icuSources/i18n/unicode/usearch.h

   1 /*
   2 **********************************************************************
   3 *   Copyright (C) 2001-2008 IBM and others. All rights reserved.
   4 **********************************************************************
   5 *   Date        Name        Description
   6 *  06/28/2001   synwee      Creation.
   7 **********************************************************************
   8 */
   9 #ifndef USEARCH_H
  10 #define USEARCH_H
  11
  12 #include "unicode/utypes.h"
  13
  14 #if !UCONFIG_NO_COLLATION && !UCONFIG_NO_BREAK_ITERATION
  15
  16 #include "unicode/ucol.h"
  17 #include "unicode/ucoleitr.h"
  18 #include "unicode/ubrk.h"
  19
  20 /**
  21  * \file
  22  * \brief C API: StringSearch
  23  *
  24  * C Apis for an engine that provides language-sensitive text searching based
  25  * on the comparison rules defined in a <tt>UCollator</tt> data struct,
  26  * see <tt>ucol.h</tt>. This ensures that language eccentricity can be
  27  * handled, e.g. for the German collator, characters &szlig; and SS will be matched
  28  * if case is chosen to be ignored.
  29  * See the <a href="http://source.icu-project.org/repos/icu/icuhtml/trunk/design/collation/ICU_collation_design.htm">
  30  * "ICU Collation Design Document"</a> for more information.
  31  * <p>
  32  * The algorithm implemented is a modified form of the Boyer Moore's search.
  33  * For more information  see
  34  * <a href="http://icu-project.org/docs/papers/efficient_text_searching_in_java.html">
  35  * "Efficient Text Searching in Java"</a>, published in <i>Java Report</i>
  36  * in February, 1999, for further information on the algorithm.
  37  * <p>
  38  * There are 2 match options for selection:<br>
  39  * Let S' be the sub-string of a text string S between the offsets start and
  40  * end <start, end>.
  41  * <br>
  42  * A pattern string P matches a text string S at the offsets <start, end>
  43  * if
  44  * <pre>
  45  * option 1. Some canonical equivalent of P matches some canonical equivalent
  46  *           of S'
  47  * option 2. P matches S' and if P starts or ends with a combining mark,
  48  *           there exists no non-ignorable combining mark before or after S'
  49  *           in S respectively.
  50  * </pre>
  51  * Option 2. will be the default.
  52  * <p>
  53  * This search has APIs similar to that of other text iteration mechanisms
  54  * such as the break iterators in <tt>ubrk.h</tt>. Using these
  55  * APIs, it is easy to scan through text looking for all occurances of
  56  * a given pattern. This search iterator allows changing of direction by
  57  * calling a <tt>reset</tt> followed by a <tt>next</tt> or <tt>previous</tt>.
  58  * Though a direction change can occur without calling <tt>reset</tt> first,
  59  * this operation comes with some speed penalty.
  60  * Generally, match results in the forward direction will match the result
  61  * matches in the backwards direction in the reverse order
  62  * <p>
  63  * <tt>usearch.h</tt> provides APIs to specify the starting position
  64  * within the text string to be searched, e.g. <tt>usearch_setOffset</tt>,
  65  * <tt>usearch_preceding</tt> and <tt>usearch_following</tt>. Since the
  66  * starting position will be set as it is specified, please take note that
  67  * there are some dangerous positions which the search may render incorrect
  68  * results:
  69  * <ul>
  70  * <li> The midst of a substring that requires normalization.
  71  * <li> If the following match is to be found, the position should not be the
  72  *      second character which requires to be swapped with the preceding
  73  *      character. Vice versa, if the preceding match is to be found,
  74  *      position to search from should not be the first character which
  75  *      requires to be swapped with the next character. E.g certain Thai and
  76  *      Lao characters require swapping.
  77  * <li> If a following pattern match is to be found, any position within a
  78  *      contracting sequence except the first will fail. Vice versa if a
  79  *      preceding pattern match is to be found, a invalid starting point
  80  *      would be any character within a contracting sequence except the last.
  81  * </ul>
  82  * <p>
  83  * A breakiterator can be used if only matches at logical breaks are desired.
  84  * Using a breakiterator will only give you results that exactly matches the
  85  * boundaries given by the breakiterator. For instance the pattern "e" will
  86  * not be found in the string "\u00e9" if a character break iterator is used.
  87  * <p>
  88  * Options are provided to handle overlapping matches.
  89  * E.g. In English, overlapping matches produces the result 0 and 2
  90  * for the pattern "abab" in the text "ababab", where else mutually
  91  * exclusive matches only produce the result of 0.
  92  * <p>
  93  * Though collator attributes will be taken into consideration while
  94  * performing matches, there are no APIs here for setting and getting the
  95  * attributes. These attributes can be set by getting the collator
  96  * from <tt>usearch_getCollator</tt> and using the APIs in <tt>ucol.h</tt>.
  97  * Lastly to update String Search to the new collator attributes,
  98  * usearch_reset() has to be called.
  99  * <p>
 100  * Restriction: <br>
 101  * Currently there are no composite characters that consists of a
 102  * character with combining class > 0 before a character with combining
 103  * class == 0. However, if such a character exists in the future, the
 104  * search mechanism does not guarantee the results for option 1.
 105  *
 106  * <p>
 107  * Example of use:<br>
 108  * <pre><code>
 109  * char *tgtstr = "The quick brown fox jumped over the lazy fox";
 110  * char *patstr = "fox";
 111  * UChar target[64];
 112  * UChar pattern[16];
 113  * UErrorCode status = U_ZERO_ERROR;
 114  * u_uastrcpy(target, tgtstr);
 115  * u_uastrcpy(pattern, patstr);
 116  *
 117  * UStringSearch *search = usearch_open(pattern, -1, target, -1, "en_US",
 118  *                                  NULL, &status);
 119  * if (U_SUCCESS(status)) {
 120  *     for (int pos = usearch_first(search, &status);
 121  *          pos != USEARCH_DONE;
 122  *          pos = usearch_next(search, &status))
 123  *     {
 124  *         printf("Found match at %d pos, length is %d\n", pos,
 125  *                                        usearch_getMatchLength(search));
 126  *     }
 127  * }
 128  *
 129  * usearch_close(search);
 130  * </code></pre>
 131  * @stable ICU 2.4
 132  */
 133
 134 /**
 135 * DONE is returned by previous() and next() after all valid matches have
 136 * been returned, and by first() and last() if there are no matches at all.
 137 * @stable ICU 2.4
 138 */
 139 #define USEARCH_DONE -1
 140
 141 /**
 142 * Data structure for searching
 143 * @stable ICU 2.4
 144 */
 145 struct UStringSearch;
 146 /**
 147 * Data structure for searching
 148 * @stable ICU 2.4
 149 */
 150 typedef struct UStringSearch UStringSearch;
 151
 152 /**
 153 * @stable ICU 2.4
 154 */
 155 typedef enum {
 156     /** Option for overlapping matches */
 157     USEARCH_OVERLAP,
 158     /**
 159     Option for canonical matches. option 1 in header documentation.
 160     The default value will be USEARCH_OFF
 161     */
 162     USEARCH_CANONICAL_MATCH,
 163     USEARCH_ATTRIBUTE_COUNT
 164 } USearchAttribute;
 165
 166 /**
 167 * @stable ICU 2.4
 168 */
 169 typedef enum {
 170     /** default value for any USearchAttribute */
 171     USEARCH_DEFAULT = -1,
 172     /** value for USEARCH_OVERLAP and USEARCH_CANONICAL_MATCH */
 173     USEARCH_OFF,
 174     /** value for USEARCH_OVERLAP and USEARCH_CANONICAL_MATCH */
 175     USEARCH_ON,
 176     USEARCH_ATTRIBUTE_VALUE_COUNT
 177 } USearchAttributeValue;
 178
 179 /* open and close ------------------------------------------------------ */
 180
 181 /**
 182 * Creating a search iterator data struct using the argument locale language
 183 * rule set. A collator will be created in the process, which will be owned by
 184 * this search and will be deleted in <tt>usearch_close</tt>.
 185 * @param pattern for matching
 186 * @param patternlength length of the pattern, -1 for null-termination
 187 * @param text text string
 188 * @param textlength length of the text string, -1 for null-termination
 189 * @param locale name of locale for the rules to be used
 190 * @param breakiter A BreakIterator that will be used to restrict the points
 191 *                  at which matches are detected. If a match is found, but
 192 *                  the match's start or end index is not a boundary as
 193 *                  determined by the <tt>BreakIterator</tt>, the match will
 194 *                  be rejected and another will be searched for.
 195 *                  If this parameter is <tt>NULL</tt>, no break detection is
 196 *                  attempted.
 197 * @param status for errors if it occurs. If pattern or text is NULL, or if
 198 *               patternlength or textlength is 0 then an
 199 *               U_ILLEGAL_ARGUMENT_ERROR is returned.
 200 * @return search iterator data structure, or NULL if there is an error.
 201 * @stable ICU 2.4
 202 */
 203 U_STABLE UStringSearch * U_EXPORT2 usearch_open(const UChar          *pattern,
 204                                               int32_t         patternlength,
 205                                         const UChar          *text,
 206                                               int32_t         textlength,
 207                                         const char           *locale,
 208                                               UBreakIterator *breakiter,
 209                                               UErrorCode     *status);
 210
 211 /**
 212 * Creating a search iterator data struct using the argument collator language
 213 * rule set. Note, user retains the ownership of this collator, thus the
 214 * responsibility of deletion lies with the user.
 215 * NOTE: string search cannot be instantiated from a collator that has
 216 * collate digits as numbers (CODAN) turned on.
 217 * @param pattern for matching
 218 * @param patternlength length of the pattern, -1 for null-termination
 219 * @param text text string
 220 * @param textlength length of the text string, -1 for null-termination
 221 * @param collator used for the language rules
 222 * @param breakiter A BreakIterator that will be used to restrict the points
 223 *                  at which matches are detected. If a match is found, but
 224 *                  the match's start or end index is not a boundary as
 225 *                  determined by the <tt>BreakIterator</tt>, the match will
 226 *                  be rejected and another will be searched for.
 227 *                  If this parameter is <tt>NULL</tt>, no break detection is
 228 *                  attempted.
 229 * @param status for errors if it occurs. If collator, pattern or text is NULL,
 230 *               or if patternlength or textlength is 0 then an
 231 *               U_ILLEGAL_ARGUMENT_ERROR is returned.
 232 * @return search iterator data structure, or NULL if there is an error.
 233 * @stable ICU 2.4
 234 */
 235 U_STABLE UStringSearch * U_EXPORT2 usearch_openFromCollator(
 236                                          const UChar *pattern,
 237                                                int32_t         patternlength,
 238                                          const UChar          *text,
 239                                                int32_t         textlength,
 240                                          const UCollator      *collator,
 241                                                UBreakIterator *breakiter,
 242                                                UErrorCode     *status);
 243
 244 /**
 245 * Destroying and cleaning up the search iterator data struct.
 246 * If a collator is created in <tt>usearch_open</tt>, it will be destroyed here.
 247 * @param searchiter data struct to clean up
 248 * @stable ICU 2.4
 249 */
 250 U_STABLE void U_EXPORT2 usearch_close(UStringSearch *searchiter);
 251
 252 /* get and set methods -------------------------------------------------- */
 253
 254 /**
 255 * Sets the current position in the text string which the next search will
 256 * start from. Clears previous states.
 257 * This method takes the argument index and sets the position in the text
 258 * string accordingly without checking if the index is pointing to a
 259 * valid starting point to begin searching.
 260 * Search positions that may render incorrect results are highlighted in the
 261 * header comments
 262 * @param strsrch search iterator data struct
 263 * @param position position to start next search from. If position is less
 264 *          than or greater than the text range for searching,
 265 *          an U_INDEX_OUTOFBOUNDS_ERROR will be returned
 266 * @param status error status if any.
 267 * @stable ICU 2.4
 268 */
 269 U_STABLE void U_EXPORT2 usearch_setOffset(UStringSearch *strsrch,
 270                                         int32_t    position,
 271                                         UErrorCode    *status);
 272
 273 /**
 274 * Return the current index in the string text being searched.
 275 * If the iteration has gone past the end of the text (or past the beginning
 276 * for a backwards search), <tt>USEARCH_DONE</tt> is returned.
 277 * @param strsrch search iterator data struct
 278 * @see #USEARCH_DONE
 279 * @stable ICU 2.4
 280 */
 281 U_STABLE int32_t U_EXPORT2 usearch_getOffset(const UStringSearch *strsrch);
 282
 283 /**
 284 * Sets the text searching attributes located in the enum USearchAttribute
 285 * with values from the enum USearchAttributeValue.
 286 * <tt>USEARCH_DEFAULT</tt> can be used for all attributes for resetting.
 287 * @param strsrch search iterator data struct
 288 * @param attribute text attribute to be set
 289 * @param value text attribute value
 290 * @param status for errors if it occurs
 291 * @see #usearch_getAttribute
 292 * @stable ICU 2.4
 293 */
 294 U_STABLE void U_EXPORT2 usearch_setAttribute(UStringSearch         *strsrch,
 295                                            USearchAttribute       attribute,
 296                                            USearchAttributeValue  value,
 297                                            UErrorCode            *status);
 298
 299 /**
 300 * Gets the text searching attributes.
 301 * @param strsrch search iterator data struct
 302 * @param attribute text attribute to be retrieve
 303 * @return text attribute value
 304 * @see #usearch_setAttribute
 305 * @stable ICU 2.4
 306 */
 307 U_STABLE USearchAttributeValue U_EXPORT2 usearch_getAttribute(
 308                                          const UStringSearch    *strsrch,
 309                                                USearchAttribute  attribute);
 310
 311 /**
 312 * Returns the index to the match in the text string that was searched.
 313 * This call returns a valid result only after a successful call to
 314 * <tt>usearch_first</tt>, <tt>usearch_next</tt>, <tt>usearch_previous</tt>,
 315 * or <tt>usearch_last</tt>.
 316 * Just after construction, or after a searching method returns
 317 * <tt>USEARCH_DONE</tt>, this method will return <tt>USEARCH_DONE</tt>.
 318 * <p>
 319 * Use <tt>usearch_getMatchedLength</tt> to get the matched string length.
 320 * @param strsrch search iterator data struct
 321 * @return index to a substring within the text string that is being
 322 *         searched.
 323 * @see #usearch_first
 324 * @see #usearch_next
 325 * @see #usearch_previous
 326 * @see #usearch_last
 327 * @see #USEARCH_DONE
 328 * @stable ICU 2.4
 329 */
 330 U_STABLE int32_t U_EXPORT2 usearch_getMatchedStart(
 331                                                const UStringSearch *strsrch);
 332
 333 /**
 334 * Returns the length of text in the string which matches the search pattern.
 335 * This call returns a valid result only after a successful call to
 336 * <tt>usearch_first</tt>, <tt>usearch_next</tt>, <tt>usearch_previous</tt>,
 337 * or <tt>usearch_last</tt>.
 338 * Just after construction, or after a searching method returns
 339 * <tt>USEARCH_DONE</tt>, this method will return 0.
 340 * @param strsrch search iterator data struct
 341 * @return The length of the match in the string text, or 0 if there is no
 342 *         match currently.
 343 * @see #usearch_first
 344 * @see #usearch_next
 345 * @see #usearch_previous
 346 * @see #usearch_last
 347 * @see #USEARCH_DONE
 348 * @stable ICU 2.4
 349 */
 350 U_STABLE int32_t U_EXPORT2 usearch_getMatchedLength(
 351                                                const UStringSearch *strsrch);
 352
 353 /**
 354 * Returns the text that was matched by the most recent call to
 355 * <tt>usearch_first</tt>, <tt>usearch_next</tt>, <tt>usearch_previous</tt>,
 356 * or <tt>usearch_last</tt>.
 357 * If the iterator is not pointing at a valid match (e.g. just after
 358 * construction or after <tt>USEARCH_DONE</tt> has been returned, returns
 359 * an empty string. If result is not large enough to store the matched text,
 360 * result will be filled with the partial text and an U_BUFFER_OVERFLOW_ERROR
 361 * will be returned in status. result will be null-terminated whenever
 362 * possible. If the buffer fits the matched text exactly, a null-termination
 363 * is not possible, then a U_STRING_NOT_TERMINATED_ERROR set in status.
 364 * Pre-flighting can be either done with length = 0 or the API
 365 * <tt>usearch_getMatchLength</tt>.
 366 * @param strsrch search iterator data struct
 367 * @param result UChar buffer to store the matched string
 368 * @param resultCapacity length of the result buffer
 369 * @param status error returned if result is not large enough
 370 * @return exact length of the matched text, not counting the null-termination
 371 * @see #usearch_first
 372 * @see #usearch_next
 373 * @see #usearch_previous
 374 * @see #usearch_last
 375 * @see #USEARCH_DONE
 376 * @stable ICU 2.4
 377 */
 378 U_STABLE int32_t U_EXPORT2 usearch_getMatchedText(const UStringSearch *strsrch,
 379                                             UChar         *result,
 380                                             int32_t        resultCapacity,
 381                                             UErrorCode    *status);
 382
 383 #if !UCONFIG_NO_BREAK_ITERATION
 384
 385 /**
 386 * Set the BreakIterator that will be used to restrict the points at which
 387 * matches are detected.
 388 * @param strsrch search iterator data struct
 389 * @param breakiter A BreakIterator that will be used to restrict the points
 390 *                  at which matches are detected. If a match is found, but
 391 *                  the match's start or end index is not a boundary as
 392 *                  determined by the <tt>BreakIterator</tt>, the match will
 393 *                  be rejected and another will be searched for.
 394 *                  If this parameter is <tt>NULL</tt>, no break detection is
 395 *                  attempted.
 396 * @param status for errors if it occurs
 397 * @see #usearch_getBreakIterator
 398 * @stable ICU 2.4
 399 */
 400 U_STABLE void U_EXPORT2 usearch_setBreakIterator(UStringSearch  *strsrch,
 401                                                UBreakIterator *breakiter,
 402                                                UErrorCode     *status);
 403
 404 /**
 405 * Returns the BreakIterator that is used to restrict the points at which
 406 * matches are detected. This will be the same object that was passed to the
 407 * constructor or to <tt>usearch_setBreakIterator</tt>. Note that
 408 * <tt>NULL</tt>
 409 * is a legal value; it means that break detection should not be attempted.
 410 * @param strsrch search iterator data struct
 411 * @return break iterator used
 412 * @see #usearch_setBreakIterator
 413 * @stable ICU 2.4
 414 */
 415 U_STABLE const UBreakIterator * U_EXPORT2 usearch_getBreakIterator(
 416                                               const UStringSearch *strsrch);
 417
 418 #endif
 419
 420 /**
 421 * Set the string text to be searched. Text iteration will hence begin at the
 422 * start of the text string. This method is useful if you want to re-use an
 423 * iterator to search for the same pattern within a different body of text.
 424 * @param strsrch search iterator data struct
 425 * @param text new string to look for match
 426 * @param textlength length of the new string, -1 for null-termination
 427 * @param status for errors if it occurs. If text is NULL, or textlength is 0
 428 *               then an U_ILLEGAL_ARGUMENT_ERROR is returned with no change
 429 *               done to strsrch.
 430 * @see #usearch_getText
 431 * @stable ICU 2.4
 432 */
 433 U_STABLE void U_EXPORT2 usearch_setText(      UStringSearch *strsrch,
 434                                       const UChar         *text,
 435                                             int32_t        textlength,
 436                                             UErrorCode    *status);
 437
 438 /**
 439 * Return the string text to be searched.
 440 * @param strsrch search iterator data struct
 441 * @param length returned string text length
 442 * @return string text
 443 * @see #usearch_setText
 444 * @stable ICU 2.4
 445 */
 446 U_STABLE const UChar * U_EXPORT2 usearch_getText(const UStringSearch *strsrch,
 447                                                int32_t       *length);
 448
 449 /**
 450 * Gets the collator used for the language rules.
 451 * <p>
 452 * Deleting the returned <tt>UCollator</tt> before calling
 453 * <tt>usearch_close</tt> would cause the string search to fail.
 454 * <tt>usearch_close</tt> will delete the collator if this search owns it.
 455 * @param strsrch search iterator data struct
 456 * @return collator
 457 * @stable ICU 2.4
 458 */
 459 U_STABLE UCollator * U_EXPORT2 usearch_getCollator(
 460                                                const UStringSearch *strsrch);
 461
 462 /**
 463 * Sets the collator used for the language rules. User retains the ownership
 464 * of this collator, thus the responsibility of deletion lies with the user.
 465 * This method causes internal data such as Boyer-Moore shift tables to
 466 * be recalculated, but the iterator's position is unchanged.
 467 * @param strsrch search iterator data struct
 468 * @param collator to be used
 469 * @param status for errors if it occurs
 470 * @stable ICU 2.4
 471 */
 472 U_STABLE void U_EXPORT2 usearch_setCollator(      UStringSearch *strsrch,
 473                                           const UCollator     *collator,
 474                                                 UErrorCode    *status);
 475
 476 /**
 477 * Sets the pattern used for matching.
 478 * Internal data like the Boyer Moore table will be recalculated, but the
 479 * iterator's position is unchanged.
 480 * @param strsrch search iterator data struct
 481 * @param pattern string
 482 * @param patternlength pattern length, -1 for null-terminated string
 483 * @param status for errors if it occurs. If text is NULL, or textlength is 0
 484 *               then an U_ILLEGAL_ARGUMENT_ERROR is returned with no change
 485 *               done to strsrch.
 486 * @stable ICU 2.4
 487 */
 488 U_STABLE void U_EXPORT2 usearch_setPattern(      UStringSearch *strsrch,
 489                                          const UChar         *pattern,
 490                                                int32_t        patternlength,
 491                                                UErrorCode    *status);
 492
 493 /**
 494 * Gets the search pattern
 495 * @param strsrch search iterator data struct
 496 * @param length return length of the pattern, -1 indicates that the pattern
 497 *               is null-terminated
 498 * @return pattern string
 499 * @stable ICU 2.4
 500 */
 501 U_STABLE const UChar * U_EXPORT2 usearch_getPattern(
 502                                                const UStringSearch *strsrch,
 503                                                      int32_t       *length);
 504
 505 /* methods ------------------------------------------------------------- */
 506
 507 /**
 508 * Returns the first index at which the string text matches the search
 509 * pattern.
 510 * The iterator is adjusted so that its current index (as returned by
 511 * <tt>usearch_getOffset</tt>) is the match position if one was found.
 512 * If a match is not found, <tt>USEARCH_DONE</tt> will be returned and
 513 * the iterator will be adjusted to the index <tt>USEARCH_DONE</tt>.
 514 * @param strsrch search iterator data struct
 515 * @param status for errors if it occurs
 516 * @return The character index of the first match, or
 517 * <tt>USEARCH_DONE</tt> if there are no matches.
 518 * @see #usearch_getOffset
 519 * @see #USEARCH_DONE
 520 * @stable ICU 2.4
 521 */
 522 U_STABLE int32_t U_EXPORT2 usearch_first(UStringSearch *strsrch,
 523                                            UErrorCode    *status);
 524
 525 /**
 526 * Returns the first index greater than <tt>position</tt> at which the string
 527 * text
 528 * matches the search pattern. The iterator is adjusted so that its current
 529 * index (as returned by <tt>usearch_getOffset</tt>) is the match position if
 530 * one was found.
 531 * If a match is not found, <tt>USEARCH_DONE</tt> will be returned and
 532 * the iterator will be adjusted to the index <tt>USEARCH_DONE</tt>
 533 * <p>
 534 * Search positions that may render incorrect results are highlighted in the
 535 * header comments. If position is less than or greater than the text range
 536 * for searching, an U_INDEX_OUTOFBOUNDS_ERROR will be returned
 537 * @param strsrch search iterator data struct
 538 * @param position to start the search at
 539 * @param status for errors if it occurs
 540 * @return The character index of the first match following <tt>pos</tt>,
 541 *         or <tt>USEARCH_DONE</tt> if there are no matches.
 542 * @see #usearch_getOffset
 543 * @see #USEARCH_DONE
 544 * @stable ICU 2.4
 545 */
 546 U_STABLE int32_t U_EXPORT2 usearch_following(UStringSearch *strsrch,
 547                                                int32_t    position,
 548                                                UErrorCode    *status);
 549
 550 /**
 551 * Returns the last index in the target text at which it matches the search
 552 * pattern. The iterator is adjusted so that its current
 553 * index (as returned by <tt>usearch_getOffset</tt>) is the match position if
 554 * one was found.
 555 * If a match is not found, <tt>USEARCH_DONE</tt> will be returned and
 556 * the iterator will be adjusted to the index <tt>USEARCH_DONE</tt>.
 557 * @param strsrch search iterator data struct
 558 * @param status for errors if it occurs
 559 * @return The index of the first match, or <tt>USEARCH_DONE</tt> if there
 560 *         are no matches.
 561 * @see #usearch_getOffset
 562 * @see #USEARCH_DONE
 563 * @stable ICU 2.4
 564 */
 565 U_STABLE int32_t U_EXPORT2 usearch_last(UStringSearch *strsrch,
 566                                           UErrorCode    *status);
 567
 568 /**
 569 * Returns the first index less than <tt>position</tt> at which the string text
 570 * matches the search pattern. The iterator is adjusted so that its current
 571 * index (as returned by <tt>usearch_getOffset</tt>) is the match position if
 572 * one was found.
 573 * If a match is not found, <tt>USEARCH_DONE</tt> will be returned and
 574 * the iterator will be adjusted to the index <tt>USEARCH_DONE</tt>
 575 * <p>
 576 * Search positions that may render incorrect results are highlighted in the
 577 * header comments. If position is less than or greater than the text range
 578 * for searching, an U_INDEX_OUTOFBOUNDS_ERROR will be returned
 579 * @param strsrch search iterator data struct
 580 * @param position index position the search is to begin at
 581 * @param status for errors if it occurs
 582 * @return The character index of the first match preceding <tt>pos</tt>,
 583 *         or <tt>USEARCH_DONE</tt> if there are no matches.
 584 * @see #usearch_getOffset
 585 * @see #USEARCH_DONE
 586 * @stable ICU 2.4
 587 */
 588 U_STABLE int32_t U_EXPORT2 usearch_preceding(UStringSearch *strsrch,
 589                                                int32_t    position,
 590                                                UErrorCode    *status);
 591
 592 /**
 593 * Returns the index of the next point at which the string text matches the
 594 * search pattern, starting from the current position.
 595 * The iterator is adjusted so that its current
 596 * index (as returned by <tt>usearch_getOffset</tt>) is the match position if
 597 * one was found.
 598 * If a match is not found, <tt>USEARCH_DONE</tt> will be returned and
 599 * the iterator will be adjusted to the index <tt>USEARCH_DONE</tt>
 600 * @param strsrch search iterator data struct
 601 * @param status for errors if it occurs
 602 * @return The index of the next match after the current position, or
 603 *         <tt>USEARCH_DONE</tt> if there are no more matches.
 604 * @see #usearch_first
 605 * @see #usearch_getOffset
 606 * @see #USEARCH_DONE
 607 * @stable ICU 2.4
 608 */
 609 U_STABLE int32_t U_EXPORT2 usearch_next(UStringSearch *strsrch,
 610                                           UErrorCode    *status);
 611
 612 /**
 613 * Returns the index of the previous point at which the string text matches
 614 * the search pattern, starting at the current position.
 615 * The iterator is adjusted so that its current
 616 * index (as returned by <tt>usearch_getOffset</tt>) is the match position if
 617 * one was found.
 618 * If a match is not found, <tt>USEARCH_DONE</tt> will be returned and
 619 * the iterator will be adjusted to the index <tt>USEARCH_DONE</tt>
 620 * @param strsrch search iterator data struct
 621 * @param status for errors if it occurs
 622 * @return The index of the previous match before the current position,
 623 *         or <tt>USEARCH_DONE</tt> if there are no more matches.
 624 * @see #usearch_last
 625 * @see #usearch_getOffset
 626 * @see #USEARCH_DONE
 627 * @stable ICU 2.4
 628 */
 629 U_STABLE int32_t U_EXPORT2 usearch_previous(UStringSearch *strsrch,
 630                                               UErrorCode    *status);
 631
 632 /**
 633 * Reset the iteration.
 634 * Search will begin at the start of the text string if a forward iteration
 635 * is initiated before a backwards iteration. Otherwise if a backwards
 636 * iteration is initiated before a forwards iteration, the search will begin
 637 * at the end of the text string.
 638 * @param strsrch search iterator data struct
 639 * @see #usearch_first
 640 * @stable ICU 2.4
 641 */
 642 U_STABLE void U_EXPORT2 usearch_reset(UStringSearch *strsrch);
 643
 644 /**
 645   *  Simple forward search for the pattern, starting at a specified index,
 646   *     and using using a default set search options.
 647   *
 648   *  This is an experimental function, and is not an official part of the
 649   *      ICU API.
 650   *
 651   *  The collator options, such as UCOL_STRENGTH and UCOL_NORMALIZTION, are honored.
 652   *
 653   *  The UStringSearch options USEARCH_CANONICAL_MATCH, USEARCH_OVERLAP and
 654   *  any Break Iterator are ignored.
 655   *
 656   *  Matches obey the following constraints:
 657   *
 658   *      Characters at the start or end positions of a match that are ignorable
 659   *      for collation are not included as part of the match, unless they
 660   *      are part of a combining sequence, as described below.
 661   *
 662   *      A match will not include a partial combining sequence.  Combining
 663   *      character sequences  are considered to be  inseperable units,
 664   *      and either match the pattern completely, or are considered to not match
 665   *      at all.  Thus, for example, an A followed a combining accent mark will
 666   *      not be found when searching for a plain (unaccented) A.   (unless
 667   *      the collation strength has been set to ignore all accents).
 668   *
 669   *      When beginning a search, the initial starting position, startIdx,
 670   *      is assumed to be an acceptable match boundary with respect to
 671   *      combining characters.  A combining sequence that spans across the
 672   *      starting point will not supress a match beginning at startIdx.
 673   *
 674   *      Characters that expand to multiple collation elements
 675   *      (German sharp-S becoming 'ss', or the composed forms of accented
 676   *      characters, for example) also must match completely.
 677   *      Searching for a single 's' in a string containing only a sharp-s will
 678   *      find no match.
 679   *
 680   *
 681   *  @param strsrch    the UStringSearch struct, which references both
 682   *                    the text to be searched  and the pattern being sought.
 683   *  @param startIdx   The index into the text to begin the search.
 684   *  @param matchStart An out parameter, the starting index of the matched text.
 685   *                    This parameter may be NULL.
 686   *                    A value of -1 will be returned if no match was found.
 687   *  @param matchLimit Out parameter, the index of the first position following the matched text.
 688   *                    The matchLimit will be at a suitable position for beginning a subsequent search
 689   *                    in the input text.
 690   *                    This parameter may be NULL.
 691   *                    A value of -1 will be returned if no match was found.
 692   *
 693   *  @param status     Report any errors.  Note that no match found is not an error.
 694   *  @return           TRUE if a match was found, FALSE otherwise.
 695   *
 696   *  @internal
 697   */
 698 U_INTERNAL UBool U_EXPORT2 usearch_search(UStringSearch *strsrch,
 699                                           int32_t        startIdx,
 700                                           int32_t        *matchStart,
 701                                           int32_t        *matchLimit,
 702                                           UErrorCode     *status);
 703
 704 /**
 705   *  Simple backwards search for the pattern, starting at a specified index,
 706   *     and using using a default set search options.
 707   *
 708   *  This is an experimental function, and is not an official part of the
 709   *      ICU API.
 710   *
 711   *  The collator options, such as UCOL_STRENGTH and UCOL_NORMALIZTION, are honored.
 712   *
 713   *  The UStringSearch options USEARCH_CANONICAL_MATCH, USEARCH_OVERLAP and
 714   *  any Break Iterator are ignored.
 715   *
 716   *  Matches obey the following constraints:
 717   *
 718   *      Characters at the start or end positions of a match that are ignorable
 719   *      for collation are not included as part of the match, unless they
 720   *      are part of a combining sequence, as described below.
 721   *
 722   *      A match will not include a partial combining sequence.  Combining
 723   *      character sequences  are considered to be  inseperable units,
 724   *      and either match the pattern completely, or are considered to not match
 725   *      at all.  Thus, for example, an A followed a combining accent mark will
 726   *      not be found when searching for a plain (unaccented) A.   (unless
 727   *      the collation strength has been set to ignore all accents).
 728   *
 729   *      When beginning a search, the initial starting position, startIdx,
 730   *      is assumed to be an acceptable match boundary with respect to
 731   *      combining characters.  A combining sequence that spans across the
 732   *      starting point will not supress a match beginning at startIdx.
 733   *
 734   *      Characters that expand to multiple collation elements
 735   *      (German sharp-S becoming 'ss', or the composed forms of accented
 736   *      characters, for example) also must match completely.
 737   *      Searching for a single 's' in a string containing only a sharp-s will
 738   *      find no match.
 739   *
 740   *
 741   *  @param strsrch    the UStringSearch struct, which references both
 742   *                    the text to be searched  and the pattern being sought.
 743   *  @param startIdx   The index into the text to begin the search.
 744   *  @param matchStart An out parameter, the starting index of the matched text.
 745   *                    This parameter may be NULL.
 746   *                    A value of -1 will be returned if no match was found.
 747   *  @param matchLimit Out parameter, the index of the first position following the matched text.
 748   *                    The matchLimit will be at a suitable position for beginning a subsequent search
 749   *                    in the input text.
 750   *                    This parameter may be NULL.
 751   *                    A value of -1 will be returned if no match was found.
 752   *
 753   *  @param status     Report any errors.  Note that no match found is not an error.
 754   *  @return           TRUE if a match was found, FALSE otherwise.
 755   *
 756   *  @internal
 757   */
 758 U_INTERNAL UBool U_EXPORT2 usearch_searchBackwards(UStringSearch *strsrch,
 759                                                    int32_t        startIdx,
 760                                                    int32_t        *matchStart,
 761                                                    int32_t        *matchLimit,
 762                                                    UErrorCode     *status);
 763
 764 #endif /* #if !UCONFIG_NO_COLLATION  && !UCONFIG_NO_BREAK_ITERATION */
 765
 766 #endif