1 // Copyright (C) 2016 and later: Unicode, Inc. and others. 2 // License & terms of use: http://www.unicode.org/copyright.html 3 /* 4 ********************************************************************** 5 * Copyright (C) 2001-2014 IBM and others. All rights reserved. 6 ********************************************************************** 7 * Date Name Description 8 * 03/22/2000 helena Creation. 9 ********************************************************************** 10 */ 11 12 #ifndef STSEARCH_H 13 #define STSEARCH_H 14 15 #include "unicode/utypes.h" 16 17 /** 18 * \file 19 * \brief C++ API: Service for searching text based on RuleBasedCollator. 20 */ 21 22 #if !UCONFIG_NO_COLLATION && !UCONFIG_NO_BREAK_ITERATION 23 24 #include "unicode/tblcoll.h" 25 #include "unicode/coleitr.h" 26 #include "unicode/search.h" 27 28 U_NAMESPACE_BEGIN 29 30 /** 31 * 32 * <tt>StringSearch</tt> is a <tt>SearchIterator</tt> that provides 33 * language-sensitive text searching based on the comparison rules defined 34 * in a {@link RuleBasedCollator} object. 35 * StringSearch ensures that language eccentricity can be 36 * handled, e.g. for the German collator, characters ß and SS will be matched 37 * if case is chosen to be ignored. 38 * See the <a href="http://source.icu-project.org/repos/icu/icuhtml/trunk/design/collation/ICU_collation_design.htm"> 39 * "ICU Collation Design Document"</a> for more information. 40 * <p> 41 * There are 2 match options for selection:<br> 42 * Let S' be the sub-string of a text string S between the offsets start and 43 * end [start, end]. 44 * <br> 45 * A pattern string P matches a text string S at the offsets [start, end] 46 * if 47 * <pre> 48 * option 1. Some canonical equivalent of P matches some canonical equivalent 49 * of S' 50 * option 2. P matches S' and if P starts or ends with a combining mark, 51 * there exists no non-ignorable combining mark before or after S? 52 * in S respectively. 53 * </pre> 54 * Option 2. will be the default. 55 * <p> 56 * This search has APIs similar to that of other text iteration mechanisms 57 * such as the break iterators in <tt>BreakIterator</tt>. Using these 58 * APIs, it is easy to scan through text looking for all occurrences of 59 * a given pattern. This search iterator allows changing of direction by 60 * calling a <tt>reset</tt> followed by a <tt>next</tt> or <tt>previous</tt>. 61 * Though a direction change can occur without calling <tt>reset</tt> first, 62 * this operation comes with some speed penalty. 63 * Match results in the forward direction will match the result matches in 64 * the backwards direction in the reverse order 65 * <p> 66 * <tt>SearchIterator</tt> provides APIs to specify the starting position 67 * within the text string to be searched, e.g. <tt>setOffset</tt>, 68 * <tt>preceding</tt> and <tt>following</tt>. Since the 69 * starting position will be set as it is specified, please take note that 70 * there are some danger points which the search may render incorrect 71 * results: 72 * <ul> 73 * <li> The midst of a substring that requires normalization. 74 * <li> If the following match is to be found, the position should not be the 75 * second character which requires to be swapped with the preceding 76 * character. Vice versa, if the preceding match is to be found, 77 * position to search from should not be the first character which 78 * requires to be swapped with the next character. E.g certain Thai and 79 * Lao characters require swapping. 80 * <li> If a following pattern match is to be found, any position within a 81 * contracting sequence except the first will fail. Vice versa if a 82 * preceding pattern match is to be found, a invalid starting point 83 * would be any character within a contracting sequence except the last. 84 * </ul> 85 * <p> 86 * A <tt>BreakIterator</tt> can be used if only matches at logical breaks are desired. 87 * Using a <tt>BreakIterator</tt> will only give you results that exactly matches the 88 * boundaries given by the breakiterator. For instance the pattern "e" will 89 * not be found in the string "\u00e9" if a character break iterator is used. 90 * <p> 91 * Options are provided to handle overlapping matches. 92 * E.g. In English, overlapping matches produces the result 0 and 2 93 * for the pattern "abab" in the text "ababab", where else mutually 94 * exclusive matches only produce the result of 0. 95 * <p> 96 * Though collator attributes will be taken into consideration while 97 * performing matches, there are no APIs here for setting and getting the 98 * attributes. These attributes can be set by getting the collator 99 * from <tt>getCollator</tt> and using the APIs in <tt>coll.h</tt>. 100 * Lastly to update <tt>StringSearch</tt> to the new collator attributes, 101 * <tt>reset</tt> has to be called. 102 * <p> 103 * Restriction: <br> 104 * Currently there are no composite characters that consists of a 105 * character with combining class > 0 before a character with combining 106 * class == 0. However, if such a character exists in the future, 107 * <tt>StringSearch</tt> does not guarantee the results for option 1. 108 * <p> 109 * Consult the <tt>SearchIterator</tt> documentation for information on 110 * and examples of how to use instances of this class to implement text 111 * searching. 112 * <pre><code> 113 * UnicodeString target("The quick brown fox jumps over the lazy dog."); 114 * UnicodeString pattern("fox"); 115 * 116 * UErrorCode error = U_ZERO_ERROR; 117 * StringSearch iter(pattern, target, Locale::getUS(), NULL, status); 118 * for (int pos = iter.first(error); 119 * pos != USEARCH_DONE; 120 * pos = iter.next(error)) 121 * { 122 * printf("Found match at %d pos, length is %d\n", pos, 123 * iter.getMatchLength()); 124 * } 125 * </code></pre> 126 * <p> 127 * Note, <tt>StringSearch</tt> is not to be subclassed. 128 * </p> 129 * @see SearchIterator 130 * @see RuleBasedCollator 131 * @since ICU 2.0 132 */ 133 134 class U_I18N_API StringSearch U_FINAL : public SearchIterator 135 { 136 public: 137 138 // public constructors and destructors -------------------------------- 139 140 /** 141 * Creating a <tt>StringSearch</tt> instance using the argument locale 142 * language rule set. A collator will be created in the process, which 143 * will be owned by this instance and will be deleted during 144 * destruction 145 * @param pattern The text for which this object will search. 146 * @param text The text in which to search for the pattern. 147 * @param locale A locale which defines the language-sensitive 148 * comparison rules used to determine whether text in the 149 * pattern and target matches. 150 * @param breakiter A <tt>BreakIterator</tt> object used to constrain 151 * the matches that are found. Matches whose start and end 152 * indices in the target text are not boundaries as 153 * determined by the <tt>BreakIterator</tt> are 154 * ignored. If this behavior is not desired, 155 * <tt>NULL</tt> can be passed in instead. 156 * @param status for errors if any. If pattern or text is NULL, or if 157 * either the length of pattern or text is 0 then an 158 * U_ILLEGAL_ARGUMENT_ERROR is returned. 159 * @stable ICU 2.0 160 */ 161 StringSearch(const UnicodeString &pattern, const UnicodeString &text, 162 const Locale &locale, 163 BreakIterator *breakiter, 164 UErrorCode &status); 165 166 /** 167 * Creating a <tt>StringSearch</tt> instance using the argument collator 168 * language rule set. Note, user retains the ownership of this collator, 169 * it does not get destroyed during this instance's destruction. 170 * @param pattern The text for which this object will search. 171 * @param text The text in which to search for the pattern. 172 * @param coll A <tt>RuleBasedCollator</tt> object which defines 173 * the language-sensitive comparison rules used to 174 * determine whether text in the pattern and target 175 * matches. User is responsible for the clearing of this 176 * object. 177 * @param breakiter A <tt>BreakIterator</tt> object used to constrain 178 * the matches that are found. Matches whose start and end 179 * indices in the target text are not boundaries as 180 * determined by the <tt>BreakIterator</tt> are 181 * ignored. If this behavior is not desired, 182 * <tt>NULL</tt> can be passed in instead. 183 * @param status for errors if any. If either the length of pattern or 184 * text is 0 then an U_ILLEGAL_ARGUMENT_ERROR is returned. 185 * @stable ICU 2.0 186 */ 187 StringSearch(const UnicodeString &pattern, 188 const UnicodeString &text, 189 RuleBasedCollator *coll, 190 BreakIterator *breakiter, 191 UErrorCode &status); 192 193 /** 194 * Creating a <tt>StringSearch</tt> instance using the argument locale 195 * language rule set. A collator will be created in the process, which 196 * will be owned by this instance and will be deleted during 197 * destruction 198 * <p> 199 * Note: No parsing of the text within the <tt>CharacterIterator</tt> 200 * will be done during searching for this version. The block of text 201 * in <tt>CharacterIterator</tt> will be used as it is. 202 * @param pattern The text for which this object will search. 203 * @param text The text iterator in which to search for the pattern. 204 * @param locale A locale which defines the language-sensitive 205 * comparison rules used to determine whether text in the 206 * pattern and target matches. User is responsible for 207 * the clearing of this object. 208 * @param breakiter A <tt>BreakIterator</tt> object used to constrain 209 * the matches that are found. Matches whose start and end 210 * indices in the target text are not boundaries as 211 * determined by the <tt>BreakIterator</tt> are 212 * ignored. If this behavior is not desired, 213 * <tt>NULL</tt> can be passed in instead. 214 * @param status for errors if any. If either the length of pattern or 215 * text is 0 then an U_ILLEGAL_ARGUMENT_ERROR is returned. 216 * @stable ICU 2.0 217 */ 218 StringSearch(const UnicodeString &pattern, CharacterIterator &text, 219 const Locale &locale, 220 BreakIterator *breakiter, 221 UErrorCode &status); 222 223 /** 224 * Creating a <tt>StringSearch</tt> instance using the argument collator 225 * language rule set. Note, user retains the ownership of this collator, 226 * it does not get destroyed during this instance's destruction. 227 * <p> 228 * Note: No parsing of the text within the <tt>CharacterIterator</tt> 229 * will be done during searching for this version. The block of text 230 * in <tt>CharacterIterator</tt> will be used as it is. 231 * @param pattern The text for which this object will search. 232 * @param text The text in which to search for the pattern. 233 * @param coll A <tt>RuleBasedCollator</tt> object which defines 234 * the language-sensitive comparison rules used to 235 * determine whether text in the pattern and target 236 * matches. User is responsible for the clearing of this 237 * object. 238 * @param breakiter A <tt>BreakIterator</tt> object used to constrain 239 * the matches that are found. Matches whose start and end 240 * indices in the target text are not boundaries as 241 * determined by the <tt>BreakIterator</tt> are 242 * ignored. If this behavior is not desired, 243 * <tt>NULL</tt> can be passed in instead. 244 * @param status for errors if any. If either the length of pattern or 245 * text is 0 then an U_ILLEGAL_ARGUMENT_ERROR is returned. 246 * @stable ICU 2.0 247 */ 248 StringSearch(const UnicodeString &pattern, CharacterIterator &text, 249 RuleBasedCollator *coll, 250 BreakIterator *breakiter, 251 UErrorCode &status); 252 253 /** 254 * Copy constructor that creates a StringSearch instance with the same 255 * behavior, and iterating over the same text. 256 * @param that StringSearch instance to be copied. 257 * @stable ICU 2.0 258 */ 259 StringSearch(const StringSearch &that); 260 261 /** 262 * Destructor. Cleans up the search iterator data struct. 263 * If a collator is created in the constructor, it will be destroyed here. 264 * @stable ICU 2.0 265 */ 266 virtual ~StringSearch(void); 267 268 /** 269 * Clone this object. 270 * Clones can be used concurrently in multiple threads. 271 * If an error occurs, then NULL is returned. 272 * The caller must delete the clone. 273 * 274 * @return a clone of this object 275 * 276 * @see getDynamicClassID 277 * @stable ICU 2.8 278 */ 279 StringSearch *clone() const; 280 281 // operator overloading --------------------------------------------- 282 283 /** 284 * Assignment operator. Sets this iterator to have the same behavior, 285 * and iterate over the same text, as the one passed in. 286 * @param that instance to be copied. 287 * @stable ICU 2.0 288 */ 289 StringSearch & operator=(const StringSearch &that); 290 291 /** 292 * Equality operator. 293 * @param that instance to be compared. 294 * @return TRUE if both instances have the same attributes, 295 * breakiterators, collators and iterate over the same text 296 * while looking for the same pattern. 297 * @stable ICU 2.0 298 */ 299 virtual UBool operator==(const SearchIterator &that) const; 300 301 // public get and set methods ---------------------------------------- 302 303 /** 304 * Sets the index to point to the given position, and clears any state 305 * that's affected. 306 * <p> 307 * This method takes the argument index and sets the position in the text 308 * string accordingly without checking if the index is pointing to a 309 * valid starting point to begin searching. 310 * @param position within the text to be set. If position is less 311 * than or greater than the text range for searching, 312 * an U_INDEX_OUTOFBOUNDS_ERROR will be returned 313 * @param status for errors if it occurs 314 * @stable ICU 2.0 315 */ 316 virtual void setOffset(int32_t position, UErrorCode &status); 317 318 /** 319 * Return the current index in the text being searched. 320 * If the iteration has gone past the end of the text 321 * (or past the beginning for a backwards search), USEARCH_DONE 322 * is returned. 323 * @return current index in the text being searched. 324 * @stable ICU 2.0 325 */ 326 virtual int32_t getOffset(void) const; 327 328 /** 329 * Set the target text to be searched. 330 * Text iteration will hence begin at the start of the text string. 331 * This method is 332 * useful if you want to re-use an iterator to search for the same 333 * pattern within a different body of text. 334 * @param text text string to be searched 335 * @param status for errors if any. If the text length is 0 then an 336 * U_ILLEGAL_ARGUMENT_ERROR is returned. 337 * @stable ICU 2.0 338 */ 339 virtual void setText(const UnicodeString &text, UErrorCode &status); 340 341 /** 342 * Set the target text to be searched. 343 * Text iteration will hence begin at the start of the text string. 344 * This method is 345 * useful if you want to re-use an iterator to search for the same 346 * pattern within a different body of text. 347 * Note: No parsing of the text within the <tt>CharacterIterator</tt> 348 * will be done during searching for this version. The block of text 349 * in <tt>CharacterIterator</tt> will be used as it is. 350 * @param text text string to be searched 351 * @param status for errors if any. If the text length is 0 then an 352 * U_ILLEGAL_ARGUMENT_ERROR is returned. 353 * @stable ICU 2.0 354 */ 355 virtual void setText(CharacterIterator &text, UErrorCode &status); 356 357 /** 358 * Gets the collator used for the language rules. 359 * <p> 360 * Caller may modify but <b>must not</b> delete the <tt>RuleBasedCollator</tt>! 361 * Modifications to this collator will affect the original collator passed in to 362 * the <tt>StringSearch></tt> constructor or to setCollator, if any. 363 * @return collator used for string search 364 * @stable ICU 2.0 365 */ 366 RuleBasedCollator * getCollator() const; 367 368 /** 369 * Sets the collator used for the language rules. User retains the 370 * ownership of this collator, thus the responsibility of deletion lies 371 * with the user. The iterator's position will not be changed by this method. 372 * @param coll collator 373 * @param status for errors if any 374 * @stable ICU 2.0 375 */ 376 void setCollator(RuleBasedCollator *coll, UErrorCode &status); 377 378 /** 379 * Sets the pattern used for matching. 380 * The iterator's position will not be changed by this method. 381 * @param pattern search pattern to be found 382 * @param status for errors if any. If the pattern length is 0 then an 383 * U_ILLEGAL_ARGUMENT_ERROR is returned. 384 * @stable ICU 2.0 385 */ 386 void setPattern(const UnicodeString &pattern, UErrorCode &status); 387 388 /** 389 * Gets the search pattern. 390 * @return pattern used for matching 391 * @stable ICU 2.0 392 */ 393 const UnicodeString & getPattern() const; 394 395 // public methods ---------------------------------------------------- 396 397 /** 398 * Reset the iteration. 399 * Search will begin at the start of the text string if a forward 400 * iteration is initiated before a backwards iteration. Otherwise if 401 * a backwards iteration is initiated before a forwards iteration, the 402 * search will begin at the end of the text string. 403 * @stable ICU 2.0 404 */ 405 virtual void reset(); 406 407 /** 408 * Returns a copy of StringSearch with the same behavior, and 409 * iterating over the same text, as this one. Note that all data will be 410 * replicated, except for the user-specified collator and the 411 * breakiterator. 412 * @return cloned object 413 * @stable ICU 2.0 414 */ 415 virtual SearchIterator * safeClone(void) const; 416 417 /** 418 * ICU "poor man's RTTI", returns a UClassID for the actual class. 419 * 420 * @stable ICU 2.2 421 */ 422 virtual UClassID getDynamicClassID() const; 423 424 /** 425 * ICU "poor man's RTTI", returns a UClassID for this class. 426 * 427 * @stable ICU 2.2 428 */ 429 static UClassID U_EXPORT2 getStaticClassID(); 430 431 protected: 432 433 // protected method ------------------------------------------------- 434 435 /** 436 * Search forward for matching text, starting at a given location. 437 * Clients should not call this method directly; instead they should 438 * call {@link SearchIterator#next }. 439 * <p> 440 * If a match is found, this method returns the index at which the match 441 * starts and calls {@link SearchIterator#setMatchLength } with the number 442 * of characters in the target text that make up the match. If no match 443 * is found, the method returns <tt>USEARCH_DONE</tt>. 444 * <p> 445 * The <tt>StringSearch</tt> is adjusted so that its current index 446 * (as returned by {@link #getOffset }) is the match position if one was 447 * found. 448 * If a match is not found, <tt>USEARCH_DONE</tt> will be returned and 449 * the <tt>StringSearch</tt> will be adjusted to the index USEARCH_DONE. 450 * @param position The index in the target text at which the search 451 * starts 452 * @param status for errors if any occurs 453 * @return The index at which the matched text in the target starts, or 454 * USEARCH_DONE if no match was found. 455 * @stable ICU 2.0 456 */ 457 virtual int32_t handleNext(int32_t position, UErrorCode &status); 458 459 /** 460 * Search backward for matching text, starting at a given location. 461 * Clients should not call this method directly; instead they should call 462 * <tt>SearchIterator.previous()</tt>, which this method overrides. 463 * <p> 464 * If a match is found, this method returns the index at which the match 465 * starts and calls {@link SearchIterator#setMatchLength } with the number 466 * of characters in the target text that make up the match. If no match 467 * is found, the method returns <tt>USEARCH_DONE</tt>. 468 * <p> 469 * The <tt>StringSearch</tt> is adjusted so that its current index 470 * (as returned by {@link #getOffset }) is the match position if one was 471 * found. 472 * If a match is not found, <tt>USEARCH_DONE</tt> will be returned and 473 * the <tt>StringSearch</tt> will be adjusted to the index USEARCH_DONE. 474 * @param position The index in the target text at which the search 475 * starts. 476 * @param status for errors if any occurs 477 * @return The index at which the matched text in the target starts, or 478 * USEARCH_DONE if no match was found. 479 * @stable ICU 2.0 480 */ 481 virtual int32_t handlePrev(int32_t position, UErrorCode &status); 482 483 private : 484 StringSearch(); // default constructor not implemented 485 486 // private data members ---------------------------------------------- 487 488 /** 489 * Pattern text 490 * @stable ICU 2.0 491 */ 492 UnicodeString m_pattern_; 493 /** 494 * String search struct data 495 * @stable ICU 2.0 496 */ 497 UStringSearch *m_strsrch_; 498 499 }; 500 501 U_NAMESPACE_END 502 503 #endif /* #if !UCONFIG_NO_COLLATION */ 504 505 #endif 506 507
