* SearchIterator defines a protocol for text searching. * Subclasses provide concrete implementations of various search algorithms. * For example, StringSearch implements language-sensitive pattern * matching based on the comparison rules defined in a * RuleBasedCollator object. *
* Other options for searching includes using a BreakIterator to restrict * the points at which matches are detected. *
* SearchIterator provides an API that is similar to that of * other text iteration classes such as BreakIterator. Using * this class, it is easy to scan through text looking for all occurrences of * a given pattern. The following example uses a StringSearch * object to find all instances of "fox" in the target string. Any other * subclass of SearchIterator can be used in an identical * manner. *
* UnicodeString target("The quick brown fox jumped over the lazy fox");
* UnicodeString pattern("fox");
*
* SearchIterator *iter = new StringSearch(pattern, target);
* UErrorCode error = U_ZERO_ERROR;
* 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());
* }
* * 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) = 0; /** * 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 = 0; /** * Sets the text searching attributes located in the enum * USearchAttribute with values from the enum USearchAttributeValue. * USEARCH_DEFAULT can be used for all attributes for resetting. * @param attribute text attribute (enum USearchAttribute) to be set * @param value text attribute value * @param status for errors if it occurs * @stable ICU 2.0 */ void setAttribute(USearchAttribute attribute, USearchAttributeValue value, UErrorCode &status); /** * Gets the text searching attributes * @param attribute text attribute (enum USearchAttribute) to be retrieve * @return text attribute value * @stable ICU 2.0 */ USearchAttributeValue getAttribute(USearchAttribute attribute) const; /** * Returns the index to the match in the text string that was searched. * This call returns a valid result only after a successful call to * first, next, previous, or last. * Just after construction, or after a searching method returns * USEARCH_DONE, this method will return USEARCH_DONE. *
* Use getMatchedLength to get the matched string length. * @return index of a substring within the text string that is being * searched. * @see #first * @see #next * @see #previous * @see #last * @stable ICU 2.0 */ int32_t getMatchedStart(void) const; /** * Returns the length of text in the string which matches the search * pattern. This call returns a valid result only after a successful call * to first, next, previous, or last. * Just after construction, or after a searching method returns * USEARCH_DONE, this method will return 0. * @return The length of the match in the target text, or 0 if there * is no match currently. * @see #first * @see #next * @see #previous * @see #last * @stable ICU 2.0 */ int32_t getMatchedLength(void) const; /** * Returns the text that was matched by the most recent call to * first, next, previous, or last. * If the iterator is not pointing at a valid match (e.g. just after * construction or after USEARCH_DONE has been returned, * returns an empty string. * @param result stores the matched string or an empty string if a match * is not found. * @see #first * @see #next * @see #previous * @see #last * @stable ICU 2.0 */ void getMatchedText(UnicodeString &result) const; /** * Set the BreakIterator that will be used to restrict the points * at which matches are detected. The user is responsible for deleting * the breakiterator. * @param breakiter A BreakIterator that will be used to restrict the * points at which matches are detected. If a match is * found, but the match's start or end index is not a * boundary as determined by the BreakIterator, * the match will be rejected and another will be searched * for. If this parameter is nullptr, no break * detection is attempted. * @param status for errors if it occurs * @see BreakIterator * @stable ICU 2.0 */ void setBreakIterator(BreakIterator *breakiter, UErrorCode &status); /** * Returns the BreakIterator that is used to restrict the points at * which matches are detected. This will be the same object that was * passed to the constructor or to setBreakIterator. * Note that nullptr is a legal value; it means that break * detection should not be attempted. * @return BreakIterator used to restrict matchings. * @see #setBreakIterator * @stable ICU 2.0 */ const BreakIterator * getBreakIterator(void) const; /** * Set the string 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. The user is responsible for deleting the text. * @param text string to be searched. * @param status for errors. If the text length is 0, * an U_ILLEGAL_ARGUMENT_ERROR is returned. * @stable ICU 2.0 */ virtual void setText(const UnicodeString &text, UErrorCode &status); /** * Set the string 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. * The user is responsible for deleting the text. * @param text string iterator 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); /** * Return the string text to be searched. * @return text string to be searched. * @stable ICU 2.0 */ const UnicodeString & getText(void) const; // operator overloading ---------------------------------------------- /** * Equality operator. * @param that SearchIterator instance to be compared. * @return true if both BreakIterators are of the same class, have the * same behavior, terates over the same text and have the same * attributes. false otherwise. * @stable ICU 2.0 */ virtual bool operator==(const SearchIterator &that) const; /** * Not-equal operator. * @param that SearchIterator instance to be compared. * @return false if operator== returns true, and vice versa. * @stable ICU 2.0 */ bool operator!=(const SearchIterator &that) const; // public methods ---------------------------------------------------- /** * Returns a copy of SearchIterator with the same behavior, and * iterating over the same text, as this one. Note that all data will be * replicated, except for the text string to be searched. * @return cloned object * @stable ICU 2.0 */ virtual SearchIterator* safeClone(void) const = 0; /** * Returns the first index at which the string text matches the search * pattern. The iterator is adjusted so that its current index (as * returned by getOffset) is the match position if one * was found. * If a match is not found, USEARCH_DONE will be returned and * the iterator will be adjusted to the index USEARCH_DONE * @param status for errors if it occurs * @return The character index of the first match, or * USEARCH_DONE if there are no matches. * @see #getOffset * @stable ICU 2.0 */ int32_t first(UErrorCode &status); /** * Returns the first index equal or greater than position at which the * string text matches the search pattern. The iterator is adjusted so * that its current index (as returned by getOffset) is the * match position if one was found. * If a match is not found, USEARCH_DONE will be returned and the * iterator will be adjusted to the index USEARCH_DONE. * @param position where search if to start from. 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 * @return The character index of the first match following * position, or USEARCH_DONE if there are no * matches. * @see #getOffset * @stable ICU 2.0 */ int32_t following(int32_t position, UErrorCode &status); /** * Returns the last index in the target text at which it matches the * search pattern. The iterator is adjusted so that its current index * (as returned by getOffset) is the match position if one was * found. * If a match is not found, USEARCH_DONE will be returned and * the iterator will be adjusted to the index USEARCH_DONE. * @param status for errors if it occurs * @return The index of the first match, or USEARCH_DONE if * there are no matches. * @see #getOffset * @stable ICU 2.0 */ int32_t last(UErrorCode &status); /** * Returns the first index less than position at which the string * text matches the search pattern. The iterator is adjusted so that its * current index (as returned by getOffset) is the match * position if one was found. If a match is not found, * USEARCH_DONE will be returned and the iterator will be * adjusted to the index USEARCH_DONE *
* When USEARCH_OVERLAP option is off, the last index of the * result match is always less than position. * When USERARCH_OVERLAP is on, the result match may span across * position. * * @param position where search is to start from. 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 * @return The character index of the first match preceding * position, or USEARCH_DONE if there are * no matches. * @see #getOffset * @stable ICU 2.0 */ int32_t preceding(int32_t position, UErrorCode &status); /** * Returns the index of the next point at which the text matches the * search pattern, starting from the current position * The iterator is adjusted so that its current index (as returned by * getOffset) is the match position if one was found. * If a match is not found, USEARCH_DONE will be returned and * the iterator will be adjusted to a position after the end of the text * string. * @param status for errors if it occurs * @return The index of the next match after the current position, * or USEARCH_DONE if there are no more matches. * @see #getOffset * @stable ICU 2.0 */ int32_t next(UErrorCode &status); /** * Returns the index of the previous point at which the string text * matches the search pattern, starting at the current position. * The iterator is adjusted so that its current index (as returned by * getOffset) is the match position if one was found. * If a match is not found, USEARCH_DONE will be returned and * the iterator will be adjusted to the index USEARCH_DONE * @param status for errors if it occurs * @return The index of the previous match before the current position, * or USEARCH_DONE if there are no more matches. * @see #getOffset * @stable ICU 2.0 */ int32_t previous(UErrorCode &status); /** * Resets 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(); protected: // protected data members --------------------------------------------- /** * C search data struct * @stable ICU 2.0 */ USearch *m_search_; /** * Break iterator. * Currently the C++ breakiterator does not have getRules etc to reproduce * another in C. Hence we keep the original around and do the verification * at the end of the match. The user is responsible for deleting this * break iterator. * @stable ICU 2.0 */ BreakIterator *m_breakiterator_; /** * Unicode string version of the search text * @stable ICU 2.0 */ UnicodeString m_text_; // protected constructors and destructors ----------------------------- /** * Default constructor. * Initializes data to the default values. * @stable ICU 2.0 */ SearchIterator(); /** * Constructor for use by subclasses. * @param text The target text to be searched. * @param breakiter A {@link BreakIterator} that is used to restrict the * points at which matches are detected. If * handleNext or handlePrev finds a * match, but the match's start or end index is not a * boundary as determined by the BreakIterator, * the match is rejected and handleNext or * handlePrev is called again. If this parameter * is nullptr, no break detection is attempted. * @see #handleNext * @see #handlePrev * @stable ICU 2.0 */ SearchIterator(const UnicodeString &text, BreakIterator *breakiter = nullptr); /** * Constructor for use by subclasses. *
* 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 The target text to be searched. * @param breakiter A {@link BreakIterator} that is used to restrict the * points at which matches are detected. If * handleNext or handlePrev finds a * match, but the match's start or end index is not a * boundary as determined by the BreakIterator, * the match is rejected and handleNext or * handlePrev is called again. If this parameter * is nullptr, no break detection is attempted. * @see #handleNext * @see #handlePrev * @stable ICU 2.0 */ SearchIterator(CharacterIterator &text, BreakIterator *breakiter = nullptr); // protected methods -------------------------------------------------- /** * 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 */ SearchIterator & operator=(const SearchIterator &that); /** * Abstract method which subclasses override to provide the mechanism * for finding the next match in the target text. This allows different * subclasses to provide different search algorithms. *
* If a match is found, the implementation should return the index at * which the match starts and should call * setMatchLength with the number of characters * in the target text that make up the match. If no match is found, the * method should return USEARCH_DONE. *
* @param position The index in the target text at which the search * should start. * @param status for error codes if it occurs. * @return index at which the match starts, else if match is not found * USEARCH_DONE is returned * @see #setMatchLength * @stable ICU 2.0 */ virtual int32_t handleNext(int32_t position, UErrorCode &status) = 0; /** * Abstract method which subclasses override to provide the mechanism for * finding the previous match in the target text. This allows different * subclasses to provide different search algorithms. *
* If a match is found, the implementation should return the index at * which the match starts and should call * setMatchLength with the number of characters * in the target text that make up the match. If no match is found, the * method should return USEARCH_DONE. *
* @param position The index in the target text at which the search * should start. * @param status for error codes if it occurs. * @return index at which the match starts, else if match is not found * USEARCH_DONE is returned * @see #setMatchLength * @stable ICU 2.0 */ virtual int32_t handlePrev(int32_t position, UErrorCode &status) = 0; /** * Sets the length of the currently matched string in the text string to * be searched. * Subclasses' handleNext and handlePrev * methods should call this when they find a match in the target text. * @param length length of the matched text. * @see #handleNext * @see #handlePrev * @stable ICU 2.0 */ virtual void setMatchLength(int32_t length); /** * Sets the offset of the currently matched string in the text string to * be searched. * Subclasses' handleNext and handlePrev * methods should call this when they find a match in the target text. * @param position start offset of the matched text. * @see #handleNext * @see #handlePrev * @stable ICU 2.0 */ virtual void setMatchStart(int32_t position); /** * sets match not found * @stable ICU 2.0 */ void setMatchNotFound(); }; inline bool SearchIterator::operator!=(const SearchIterator &that) const { return !operator==(that); } U_NAMESPACE_END #endif /* #if !UCONFIG_NO_COLLATION */ #endif /* U_SHOW_CPLUSPLUS_API */ #endif