icuSources/i18n/unicode/search.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) 2001-2011 IBM and others. All rights reserved.
   6 **********************************************************************
   7 *   Date        Name        Description
   8 *  03/22/2000   helena      Creation.
   9 **********************************************************************
  10 */
  11
  12 #ifndef SEARCH_H
  13 #define SEARCH_H
  14
  15 #include "unicode/utypes.h"
  16
  17 /**
  18  * \file
  19  * \brief C++ API: SearchIterator object.
  20  */
  21
  22 #if !UCONFIG_NO_COLLATION && !UCONFIG_NO_BREAK_ITERATION
  23
  24 #include "unicode/uobject.h"
  25 #include "unicode/unistr.h"
  26 #include "unicode/chariter.h"
  27 #include "unicode/brkiter.h"
  28 #include "unicode/usearch.h"
  29
  30 /**
  31 * @stable ICU 2.0
  32 */
  33 struct USearch;
  34 /**
  35 * @stable ICU 2.0
  36 */
  37 typedef struct USearch USearch;
  38
  39 #if U_SHOW_CPLUSPLUS_API
  40 U_NAMESPACE_BEGIN
  41
  42 /**
  43  *
  44  * <tt>SearchIterator</tt> is an abstract base class that provides
  45  * methods to search for a pattern within a text string. Instances of
  46  * <tt>SearchIterator</tt> maintain a current position and scans over the
  47  * target text, returning the indices the pattern is matched and the length
  48  * of each match.
  49  * <p>
  50  * <tt>SearchIterator</tt> defines a protocol for text searching.
  51  * Subclasses provide concrete implementations of various search algorithms.
  52  * For example, <tt>StringSearch</tt> implements language-sensitive pattern
  53  * matching based on the comparison rules defined in a
  54  * <tt>RuleBasedCollator</tt> object.
  55  * <p>
  56  * Other options for searching includes using a BreakIterator to restrict
  57  * the points at which matches are detected.
  58  * <p>
  59  * <tt>SearchIterator</tt> provides an API that is similar to that of
  60  * other text iteration classes such as <tt>BreakIterator</tt>. Using
  61  * this class, it is easy to scan through text looking for all occurances of
  62  * a given pattern. The following example uses a <tt>StringSearch</tt>
  63  * object to find all instances of "fox" in the target string. Any other
  64  * subclass of <tt>SearchIterator</tt> can be used in an identical
  65  * manner.
  66  * <pre><code>
  67  * UnicodeString target("The quick brown fox jumped over the lazy fox");
  68  * UnicodeString pattern("fox");
  69  *
  70  * SearchIterator *iter  = new StringSearch(pattern, target);
  71  * UErrorCode      error = U_ZERO_ERROR;
  72  * for (int pos = iter->first(error); pos != USEARCH_DONE;
  73  *                               pos = iter->next(error)) {
  74  *     printf("Found match at %d pos, length is %d\n", pos,
  75  *                                             iter.getMatchLength());
  76  * }
  77  * </code></pre>
  78  *
  79  * @see StringSearch
  80  * @see RuleBasedCollator
  81  */
  82 class U_I18N_API SearchIterator : public UObject {
  83
  84 public:
  85
  86     // public constructors and destructors -------------------------------
  87
  88     /**
  89     * Copy constructor that creates a SearchIterator instance with the same
  90     * behavior, and iterating over the same text.
  91     * @param other the SearchIterator instance to be copied.
  92     * @stable ICU 2.0
  93     */
  94     SearchIterator(const SearchIterator &other);
  95
  96     /**
  97      * Destructor. Cleans up the search iterator data struct.
  98      * @stable ICU 2.0
  99      */
 100     virtual ~SearchIterator();
 101
 102     // public get and set methods ----------------------------------------
 103
 104     /**
 105      * Sets the index to point to the given position, and clears any state
 106      * that's affected.
 107      * <p>
 108      * This method takes the argument index and sets the position in the text
 109      * string accordingly without checking if the index is pointing to a
 110      * valid starting point to begin searching.
 111      * @param position within the text to be set. If position is less
 112      *             than or greater than the text range for searching,
 113      *          an U_INDEX_OUTOFBOUNDS_ERROR will be returned
 114      * @param status for errors if it occurs
 115      * @stable ICU 2.0
 116      */
 117     virtual void setOffset(int32_t position, UErrorCode &status) = 0;
 118
 119     /**
 120      * Return the current index in the text being searched.
 121      * If the iteration has gone past the end of the text
 122      * (or past the beginning for a backwards search), USEARCH_DONE
 123      * is returned.
 124      * @return current index in the text being searched.
 125      * @stable ICU 2.0
 126      */
 127     virtual int32_t getOffset(void) const = 0;
 128
 129     /**
 130     * Sets the text searching attributes located in the enum
 131     * USearchAttribute with values from the enum USearchAttributeValue.
 132     * USEARCH_DEFAULT can be used for all attributes for resetting.
 133     * @param attribute text attribute (enum USearchAttribute) to be set
 134     * @param value text attribute value
 135     * @param status for errors if it occurs
 136     * @stable ICU 2.0
 137     */
 138     void setAttribute(USearchAttribute       attribute,
 139                       USearchAttributeValue  value,
 140                       UErrorCode            &status);
 141
 142     /**
 143     * Gets the text searching attributes
 144     * @param attribute text attribute (enum USearchAttribute) to be retrieve
 145     * @return text attribute value
 146     * @stable ICU 2.0
 147     */
 148     USearchAttributeValue getAttribute(USearchAttribute  attribute) const;
 149
 150     /**
 151     * Returns the index to the match in the text string that was searched.
 152     * This call returns a valid result only after a successful call to
 153     * <tt>first</tt>, <tt>next</tt>, <tt>previous</tt>, or <tt>last</tt>.
 154     * Just after construction, or after a searching method returns
 155     * <tt>USEARCH_DONE</tt>, this method will return <tt>USEARCH_DONE</tt>.
 156     * <p>
 157     * Use getMatchedLength to get the matched string length.
 158     * @return index of a substring within the text string that is being
 159     *         searched.
 160     * @see #first
 161     * @see #next
 162     * @see #previous
 163     * @see #last
 164     * @stable ICU 2.0
 165     */
 166     int32_t getMatchedStart(void) const;
 167
 168     /**
 169      * Returns the length of text in the string which matches the search
 170      * pattern. This call returns a valid result only after a successful call
 171      * to <tt>first</tt>, <tt>next</tt>, <tt>previous</tt>, or <tt>last</tt>.
 172      * Just after construction, or after a searching method returns
 173      * <tt>USEARCH_DONE</tt>, this method will return 0.
 174      * @return The length of the match in the target text, or 0 if there
 175      *         is no match currently.
 176      * @see #first
 177      * @see #next
 178      * @see #previous
 179      * @see #last
 180      * @stable ICU 2.0
 181      */
 182     int32_t getMatchedLength(void) const;
 183
 184     /**
 185      * Returns the text that was matched by the most recent call to
 186      * <tt>first</tt>, <tt>next</tt>, <tt>previous</tt>, or <tt>last</tt>.
 187      * If the iterator is not pointing at a valid match (e.g. just after
 188      * construction or after <tt>USEARCH_DONE</tt> has been returned,
 189      * returns an empty string.
 190      * @param result stores the matched string or an empty string if a match
 191      *        is not found.
 192      * @see #first
 193      * @see #next
 194      * @see #previous
 195      * @see #last
 196      * @stable ICU 2.0
 197      */
 198     void getMatchedText(UnicodeString &result) const;
 199
 200     /**
 201      * Set the BreakIterator that will be used to restrict the points
 202      * at which matches are detected. The user is responsible for deleting
 203      * the breakiterator.
 204      * @param breakiter A BreakIterator that will be used to restrict the
 205      *                points at which matches are detected. If a match is
 206      *                found, but the match's start or end index is not a
 207      *                boundary as determined by the <tt>BreakIterator</tt>,
 208      *                the match will be rejected and another will be searched
 209      *                for. If this parameter is <tt>NULL</tt>, no break
 210      *                detection is attempted.
 211      * @param status for errors if it occurs
 212      * @see BreakIterator
 213      * @stable ICU 2.0
 214      */
 215     void setBreakIterator(BreakIterator *breakiter, UErrorCode &status);
 216
 217     /**
 218      * Returns the BreakIterator that is used to restrict the points at
 219      * which matches are detected.  This will be the same object that was
 220      * passed to the constructor or to <tt>setBreakIterator</tt>.
 221      * Note that <tt>NULL</tt> is a legal value; it means that break
 222      * detection should not be attempted.
 223      * @return BreakIterator used to restrict matchings.
 224      * @see #setBreakIterator
 225      * @stable ICU 2.0
 226      */
 227     const BreakIterator * getBreakIterator(void) const;
 228
 229     /**
 230      * Set the string text to be searched. Text iteration will hence begin at
 231      * the start of the text string. This method is useful if you want to
 232      * re-use an iterator to search for the same pattern within a different
 233      * body of text. The user is responsible for deleting the text.
 234      * @param text string to be searched.
 235      * @param status for errors. If the text length is 0,
 236      *        an U_ILLEGAL_ARGUMENT_ERROR is returned.
 237      * @stable ICU 2.0
 238      */
 239     virtual void setText(const UnicodeString &text, UErrorCode &status);
 240
 241     /**
 242      * Set the string text to be searched. Text iteration will hence begin at
 243      * the start of the text string. This method is useful if you want to
 244      * re-use an iterator to search for the same pattern within a different
 245      * body of text.
 246      * <p>
 247      * Note: No parsing of the text within the <tt>CharacterIterator</tt>
 248      * will be done during searching for this version. The block of text
 249      * in <tt>CharacterIterator</tt> will be used as it is.
 250      * The user is responsible for deleting the text.
 251      * @param text string iterator to be searched.
 252      * @param status for errors if any. If the text length is 0 then an
 253      *        U_ILLEGAL_ARGUMENT_ERROR is returned.
 254      * @stable ICU 2.0
 255      */
 256     virtual void setText(CharacterIterator &text, UErrorCode &status);
 257
 258     /**
 259      * Return the string text to be searched.
 260      * @return text string to be searched.
 261      * @stable ICU 2.0
 262      */
 263     const UnicodeString & getText(void) const;
 264
 265     // operator overloading ----------------------------------------------
 266
 267     /**
 268      * Equality operator.
 269      * @param that SearchIterator instance to be compared.
 270      * @return TRUE if both BreakIterators are of the same class, have the
 271      *         same behavior, terates over the same text and have the same
 272      *         attributes. FALSE otherwise.
 273      * @stable ICU 2.0
 274      */
 275     virtual UBool operator==(const SearchIterator &that) const;
 276
 277     /**
 278      * Not-equal operator.
 279      * @param that SearchIterator instance to be compared.
 280      * @return FALSE if operator== returns TRUE, and vice versa.
 281      * @stable ICU 2.0
 282      */
 283     UBool operator!=(const SearchIterator &that) const;
 284
 285     // public methods ----------------------------------------------------
 286
 287     /**
 288      * Returns a copy of SearchIterator with the same behavior, and
 289      * iterating over the same text, as this one. Note that all data will be
 290      * replicated, except for the text string to be searched.
 291      * @return cloned object
 292      * @stable ICU 2.0
 293      */
 294     virtual SearchIterator* safeClone(void) const = 0;
 295
 296     /**
 297      * Returns the first index at which the string text matches the search
 298      * pattern. The iterator is adjusted so that its current index (as
 299      * returned by <tt>getOffset</tt>) is the match position if one
 300      * was found.
 301      * If a match is not found, <tt>USEARCH_DONE</tt> will be returned and
 302      * the iterator will be adjusted to the index USEARCH_DONE
 303      * @param  status for errors if it occurs
 304      * @return The character index of the first match, or
 305      *         <tt>USEARCH_DONE</tt> if there are no matches.
 306      * @see #getOffset
 307      * @stable ICU 2.0
 308      */
 309     int32_t first(UErrorCode &status);
 310
 311     /**
 312      * Returns the first index equal or greater than <tt>position</tt> at which the
 313      * string text matches the search pattern. The iterator is adjusted so
 314      * that its current index (as returned by <tt>getOffset</tt>) is the
 315      * match position if one was found.
 316      * If a match is not found, <tt>USEARCH_DONE</tt> will be returned and the
 317      * iterator will be adjusted to the index <tt>USEARCH_DONE</tt>.
 318      * @param  position where search if to start from. If position is less
 319      *             than or greater than the text range for searching,
 320      *          an U_INDEX_OUTOFBOUNDS_ERROR will be returned
 321      * @param  status for errors if it occurs
 322      * @return The character index of the first match following
 323      *         <tt>position</tt>, or <tt>USEARCH_DONE</tt> if there are no
 324      *         matches.
 325      * @see #getOffset
 326      * @stable ICU 2.0
 327      */
 328     int32_t following(int32_t position, UErrorCode &status);
 329
 330     /**
 331      * Returns the last index in the target text at which it matches the
 332      * search pattern. The iterator is adjusted so that its current index
 333      * (as returned by <tt>getOffset</tt>) is the match position if one was
 334      * found.
 335      * If a match is not found, <tt>USEARCH_DONE</tt> will be returned and
 336      * the iterator will be adjusted to the index USEARCH_DONE.
 337      * @param  status for errors if it occurs
 338      * @return The index of the first match, or <tt>USEARCH_DONE</tt> if
 339      *         there are no matches.
 340      * @see #getOffset
 341      * @stable ICU 2.0
 342      */
 343     int32_t last(UErrorCode &status);
 344
 345     /**
 346      * Returns the first index less than <tt>position</tt> at which the string
 347      * text matches the search pattern. The iterator is adjusted so that its
 348      * current index (as returned by <tt>getOffset</tt>) is the match
 349      * position if one was found. If a match is not found,
 350      * <tt>USEARCH_DONE</tt> will be returned and the iterator will be
 351      * adjusted to the index USEARCH_DONE
 352      * <p>
 353      * When <tt>USEARCH_OVERLAP</tt> option is off, the last index of the
 354      * result match is always less than <tt>position</tt>.
 355      * When <tt>USERARCH_OVERLAP</tt> is on, the result match may span across
 356      * <tt>position</tt>.
 357      *
 358      * @param  position where search is to start from. If position is less
 359      *             than or greater than the text range for searching,
 360      *          an U_INDEX_OUTOFBOUNDS_ERROR will be returned
 361      * @param  status for errors if it occurs
 362      * @return The character index of the first match preceding
 363      *         <tt>position</tt>, or <tt>USEARCH_DONE</tt> if there are
 364      *         no matches.
 365      * @see #getOffset
 366      * @stable ICU 2.0
 367      */
 368     int32_t preceding(int32_t position, UErrorCode &status);
 369
 370     /**
 371      * Returns the index of the next point at which the text matches the
 372      * search pattern, starting from the current position
 373      * The iterator is adjusted so that its current index (as returned by
 374      * <tt>getOffset</tt>) is the match position if one was found.
 375      * If a match is not found, <tt>USEARCH_DONE</tt> will be returned and
 376      * the iterator will be adjusted to a position after the end of the text
 377      * string.
 378      * @param  status for errors if it occurs
 379      * @return The index of the next match after the current position,
 380      *          or <tt>USEARCH_DONE</tt> if there are no more matches.
 381      * @see #getOffset
 382      * @stable ICU 2.0
 383      */
 384      int32_t next(UErrorCode &status);
 385
 386     /**
 387      * Returns the index of the previous point at which the string text
 388      * matches the search pattern, starting at the current position.
 389      * The iterator is adjusted so that its current index (as returned by
 390      * <tt>getOffset</tt>) is the match position if one was found.
 391      * If a match is not found, <tt>USEARCH_DONE</tt> will be returned and
 392      * the iterator will be adjusted to the index USEARCH_DONE
 393      * @param  status for errors if it occurs
 394      * @return The index of the previous match before the current position,
 395      *          or <tt>USEARCH_DONE</tt> if there are no more matches.
 396      * @see #getOffset
 397      * @stable ICU 2.0
 398      */
 399     int32_t previous(UErrorCode &status);
 400
 401     /**
 402     * Resets the iteration.
 403     * Search will begin at the start of the text string if a forward
 404     * iteration is initiated before a backwards iteration. Otherwise if a
 405     * backwards iteration is initiated before a forwards iteration, the
 406     * search will begin at the end of the text string.
 407     * @stable ICU 2.0
 408     */
 409     virtual void reset();
 410
 411 protected:
 412     // protected data members ---------------------------------------------
 413
 414     /**
 415     * C search data struct
 416     * @stable ICU 2.0
 417     */
 418     USearch *m_search_;
 419
 420     /**
 421     * Break iterator.
 422     * Currently the C++ breakiterator does not have getRules etc to reproduce
 423     * another in C. Hence we keep the original around and do the verification
 424     * at the end of the match. The user is responsible for deleting this
 425     * break iterator.
 426     * @stable ICU 2.0
 427     */
 428     BreakIterator *m_breakiterator_;
 429
 430     /**
 431     * Unicode string version of the search text
 432     * @stable ICU 2.0
 433     */
 434     UnicodeString  m_text_;
 435
 436     // protected constructors and destructors -----------------------------
 437
 438     /**
 439     * Default constructor.
 440     * Initializes data to the default values.
 441     * @stable ICU 2.0
 442     */
 443     SearchIterator();
 444
 445     /**
 446      * Constructor for use by subclasses.
 447      * @param text The target text to be searched.
 448      * @param breakiter A {@link BreakIterator} that is used to restrict the
 449      *                points at which matches are detected. If
 450      *                <tt>handleNext</tt> or <tt>handlePrev</tt> finds a
 451      *                match, but the match's start or end index is not a
 452      *                boundary as determined by the <tt>BreakIterator</tt>,
 453      *                the match is rejected and <tt>handleNext</tt> or
 454      *                <tt>handlePrev</tt> is called again. If this parameter
 455      *                is <tt>NULL</tt>, no break detection is attempted.
 456      * @see #handleNext
 457      * @see #handlePrev
 458      * @stable ICU 2.0
 459      */
 460     SearchIterator(const UnicodeString &text,
 461                          BreakIterator *breakiter = NULL);
 462
 463     /**
 464      * Constructor for use by subclasses.
 465      * <p>
 466      * Note: No parsing of the text within the <tt>CharacterIterator</tt>
 467      * will be done during searching for this version. The block of text
 468      * in <tt>CharacterIterator</tt> will be used as it is.
 469      * @param text The target text to be searched.
 470      * @param breakiter A {@link BreakIterator} that is used to restrict the
 471      *                points at which matches are detected. If
 472      *                <tt>handleNext</tt> or <tt>handlePrev</tt> finds a
 473      *                match, but the match's start or end index is not a
 474      *                boundary as determined by the <tt>BreakIterator</tt>,
 475      *                the match is rejected and <tt>handleNext</tt> or
 476      *                <tt>handlePrev</tt> is called again. If this parameter
 477      *                is <tt>NULL</tt>, no break detection is attempted.
 478      * @see #handleNext
 479      * @see #handlePrev
 480      * @stable ICU 2.0
 481      */
 482     SearchIterator(CharacterIterator &text, BreakIterator *breakiter = NULL);
 483
 484     // protected methods --------------------------------------------------
 485
 486     /**
 487      * Assignment operator. Sets this iterator to have the same behavior,
 488      * and iterate over the same text, as the one passed in.
 489      * @param that instance to be copied.
 490      * @stable ICU 2.0
 491      */
 492     SearchIterator & operator=(const SearchIterator &that);
 493
 494     /**
 495      * Abstract method which subclasses override to provide the mechanism
 496      * for finding the next match in the target text. This allows different
 497      * subclasses to provide different search algorithms.
 498      * <p>
 499      * If a match is found, the implementation should return the index at
 500      * which the match starts and should call
 501      * <tt>setMatchLength</tt> with the number of characters
 502      * in the target text that make up the match. If no match is found, the
 503      * method should return USEARCH_DONE.
 504      * <p>
 505      * @param position The index in the target text at which the search
 506      *                 should start.
 507      * @param status for error codes if it occurs.
 508      * @return index at which the match starts, else if match is not found
 509      *         USEARCH_DONE is returned
 510      * @see #setMatchLength
 511      * @stable ICU 2.0
 512      */
 513     virtual int32_t handleNext(int32_t position, UErrorCode &status)
 514                                                                          = 0;
 515
 516     /**
 517      * Abstract method which subclasses override to provide the mechanism for
 518      * finding the previous match in the target text. This allows different
 519      * subclasses to provide different search algorithms.
 520      * <p>
 521      * If a match is found, the implementation should return the index at
 522      * which the match starts and should call
 523      * <tt>setMatchLength</tt> with the number of characters
 524      * in the target text that make up the match. If no match is found, the
 525      * method should return USEARCH_DONE.
 526      * <p>
 527      * @param position The index in the target text at which the search
 528      *                 should start.
 529      * @param status for error codes if it occurs.
 530      * @return index at which the match starts, else if match is not found
 531      *         USEARCH_DONE is returned
 532      * @see #setMatchLength
 533      * @stable ICU 2.0
 534      */
 535      virtual int32_t handlePrev(int32_t position, UErrorCode &status)
 536                                                                          = 0;
 537
 538     /**
 539      * Sets the length of the currently matched string in the text string to
 540      * be searched.
 541      * Subclasses' <tt>handleNext</tt> and <tt>handlePrev</tt>
 542      * methods should call this when they find a match in the target text.
 543      * @param length length of the matched text.
 544      * @see #handleNext
 545      * @see #handlePrev
 546      * @stable ICU 2.0
 547      */
 548     virtual void setMatchLength(int32_t length);
 549
 550     /**
 551      * Sets the offset of the currently matched string in the text string to
 552      * be searched.
 553      * Subclasses' <tt>handleNext</tt> and <tt>handlePrev</tt>
 554      * methods should call this when they find a match in the target text.
 555      * @param position start offset of the matched text.
 556      * @see #handleNext
 557      * @see #handlePrev
 558      * @stable ICU 2.0
 559      */
 560     virtual void setMatchStart(int32_t position);
 561
 562     /**
 563     * sets match not found
 564     * @stable ICU 2.0
 565     */
 566     void setMatchNotFound();
 567 };
 568
 569 inline UBool SearchIterator::operator!=(const SearchIterator &that) const
 570 {
 571    return !operator==(that);
 572 }
 573 U_NAMESPACE_END
 574 #endif // U_SHOW_CPLUSPLUS_API
 575
 576 #endif /* #if !UCONFIG_NO_COLLATION */
 577
 578 #endif
 579