icuSources/i18n/unicode/usearch.h

   1 /*
   2 **********************************************************************
   3 *   Copyright (C) 2001-2011 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/localpointer.h"
  17 #include "unicode/ucol.h"
  18 #include "unicode/ucoleitr.h"
  19 #include "unicode/ubrk.h"
  20
  21 /**
  22  * \file
  23  * \brief C API: StringSearch
  24  *
  25  * C Apis for an engine that provides language-sensitive text searching based
  26  * on the comparison rules defined in a <tt>UCollator</tt> data struct,
  27  * see <tt>ucol.h</tt>. This ensures that language eccentricity can be
  28  * handled, e.g. for the German collator, characters &szlig; and SS will be matched
  29  * if case is chosen to be ignored.
  30  * See the <a href="http://source.icu-project.org/repos/icu/icuhtml/trunk/design/collation/ICU_collation_design.htm">
  31  * "ICU Collation Design Document"</a> for more information.
  32  * <p>
  33  * The algorithm implemented is a modified form of the Boyer Moore's search.
  34  * For more information  see
  35  * <a href="http://icu-project.org/docs/papers/efficient_text_searching_in_java.html">
  36  * "Efficient Text Searching in Java"</a>, published in <i>Java Report</i>
  37  * in February, 1999, for further information on the algorithm.
  38  * <p>
  39  * There are 2 match options for selection:<br>
  40  * Let S' be the sub-string of a text string S between the offsets start and
  41  * end <start, end>.
  42  * <br>
  43  * A pattern string P matches a text string S at the offsets <start, end>
  44  * if
  45  * <pre>
  46  * option 1. Some canonical equivalent of P matches some canonical equivalent
  47  *           of S'
  48  * option 2. P matches S' and if P starts or ends with a combining mark,
  49  *           there exists no non-ignorable combining mark before or after S'
  50  *           in S respectively.
  51  * </pre>
  52  * Option 2. will be the default.
  53  * <p>
  54  * This search has APIs similar to that of other text iteration mechanisms
  55  * such as the break iterators in <tt>ubrk.h</tt>. Using these
  56  * APIs, it is easy to scan through text looking for all occurances of
  57  * a given pattern. This search iterator allows changing of direction by
  58  * calling a <tt>reset</tt> followed by a <tt>next</tt> or <tt>previous</tt>.
  59  * Though a direction change can occur without calling <tt>reset</tt> first,
  60  * this operation comes with some speed penalty.
  61  * Generally, match results in the forward direction will match the result
  62  * matches in the backwards direction in the reverse order
  63  * <p>
  64  * <tt>usearch.h</tt> provides APIs to specify the starting position
  65  * within the text string to be searched, e.g. <tt>usearch_setOffset</tt>,
  66  * <tt>usearch_preceding</tt> and <tt>usearch_following</tt>. Since the
  67  * starting position will be set as it is specified, please take note that
  68  * there are some dangerous positions which the search may render incorrect
  69  * results:
  70  * <ul>
  71  * <li> The midst of a substring that requires normalization.
  72  * <li> If the following match is to be found, the position should not be the
  73  *      second character which requires to be swapped with the preceding
  74  *      character. Vice versa, if the preceding match is to be found,
  75  *      position to search from should not be the first character which
  76  *      requires to be swapped with the next character. E.g certain Thai and
  77  *      Lao characters require swapping.
  78  * <li> If a following pattern match is to be found, any position within a
  79  *      contracting sequence except the first will fail. Vice versa if a
  80  *      preceding pattern match is to be found, a invalid starting point
  81  *      would be any character within a contracting sequence except the last.
  82  * </ul>
  83  * <p>
  84  * A breakiterator can be used if only matches at logical breaks are desired.
  85  * Using a breakiterator will only give you results that exactly matches the
  86  * boundaries given by the breakiterator. For instance the pattern "e" will
  87  * not be found in the string "\u00e9" if a character break iterator is used.
  88  * <p>
  89  * Options are provided to handle overlapping matches.
  90  * E.g. In English, overlapping matches produces the result 0 and 2
  91  * for the pattern "abab" in the text "ababab", where else mutually
  92  * exclusive matches only produce the result of 0.
  93  * <p>
  94  * Though collator attributes will be taken into consideration while
  95  * performing matches, there are no APIs here for setting and getting the
  96  * attributes. These attributes can be set by getting the collator
  97  * from <tt>usearch_getCollator</tt> and using the APIs in <tt>ucol.h</tt>.
  98  * Lastly to update String Search to the new collator attributes,
  99  * usearch_reset() has to be called.
 100  * <p>
 101  * Restriction: <br>
 102  * Currently there are no composite characters that consists of a
 103  * character with combining class > 0 before a character with combining
 104  * class == 0. However, if such a character exists in the future, the
 105  * search mechanism does not guarantee the results for option 1.
 106  *
 107  * <p>
 108  * Example of use:<br>
 109  * <pre><code>
 110  * char *tgtstr = "The quick brown fox jumped over the lazy fox";
 111  * char *patstr = "fox";
 112  * UChar target[64];
 113  * UChar pattern[16];
 114  * UErrorCode status = U_ZERO_ERROR;
 115  * u_uastrcpy(target, tgtstr);
 116  * u_uastrcpy(pattern, patstr);
 117  *
 118  * UStringSearch *search = usearch_open(pattern, -1, target, -1, "en_US",
 119  *                                  NULL, &status);
 120  * if (U_SUCCESS(status)) {
 121  *     for (int pos = usearch_first(search, &status);
 122  *          pos != USEARCH_DONE;
 123  *          pos = usearch_next(search, &status))
 124  *     {
 125  *         printf("Found match at %d pos, length is %d\n", pos,
 126  *                                        usearch_getMatchLength(search));
 127  *     }
 128  * }
 129  *
 130  * usearch_close(search);
 131  * </code></pre>
 132  * @stable ICU 2.4
 133  */
 134
 135 /**
 136 * DONE is returned by previous() and next() after all valid matches have
 137 * been returned, and by first() and last() if there are no matches at all.
 138 * @stable ICU 2.4
 139 */
 140 #define USEARCH_DONE -1
 141
 142 /**
 143 * Data structure for searching
 144 * @stable ICU 2.4
 145 */
 146 struct UStringSearch;
 147 /**
 148 * Data structure for searching
 149 * @stable ICU 2.4
 150 */
 151 typedef struct UStringSearch UStringSearch;
 152
 153 /**
 154 * @stable ICU 2.4
 155 */
 156 typedef enum {
 157     /** Option for overlapping matches */
 158     USEARCH_OVERLAP,
 159     /**
 160      * Option for canonical matches. option 1 in header documentation.
 161      * The default value will be USEARCH_OFF
 162      */
 163     USEARCH_CANONICAL_MATCH,
 164     /**
 165      * Option to control how collation elements are compared.
 166      * The default value will be USEARCH_STANDARD_ELEMENT_COMPARISON.
 167      * @stable ICU 4.4
 168      */
 169     USEARCH_ELEMENT_COMPARISON,
 170
 171     USEARCH_ATTRIBUTE_COUNT
 172 } USearchAttribute;
 173
 174 /**
 175 * @stable ICU 2.4
 176 */
 177 typedef enum {
 178     /** Default value for any USearchAttribute */
 179     USEARCH_DEFAULT = -1,
 180     /** Value for USEARCH_OVERLAP and USEARCH_CANONICAL_MATCH */
 181     USEARCH_OFF,
 182     /** Value for USEARCH_OVERLAP and USEARCH_CANONICAL_MATCH */
 183     USEARCH_ON,
 184     /**
 185      * Value (default) for USEARCH_ELEMENT_COMPARISON;
 186      * standard collation element comparison at the specified collator
 187      * strength.
 188      * @stable ICU 4.4
 189      */
 190     USEARCH_STANDARD_ELEMENT_COMPARISON,
 191     /**
 192      * Value for USEARCH_ELEMENT_COMPARISON;
 193      * collation element comparison is modified to effectively provide
 194      * behavior between the specified strength and strength - 1. Collation
 195      * elements in the pattern that have the base weight for the specified
 196      * strength are treated as "wildcards" that match an element with any
 197      * other weight at that collation level in the searched text. For
 198      * example, with a secondary-strength English collator, a plain 'e' in
 199      * the pattern will match a plain e or an e with any diacritic in the
 200      * searched text, but an e with diacritic in the pattern will only
 201      * match an e with the same diacritic in the searched text.
 202      * @stable ICU 4.4
 203      */
 204     USEARCH_PATTERN_BASE_WEIGHT_IS_WILDCARD,
 205     /**
 206      * Value for USEARCH_ELEMENT_COMPARISON.
 207      * collation element comparison is modified to effectively provide
 208      * behavior between the specified strength and strength - 1. Collation
 209      * elements in either the pattern or the searched text that have the
 210      * base weight for the specified strength are treated as "wildcards"
 211      * that match an element with any other weight at that collation level.
 212      * For example, with a secondary-strength English collator, a plain 'e'
 213      * in the pattern will match a plain e or an e with any diacritic in the
 214      * searched text, but an e with diacritic in the pattern will only
 215      * match an e with the same diacritic or a plain e in the searched text.
 216      * @stable ICU 4.4
 217      */
 218     USEARCH_ANY_BASE_WEIGHT_IS_WILDCARD,
 219
 220     USEARCH_ATTRIBUTE_VALUE_COUNT
 221 } USearchAttributeValue;
 222
 223 /* open and close ------------------------------------------------------ */
 224
 225 /**
 226 * Creating a search iterator data struct using the argument locale language
 227 * rule set. A collator will be created in the process, which will be owned by
 228 * this search and will be deleted in <tt>usearch_close</tt>.
 229 * @param pattern for matching
 230 * @param patternlength length of the pattern, -1 for null-termination
 231 * @param text text string
 232 * @param textlength length of the text string, -1 for null-termination
 233 * @param locale name of locale for the rules to be used
 234 * @param breakiter A BreakIterator that will be used to restrict the points
 235 *                  at which matches are detected. If a match is found, but
 236 *                  the match's start or end index is not a boundary as
 237 *                  determined by the <tt>BreakIterator</tt>, the match will
 238 *                  be rejected and another will be searched for.
 239 *                  If this parameter is <tt>NULL</tt>, no break detection is
 240 *                  attempted.
 241 * @param status for errors if it occurs. If pattern or text is NULL, or if
 242 *               patternlength or textlength is 0 then an
 243 *               U_ILLEGAL_ARGUMENT_ERROR is returned.
 244 * @return search iterator data structure, or NULL if there is an error.
 245 * @stable ICU 2.4
 246 */
 247 U_STABLE UStringSearch * U_EXPORT2 usearch_open(const UChar          *pattern,
 248                                               int32_t         patternlength,
 249                                         const UChar          *text,
 250                                               int32_t         textlength,
 251                                         const char           *locale,
 252                                               UBreakIterator *breakiter,
 253                                               UErrorCode     *status);
 254
 255 /**
 256 * Creating a search iterator data struct using the argument collator language
 257 * rule set. Note, user retains the ownership of this collator, thus the
 258 * responsibility of deletion lies with the user.
 259 * NOTE: string search cannot be instantiated from a collator that has
 260 * collate digits as numbers (CODAN) turned on.
 261 * @param pattern for matching
 262 * @param patternlength length of the pattern, -1 for null-termination
 263 * @param text text string
 264 * @param textlength length of the text string, -1 for null-termination
 265 * @param collator used for the language rules
 266 * @param breakiter A BreakIterator that will be used to restrict the points
 267 *                  at which matches are detected. If a match is found, but
 268 *                  the match's start or end index is not a boundary as
 269 *                  determined by the <tt>BreakIterator</tt>, the match will
 270 *                  be rejected and another will be searched for.
 271 *                  If this parameter is <tt>NULL</tt>, no break detection is
 272 *                  attempted.
 273 * @param status for errors if it occurs. If collator, pattern or text is NULL,
 274 *               or if patternlength or textlength is 0 then an
 275 *               U_ILLEGAL_ARGUMENT_ERROR is returned.
 276 * @return search iterator data structure, or NULL if there is an error.
 277 * @stable ICU 2.4
 278 */
 279 U_STABLE UStringSearch * U_EXPORT2 usearch_openFromCollator(
 280                                          const UChar *pattern,
 281                                                int32_t         patternlength,
 282                                          const UChar          *text,
 283                                                int32_t         textlength,
 284                                          const UCollator      *collator,
 285                                                UBreakIterator *breakiter,
 286                                                UErrorCode     *status);
 287
 288 /**
 289 * Destroying and cleaning up the search iterator data struct.
 290 * If a collator is created in <tt>usearch_open</tt>, it will be destroyed here.
 291 * @param searchiter data struct to clean up
 292 * @stable ICU 2.4
 293 */
 294 U_STABLE void U_EXPORT2 usearch_close(UStringSearch *searchiter);
 295
 296 #if U_SHOW_CPLUSPLUS_API
 297
 298 U_NAMESPACE_BEGIN
 299
 300 /**
 301  * \class LocalUStringSearchPointer
 302  * "Smart pointer" class, closes a UStringSearch via usearch_close().
 303  * For most methods see the LocalPointerBase base class.
 304  *
 305  * @see LocalPointerBase
 306  * @see LocalPointer
 307  * @stable ICU 4.4
 308  */
 309 U_DEFINE_LOCAL_OPEN_POINTER(LocalUStringSearchPointer, UStringSearch, usearch_close);
 310
 311 U_NAMESPACE_END
 312
 313 #endif
 314
 315 /* get and set methods -------------------------------------------------- */
 316
 317 /**
 318 * Sets the current position in the text string which the next search will
 319 * start from. Clears previous states.
 320 * This method takes the argument index and sets the position in the text
 321 * string accordingly without checking if the index is pointing to a
 322 * valid starting point to begin searching.
 323 * Search positions that may render incorrect results are highlighted in the
 324 * header comments
 325 * @param strsrch search iterator data struct
 326 * @param position position to start next search from. If position is less
 327 *          than or greater than the text range for searching,
 328 *          an U_INDEX_OUTOFBOUNDS_ERROR will be returned
 329 * @param status error status if any.
 330 * @stable ICU 2.4
 331 */
 332 U_STABLE void U_EXPORT2 usearch_setOffset(UStringSearch *strsrch,
 333                                         int32_t    position,
 334                                         UErrorCode    *status);
 335
 336 /**
 337 * Return the current index in the string text being searched.
 338 * If the iteration has gone past the end of the text (or past the beginning
 339 * for a backwards search), <tt>USEARCH_DONE</tt> is returned.
 340 * @param strsrch search iterator data struct
 341 * @see #USEARCH_DONE
 342 * @stable ICU 2.4
 343 */
 344 U_STABLE int32_t U_EXPORT2 usearch_getOffset(const UStringSearch *strsrch);
 345
 346 /**
 347 * Sets the text searching attributes located in the enum USearchAttribute
 348 * with values from the enum USearchAttributeValue.
 349 * <tt>USEARCH_DEFAULT</tt> can be used for all attributes for resetting.
 350 * @param strsrch search iterator data struct
 351 * @param attribute text attribute to be set
 352 * @param value text attribute value
 353 * @param status for errors if it occurs
 354 * @see #usearch_getAttribute
 355 * @stable ICU 2.4
 356 */
 357 U_STABLE void U_EXPORT2 usearch_setAttribute(UStringSearch         *strsrch,
 358                                            USearchAttribute       attribute,
 359                                            USearchAttributeValue  value,
 360                                            UErrorCode            *status);
 361
 362 /**
 363 * Gets the text searching attributes.
 364 * @param strsrch search iterator data struct
 365 * @param attribute text attribute to be retrieve
 366 * @return text attribute value
 367 * @see #usearch_setAttribute
 368 * @stable ICU 2.4
 369 */
 370 U_STABLE USearchAttributeValue U_EXPORT2 usearch_getAttribute(
 371                                          const UStringSearch    *strsrch,
 372                                                USearchAttribute  attribute);
 373
 374 /**
 375 * Returns the index to the match in the text string that was searched.
 376 * This call returns a valid result only after a successful call to
 377 * <tt>usearch_first</tt>, <tt>usearch_next</tt>, <tt>usearch_previous</tt>,
 378 * or <tt>usearch_last</tt>.
 379 * Just after construction, or after a searching method returns
 380 * <tt>USEARCH_DONE</tt>, this method will return <tt>USEARCH_DONE</tt>.
 381 * <p>
 382 * Use <tt>usearch_getMatchedLength</tt> to get the matched string length.
 383 * @param strsrch search iterator data struct
 384 * @return index to a substring within the text string that is being
 385 *         searched.
 386 * @see #usearch_first
 387 * @see #usearch_next
 388 * @see #usearch_previous
 389 * @see #usearch_last
 390 * @see #USEARCH_DONE
 391 * @stable ICU 2.4
 392 */
 393 U_STABLE int32_t U_EXPORT2 usearch_getMatchedStart(
 394                                                const UStringSearch *strsrch);
 395
 396 /**
 397 * Returns the length of text in the string which matches the search pattern.
 398 * This call returns a valid result only after a successful call to
 399 * <tt>usearch_first</tt>, <tt>usearch_next</tt>, <tt>usearch_previous</tt>,
 400 * or <tt>usearch_last</tt>.
 401 * Just after construction, or after a searching method returns
 402 * <tt>USEARCH_DONE</tt>, this method will return 0.
 403 * @param strsrch search iterator data struct
 404 * @return The length of the match in the string text, or 0 if there is no
 405 *         match currently.
 406 * @see #usearch_first
 407 * @see #usearch_next
 408 * @see #usearch_previous
 409 * @see #usearch_last
 410 * @see #USEARCH_DONE
 411 * @stable ICU 2.4
 412 */
 413 U_STABLE int32_t U_EXPORT2 usearch_getMatchedLength(
 414                                                const UStringSearch *strsrch);
 415
 416 /**
 417 * Returns the text that was matched by the most recent call to
 418 * <tt>usearch_first</tt>, <tt>usearch_next</tt>, <tt>usearch_previous</tt>,
 419 * or <tt>usearch_last</tt>.
 420 * If the iterator is not pointing at a valid match (e.g. just after
 421 * construction or after <tt>USEARCH_DONE</tt> has been returned, returns
 422 * an empty string. If result is not large enough to store the matched text,
 423 * result will be filled with the partial text and an U_BUFFER_OVERFLOW_ERROR
 424 * will be returned in status. result will be null-terminated whenever
 425 * possible. If the buffer fits the matched text exactly, a null-termination
 426 * is not possible, then a U_STRING_NOT_TERMINATED_ERROR set in status.
 427 * Pre-flighting can be either done with length = 0 or the API
 428 * <tt>usearch_getMatchLength</tt>.
 429 * @param strsrch search iterator data struct
 430 * @param result UChar buffer to store the matched string
 431 * @param resultCapacity length of the result buffer
 432 * @param status error returned if result is not large enough
 433 * @return exact length of the matched text, not counting the null-termination
 434 * @see #usearch_first
 435 * @see #usearch_next
 436 * @see #usearch_previous
 437 * @see #usearch_last
 438 * @see #USEARCH_DONE
 439 * @stable ICU 2.4
 440 */
 441 U_STABLE int32_t U_EXPORT2 usearch_getMatchedText(const UStringSearch *strsrch,
 442                                             UChar         *result,
 443                                             int32_t        resultCapacity,
 444                                             UErrorCode    *status);
 445
 446 #if !UCONFIG_NO_BREAK_ITERATION
 447
 448 /**
 449 * Set the BreakIterator that will be used to restrict the points at which
 450 * matches are detected.
 451 * @param strsrch search iterator data struct
 452 * @param breakiter A BreakIterator that will be used to restrict the points
 453 *                  at which matches are detected. If a match is found, but
 454 *                  the match's start or end index is not a boundary as
 455 *                  determined by the <tt>BreakIterator</tt>, the match will
 456 *                  be rejected and another will be searched for.
 457 *                  If this parameter is <tt>NULL</tt>, no break detection is
 458 *                  attempted.
 459 * @param status for errors if it occurs
 460 * @see #usearch_getBreakIterator
 461 * @stable ICU 2.4
 462 */
 463 U_STABLE void U_EXPORT2 usearch_setBreakIterator(UStringSearch  *strsrch,
 464                                                UBreakIterator *breakiter,
 465                                                UErrorCode     *status);
 466
 467 /**
 468 * Returns the BreakIterator that is used to restrict the points at which
 469 * matches are detected. This will be the same object that was passed to the
 470 * constructor or to <tt>usearch_setBreakIterator</tt>. Note that
 471 * <tt>NULL</tt>
 472 * is a legal value; it means that break detection should not be attempted.
 473 * @param strsrch search iterator data struct
 474 * @return break iterator used
 475 * @see #usearch_setBreakIterator
 476 * @stable ICU 2.4
 477 */
 478 U_STABLE const UBreakIterator * U_EXPORT2 usearch_getBreakIterator(
 479                                               const UStringSearch *strsrch);
 480
 481 #endif
 482
 483 /**
 484 * Set the string text to be searched. Text iteration will hence begin at the
 485 * start of the text string. This method is useful if you want to re-use an
 486 * iterator to search for the same pattern within a different body of text.
 487 * @param strsrch search iterator data struct
 488 * @param text new string to look for match
 489 * @param textlength length of the new string, -1 for null-termination
 490 * @param status for errors if it occurs. If text is NULL, or textlength is 0
 491 *               then an U_ILLEGAL_ARGUMENT_ERROR is returned with no change
 492 *               done to strsrch.
 493 * @see #usearch_getText
 494 * @stable ICU 2.4
 495 */
 496 U_STABLE void U_EXPORT2 usearch_setText(      UStringSearch *strsrch,
 497                                       const UChar         *text,
 498                                             int32_t        textlength,
 499                                             UErrorCode    *status);
 500
 501 /**
 502 * Return the string text to be searched.
 503 * @param strsrch search iterator data struct
 504 * @param length returned string text length
 505 * @return string text
 506 * @see #usearch_setText
 507 * @stable ICU 2.4
 508 */
 509 U_STABLE const UChar * U_EXPORT2 usearch_getText(const UStringSearch *strsrch,
 510                                                int32_t       *length);
 511
 512 /**
 513 * Gets the collator used for the language rules.
 514 * <p>
 515 * Deleting the returned <tt>UCollator</tt> before calling
 516 * <tt>usearch_close</tt> would cause the string search to fail.
 517 * <tt>usearch_close</tt> will delete the collator if this search owns it.
 518 * @param strsrch search iterator data struct
 519 * @return collator
 520 * @stable ICU 2.4
 521 */
 522 U_STABLE UCollator * U_EXPORT2 usearch_getCollator(
 523                                                const UStringSearch *strsrch);
 524
 525 /**
 526 * Sets the collator used for the language rules. User retains the ownership
 527 * of this collator, thus the responsibility of deletion lies with the user.
 528 * This method causes internal data such as Boyer-Moore shift tables to
 529 * be recalculated, but the iterator's position is unchanged.
 530 * @param strsrch search iterator data struct
 531 * @param collator to be used
 532 * @param status for errors if it occurs
 533 * @stable ICU 2.4
 534 */
 535 U_STABLE void U_EXPORT2 usearch_setCollator(      UStringSearch *strsrch,
 536                                           const UCollator     *collator,
 537                                                 UErrorCode    *status);
 538
 539 /**
 540 * Sets the pattern used for matching.
 541 * Internal data like the Boyer Moore table will be recalculated, but the
 542 * iterator's position is unchanged.
 543 * @param strsrch search iterator data struct
 544 * @param pattern string
 545 * @param patternlength pattern length, -1 for null-terminated string
 546 * @param status for errors if it occurs. If text is NULL, or textlength is 0
 547 *               then an U_ILLEGAL_ARGUMENT_ERROR is returned with no change
 548 *               done to strsrch.
 549 * @stable ICU 2.4
 550 */
 551 U_STABLE void U_EXPORT2 usearch_setPattern(      UStringSearch *strsrch,
 552                                          const UChar         *pattern,
 553                                                int32_t        patternlength,
 554                                                UErrorCode    *status);
 555
 556 /**
 557 * Gets the search pattern
 558 * @param strsrch search iterator data struct
 559 * @param length return length of the pattern, -1 indicates that the pattern
 560 *               is null-terminated
 561 * @return pattern string
 562 * @stable ICU 2.4
 563 */
 564 U_STABLE const UChar * U_EXPORT2 usearch_getPattern(
 565                                                const UStringSearch *strsrch,
 566                                                      int32_t       *length);
 567
 568 /* methods ------------------------------------------------------------- */
 569
 570 /**
 571 * Returns the first index at which the string text matches the search
 572 * pattern.
 573 * The iterator is adjusted so that its current index (as returned by
 574 * <tt>usearch_getOffset</tt>) is the match position if one was found.
 575 * If a match is not found, <tt>USEARCH_DONE</tt> will be returned and
 576 * the iterator will be adjusted to the index <tt>USEARCH_DONE</tt>.
 577 * @param strsrch search iterator data struct
 578 * @param status for errors if it occurs
 579 * @return The character index of the first match, or
 580 * <tt>USEARCH_DONE</tt> if there are no matches.
 581 * @see #usearch_getOffset
 582 * @see #USEARCH_DONE
 583 * @stable ICU 2.4
 584 */
 585 U_STABLE int32_t U_EXPORT2 usearch_first(UStringSearch *strsrch,
 586                                            UErrorCode    *status);
 587
 588 /**
 589 * Returns the first index equal or greater than <tt>position</tt> at which
 590 * the string text
 591 * matches the search pattern. The iterator is adjusted so that its current
 592 * index (as returned by <tt>usearch_getOffset</tt>) is the match position if
 593 * one was found.
 594 * If a match is not found, <tt>USEARCH_DONE</tt> will be returned and
 595 * the iterator will be adjusted to the index <tt>USEARCH_DONE</tt>
 596 * <p>
 597 * Search positions that may render incorrect results are highlighted in the
 598 * header comments. If position is less than or greater than the text range
 599 * for searching, an U_INDEX_OUTOFBOUNDS_ERROR will be returned
 600 * @param strsrch search iterator data struct
 601 * @param position to start the search at
 602 * @param status for errors if it occurs
 603 * @return The character index of the first match following <tt>pos</tt>,
 604 *         or <tt>USEARCH_DONE</tt> if there are no matches.
 605 * @see #usearch_getOffset
 606 * @see #USEARCH_DONE
 607 * @stable ICU 2.4
 608 */
 609 U_STABLE int32_t U_EXPORT2 usearch_following(UStringSearch *strsrch,
 610                                                int32_t    position,
 611                                                UErrorCode    *status);
 612
 613 /**
 614 * Returns the last index in the target text at which it matches the search
 615 * pattern. 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 first match, or <tt>USEARCH_DONE</tt> if there
 623 *         are no matches.
 624 * @see #usearch_getOffset
 625 * @see #USEARCH_DONE
 626 * @stable ICU 2.4
 627 */
 628 U_STABLE int32_t U_EXPORT2 usearch_last(UStringSearch *strsrch,
 629                                           UErrorCode    *status);
 630
 631 /**
 632 * Returns the first index less than <tt>position</tt> at which the string text
 633 * matches the search pattern. The iterator is adjusted so that its current
 634 * index (as returned by <tt>usearch_getOffset</tt>) is the match position if
 635 * one was found.
 636 * If a match is not found, <tt>USEARCH_DONE</tt> will be returned and
 637 * the iterator will be adjusted to the index <tt>USEARCH_DONE</tt>
 638 * <p>
 639 * Search positions that may render incorrect results are highlighted in the
 640 * header comments. If position is less than or greater than the text range
 641 * for searching, an U_INDEX_OUTOFBOUNDS_ERROR will be returned.
 642 * <p>
 643 * When <tt>USEARCH_OVERLAP</tt> option is off, the last index of the
 644 * result match is always less than <tt>position</tt>.
 645 * When <tt>USERARCH_OVERLAP</tt> is on, the result match may span across
 646 * <tt>position</tt>.
 647 * @param strsrch search iterator data struct
 648 * @param position index position the search is to begin at
 649 * @param status for errors if it occurs
 650 * @return The character index of the first match preceding <tt>pos</tt>,
 651 *         or <tt>USEARCH_DONE</tt> if there are no matches.
 652 * @see #usearch_getOffset
 653 * @see #USEARCH_DONE
 654 * @stable ICU 2.4
 655 */
 656 U_STABLE int32_t U_EXPORT2 usearch_preceding(UStringSearch *strsrch,
 657                                                int32_t    position,
 658                                                UErrorCode    *status);
 659
 660 /**
 661 * Returns the index of the next point at which the string text matches the
 662 * search pattern, starting from the current position.
 663 * The iterator is adjusted so that its current
 664 * index (as returned by <tt>usearch_getOffset</tt>) is the match position if
 665 * one was found.
 666 * If a match is not found, <tt>USEARCH_DONE</tt> will be returned and
 667 * the iterator will be adjusted to the index <tt>USEARCH_DONE</tt>
 668 * @param strsrch search iterator data struct
 669 * @param status for errors if it occurs
 670 * @return The index of the next match after the current position, or
 671 *         <tt>USEARCH_DONE</tt> if there are no more matches.
 672 * @see #usearch_first
 673 * @see #usearch_getOffset
 674 * @see #USEARCH_DONE
 675 * @stable ICU 2.4
 676 */
 677 U_STABLE int32_t U_EXPORT2 usearch_next(UStringSearch *strsrch,
 678                                           UErrorCode    *status);
 679
 680 /**
 681 * Returns the index of the previous point at which the string text matches
 682 * the search pattern, starting at the current position.
 683 * The iterator is adjusted so that its current
 684 * index (as returned by <tt>usearch_getOffset</tt>) is the match position if
 685 * one was found.
 686 * If a match is not found, <tt>USEARCH_DONE</tt> will be returned and
 687 * the iterator will be adjusted to the index <tt>USEARCH_DONE</tt>
 688 * @param strsrch search iterator data struct
 689 * @param status for errors if it occurs
 690 * @return The index of the previous match before the current position,
 691 *         or <tt>USEARCH_DONE</tt> if there are no more matches.
 692 * @see #usearch_last
 693 * @see #usearch_getOffset
 694 * @see #USEARCH_DONE
 695 * @stable ICU 2.4
 696 */
 697 U_STABLE int32_t U_EXPORT2 usearch_previous(UStringSearch *strsrch,
 698                                               UErrorCode    *status);
 699
 700 /**
 701 * Reset the iteration.
 702 * Search will begin at the start of the text string if a forward iteration
 703 * is initiated before a backwards iteration. Otherwise if a backwards
 704 * iteration is initiated before a forwards iteration, the search will begin
 705 * at the end of the text string.
 706 * @param strsrch search iterator data struct
 707 * @see #usearch_first
 708 * @stable ICU 2.4
 709 */
 710 U_STABLE void U_EXPORT2 usearch_reset(UStringSearch *strsrch);
 711
 712 #ifndef U_HIDE_INTERNAL_API
 713 /**
 714   *  Simple forward search for the pattern, starting at a specified index,
 715   *     and using using a default set search options.
 716   *
 717   *  This is an experimental function, and is not an official part of the
 718   *      ICU API.
 719   *
 720   *  The collator options, such as UCOL_STRENGTH and UCOL_NORMALIZTION, are honored.
 721   *
 722   *  The UStringSearch options USEARCH_CANONICAL_MATCH, USEARCH_OVERLAP and
 723   *  any Break Iterator are ignored.
 724   *
 725   *  Matches obey the following constraints:
 726   *
 727   *      Characters at the start or end positions of a match that are ignorable
 728   *      for collation are not included as part of the match, unless they
 729   *      are part of a combining sequence, as described below.
 730   *
 731   *      A match will not include a partial combining sequence.  Combining
 732   *      character sequences  are considered to be  inseperable units,
 733   *      and either match the pattern completely, or are considered to not match
 734   *      at all.  Thus, for example, an A followed a combining accent mark will
 735   *      not be found when searching for a plain (unaccented) A.   (unless
 736   *      the collation strength has been set to ignore all accents).
 737   *
 738   *      When beginning a search, the initial starting position, startIdx,
 739   *      is assumed to be an acceptable match boundary with respect to
 740   *      combining characters.  A combining sequence that spans across the
 741   *      starting point will not supress a match beginning at startIdx.
 742   *
 743   *      Characters that expand to multiple collation elements
 744   *      (German sharp-S becoming 'ss', or the composed forms of accented
 745   *      characters, for example) also must match completely.
 746   *      Searching for a single 's' in a string containing only a sharp-s will
 747   *      find no match.
 748   *
 749   *
 750   *  @param strsrch    the UStringSearch struct, which references both
 751   *                    the text to be searched  and the pattern being sought.
 752   *  @param startIdx   The index into the text to begin the search.
 753   *  @param matchStart An out parameter, the starting index of the matched text.
 754   *                    This parameter may be NULL.
 755   *                    A value of -1 will be returned if no match was found.
 756   *  @param matchLimit Out parameter, the index of the first position following the matched text.
 757   *                    The matchLimit will be at a suitable position for beginning a subsequent search
 758   *                    in the input text.
 759   *                    This parameter may be NULL.
 760   *                    A value of -1 will be returned if no match was found.
 761   *
 762   *  @param status     Report any errors.  Note that no match found is not an error.
 763   *  @return           TRUE if a match was found, FALSE otherwise.
 764   *
 765   *  @internal
 766   */
 767 U_INTERNAL UBool U_EXPORT2 usearch_search(UStringSearch *strsrch,
 768                                           int32_t        startIdx,
 769                                           int32_t        *matchStart,
 770                                           int32_t        *matchLimit,
 771                                           UErrorCode     *status);
 772
 773 /**
 774   *  Simple backwards search for the pattern, starting at a specified index,
 775   *     and using using a default set search options.
 776   *
 777   *  This is an experimental function, and is not an official part of the
 778   *      ICU API.
 779   *
 780   *  The collator options, such as UCOL_STRENGTH and UCOL_NORMALIZTION, are honored.
 781   *
 782   *  The UStringSearch options USEARCH_CANONICAL_MATCH, USEARCH_OVERLAP and
 783   *  any Break Iterator are ignored.
 784   *
 785   *  Matches obey the following constraints:
 786   *
 787   *      Characters at the start or end positions of a match that are ignorable
 788   *      for collation are not included as part of the match, unless they
 789   *      are part of a combining sequence, as described below.
 790   *
 791   *      A match will not include a partial combining sequence.  Combining
 792   *      character sequences  are considered to be  inseperable units,
 793   *      and either match the pattern completely, or are considered to not match
 794   *      at all.  Thus, for example, an A followed a combining accent mark will
 795   *      not be found when searching for a plain (unaccented) A.   (unless
 796   *      the collation strength has been set to ignore all accents).
 797   *
 798   *      When beginning a search, the initial starting position, startIdx,
 799   *      is assumed to be an acceptable match boundary with respect to
 800   *      combining characters.  A combining sequence that spans across the
 801   *      starting point will not supress a match beginning at startIdx.
 802   *
 803   *      Characters that expand to multiple collation elements
 804   *      (German sharp-S becoming 'ss', or the composed forms of accented
 805   *      characters, for example) also must match completely.
 806   *      Searching for a single 's' in a string containing only a sharp-s will
 807   *      find no match.
 808   *
 809   *
 810   *  @param strsrch    the UStringSearch struct, which references both
 811   *                    the text to be searched  and the pattern being sought.
 812   *  @param startIdx   The index into the text to begin the search.
 813   *  @param matchStart An out parameter, the starting index of the matched text.
 814   *                    This parameter may be NULL.
 815   *                    A value of -1 will be returned if no match was found.
 816   *  @param matchLimit Out parameter, the index of the first position following the matched text.
 817   *                    The matchLimit will be at a suitable position for beginning a subsequent search
 818   *                    in the input text.
 819   *                    This parameter may be NULL.
 820   *                    A value of -1 will be returned if no match was found.
 821   *
 822   *  @param status     Report any errors.  Note that no match found is not an error.
 823   *  @return           TRUE if a match was found, FALSE otherwise.
 824   *
 825   *  @internal
 826   */
 827 U_INTERNAL UBool U_EXPORT2 usearch_searchBackwards(UStringSearch *strsrch,
 828                                                    int32_t        startIdx,
 829                                                    int32_t        *matchStart,
 830                                                    int32_t        *matchLimit,
 831                                                    UErrorCode     *status);
 832 #endif  /* U_HIDE_INTERNAL_API */
 833
 834 #endif /* #if !UCONFIG_NO_COLLATION  && !UCONFIG_NO_BREAK_ITERATION */
 835
 836 #endif