* There are 2 match options for selection:
* Let S' be the sub-string of a text string S between the offsets start and
* end [start, end].
*
* A pattern string P matches a text string S at the offsets [start, end]
* if
*
* option 1. Some canonical equivalent of P matches some canonical equivalent * of S' * option 2. P matches S' and if P starts or ends with a combining mark, * there exists no non-ignorable combining mark before or after S? * in S respectively. ** Option 2. will be the default. *
* This search has APIs similar to that of other text iteration mechanisms * such as the break iterators in BreakIterator. Using these * APIs, it is easy to scan through text looking for all occurrences of * a given pattern. This search iterator allows changing of direction by * calling a reset followed by a next or previous. * Though a direction change can occur without calling reset first, * this operation comes with some speed penalty. * Match results in the forward direction will match the result matches in * the backwards direction in the reverse order *
* SearchIterator provides APIs to specify the starting position * within the text string to be searched, e.g. setOffset, * preceding and following. Since the * starting position will be set as it is specified, please take note that * there are some danger points which the search may render incorrect * results: *
* A BreakIterator can be used if only matches at logical breaks are desired. * Using a BreakIterator will only give you results that exactly matches the * boundaries given by the breakiterator. For instance the pattern "e" will * not be found in the string "\u00e9" if a character break iterator is used. *
* Options are provided to handle overlapping matches. * E.g. In English, overlapping matches produces the result 0 and 2 * for the pattern "abab" in the text "ababab", where else mutually * exclusive matches only produce the result of 0. *
* Though collator attributes will be taken into consideration while * performing matches, there are no APIs here for setting and getting the * attributes. These attributes can be set by getting the collator * from getCollator and using the APIs in coll.h. * Lastly to update StringSearch to the new collator attributes, * reset has to be called. *
* Restriction:
* Currently there are no composite characters that consists of a
* character with combining class > 0 before a character with combining
* class == 0. However, if such a character exists in the future,
* StringSearch does not guarantee the results for option 1.
*
* Consult the SearchIterator documentation for information on * and examples of how to use instances of this class to implement text * searching. *
* UnicodeString target("The quick brown fox jumps over the lazy dog.");
* UnicodeString pattern("fox");
*
* UErrorCode error = U_ZERO_ERROR;
* StringSearch iter(pattern, target, Locale::getUS(), nullptr, status);
* for (int pos = iter.first(error);
* pos != USEARCH_DONE;
* pos = iter.next(error))
* {
* printf("Found match at %d pos, length is %d\n", pos, iter.getMatchedLength());
* }
* * Note, StringSearch is not to be subclassed. *
* @see SearchIterator * @see RuleBasedCollator * @since ICU 2.0 */ class U_I18N_API StringSearch final : public SearchIterator { public: // public constructors and destructors -------------------------------- /** * Creating a StringSearch instance using the argument locale * language rule set. A collator will be created in the process, which * will be owned by this instance and will be deleted during * destruction * @param pattern The text for which this object will search. * @param text The text in which to search for the pattern. * @param locale A locale which defines the language-sensitive * comparison rules used to determine whether text in the * pattern and target matches. * @param breakiter A BreakIterator object used to constrain * the matches that are found. Matches whose start and end * indices in the target text are not boundaries as * determined by the BreakIterator are * ignored. If this behavior is not desired, * nullptr can be passed in instead. * @param status for errors if any. If pattern or text is nullptr, or if * either the length of pattern or text is 0 then an * U_ILLEGAL_ARGUMENT_ERROR is returned. * @stable ICU 2.0 */ StringSearch(const UnicodeString &pattern, const UnicodeString &text, const Locale &locale, BreakIterator *breakiter, UErrorCode &status); /** * Creating a StringSearch instance using the argument collator * language rule set. Note, user retains the ownership of this collator, * it does not get destroyed during this instance's destruction. * @param pattern The text for which this object will search. * @param text The text in which to search for the pattern. * @param coll A RuleBasedCollator object which defines * the language-sensitive comparison rules used to * determine whether text in the pattern and target * matches. User is responsible for the clearing of this * object. * @param breakiter A BreakIterator object used to constrain * the matches that are found. Matches whose start and end * indices in the target text are not boundaries as * determined by the BreakIterator are * ignored. If this behavior is not desired, * nullptr can be passed in instead. * @param status for errors if any. If either the length of pattern or * text is 0 then an U_ILLEGAL_ARGUMENT_ERROR is returned. * @stable ICU 2.0 */ StringSearch(const UnicodeString &pattern, const UnicodeString &text, RuleBasedCollator *coll, BreakIterator *breakiter, UErrorCode &status); /** * Creating a StringSearch instance using the argument locale * language rule set. A collator will be created in the process, which * will be owned by this instance and will be deleted during * destruction ** Note: No parsing of the text within the CharacterIterator * will be done during searching for this version. The block of text * in CharacterIterator will be used as it is. * @param pattern The text for which this object will search. * @param text The text iterator in which to search for the pattern. * @param locale A locale which defines the language-sensitive * comparison rules used to determine whether text in the * pattern and target matches. User is responsible for * the clearing of this object. * @param breakiter A BreakIterator object used to constrain * the matches that are found. Matches whose start and end * indices in the target text are not boundaries as * determined by the BreakIterator are * ignored. If this behavior is not desired, * nullptr can be passed in instead. * @param status for errors if any. If either the length of pattern or * text is 0 then an U_ILLEGAL_ARGUMENT_ERROR is returned. * @stable ICU 2.0 */ StringSearch(const UnicodeString &pattern, CharacterIterator &text, const Locale &locale, BreakIterator *breakiter, UErrorCode &status); /** * Creating a StringSearch instance using the argument collator * language rule set. Note, user retains the ownership of this collator, * it does not get destroyed during this instance's destruction. *
* Note: No parsing of the text within the CharacterIterator * will be done during searching for this version. The block of text * in CharacterIterator will be used as it is. * @param pattern The text for which this object will search. * @param text The text in which to search for the pattern. * @param coll A RuleBasedCollator object which defines * the language-sensitive comparison rules used to * determine whether text in the pattern and target * matches. User is responsible for the clearing of this * object. * @param breakiter A BreakIterator object used to constrain * the matches that are found. Matches whose start and end * indices in the target text are not boundaries as * determined by the BreakIterator are * ignored. If this behavior is not desired, * nullptr can be passed in instead. * @param status for errors if any. If either the length of pattern or * text is 0 then an U_ILLEGAL_ARGUMENT_ERROR is returned. * @stable ICU 2.0 */ StringSearch(const UnicodeString &pattern, CharacterIterator &text, RuleBasedCollator *coll, BreakIterator *breakiter, UErrorCode &status); /** * Copy constructor that creates a StringSearch instance with the same * behavior, and iterating over the same text. * @param that StringSearch instance to be copied. * @stable ICU 2.0 */ StringSearch(const StringSearch &that); /** * Destructor. Cleans up the search iterator data struct. * If a collator is created in the constructor, it will be destroyed here. * @stable ICU 2.0 */ virtual ~StringSearch(void); /** * Clone this object. * Clones can be used concurrently in multiple threads. * If an error occurs, then nullptr is returned. * The caller must delete the clone. * * @return a clone of this object * * @see getDynamicClassID * @stable ICU 2.8 */ StringSearch *clone() const; // operator overloading --------------------------------------------- /** * Assignment operator. Sets this iterator to have the same behavior, * and iterate over the same text, as the one passed in. * @param that instance to be copied. * @stable ICU 2.0 */ StringSearch & operator=(const StringSearch &that); /** * Equality operator. * @param that instance to be compared. * @return true if both instances have the same attributes, * breakiterators, collators and iterate over the same text * while looking for the same pattern. * @stable ICU 2.0 */ virtual bool operator==(const SearchIterator &that) const override; // public get and set methods ---------------------------------------- /** * Sets the index to point to the given position, and clears any state * that's affected. *
* This method takes the argument index and sets the position in the text * string accordingly without checking if the index is pointing to a * valid starting point to begin searching. * @param position within the text to be set. If position is less * than or greater than the text range for searching, * an U_INDEX_OUTOFBOUNDS_ERROR will be returned * @param status for errors if it occurs * @stable ICU 2.0 */ virtual void setOffset(int32_t position, UErrorCode &status) override; /** * Return the current index in the text being searched. * If the iteration has gone past the end of the text * (or past the beginning for a backwards search), USEARCH_DONE * is returned. * @return current index in the text being searched. * @stable ICU 2.0 */ virtual int32_t getOffset(void) const override; /** * Set the target text to be searched. * Text iteration will hence begin at the start of the text string. * This method is * useful if you want to re-use an iterator to search for the same * pattern within a different body of text. * @param text text string to be searched * @param status for errors if any. If the text length is 0 then an * U_ILLEGAL_ARGUMENT_ERROR is returned. * @stable ICU 2.0 */ virtual void setText(const UnicodeString &text, UErrorCode &status) override; /** * Set the target text to be searched. * Text iteration will hence begin at the start of the text string. * This method is * useful if you want to re-use an iterator to search for the same * pattern within a different body of text. * Note: No parsing of the text within the CharacterIterator * will be done during searching for this version. The block of text * in CharacterIterator will be used as it is. * @param text text string to be searched * @param status for errors if any. If the text length is 0 then an * U_ILLEGAL_ARGUMENT_ERROR is returned. * @stable ICU 2.0 */ virtual void setText(CharacterIterator &text, UErrorCode &status) override; /** * Gets the collator used for the language rules. *
* Caller may modify but must not delete the RuleBasedCollator! * Modifications to this collator will affect the original collator passed in to * the StringSearch> constructor or to setCollator, if any. * @return collator used for string search * @stable ICU 2.0 */ RuleBasedCollator * getCollator() const; /** * Sets the collator used for the language rules. User retains the * ownership of this collator, thus the responsibility of deletion lies * with the user. The iterator's position will not be changed by this method. * @param coll collator * @param status for errors if any * @stable ICU 2.0 */ void setCollator(RuleBasedCollator *coll, UErrorCode &status); /** * Sets the pattern used for matching. * The iterator's position will not be changed by this method. * @param pattern search pattern to be found * @param status for errors if any. If the pattern length is 0 then an * U_ILLEGAL_ARGUMENT_ERROR is returned. * @stable ICU 2.0 */ void setPattern(const UnicodeString &pattern, UErrorCode &status); /** * Gets the search pattern. * @return pattern used for matching * @stable ICU 2.0 */ const UnicodeString & getPattern() const; // public methods ---------------------------------------------------- /** * Reset the iteration. * Search will begin at the start of the text string if a forward * iteration is initiated before a backwards iteration. Otherwise if * a backwards iteration is initiated before a forwards iteration, the * search will begin at the end of the text string. * @stable ICU 2.0 */ virtual void reset() override; /** * Returns a copy of StringSearch with the same behavior, and * iterating over the same text, as this one. Note that all data will be * replicated, except for the user-specified collator and the * breakiterator. * @return cloned object * @stable ICU 2.0 */ virtual StringSearch * safeClone() const override; /** * ICU "poor man's RTTI", returns a UClassID for the actual class. * * @stable ICU 2.2 */ virtual UClassID getDynamicClassID() const override; /** * ICU "poor man's RTTI", returns a UClassID for this class. * * @stable ICU 2.2 */ static UClassID U_EXPORT2 getStaticClassID(); protected: // protected method ------------------------------------------------- /** * Search forward for matching text, starting at a given location. * Clients should not call this method directly; instead they should * call {@link SearchIterator#next }. *
* If a match is found, this method returns the index at which the match * starts and calls {@link SearchIterator#setMatchLength } with the number * of characters in the target text that make up the match. If no match * is found, the method returns USEARCH_DONE. *
* The StringSearch is adjusted so that its current index * (as returned by {@link #getOffset }) is the match position if one was * found. * If a match is not found, USEARCH_DONE will be returned and * the StringSearch will be adjusted to the index USEARCH_DONE. * @param position The index in the target text at which the search * starts * @param status for errors if any occurs * @return The index at which the matched text in the target starts, or * USEARCH_DONE if no match was found. * @stable ICU 2.0 */ virtual int32_t handleNext(int32_t position, UErrorCode &status) override; /** * Search backward for matching text, starting at a given location. * Clients should not call this method directly; instead they should call * SearchIterator.previous(), which this method overrides. *
* If a match is found, this method returns the index at which the match * starts and calls {@link SearchIterator#setMatchLength } with the number * of characters in the target text that make up the match. If no match * is found, the method returns USEARCH_DONE. *
* The StringSearch is adjusted so that its current index * (as returned by {@link #getOffset }) is the match position if one was * found. * If a match is not found, USEARCH_DONE will be returned and * the StringSearch will be adjusted to the index USEARCH_DONE. * @param position The index in the target text at which the search * starts. * @param status for errors if any occurs * @return The index at which the matched text in the target starts, or * USEARCH_DONE if no match was found. * @stable ICU 2.0 */ virtual int32_t handlePrev(int32_t position, UErrorCode &status) override; private : StringSearch() = delete; // default constructor not implemented // private data members ---------------------------------------------- /** * Pattern text * @stable ICU 2.0 */ UnicodeString m_pattern_; /** * String search struct data * @stable ICU 2.0 */ UStringSearch *m_strsrch_; }; U_NAMESPACE_END #endif /* #if !UCONFIG_NO_COLLATION */ #endif /* U_SHOW_CPLUSPLUS_API */ #endif