icuSources/i18n/unicode/usearch.h

   1 /*
   2 **********************************************************************
   3 *   Copyright (C) 2001-2011,2014 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 implementation may use a linear search or a modified form of the Boyer-Moore
  34  * search; for more information on the latter 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.
  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  * Options are also provided to implement "asymmetric search" as described in
  95  * <a href="http://www.unicode.org/reports/tr10/#Asymmetric_Search">
  96  * UTS #10 Unicode Collation Algorithm</a>, specifically the USearchAttribute
  97  * USEARCH_ELEMENT_COMPARISON and its values.
  98  * <p>
  99  * E.g. In English, overlapping matches produces the result 0 and 2
 100  * for the pattern "abab" in the text "ababab", where else mutually
 101  * exclusive matches only produce the result of 0.
 102  * <p>
 103  * Though collator attributes will be taken into consideration while
 104  * performing matches, there are no APIs here for setting and getting the
 105  * attributes. These attributes can be set by getting the collator
 106  * from <tt>usearch_getCollator</tt> and using the APIs in <tt>ucol.h</tt>.
 107  * Lastly to update String Search to the new collator attributes,
 108  * usearch_reset() has to be called.
 109  * <p>
 110  * Restriction: <br>
 111  * Currently there are no composite characters that consists of a
 112  * character with combining class > 0 before a character with combining
 113  * class == 0. However, if such a character exists in the future, the
 114  * search mechanism does not guarantee the results for option 1.
 115  *
 116  * <p>
 117  * Example of use:<br>
 118  * <pre><code>
 119  * char *tgtstr = "The quick brown fox jumped over the lazy fox";
 120  * char *patstr = "fox";
 121  * UChar target[64];
 122  * UChar pattern[16];
 123  * UErrorCode status = U_ZERO_ERROR;
 124  * u_uastrcpy(target, tgtstr);
 125  * u_uastrcpy(pattern, patstr);
 126  *
 127  * UStringSearch *search = usearch_open(pattern, -1, target, -1, "en_US",
 128  *                                  NULL, &status);
 129  * if (U_SUCCESS(status)) {
 130  *     for (int pos = usearch_first(search, &status);
 131  *          pos != USEARCH_DONE;
 132  *          pos = usearch_next(search, &status))
 133  *     {
 134  *         printf("Found match at %d pos, length is %d\n", pos,
 135  *                                        usearch_getMatchLength(search));
 136  *     }
 137  * }
 138  *
 139  * usearch_close(search);
 140  * </code></pre>
 141  * @stable ICU 2.4
 142  */
 143
 144 /**
 145 * DONE is returned by previous() and next() after all valid matches have
 146 * been returned, and by first() and last() if there are no matches at all.
 147 * @stable ICU 2.4
 148 */
 149 #define USEARCH_DONE -1
 150
 151 /**
 152 * Data structure for searching
 153 * @stable ICU 2.4
 154 */
 155 struct UStringSearch;
 156 /**
 157 * Data structure for searching
 158 * @stable ICU 2.4
 159 */
 160 typedef struct UStringSearch UStringSearch;
 161
 162 /**
 163 * @stable ICU 2.4
 164 */
 165 typedef enum {
 166     /**
 167      * Option for overlapping matches
 168      * @stable ICU 2.4
 169      */
 170     USEARCH_OVERLAP = 0,
 171 #ifndef U_HIDE_DEPRECATED_API
 172     /**
 173      * Option for canonical matches; option 1 in header documentation.
 174      * The default value will be USEARCH_OFF.
 175      * Note: Setting this option to USEARCH_ON currently has no effect on
 176      * search behavior, and this option is deprecated. Instead, to control
 177      * canonical match behavior, you must set UCOL_NORMALIZATION_MODE
 178      * appropriately (to UCOL_OFF or UCOL_ON) in the UCollator used by
 179      * the UStringSearch object.
 180      * @see usearch_openFromCollator
 181      * @see usearch_getCollator
 182      * @see usearch_setCollator
 183      * @see ucol_getAttribute
 184      * @deprecated ICU 53
 185      */
 186     USEARCH_CANONICAL_MATCH = 1,
 187 #endif  /* U_HIDE_DEPRECATED_API */
 188     /**
 189      * Option to control how collation elements are compared.
 190      * The default value will be USEARCH_STANDARD_ELEMENT_COMPARISON.
 191      * @stable ICU 4.4
 192      */
 193     USEARCH_ELEMENT_COMPARISON = 2,
 194
 195     /**
 196      * Count of attribute types
 197      * @stable ICU 2.4
 198      */
 199     USEARCH_ATTRIBUTE_COUNT = 3
 200 } USearchAttribute;
 201
 202 /**
 203 * @stable ICU 2.4
 204 */
 205 typedef enum {
 206     /**
 207      * Default value for any USearchAttribute
 208      * @stable ICU 2.4
 209      */
 210     USEARCH_DEFAULT = -1,
 211     /**
 212      * Value for USEARCH_OVERLAP and USEARCH_CANONICAL_MATCH
 213      * @stable ICU 2.4
 214      */
 215     USEARCH_OFF,
 216     /**
 217      * Value for USEARCH_OVERLAP and USEARCH_CANONICAL_MATCH
 218      * @stable ICU 2.4
 219      */
 220     USEARCH_ON,
 221     /**
 222      * Value (default) for USEARCH_ELEMENT_COMPARISON;
 223      * standard collation element comparison at the specified collator
 224      * strength.
 225      * @stable ICU 4.4
 226      */
 227     USEARCH_STANDARD_ELEMENT_COMPARISON,
 228     /**
 229      * Value for USEARCH_ELEMENT_COMPARISON;
 230      * collation element comparison is modified to effectively provide
 231      * behavior between the specified strength and strength - 1. Collation
 232      * elements in the pattern that have the base weight for the specified
 233      * strength are treated as "wildcards" that match an element with any
 234      * other weight at that collation level in the searched text. For
 235      * example, with a secondary-strength English collator, a plain 'e' in
 236      * the pattern will match a plain e or an e with any diacritic in the
 237      * searched text, but an e with diacritic in the pattern will only
 238      * match an e with the same diacritic in the searched text.
 239      *
 240      * This supports "asymmetric search" as described in
 241      * <a href="http://www.unicode.org/reports/tr10/#Asymmetric_Search">
 242      * UTS #10 Unicode Collation Algorithm</a>.
 243      *
 244      * @stable ICU 4.4
 245      */
 246     USEARCH_PATTERN_BASE_WEIGHT_IS_WILDCARD,
 247     /**
 248      * Value for USEARCH_ELEMENT_COMPARISON.
 249      * collation element comparison is modified to effectively provide
 250      * behavior between the specified strength and strength - 1. Collation
 251      * elements in either the pattern or the searched text that have the
 252      * base weight for the specified strength are treated as "wildcards"
 253      * that match an element with any other weight at that collation level.
 254      * For example, with a secondary-strength English collator, a plain 'e'
 255      * in the pattern will match a plain e or an e with any diacritic in the
 256      * searched text, but an e with diacritic in the pattern will only
 257      * match an e with the same diacritic or a plain e in the searched text.
 258      *
 259      * This option is similar to "asymmetric search" as described in
 260      * <a href="http://www.unicode.org/reports/tr10/#Asymmetric_Search">
 261      * UTS #10 Unicode Collation Algorithm</a, but also allows unmarked
 262      * characters in the searched text to match marked or unmarked versions of
 263      * that character in the pattern.
 264      *
 265      * @stable ICU 4.4
 266      */
 267     USEARCH_ANY_BASE_WEIGHT_IS_WILDCARD,
 268
 269     /**
 270      * Count of attribute values
 271      * @stable ICU 2.4
 272      */
 273     USEARCH_ATTRIBUTE_VALUE_COUNT
 274 } USearchAttributeValue;
 275
 276 /* open and close ------------------------------------------------------ */
 277
 278 /**
 279 * Creating a search iterator data struct using the argument locale language
 280 * rule set. A collator will be created in the process, which will be owned by
 281 * this search and will be deleted in <tt>usearch_close</tt>.
 282 * @param pattern for matching
 283 * @param patternlength length of the pattern, -1 for null-termination
 284 * @param text text string
 285 * @param textlength length of the text string, -1 for null-termination
 286 * @param locale name of locale for the rules to be used
 287 * @param breakiter A BreakIterator that will be used to restrict the points
 288 *                  at which matches are detected. If a match is found, but
 289 *                  the match's start or end index is not a boundary as
 290 *                  determined by the <tt>BreakIterator</tt>, the match will
 291 *                  be rejected and another will be searched for.
 292 *                  If this parameter is <tt>NULL</tt>, no break detection is
 293 *                  attempted.
 294 * @param status for errors if it occurs. If pattern or text is NULL, or if
 295 *               patternlength or textlength is 0 then an
 296 *               U_ILLEGAL_ARGUMENT_ERROR is returned.
 297 * @return search iterator data structure, or NULL if there is an error.
 298 * @stable ICU 2.4
 299 */
 300 U_STABLE UStringSearch * U_EXPORT2 usearch_open(const UChar          *pattern,
 301                                               int32_t         patternlength,
 302                                         const UChar          *text,
 303                                               int32_t         textlength,
 304                                         const char           *locale,
 305                                               UBreakIterator *breakiter,
 306                                               UErrorCode     *status);
 307
 308 /**
 309 * Creating a search iterator data struct using the argument collator language
 310 * rule set. Note, user retains the ownership of this collator, thus the
 311 * responsibility of deletion lies with the user.
 312 * NOTE: string search cannot be instantiated from a collator that has
 313 * collate digits as numbers (CODAN) turned on.
 314 * @param pattern for matching
 315 * @param patternlength length of the pattern, -1 for null-termination
 316 * @param text text string
 317 * @param textlength length of the text string, -1 for null-termination
 318 * @param collator used for the language rules
 319 * @param breakiter A BreakIterator that will be used to restrict the points
 320 *                  at which matches are detected. If a match is found, but
 321 *                  the match's start or end index is not a boundary as
 322 *                  determined by the <tt>BreakIterator</tt>, the match will
 323 *                  be rejected and another will be searched for.
 324 *                  If this parameter is <tt>NULL</tt>, no break detection is
 325 *                  attempted.
 326 * @param status for errors if it occurs. If collator, pattern or text is NULL,
 327 *               or if patternlength or textlength is 0 then an
 328 *               U_ILLEGAL_ARGUMENT_ERROR is returned.
 329 * @return search iterator data structure, or NULL if there is an error.
 330 * @stable ICU 2.4
 331 */
 332 U_STABLE UStringSearch * U_EXPORT2 usearch_openFromCollator(
 333                                          const UChar *pattern,
 334                                                int32_t         patternlength,
 335                                          const UChar          *text,
 336                                                int32_t         textlength,
 337                                          const UCollator      *collator,
 338                                                UBreakIterator *breakiter,
 339                                                UErrorCode     *status);
 340
 341 /**
 342 * Destroying and cleaning up the search iterator data struct.
 343 * If a collator is created in <tt>usearch_open</tt>, it will be destroyed here.
 344 * @param searchiter data struct to clean up
 345 * @stable ICU 2.4
 346 */
 347 U_STABLE void U_EXPORT2 usearch_close(UStringSearch *searchiter);
 348
 349 #if U_SHOW_CPLUSPLUS_API
 350
 351 U_NAMESPACE_BEGIN
 352
 353 /**
 354  * \class LocalUStringSearchPointer
 355  * "Smart pointer" class, closes a UStringSearch via usearch_close().
 356  * For most methods see the LocalPointerBase base class.
 357  *
 358  * @see LocalPointerBase
 359  * @see LocalPointer
 360  * @stable ICU 4.4
 361  */
 362 U_DEFINE_LOCAL_OPEN_POINTER(LocalUStringSearchPointer, UStringSearch, usearch_close);
 363
 364 U_NAMESPACE_END
 365
 366 #endif
 367
 368 /* get and set methods -------------------------------------------------- */
 369
 370 /**
 371 * Sets the current position in the text string which the next search will
 372 * start from. Clears previous states.
 373 * This method takes the argument index and sets the position in the text
 374 * string accordingly without checking if the index is pointing to a
 375 * valid starting point to begin searching.
 376 * Search positions that may render incorrect results are highlighted in the
 377 * header comments
 378 * @param strsrch search iterator data struct
 379 * @param position position to start next search from. If position is less
 380 *          than or greater than the text range for searching,
 381 *          an U_INDEX_OUTOFBOUNDS_ERROR will be returned
 382 * @param status error status if any.
 383 * @stable ICU 2.4
 384 */
 385 U_STABLE void U_EXPORT2 usearch_setOffset(UStringSearch *strsrch,
 386                                         int32_t    position,
 387                                         UErrorCode    *status);
 388
 389 /**
 390 * Return the current index in the string text being searched.
 391 * If the iteration has gone past the end of the text (or past the beginning
 392 * for a backwards search), <tt>USEARCH_DONE</tt> is returned.
 393 * @param strsrch search iterator data struct
 394 * @see #USEARCH_DONE
 395 * @stable ICU 2.4
 396 */
 397 U_STABLE int32_t U_EXPORT2 usearch_getOffset(const UStringSearch *strsrch);
 398
 399 /**
 400 * Sets the text searching attributes located in the enum USearchAttribute
 401 * with values from the enum USearchAttributeValue.
 402 * <tt>USEARCH_DEFAULT</tt> can be used for all attributes for resetting.
 403 * @param strsrch search iterator data struct
 404 * @param attribute text attribute to be set
 405 * @param value text attribute value
 406 * @param status for errors if it occurs
 407 * @see #usearch_getAttribute
 408 * @stable ICU 2.4
 409 */
 410 U_STABLE void U_EXPORT2 usearch_setAttribute(UStringSearch         *strsrch,
 411                                            USearchAttribute       attribute,
 412                                            USearchAttributeValue  value,
 413                                            UErrorCode            *status);
 414
 415 /**
 416 * Gets the text searching attributes.
 417 * @param strsrch search iterator data struct
 418 * @param attribute text attribute to be retrieve
 419 * @return text attribute value
 420 * @see #usearch_setAttribute
 421 * @stable ICU 2.4
 422 */
 423 U_STABLE USearchAttributeValue U_EXPORT2 usearch_getAttribute(
 424                                          const UStringSearch    *strsrch,
 425                                                USearchAttribute  attribute);
 426
 427 /**
 428 * Returns the index to the match in the text string that was searched.
 429 * This call returns a valid result only after a successful call to
 430 * <tt>usearch_first</tt>, <tt>usearch_next</tt>, <tt>usearch_previous</tt>,
 431 * or <tt>usearch_last</tt>.
 432 * Just after construction, or after a searching method returns
 433 * <tt>USEARCH_DONE</tt>, this method will return <tt>USEARCH_DONE</tt>.
 434 * <p>
 435 * Use <tt>usearch_getMatchedLength</tt> to get the matched string length.
 436 * @param strsrch search iterator data struct
 437 * @return index to a substring within the text string that is being
 438 *         searched.
 439 * @see #usearch_first
 440 * @see #usearch_next
 441 * @see #usearch_previous
 442 * @see #usearch_last
 443 * @see #USEARCH_DONE
 444 * @stable ICU 2.4
 445 */
 446 U_STABLE int32_t U_EXPORT2 usearch_getMatchedStart(
 447                                                const UStringSearch *strsrch);
 448
 449 /**
 450 * Returns the length of text in the string which matches the search pattern.
 451 * This call returns a valid result only after a successful call to
 452 * <tt>usearch_first</tt>, <tt>usearch_next</tt>, <tt>usearch_previous</tt>,
 453 * or <tt>usearch_last</tt>.
 454 * Just after construction, or after a searching method returns
 455 * <tt>USEARCH_DONE</tt>, this method will return 0.
 456 * @param strsrch search iterator data struct
 457 * @return The length of the match in the string text, or 0 if there is no
 458 *         match currently.
 459 * @see #usearch_first
 460 * @see #usearch_next
 461 * @see #usearch_previous
 462 * @see #usearch_last
 463 * @see #USEARCH_DONE
 464 * @stable ICU 2.4
 465 */
 466 U_STABLE int32_t U_EXPORT2 usearch_getMatchedLength(
 467                                                const UStringSearch *strsrch);
 468
 469 /**
 470 * Returns the text that was matched by the most recent call to
 471 * <tt>usearch_first</tt>, <tt>usearch_next</tt>, <tt>usearch_previous</tt>,
 472 * or <tt>usearch_last</tt>.
 473 * If the iterator is not pointing at a valid match (e.g. just after
 474 * construction or after <tt>USEARCH_DONE</tt> has been returned, returns
 475 * an empty string. If result is not large enough to store the matched text,
 476 * result will be filled with the partial text and an U_BUFFER_OVERFLOW_ERROR
 477 * will be returned in status. result will be null-terminated whenever
 478 * possible. If the buffer fits the matched text exactly, a null-termination
 479 * is not possible, then a U_STRING_NOT_TERMINATED_ERROR set in status.
 480 * Pre-flighting can be either done with length = 0 or the API
 481 * <tt>usearch_getMatchLength</tt>.
 482 * @param strsrch search iterator data struct
 483 * @param result UChar buffer to store the matched string
 484 * @param resultCapacity length of the result buffer
 485 * @param status error returned if result is not large enough
 486 * @return exact length of the matched text, not counting the null-termination
 487 * @see #usearch_first
 488 * @see #usearch_next
 489 * @see #usearch_previous
 490 * @see #usearch_last
 491 * @see #USEARCH_DONE
 492 * @stable ICU 2.4
 493 */
 494 U_STABLE int32_t U_EXPORT2 usearch_getMatchedText(const UStringSearch *strsrch,
 495                                             UChar         *result,
 496                                             int32_t        resultCapacity,
 497                                             UErrorCode    *status);
 498
 499 #if !UCONFIG_NO_BREAK_ITERATION
 500
 501 /**
 502 * Set the BreakIterator that will be used to restrict the points at which
 503 * matches are detected.
 504 * @param strsrch search iterator data struct
 505 * @param breakiter A BreakIterator that will be used to restrict the points
 506 *                  at which matches are detected. If a match is found, but
 507 *                  the match's start or end index is not a boundary as
 508 *                  determined by the <tt>BreakIterator</tt>, the match will
 509 *                  be rejected and another will be searched for.
 510 *                  If this parameter is <tt>NULL</tt>, no break detection is
 511 *                  attempted.
 512 * @param status for errors if it occurs
 513 * @see #usearch_getBreakIterator
 514 * @stable ICU 2.4
 515 */
 516 U_STABLE void U_EXPORT2 usearch_setBreakIterator(UStringSearch  *strsrch,
 517                                                UBreakIterator *breakiter,
 518                                                UErrorCode     *status);
 519
 520 /**
 521 * Returns the BreakIterator that is used to restrict the points at which
 522 * matches are detected. This will be the same object that was passed to the
 523 * constructor or to <tt>usearch_setBreakIterator</tt>. Note that
 524 * <tt>NULL</tt>
 525 * is a legal value; it means that break detection should not be attempted.
 526 * @param strsrch search iterator data struct
 527 * @return break iterator used
 528 * @see #usearch_setBreakIterator
 529 * @stable ICU 2.4
 530 */
 531 U_STABLE const UBreakIterator * U_EXPORT2 usearch_getBreakIterator(
 532                                               const UStringSearch *strsrch);
 533
 534 #endif
 535
 536 /**
 537 * Set the string text to be searched. Text iteration will hence begin at the
 538 * start of the text string. This method is useful if you want to re-use an
 539 * iterator to search for the same pattern within a different body of text.
 540 * @param strsrch search iterator data struct
 541 * @param text new string to look for match
 542 * @param textlength length of the new string, -1 for null-termination
 543 * @param status for errors if it occurs. If text is NULL, or textlength is 0
 544 *               then an U_ILLEGAL_ARGUMENT_ERROR is returned with no change
 545 *               done to strsrch.
 546 * @see #usearch_getText
 547 * @stable ICU 2.4
 548 */
 549 U_STABLE void U_EXPORT2 usearch_setText(      UStringSearch *strsrch,
 550                                       const UChar         *text,
 551                                             int32_t        textlength,
 552                                             UErrorCode    *status);
 553
 554 /**
 555 * Return the string text to be searched.
 556 * @param strsrch search iterator data struct
 557 * @param length returned string text length
 558 * @return string text
 559 * @see #usearch_setText
 560 * @stable ICU 2.4
 561 */
 562 U_STABLE const UChar * U_EXPORT2 usearch_getText(const UStringSearch *strsrch,
 563                                                int32_t       *length);
 564
 565 /**
 566 * Gets the collator used for the language rules.
 567 * <p>
 568 * Deleting the returned <tt>UCollator</tt> before calling
 569 * <tt>usearch_close</tt> would cause the string search to fail.
 570 * <tt>usearch_close</tt> will delete the collator if this search owns it.
 571 * @param strsrch search iterator data struct
 572 * @return collator
 573 * @stable ICU 2.4
 574 */
 575 U_STABLE UCollator * U_EXPORT2 usearch_getCollator(
 576                                                const UStringSearch *strsrch);
 577
 578 /**
 579 * Sets the collator used for the language rules. User retains the ownership
 580 * of this collator, thus the responsibility of deletion lies with the user.
 581 * This method causes internal data such as Boyer-Moore shift tables to
 582 * be recalculated, but the iterator's position is unchanged.
 583 * @param strsrch search iterator data struct
 584 * @param collator to be used
 585 * @param status for errors if it occurs
 586 * @stable ICU 2.4
 587 */
 588 U_STABLE void U_EXPORT2 usearch_setCollator(      UStringSearch *strsrch,
 589                                           const UCollator     *collator,
 590                                                 UErrorCode    *status);
 591
 592 /**
 593 * Sets the pattern used for matching.
 594 * Internal data like the Boyer Moore table will be recalculated, but the
 595 * iterator's position is unchanged.
 596 * @param strsrch search iterator data struct
 597 * @param pattern string
 598 * @param patternlength pattern length, -1 for null-terminated string
 599 * @param status for errors if it occurs. If text is NULL, or textlength is 0
 600 *               then an U_ILLEGAL_ARGUMENT_ERROR is returned with no change
 601 *               done to strsrch.
 602 * @stable ICU 2.4
 603 */
 604 U_STABLE void U_EXPORT2 usearch_setPattern(      UStringSearch *strsrch,
 605                                          const UChar         *pattern,
 606                                                int32_t        patternlength,
 607                                                UErrorCode    *status);
 608
 609 /**
 610 * Gets the search pattern
 611 * @param strsrch search iterator data struct
 612 * @param length return length of the pattern, -1 indicates that the pattern
 613 *               is null-terminated
 614 * @return pattern string
 615 * @stable ICU 2.4
 616 */
 617 U_STABLE const UChar * U_EXPORT2 usearch_getPattern(
 618                                                const UStringSearch *strsrch,
 619                                                      int32_t       *length);
 620
 621 /* methods ------------------------------------------------------------- */
 622
 623 /**
 624 * Returns the first index at which the string text matches the search
 625 * pattern.
 626 * The iterator is adjusted so that its current index (as returned by
 627 * <tt>usearch_getOffset</tt>) is the match position if one was found.
 628 * If a match is not found, <tt>USEARCH_DONE</tt> will be returned and
 629 * the iterator will be adjusted to the index <tt>USEARCH_DONE</tt>.
 630 * @param strsrch search iterator data struct
 631 * @param status for errors if it occurs
 632 * @return The character index of the first match, or
 633 * <tt>USEARCH_DONE</tt> if there are no matches.
 634 * @see #usearch_getOffset
 635 * @see #USEARCH_DONE
 636 * @stable ICU 2.4
 637 */
 638 U_STABLE int32_t U_EXPORT2 usearch_first(UStringSearch *strsrch,
 639                                            UErrorCode    *status);
 640
 641 /**
 642 * Returns the first index equal or greater than <tt>position</tt> at which
 643 * the string text
 644 * matches the search pattern. The iterator is adjusted so that its current
 645 * index (as returned by <tt>usearch_getOffset</tt>) is the match position if
 646 * one was found.
 647 * If a match is not found, <tt>USEARCH_DONE</tt> will be returned and
 648 * the iterator will be adjusted to the index <tt>USEARCH_DONE</tt>
 649 * <p>
 650 * Search positions that may render incorrect results are highlighted in the
 651 * header comments. If position is less than or greater than the text range
 652 * for searching, an U_INDEX_OUTOFBOUNDS_ERROR will be returned
 653 * @param strsrch search iterator data struct
 654 * @param position to start the search at
 655 * @param status for errors if it occurs
 656 * @return The character index of the first match following <tt>pos</tt>,
 657 *         or <tt>USEARCH_DONE</tt> if there are no matches.
 658 * @see #usearch_getOffset
 659 * @see #USEARCH_DONE
 660 * @stable ICU 2.4
 661 */
 662 U_STABLE int32_t U_EXPORT2 usearch_following(UStringSearch *strsrch,
 663                                                int32_t    position,
 664                                                UErrorCode    *status);
 665
 666 /**
 667 * Returns the last index in the target text at which it matches the search
 668 * pattern. The iterator is adjusted so that its current
 669 * index (as returned by <tt>usearch_getOffset</tt>) is the match position if
 670 * one was found.
 671 * If a match is not found, <tt>USEARCH_DONE</tt> will be returned and
 672 * the iterator will be adjusted to the index <tt>USEARCH_DONE</tt>.
 673 * @param strsrch search iterator data struct
 674 * @param status for errors if it occurs
 675 * @return The index of the first match, or <tt>USEARCH_DONE</tt> if there
 676 *         are no matches.
 677 * @see #usearch_getOffset
 678 * @see #USEARCH_DONE
 679 * @stable ICU 2.4
 680 */
 681 U_STABLE int32_t U_EXPORT2 usearch_last(UStringSearch *strsrch,
 682                                           UErrorCode    *status);
 683
 684 /**
 685 * Returns the first index less than <tt>position</tt> at which the string text
 686 * matches the search pattern. The iterator is adjusted so that its current
 687 * index (as returned by <tt>usearch_getOffset</tt>) is the match position if
 688 * one was found.
 689 * If a match is not found, <tt>USEARCH_DONE</tt> will be returned and
 690 * the iterator will be adjusted to the index <tt>USEARCH_DONE</tt>
 691 * <p>
 692 * Search positions that may render incorrect results are highlighted in the
 693 * header comments. If position is less than or greater than the text range
 694 * for searching, an U_INDEX_OUTOFBOUNDS_ERROR will be returned.
 695 * <p>
 696 * When <tt>USEARCH_OVERLAP</tt> option is off, the last index of the
 697 * result match is always less than <tt>position</tt>.
 698 * When <tt>USERARCH_OVERLAP</tt> is on, the result match may span across
 699 * <tt>position</tt>.
 700 * @param strsrch search iterator data struct
 701 * @param position index position the search is to begin at
 702 * @param status for errors if it occurs
 703 * @return The character index of the first match preceding <tt>pos</tt>,
 704 *         or <tt>USEARCH_DONE</tt> if there are no matches.
 705 * @see #usearch_getOffset
 706 * @see #USEARCH_DONE
 707 * @stable ICU 2.4
 708 */
 709 U_STABLE int32_t U_EXPORT2 usearch_preceding(UStringSearch *strsrch,
 710                                                int32_t    position,
 711                                                UErrorCode    *status);
 712
 713 /**
 714 * Returns the index of the next point at which the string text matches the
 715 * search pattern, starting from the current position.
 716 * The iterator is adjusted so that its current
 717 * index (as returned by <tt>usearch_getOffset</tt>) is the match position if
 718 * one was found.
 719 * If a match is not found, <tt>USEARCH_DONE</tt> will be returned and
 720 * the iterator will be adjusted to the index <tt>USEARCH_DONE</tt>
 721 * @param strsrch search iterator data struct
 722 * @param status for errors if it occurs
 723 * @return The index of the next match after the current position, or
 724 *         <tt>USEARCH_DONE</tt> if there are no more matches.
 725 * @see #usearch_first
 726 * @see #usearch_getOffset
 727 * @see #USEARCH_DONE
 728 * @stable ICU 2.4
 729 */
 730 U_STABLE int32_t U_EXPORT2 usearch_next(UStringSearch *strsrch,
 731                                           UErrorCode    *status);
 732
 733 /**
 734 * Returns the index of the previous point at which the string text matches
 735 * the search pattern, starting at the current position.
 736 * The iterator is adjusted so that its current
 737 * index (as returned by <tt>usearch_getOffset</tt>) is the match position if
 738 * one was found.
 739 * If a match is not found, <tt>USEARCH_DONE</tt> will be returned and
 740 * the iterator will be adjusted to the index <tt>USEARCH_DONE</tt>
 741 * @param strsrch search iterator data struct
 742 * @param status for errors if it occurs
 743 * @return The index of the previous match before the current position,
 744 *         or <tt>USEARCH_DONE</tt> if there are no more matches.
 745 * @see #usearch_last
 746 * @see #usearch_getOffset
 747 * @see #USEARCH_DONE
 748 * @stable ICU 2.4
 749 */
 750 U_STABLE int32_t U_EXPORT2 usearch_previous(UStringSearch *strsrch,
 751                                               UErrorCode    *status);
 752
 753 /**
 754 * Reset the iteration.
 755 * Search will begin at the start of the text string if a forward iteration
 756 * is initiated before a backwards iteration. Otherwise if a backwards
 757 * iteration is initiated before a forwards iteration, the search will begin
 758 * at the end of the text string.
 759 * @param strsrch search iterator data struct
 760 * @see #usearch_first
 761 * @stable ICU 2.4
 762 */
 763 U_STABLE void U_EXPORT2 usearch_reset(UStringSearch *strsrch);
 764
 765 #ifndef U_HIDE_INTERNAL_API
 766 /**
 767   *  Simple forward search for the pattern, starting at a specified index,
 768   *     and using using a default set search options.
 769   *
 770   *  This is an experimental function, and is not an official part of the
 771   *      ICU API.
 772   *
 773   *  The collator options, such as UCOL_STRENGTH and UCOL_NORMALIZTION, are honored.
 774   *
 775   *  The UStringSearch options USEARCH_CANONICAL_MATCH, USEARCH_OVERLAP and
 776   *  any Break Iterator are ignored.
 777   *
 778   *  Matches obey the following constraints:
 779   *
 780   *      Characters at the start or end positions of a match that are ignorable
 781   *      for collation are not included as part of the match, unless they
 782   *      are part of a combining sequence, as described below.
 783   *
 784   *      A match will not include a partial combining sequence.  Combining
 785   *      character sequences  are considered to be  inseperable units,
 786   *      and either match the pattern completely, or are considered to not match
 787   *      at all.  Thus, for example, an A followed a combining accent mark will
 788   *      not be found when searching for a plain (unaccented) A.   (unless
 789   *      the collation strength has been set to ignore all accents).
 790   *
 791   *      When beginning a search, the initial starting position, startIdx,
 792   *      is assumed to be an acceptable match boundary with respect to
 793   *      combining characters.  A combining sequence that spans across the
 794   *      starting point will not supress a match beginning at startIdx.
 795   *
 796   *      Characters that expand to multiple collation elements
 797   *      (German sharp-S becoming 'ss', or the composed forms of accented
 798   *      characters, for example) also must match completely.
 799   *      Searching for a single 's' in a string containing only a sharp-s will
 800   *      find no match.
 801   *
 802   *
 803   *  @param strsrch    the UStringSearch struct, which references both
 804   *                    the text to be searched  and the pattern being sought.
 805   *  @param startIdx   The index into the text to begin the search.
 806   *  @param matchStart An out parameter, the starting index of the matched text.
 807   *                    This parameter may be NULL.
 808   *                    A value of -1 will be returned if no match was found.
 809   *  @param matchLimit Out parameter, the index of the first position following the matched text.
 810   *                    The matchLimit will be at a suitable position for beginning a subsequent search
 811   *                    in the input text.
 812   *                    This parameter may be NULL.
 813   *                    A value of -1 will be returned if no match was found.
 814   *
 815   *  @param status     Report any errors.  Note that no match found is not an error.
 816   *  @return           TRUE if a match was found, FALSE otherwise.
 817   *
 818   *  @internal
 819   */
 820 U_INTERNAL UBool U_EXPORT2 usearch_search(UStringSearch *strsrch,
 821                                           int32_t        startIdx,
 822                                           int32_t        *matchStart,
 823                                           int32_t        *matchLimit,
 824                                           UErrorCode     *status);
 825
 826 /**
 827   *  Simple backwards search for the pattern, starting at a specified index,
 828   *     and using using a default set search options.
 829   *
 830   *  This is an experimental function, and is not an official part of the
 831   *      ICU API.
 832   *
 833   *  The collator options, such as UCOL_STRENGTH and UCOL_NORMALIZTION, are honored.
 834   *
 835   *  The UStringSearch options USEARCH_CANONICAL_MATCH, USEARCH_OVERLAP and
 836   *  any Break Iterator are ignored.
 837   *
 838   *  Matches obey the following constraints:
 839   *
 840   *      Characters at the start or end positions of a match that are ignorable
 841   *      for collation are not included as part of the match, unless they
 842   *      are part of a combining sequence, as described below.
 843   *
 844   *      A match will not include a partial combining sequence.  Combining
 845   *      character sequences  are considered to be  inseperable units,
 846   *      and either match the pattern completely, or are considered to not match
 847   *      at all.  Thus, for example, an A followed a combining accent mark will
 848   *      not be found when searching for a plain (unaccented) A.   (unless
 849   *      the collation strength has been set to ignore all accents).
 850   *
 851   *      When beginning a search, the initial starting position, startIdx,
 852   *      is assumed to be an acceptable match boundary with respect to
 853   *      combining characters.  A combining sequence that spans across the
 854   *      starting point will not supress a match beginning at startIdx.
 855   *
 856   *      Characters that expand to multiple collation elements
 857   *      (German sharp-S becoming 'ss', or the composed forms of accented
 858   *      characters, for example) also must match completely.
 859   *      Searching for a single 's' in a string containing only a sharp-s will
 860   *      find no match.
 861   *
 862   *
 863   *  @param strsrch    the UStringSearch struct, which references both
 864   *                    the text to be searched  and the pattern being sought.
 865   *  @param startIdx   The index into the text to begin the search.
 866   *  @param matchStart An out parameter, the starting index of the matched text.
 867   *                    This parameter may be NULL.
 868   *                    A value of -1 will be returned if no match was found.
 869   *  @param matchLimit Out parameter, the index of the first position following the matched text.
 870   *                    The matchLimit will be at a suitable position for beginning a subsequent search
 871   *                    in the input text.
 872   *                    This parameter may be NULL.
 873   *                    A value of -1 will be returned if no match was found.
 874   *
 875   *  @param status     Report any errors.  Note that no match found is not an error.
 876   *  @return           TRUE if a match was found, FALSE otherwise.
 877   *
 878   *  @internal
 879   */
 880 U_INTERNAL UBool U_EXPORT2 usearch_searchBackwards(UStringSearch *strsrch,
 881                                                    int32_t        startIdx,
 882                                                    int32_t        *matchStart,
 883                                                    int32_t        *matchLimit,
 884                                                    UErrorCode     *status);
 885 #endif  /* U_HIDE_INTERNAL_API */
 886
 887 #endif /* #if !UCONFIG_NO_COLLATION  && !UCONFIG_NO_BREAK_ITERATION */
 888
 889 #endif