icuSources/i18n/unicode/stsearch.h

   1 // © 2016 and later: Unicode, Inc. and others.
   2 // License & terms of use: http://www.unicode.org/copyright.html
   3 /*
   4 **********************************************************************
   5 *   Copyright (C) 2001-2014 IBM and others. All rights reserved.
   6 **********************************************************************
   7 *   Date        Name        Description
   8 *  03/22/2000   helena      Creation.
   9 **********************************************************************
  10 */
  11
  12 #ifndef STSEARCH_H
  13 #define STSEARCH_H
  14
  15 #include "unicode/utypes.h"
  16
  17 /**
  18  * \file
  19  * \brief C++ API: Service for searching text based on RuleBasedCollator.
  20  */
  21
  22 #if !UCONFIG_NO_COLLATION && !UCONFIG_NO_BREAK_ITERATION
  23
  24 #include "unicode/tblcoll.h"
  25 #include "unicode/coleitr.h"
  26 #include "unicode/search.h"
  27
  28 #if U_SHOW_CPLUSPLUS_API
  29 U_NAMESPACE_BEGIN
  30
  31 /**
  32  *
  33  * <tt>StringSearch</tt> is a <tt>SearchIterator</tt> that provides
  34  * language-sensitive text searching based on the comparison rules defined
  35  * in a {@link RuleBasedCollator} object.
  36  * StringSearch ensures that language eccentricity can be
  37  * handled, e.g. for the German collator, characters &szlig; and SS will be matched
  38  * if case is chosen to be ignored.
  39  * See the <a href="http://source.icu-project.org/repos/icu/icuhtml/trunk/design/collation/ICU_collation_design.htm">
  40  * "ICU Collation Design Document"</a> for more information.
  41  * <p>
  42  * There are 2 match options for selection:<br>
  43  * Let S' be the sub-string of a text string S between the offsets start and
  44  * end [start, end].
  45  * <br>
  46  * A pattern string P matches a text string S at the offsets [start, end]
  47  * if
  48  * <pre>
  49  * option 1. Some canonical equivalent of P matches some canonical equivalent
  50  *           of S'
  51  * option 2. P matches S' and if P starts or ends with a combining mark,
  52  *           there exists no non-ignorable combining mark before or after S?
  53  *           in S respectively.
  54  * </pre>
  55  * Option 2. will be the default.
  56  * <p>
  57  * This search has APIs similar to that of other text iteration mechanisms
  58  * such as the break iterators in <tt>BreakIterator</tt>. Using these
  59  * APIs, it is easy to scan through text looking for all occurrences of
  60  * a given pattern. This search iterator allows changing of direction by
  61  * calling a <tt>reset</tt> followed by a <tt>next</tt> or <tt>previous</tt>.
  62  * Though a direction change can occur without calling <tt>reset</tt> first,
  63  * this operation comes with some speed penalty.
  64  * Match results in the forward direction will match the result matches in
  65  * the backwards direction in the reverse order
  66  * <p>
  67  * <tt>SearchIterator</tt> provides APIs to specify the starting position
  68  * within the text string to be searched, e.g. <tt>setOffset</tt>,
  69  * <tt>preceding</tt> and <tt>following</tt>. Since the
  70  * starting position will be set as it is specified, please take note that
  71  * there are some danger points which the search may render incorrect
  72  * results:
  73  * <ul>
  74  * <li> The midst of a substring that requires normalization.
  75  * <li> If the following match is to be found, the position should not be the
  76  *      second character which requires to be swapped with the preceding
  77  *      character. Vice versa, if the preceding match is to be found,
  78  *      position to search from should not be the first character which
  79  *      requires to be swapped with the next character. E.g certain Thai and
  80  *      Lao characters require swapping.
  81  * <li> If a following pattern match is to be found, any position within a
  82  *      contracting sequence except the first will fail. Vice versa if a
  83  *      preceding pattern match is to be found, a invalid starting point
  84  *      would be any character within a contracting sequence except the last.
  85  * </ul>
  86  * <p>
  87  * A <tt>BreakIterator</tt> can be used if only matches at logical breaks are desired.
  88  * Using a <tt>BreakIterator</tt> will only give you results that exactly matches the
  89  * boundaries given by the breakiterator. For instance the pattern "e" will
  90  * not be found in the string "\u00e9" if a character break iterator is used.
  91  * <p>
  92  * Options are provided to handle overlapping matches.
  93  * E.g. In English, overlapping matches produces the result 0 and 2
  94  * for the pattern "abab" in the text "ababab", where else mutually
  95  * exclusive matches only produce the result of 0.
  96  * <p>
  97  * Though collator attributes will be taken into consideration while
  98  * performing matches, there are no APIs here for setting and getting the
  99  * attributes. These attributes can be set by getting the collator
 100  * from <tt>getCollator</tt> and using the APIs in <tt>coll.h</tt>.
 101  * Lastly to update <tt>StringSearch</tt> to the new collator attributes,
 102  * <tt>reset</tt> has to be called.
 103  * <p>
 104  * Restriction: <br>
 105  * Currently there are no composite characters that consists of a
 106  * character with combining class > 0 before a character with combining
 107  * class == 0. However, if such a character exists in the future,
 108  * <tt>StringSearch</tt> does not guarantee the results for option 1.
 109  * <p>
 110  * Consult the <tt>SearchIterator</tt> documentation for information on
 111  * and examples of how to use instances of this class to implement text
 112  * searching.
 113  * <pre><code>
 114  * UnicodeString target("The quick brown fox jumps over the lazy dog.");
 115  * UnicodeString pattern("fox");
 116  *
 117  * UErrorCode      error = U_ZERO_ERROR;
 118  * StringSearch iter(pattern, target, Locale::getUS(), NULL, status);
 119  * for (int pos = iter.first(error);
 120  *      pos != USEARCH_DONE;
 121  *      pos = iter.next(error))
 122  * {
 123  *     printf("Found match at %d pos, length is %d\n", pos,
 124  *                                             iter.getMatchLength());
 125  * }
 126  * </code></pre>
 127  * <p>
 128  * Note, <tt>StringSearch</tt> is not to be subclassed.
 129  * </p>
 130  * @see SearchIterator
 131  * @see RuleBasedCollator
 132  * @since ICU 2.0
 133  */
 134
 135 class U_I18N_API StringSearch U_FINAL : public SearchIterator
 136 {
 137 public:
 138
 139     // public constructors and destructors --------------------------------
 140
 141     /**
 142      * Creating a <tt>StringSearch</tt> instance using the argument locale
 143      * language rule set. A collator will be created in the process, which
 144      * will be owned by this instance and will be deleted during
 145      * destruction
 146      * @param pattern The text for which this object will search.
 147      * @param text    The text in which to search for the pattern.
 148      * @param locale  A locale which defines the language-sensitive
 149      *                comparison rules used to determine whether text in the
 150      *                pattern and target matches.
 151      * @param breakiter A <tt>BreakIterator</tt> object used to constrain
 152      *                the matches that are found. Matches whose start and end
 153      *                indices in the target text are not boundaries as
 154      *                determined by the <tt>BreakIterator</tt> are
 155      *                ignored. If this behavior is not desired,
 156      *                <tt>NULL</tt> can be passed in instead.
 157      * @param status  for errors if any. If pattern or text is NULL, or if
 158      *               either the length of pattern or text is 0 then an
 159      *               U_ILLEGAL_ARGUMENT_ERROR is returned.
 160      * @stable ICU 2.0
 161      */
 162     StringSearch(const UnicodeString &pattern, const UnicodeString &text,
 163                  const Locale        &locale,
 164                        BreakIterator *breakiter,
 165                        UErrorCode    &status);
 166
 167     /**
 168      * Creating a <tt>StringSearch</tt> instance using the argument collator
 169      * language rule set. Note, user retains the ownership of this collator,
 170      * it does not get destroyed during this instance's destruction.
 171      * @param pattern The text for which this object will search.
 172      * @param text    The text in which to search for the pattern.
 173      * @param coll    A <tt>RuleBasedCollator</tt> object which defines
 174      *                the language-sensitive comparison rules used to
 175      *                determine whether text in the pattern and target
 176      *                matches. User is responsible for the clearing of this
 177      *                object.
 178      * @param breakiter A <tt>BreakIterator</tt> object used to constrain
 179      *                the matches that are found. Matches whose start and end
 180      *                indices in the target text are not boundaries as
 181      *                determined by the <tt>BreakIterator</tt> are
 182      *                ignored. If this behavior is not desired,
 183      *                <tt>NULL</tt> can be passed in instead.
 184      * @param status for errors if any. If either the length of pattern or
 185      *               text is 0 then an U_ILLEGAL_ARGUMENT_ERROR is returned.
 186      * @stable ICU 2.0
 187      */
 188     StringSearch(const UnicodeString     &pattern,
 189                  const UnicodeString     &text,
 190                        RuleBasedCollator *coll,
 191                        BreakIterator     *breakiter,
 192                        UErrorCode        &status);
 193
 194     /**
 195      * Creating a <tt>StringSearch</tt> instance using the argument locale
 196      * language rule set. A collator will be created in the process, which
 197      * will be owned by this instance and will be deleted during
 198      * destruction
 199      * <p>
 200      * Note: No parsing of the text within the <tt>CharacterIterator</tt>
 201      * will be done during searching for this version. The block of text
 202      * in <tt>CharacterIterator</tt> will be used as it is.
 203      * @param pattern The text for which this object will search.
 204      * @param text    The text iterator in which to search for the pattern.
 205      * @param locale  A locale which defines the language-sensitive
 206      *                comparison rules used to determine whether text in the
 207      *                pattern and target matches. User is responsible for
 208      *                the clearing of this object.
 209      * @param breakiter A <tt>BreakIterator</tt> object used to constrain
 210      *                the matches that are found. Matches whose start and end
 211      *                indices in the target text are not boundaries as
 212      *                determined by the <tt>BreakIterator</tt> are
 213      *                ignored. If this behavior is not desired,
 214      *                <tt>NULL</tt> can be passed in instead.
 215      * @param status for errors if any. If either the length of pattern or
 216      *               text is 0 then an U_ILLEGAL_ARGUMENT_ERROR is returned.
 217      * @stable ICU 2.0
 218      */
 219     StringSearch(const UnicodeString &pattern, CharacterIterator &text,
 220                  const Locale        &locale,
 221                        BreakIterator *breakiter,
 222                        UErrorCode    &status);
 223
 224     /**
 225      * Creating a <tt>StringSearch</tt> instance using the argument collator
 226      * language rule set. Note, user retains the ownership of this collator,
 227      * it does not get destroyed during this instance's destruction.
 228      * <p>
 229      * Note: No parsing of the text within the <tt>CharacterIterator</tt>
 230      * will be done during searching for this version. The block of text
 231      * in <tt>CharacterIterator</tt> will be used as it is.
 232      * @param pattern The text for which this object will search.
 233      * @param text    The text in which to search for the pattern.
 234      * @param coll    A <tt>RuleBasedCollator</tt> object which defines
 235      *                the language-sensitive comparison rules used to
 236      *                determine whether text in the pattern and target
 237      *                matches. User is responsible for the clearing of this
 238      *                object.
 239      * @param breakiter A <tt>BreakIterator</tt> object used to constrain
 240      *                the matches that are found. Matches whose start and end
 241      *                indices in the target text are not boundaries as
 242      *                determined by the <tt>BreakIterator</tt> are
 243      *                ignored. If this behavior is not desired,
 244      *                <tt>NULL</tt> can be passed in instead.
 245      * @param status for errors if any. If either the length of pattern or
 246      *               text is 0 then an U_ILLEGAL_ARGUMENT_ERROR is returned.
 247      * @stable ICU 2.0
 248      */
 249     StringSearch(const UnicodeString     &pattern, CharacterIterator &text,
 250                        RuleBasedCollator *coll,
 251                        BreakIterator     *breakiter,
 252                        UErrorCode        &status);
 253
 254     /**
 255      * Copy constructor that creates a StringSearch instance with the same
 256      * behavior, and iterating over the same text.
 257      * @param that StringSearch instance to be copied.
 258      * @stable ICU 2.0
 259      */
 260     StringSearch(const StringSearch &that);
 261
 262     /**
 263     * Destructor. Cleans up the search iterator data struct.
 264     * If a collator is created in the constructor, it will be destroyed here.
 265     * @stable ICU 2.0
 266     */
 267     virtual ~StringSearch(void);
 268
 269     /**
 270      * Clone this object.
 271      * Clones can be used concurrently in multiple threads.
 272      * If an error occurs, then NULL is returned.
 273      * The caller must delete the clone.
 274      *
 275      * @return a clone of this object
 276      *
 277      * @see getDynamicClassID
 278      * @stable ICU 2.8
 279      */
 280     StringSearch *clone() const;
 281
 282     // operator overloading ---------------------------------------------
 283
 284     /**
 285      * Assignment operator. Sets this iterator to have the same behavior,
 286      * and iterate over the same text, as the one passed in.
 287      * @param that instance to be copied.
 288      * @stable ICU 2.0
 289      */
 290     StringSearch & operator=(const StringSearch &that);
 291
 292     /**
 293      * Equality operator.
 294      * @param that instance to be compared.
 295      * @return TRUE if both instances have the same attributes,
 296      *         breakiterators, collators and iterate over the same text
 297      *         while looking for the same pattern.
 298      * @stable ICU 2.0
 299      */
 300     virtual UBool operator==(const SearchIterator &that) const;
 301
 302     // public get and set methods ----------------------------------------
 303
 304     /**
 305      * Sets the index to point to the given position, and clears any state
 306      * that's affected.
 307      * <p>
 308      * This method takes the argument index and sets the position in the text
 309      * string accordingly without checking if the index is pointing to a
 310      * valid starting point to begin searching.
 311      * @param position within the text to be set. If position is less
 312      *          than or greater than the text range for searching,
 313      *          an U_INDEX_OUTOFBOUNDS_ERROR will be returned
 314      * @param status for errors if it occurs
 315      * @stable ICU 2.0
 316      */
 317     virtual void setOffset(int32_t position, UErrorCode &status);
 318
 319     /**
 320      * Return the current index in the text being searched.
 321      * If the iteration has gone past the end of the text
 322      * (or past the beginning for a backwards search), USEARCH_DONE
 323      * is returned.
 324      * @return current index in the text being searched.
 325      * @stable ICU 2.0
 326      */
 327     virtual int32_t getOffset(void) const;
 328
 329     /**
 330      * Set the target text to be searched.
 331      * Text iteration will hence begin at the start of the text string.
 332      * This method is
 333      * useful if you want to re-use an iterator to search for the same
 334      * pattern within a different body of text.
 335      * @param text text string to be searched
 336      * @param status for errors if any. If the text length is 0 then an
 337      *        U_ILLEGAL_ARGUMENT_ERROR is returned.
 338      * @stable ICU 2.0
 339      */
 340     virtual void setText(const UnicodeString &text, UErrorCode &status);
 341
 342     /**
 343      * Set the target text to be searched.
 344      * Text iteration will hence begin at the start of the text string.
 345      * This method is
 346      * useful if you want to re-use an iterator to search for the same
 347      * pattern within a different body of text.
 348      * Note: No parsing of the text within the <tt>CharacterIterator</tt>
 349      * will be done during searching for this version. The block of text
 350      * in <tt>CharacterIterator</tt> will be used as it is.
 351      * @param text text string to be searched
 352      * @param status for errors if any. If the text length is 0 then an
 353      *        U_ILLEGAL_ARGUMENT_ERROR is returned.
 354      * @stable ICU 2.0
 355      */
 356     virtual void setText(CharacterIterator &text, UErrorCode &status);
 357
 358     /**
 359      * Gets the collator used for the language rules.
 360      * <p>
 361      * Caller may modify but <b>must not</b> delete the <tt>RuleBasedCollator</tt>!
 362      * Modifications to this collator will affect the original collator passed in to
 363      * the <tt>StringSearch></tt> constructor or to setCollator, if any.
 364      * @return collator used for string search
 365      * @stable ICU 2.0
 366      */
 367     RuleBasedCollator * getCollator() const;
 368
 369     /**
 370      * Sets the collator used for the language rules. User retains the
 371      * ownership of this collator, thus the responsibility of deletion lies
 372      * with the user. The iterator's position will not be changed by this method.
 373      * @param coll    collator
 374      * @param status  for errors if any
 375      * @stable ICU 2.0
 376      */
 377     void setCollator(RuleBasedCollator *coll, UErrorCode &status);
 378
 379     /**
 380      * Sets the pattern used for matching.
 381      * The iterator's position will not be changed by this method.
 382      * @param pattern search pattern to be found
 383      * @param status for errors if any. If the pattern length is 0 then an
 384      *               U_ILLEGAL_ARGUMENT_ERROR is returned.
 385      * @stable ICU 2.0
 386      */
 387     void setPattern(const UnicodeString &pattern, UErrorCode &status);
 388
 389     /**
 390      * Gets the search pattern.
 391      * @return pattern used for matching
 392      * @stable ICU 2.0
 393      */
 394     const UnicodeString & getPattern() const;
 395
 396     // public methods ----------------------------------------------------
 397
 398     /**
 399      * Reset the iteration.
 400      * Search will begin at the start of the text string if a forward
 401      * iteration is initiated before a backwards iteration. Otherwise if
 402      * a backwards iteration is initiated before a forwards iteration, the
 403      * search will begin at the end of the text string.
 404      * @stable ICU 2.0
 405      */
 406     virtual void reset();
 407
 408     /**
 409      * Returns a copy of StringSearch with the same behavior, and
 410      * iterating over the same text, as this one. Note that all data will be
 411      * replicated, except for the user-specified collator and the
 412      * breakiterator.
 413      * @return cloned object
 414      * @stable ICU 2.0
 415      */
 416     virtual SearchIterator * safeClone(void) const;
 417
 418     /**
 419      * ICU "poor man's RTTI", returns a UClassID for the actual class.
 420      *
 421      * @stable ICU 2.2
 422      */
 423     virtual UClassID getDynamicClassID() const;
 424
 425     /**
 426      * ICU "poor man's RTTI", returns a UClassID for this class.
 427      *
 428      * @stable ICU 2.2
 429      */
 430     static UClassID U_EXPORT2 getStaticClassID();
 431
 432 protected:
 433
 434     // protected method -------------------------------------------------
 435
 436     /**
 437      * Search forward for matching text, starting at a given location.
 438      * Clients should not call this method directly; instead they should
 439      * call {@link SearchIterator#next }.
 440      * <p>
 441      * If a match is found, this method returns the index at which the match
 442      * starts and calls {@link SearchIterator#setMatchLength } with the number
 443      * of characters in the target text that make up the match. If no match
 444      * is found, the method returns <tt>USEARCH_DONE</tt>.
 445      * <p>
 446      * The <tt>StringSearch</tt> is adjusted so that its current index
 447      * (as returned by {@link #getOffset }) is the match position if one was
 448      * found.
 449      * If a match is not found, <tt>USEARCH_DONE</tt> will be returned and
 450      * the <tt>StringSearch</tt> will be adjusted to the index USEARCH_DONE.
 451      * @param position The index in the target text at which the search
 452      *                 starts
 453      * @param status for errors if any occurs
 454      * @return The index at which the matched text in the target starts, or
 455      *         USEARCH_DONE if no match was found.
 456      * @stable ICU 2.0
 457      */
 458     virtual int32_t handleNext(int32_t position, UErrorCode &status);
 459
 460     /**
 461      * Search backward for matching text, starting at a given location.
 462      * Clients should not call this method directly; instead they should call
 463      * <tt>SearchIterator.previous()</tt>, which this method overrides.
 464      * <p>
 465      * If a match is found, this method returns the index at which the match
 466      * starts and calls {@link SearchIterator#setMatchLength } with the number
 467      * of characters in the target text that make up the match. If no match
 468      * is found, the method returns <tt>USEARCH_DONE</tt>.
 469      * <p>
 470      * The <tt>StringSearch</tt> is adjusted so that its current index
 471      * (as returned by {@link #getOffset }) is the match position if one was
 472      * found.
 473      * If a match is not found, <tt>USEARCH_DONE</tt> will be returned and
 474      * the <tt>StringSearch</tt> will be adjusted to the index USEARCH_DONE.
 475      * @param position The index in the target text at which the search
 476      *                 starts.
 477      * @param status for errors if any occurs
 478      * @return The index at which the matched text in the target starts, or
 479      *         USEARCH_DONE if no match was found.
 480      * @stable ICU 2.0
 481      */
 482     virtual int32_t handlePrev(int32_t position, UErrorCode &status);
 483
 484 private :
 485     StringSearch(); // default constructor not implemented
 486
 487     // private data members ----------------------------------------------
 488
 489     /**
 490     * Pattern text
 491     * @stable ICU 2.0
 492     */
 493     UnicodeString      m_pattern_;
 494     /**
 495     * String search struct data
 496     * @stable ICU 2.0
 497     */
 498     UStringSearch     *m_strsrch_;
 499
 500 };
 501
 502 U_NAMESPACE_END
 503 #endif // U_SHOW_CPLUSPLUS_API
 504
 505 #endif /* #if !UCONFIG_NO_COLLATION */
 506
 507 #endif
 508