined by <code>Character.isWhitespace()</code>, | |
| 35 * is ignored. If the first non-blank character on a line is '#', | |
| 36 * the entire line is ignored as a comment. </p> | |
| 37 * | |
| 38 * <p>Each set of rules consists of two groups, one forward, and one | |
| 39 * reverse. This is a convention that is not enforced; rules for one | |
| 40 * direction may be omitted, with the result that translations in | |
| 41 * that direction will not modify the source text. In addition, | |
| 42 * bidirectional forward-reverse rules may be specified for | |
| 43 * symmetrical transformations.</p> | |
| 44 * | |
| 45 * <p><b>Rule syntax</b> </p> | |
| 46 * | |
| 47 * <p>Rule statements take one of the following forms: </p> | |
| 48 * | |
| 49 * <dl> | |
| 50 * <dt><code>$alefmadda=\u0622;</code></dt> | |
| 51 * <dd><strong>Variable definition.</strong> The name on the | |
| 52 * left is assigned the text on the right. In this example, | |
| 53 * after this statement, instances of the left hand name, | |
| 54 * "<code>$alefmadda</code>", will be replaced by | |
| 55 * the Unicode character U+0622. Variable names must begin | |
| 56 * with a letter and consist only of letters, digits, and | |
| 57 * underscores. Case is significant. Duplicate names cause | |
| 58 * an exception to be thrown, that is, variables cannot be | |
| 59 * redefined. The right hand side may contain well-formed | |
| 60 * text of any length, including no text at all ("<code>$empty=;</code>"). | |
| 61 * The right hand side may contain embedded <code>UnicodeSet</code> | |
| 62 * patterns, for example, "<code>$softvowel=[eiyEIY]</code>".</dd> | |
| 63 * <dd> </dd> | |
| 64 * <dt><code>ai>$alefmadda;</code></dt> | |
| 65 * <dd><strong>Forward translation rule.</strong> This rule | |
| 66 * states that the string on the left will be changed to the | |
| 67 * string on the right when performing forward | |
| 68 * transliteration.</dd> | |
| 69 * <dt> </dt> | |
| 70 * <dt><code>ai<$alefmadda;</code></dt> | |
| 71 * <dd><strong>Reverse translation rule.</strong> This rule | |
| 72 * states that the string on the right will be changed to | |
| 73 * the string on the left when performing reverse | |
| 74 * transliteration.</dd> | |
| 75 * </dl> | |
| 76 * | |
| 77 * <dl> | |
| 78 * <dt><code>ai<>$alefmadda;</code></dt> | |
| 79 * <dd><strong>Bidirectional translation rule.</strong> This | |
| 80 * rule states that the string on the right will be changed | |
| 81 * to the string on the left when performing forward | |
| 82 * transliteration, and vice versa when performing reverse | |
| 83 * transliteration.</dd> | |
| 84 * </dl> | |
| 85 * | |
| 86 * <p>Translation rules consist of a <em>match pattern</em> and an <em>output | |
| 87 * string</em>. The match pattern consists of literal characters, | |
| 88 * optionally preceded by context, and optionally followed by | |
| 89 * context. Context characters, like literal pattern characters, | |
| 90 * must be matched in the text being transliterated. However, unlike | |
| 91 * literal pattern characters, they are not replaced by the output | |
| 92 * text. For example, the pattern "<code>abc{def}</code>" | |
| 93 * indicates the characters "<code>def</code>" must be | |
| 94 * preceded by "<code>abc</code>" for a successful match. | |
| 95 * If there is a successful match, "<code>def</code>" will | |
| 96 * be replaced, but not "<code>abc</code>". The final '<code>}</code>' | |
| 97 * is optional, so "<code>abc{def</code>" is equivalent to | |
| 98 * "<code>abc{def}</code>". Another example is "<code>{123}456</code>" | |
| 99 * (or "<code>123}456</code>") in which the literal | |
| 100 * pattern "<code>123</code>" must be followed by "<code>456</code>". | |
| 101 * </p> | |
| 102 * | |
| 103 * <p>The output string of a forward or reverse rule consists of | |
| 104 * characters to replace the literal pattern characters. If the | |
| 105 * output string contains the character '<code>|</code>', this is | |
| 106 * taken to indicate the location of the <em>cursor</em> after | |
| 107 * replacement. The cursor is the point in the text at which the | |
| 108 * next replacement, if any, will be applied. The cursor is usually | |
| 109 * placed within the replacement text; however, it can actually be | |
| 110 * placed into the precending or following context by using the | |
| 111 * special character '<code>@</code>'. Examples:</p> | |
| 112 * | |
| 113 * <blockquote> | |
| 114 * <p><code>a {foo} z > | @ bar; # foo -> bar, move cursor | |
| 115 * before a<br> | |
| 116 * {foo} xyz > bar @@|; # foo -> bar, cursor between | |
| 117 * y and z</code></p> | |
| 118 * </blockquote> | |
| 119 * | |
| 120 * <p><b>UnicodeSet</b></p> | |
| 121 * | |
| 122 * <p><code>UnicodeSet</code> patterns may appear anywhere that | |
| 123 * makes sense. They may appear in variable definitions. | |
| 124 * Contrariwise, <code>UnicodeSet</code> patterns may themselves | |
| 125 * contain variable references, such as "<code>$a=[a-z];$not_a=[^$a]</code>", | |
| 126 * or "<code>$range=a-z;$ll=[$range]</code>".</p> | |
| 127 * | |
| 128 * <p><code>UnicodeSet</code> patterns may also be embedded directly | |
| 129 * into rule strings. Thus, the following two rules are equivalent:</p> | |
| 130 * | |
| 131 * <blockquote> | |
| 132 * <p><code>$vowel=[aeiou]; $vowel>'*'; # One way to do this<br> | |
| 133 * [aeiou]>'*'; | |
| 134 * # | |
| 135 * Another way</code></p> | |
| 136 * </blockquote> | |
| 137 * | |
| 138 * <p>See {@link UnicodeSet} for more documentation and examples.</p> | |
| 139 * | |
| 140 * <p><b>Segments</b></p> | |
| 141 * | |
| 142 * <p>Segments of the input string can be matched and copied to the | |
| 143 * output string. This makes certain sets of rules simpler and more | |
| 144 * general, and makes reordering possible. For example:</p> | |
| 145 * | |
| 146 * <blockquote> | |
| 147 * <p><code>([a-z]) > $1 $1; | |
| 148 * # | |
| 149 * double lowercase letters<br> | |
| 150 * ([:Lu:]) ([:Ll:]) > $2 $1; # reverse order of Lu-Ll pairs</code></p> | |
| 151 * </blockquote> | |
| 152 * | |
| 153 * <p>The segment of the input string to be copied is delimited by | |
| 154 * "<code>(</code>" and "<code>)</code>". Up to | |
| 155 * nine segments may be defined. Segments may not overlap. In the | |
| 156 * output string, "<code>$1</code>" through "<code>$9</code>" | |
| 157 * represent the input string segments, in left-to-right order of | |
| 158 * definition.</p> | |
| 159 * | |
| 160 * <p><b>Anchors</b></p> | |
| 161 * | |
| 162 * <p>Patterns can be anchored to the beginning or the end of the text. This is done with the | |
| 163 * special characters '<code>^</code>' and '<code>$</code>'. For example:</p> | |
| 164 * | |
| 165 * <blockquote> | |
| 166 * <p><code>^ a > 'BEG_A'; # match 'a' at start of text<br> | |
| 167 * a > 'A'; # match other instances | |
| 168 * of 'a'<br> | |
| 169 * z $ > 'END_Z'; # match 'z' at end of text<br> | |
| 170 * z > 'Z'; # match other instances | |
| 171 * of 'z'</code></p> | |
| 172 * </blockquote> | |
| 173 * | |
| 174 * <p>It is also possible to match the beginning or the end of the text using a <code>UnicodeSet</code>. | |
| 175 * This is done by including a virtual anchor character '<code>$</code>' at the end of the | |
| 176 * set pattern. Although this is usually the match chafacter for the end anchor, the set will | |
| 177 * match either the beginning or the end of the text, depending on its placement. For | |
| 178 * example:</p> | |
| 179 * | |
| 180 * <blockquote> | |
| 181 * <p><code>$x = [a-z$]; # match 'a' through 'z' OR anchor<br> | |
| 182 * $x 1 > 2; # match '1' after a-z or at the start<br> | |
| 183 * 3 $x > 4; # match '3' before a-z or at the end</code></p> | |
| 184 * </blockquote> | |
| 185 * | |
| 186 * <p><b>Example</b> </p> | |
| 187 * | |
| 188 * <p>The following example rules illustrate many of the features of | |
| 189 * the rule language. </p> | |
| 190 * | |
| 191 * <table border="0" cellpadding="4"> | |
| 192 * <tr> | |
| 193 * <td valign="top">Rule 1.</td> | |
| 194 * <td valign="top" nowrap><code>abc{def}>x|y</code></td> | |
| 195 * </tr> | |
| 196 * <tr> | |
| 197 * <td valign="top">Rule 2.</td> | |
| 198 * <td valign="top" nowrap><code>xyz>r</code></td> | |
| 199 * </tr> | |
| 200 * <tr> | |
| 201 * <td valign="top">Rule 3.</td> | |
| 202 * <td valign="top" nowrap><code>yz>q</code></td> | |
| 203 * </tr> | |
| 204 * </table> | |
| 205 * | |
| 206 * <p>Applying these rules to the string "<code>adefabcdefz</code>" | |
| 207 * yields the following results: </p> | |
| 208 * | |
| 209 * <table border="0" cellpadding="4"> | |
| 210 * <tr> | |
| 211 * <td valign="top" nowrap><code>|adefabcdefz</code></td> | |
| 212 * <td valign="top">Initial state, no rules match. Advance | |
| 213 * cursor.</td> | |
| 214 * </tr> | |
| 215 * <tr> | |
| 216 * <td valign="top" nowrap><code>a|defabcdefz</code></td> | |
| 217 * <td valign="top">Still no match. Rule 1 does not match | |
| 218 * because the preceding context is not present.</td> | |
| 219 * </tr> | |
| 220 * <tr> | |
| 221 * <td valign="top" nowrap><code>ad|efabcdefz</code></td> | |
| 222 * <td valign="top">Still no match. Keep advancing until | |
| 223 * there is a match...</td> | |
| 224 * </tr> | |
| 225 * <tr> | |
| 226 * <td valign="top" nowrap><code>ade|fabcdefz</code></td> | |
| 227 * <td valign="top">...</td> | |
| 228 * </tr> | |
| 229 * <tr> | |
| 230 * <td valign="top" nowrap><code>adef|abcdefz</code></td> | |
| 231 * <td valign="top">...</td> | |
| 232 * </tr> | |
| 233 * <tr> | |
| 234 * <td valign="top" nowrap><code>adefa|bcdefz</code></td> | |
| 235 * <td valign="top">...</td> | |
| 236 * </tr> | |
| 237 * <tr> | |
| 238 * <td valign="top" nowrap><code>adefab|cdefz</code></td> | |
| 239 * <td valign="top">...</td> | |
| 240 * </tr> | |
| 241 * <tr> | |
| 242 * <td valign="top" nowrap><code>adefabc|defz</code></td> | |
| 243 * <td valign="top">Rule 1 matches; replace "<code>def</code>" | |
| 244 * with "<code>xy</code>" and back up the cursor | |
| 245 * to before the '<code>y</code>'.</td> | |
| 246 * </tr> | |
| 247 * <tr> | |
| 248 * <td valign="top" nowrap><code>adefabcx|yz</code></td> | |
| 249 * <td valign="top">Although "<code>xyz</code>" is | |
| 250 * present, rule 2 does not match because the cursor is | |
| 251 * before the '<code>y</code>', not before the '<code>x</code>'. | |
| 252 * Rule 3 does match. Replace "<code>yz</code>" | |
| 253 * with "<code>q</code>".</td> | |
| 254 * </tr> | |
| 255 * <tr> | |
| 256 * <td valign="top" nowrap><code>adefabcxq|</code></td> | |
| 257 * <td valign="top">The cursor is at the end; | |
| 258 * transliteration is complete.</td> | |
| 259 * </tr> | |
| 260 * </table> | |
| 261 * | |
| 262 * <p>The order of rules is significant. If multiple rules may match | |
| 263 * at some point, the first matching rule is applied. </p> | |
| 264 * | |
| 265 * <p>Forward and reverse rules may have an empty output string. | |
| 266 * Otherwise, an empty left or right hand side of any statement is a | |
| 267 * syntax error. </p> | |
| 268 * | |
| 269 * <p>Single quotes are used to quote any character other than a | |
| 270 * digit or letter. To specify a single quote itself, inside or | |
| 271 * outside of quotes, use two single quotes in a row. For example, | |
| 272 * the rule "<code>'>'>o''clock</code>" changes the | |
| 273 * string "<code>></code>" to the string "<code>o'clock</code>". | |
| 274 * </p> | |
| 275 * | |
| 276 * <p><b>Notes</b> </p> | |
| 277 * | |
| 278 * <p>While a RuleBasedTransliterator is being built, it checks that | |
| 279 * the rules are added in proper order. For example, if the rule | |
| 280 * "a>x" is followed by the rule "ab>y", | |
| 281 * then the second rule will throw an exception. The reason is that | |
| 282 * the second rule can never be triggered, since the first rule | |
| 283 * always matches anything it matches. In other words, the first | |
| 284 * rule <em>masks</em> the second rule. </p> | |
| 285 * | |
| 286 * @author Alan Liu | |
| 287 * @internal Use transliterator factory methods instead since this class will be removed in that release. | |
| 288 */ | |
| 289 class RuleBasedTransliterator : public Transliterator { | |
| 290 private: | |
| 291 /** | |
| 292 * The data object is immutable, so we can freely share it with | |
| 293 * other instances of RBT, as long as we do NOT own this object. | |
| 294 * TODO: data is no longer immutable. See bugs #1866, 2155 | |
| 295 */ | |
| 296 TransliterationRuleData* fData; | |
| 297 | |
| 298 /** | |
| 299 * If true, we own the data object and must delete it. | |
| 300 */ | |
| 301 UBool isDataOwned; | |
| 302 | |
| 303 public: | |
| 304 | |
| 305 /** | |
| 306 * Constructs a new transliterator from the given rules. | |
| 307 * @param rules rules, separated by ';' | |
| 308 * @param direction either FORWARD or REVERSE. | |
| 309 * @exception IllegalArgumentException if rules are malformed. | |
| 310 * @internal Use transliterator factory methods instead since this class will be removed in that release. | |
| 311 */ | |
| 312 RuleBasedTransliterator(const UnicodeString& id, | |
| 313 const UnicodeString& rules, | |
| 314 UTransDirection direction, | |
| 315 UnicodeFilter* adoptedFilter, | |
| 316 UParseError& parseError, | |
| 317 UErrorCode& status); | |
| 318 | |
| 319 /** | |
| 320 * Constructs a new transliterator from the given rules. | |
| 321 * @param rules rules, separated by ';' | |
| 322 * @param direction either FORWARD or REVERSE. | |
| 323 * @exception IllegalArgumentException if rules are malformed. | |
| 324 * @internal Use transliterator factory methods instead since this class will be removed in that release. | |
| 325 */ | |
| 326 /*RuleBasedTransliterator(const UnicodeString& id, | |
| 327 const UnicodeString& rules, | |
| 328 UTransDirection direction, | |
| 329 UnicodeFilter* adoptedFilter, | |
| 330 UErrorCode& status);*/ | |
| 331 | |
| 332 /** | |
| 333 * Covenience constructor with no filter. | |
| 334 * @internal Use transliterator factory methods instead since this class will be removed in that release. | |
| 335 */ | |
| 336 /*RuleBasedTransliterator(const UnicodeString& id, | |
| 337 const UnicodeString& rules, | |
| 338 UTransDirection direction, | |
| 339 UErrorCode& status);*/ | |
| 340 | |
| 341 /** | |
| 342 * Covenience constructor with no filter and FORWARD direction. | |
| 343 * @internal Use transliterator factory methods instead since this class will be removed in that release. | |
| 344 */ | |
| 345 /*RuleBasedTransliterator(const UnicodeString& id, | |
| 346 const UnicodeString& rules, | |
| 347 UErrorCode& status);*/ | |
| 348 | |
| 349 /** | |
| 350 * Covenience constructor with FORWARD direction. | |
| 351 * @internal Use transliterator factory methods instead since this class will be removed in that release. | |
| 352 */ | |
| 353 /*RuleBasedTransliterator(const UnicodeString& id, | |
| 354 const UnicodeString& rules, | |
| 355 UnicodeFilter* adoptedFilter, | |
| 356 UErrorCode& status);*/ | |
| 357 private: | |
| 358 | |
| 359 friend class TransliteratorRegistry; // to access TransliterationRuleData convenience ctor | |
| 360 /** | |
| 361 * Covenience constructor. | |
| 362 * @param id the id for the transliterator. | |
| 363 * @param theData the rule data for the transliterator. | |
| 364 * @param adoptedFilter the filter for the transliterator | |
| 365 */ | |
| 366 RuleBasedTransliterator(const UnicodeString& id, | |
| 367 const TransliterationRuleData* theData, | |
| 368 UnicodeFilter* adoptedFilter = 0); | |
| 369 | |
| 370 | |
| 371 friend class Transliterator; // to access following ct | |
| 372 | |
| 373 /** | |
| 374 * Internal constructor. | |
| 375 * @param id the id for the transliterator. | |
| 376 * @param theData the rule data for the transliterator. | |
| 377 * @param isDataAdopted determine who will own the 'data' object. True, the caller should not delete 'data'. | |
| 378 */ | |
| 379 RuleBasedTransliterator(const UnicodeString& id, | |
| 380 TransliterationRuleData* data, | |
| 381 UBool isDataAdopted); | |
| 382 | |
| 383 public: | |
| 384 | |
| 385 /** | |
| 386 * Copy constructor. | |
| 387 * @internal Use transliterator factory methods instead since this class will be removed in that release. | |
| 388 */ | |
| 389 RuleBasedTransliterator(const RuleBasedTransliterator&); | |
| 390 | |
| 391 virtual ~RuleBasedTransliterator(); | |
| 392 | |
| 393 /** | |
| 394 * Implement Transliterator API. | |
| 395 * @internal Use transliterator factory methods instead since this class will be removed in that release. | |
| 396 */ | |
| 397 virtual Transliterator* clone(void) const; | |
| 398 | |
| 399 protected: | |
| 400 /** | |
| 401 * Implements {@link Transliterator#handleTransliterate}. | |
| 402 * @internal Use transliterator factory methods instead since this class will be removed in that release. | |
| 403 */ | |
| 404 virtual void handleTransliterate(Replaceable& text, UTransPosition& offsets, | |
| 405 UBool isIncremental) const; | |
| 406 | |
| 407 public: | |
| 408 /** | |
| 409 * Return a representation of this transliterator as source rules. | |
| 410 * These rules will produce an equivalent transliterator if used | |
| 411 * to construct a new transliterator. | |
| 412 * @param result the string to receive the rules. Previous | |
| 413 * contents will be deleted. | |
| 414 * @param escapeUnprintable if TRUE then convert unprintable | |
| 415 * character to their hex escape representations, \uxxxx or | |
| 416 * \Uxxxxxxxx. Unprintable characters are those other than | |
| 417 * U+000A, U+0020..U+007E. | |
| 418 * @internal Use transliterator factory methods instead since this class will be removed in that release. | |
| 419 */ | |
| 420 virtual UnicodeString& toRules(UnicodeString& result, | |
| 421 UBool escapeUnprintable) const; | |
| 422 | |
| 423 protected: | |
| 424 /** | |
| 425 * Implement Transliterator framework | |
| 426 */ | |
| 427 virtual void handleGetSourceSet(UnicodeSet& result) const; | |
| 428 | |
| 429 public: | |
| 430 /** | |
| 431 * Override Transliterator framework | |
| 432 */ | |
| 433 virtual UnicodeSet& getTargetSet(UnicodeSet& result) const; | |
| 434 | |
| 435 /** | |
| 436 * Return the class ID for this class. This is useful only for | |
| 437 * comparing to a return value from getDynamicClassID(). For example: | |
| 438 * <pre> | |
| 439 * . Base* polymorphic_pointer = createPolymorphicObject(); | |
| 440 * . if (polymorphic_pointer->getDynamicClassID() == | |
| 441 * . Derived::getStaticClassID()) ... | |
| 442 * </pre> | |
| 443 * @return The class ID for all objects of this class. | |
| 444 * @internal Use transliterator factory methods instead since this class will be removed in that release. | |
| 445 */ | |
| 446 U_I18N_API static UClassID U_EXPORT2 getStaticClassID(void); | |
| 447 | |
| 448 /** | |
| 449 * Returns a unique class ID <b>polymorphically</b>. This method | |
| 450 * is to implement a simple version of RTTI, since not all C++ | |
| 451 * compilers support genuine RTTI. Polymorphic operator==() and | |
| 452 * clone() methods call this method. | |
| 453 * | |
| 454 * @return The class ID for this object. All objects of a given | |
| 455 * class have the same class ID. Objects of other classes have | |
| 456 * different class IDs. | |
| 457 */ | |
| 458 virtual UClassID getDynamicClassID(void) const; | |
| 459 | |
| 460 private: | |
| 461 | |
| 462 void _construct(const UnicodeString& rules, | |
| 463 UTransDirection direction, | |
| 464 UParseError& parseError, | |
| 465 UErrorCode& status); | |
| 466 }; | |
| 467 | |
| 468 | |
| 469 U_NAMESPACE_END | |
| 470 | |
| 471 #endif /* #if !UCONFIG_NO_TRANSLITERATION */ | |
| 472 | |
| 473 #endif |
