* Line boundary analysis determines where a text string can be broken * when line-wrapping. The mechanism correctly handles punctuation and * hyphenated words. *
* Sentence boundary analysis allows selection with correct * interpretation of periods within numbers and abbreviations, and * trailing punctuation marks such as quotation marks and parentheses. *
* Word boundary analysis is used by search and replace functions, as * well as within text editing applications that allow the user to * select words with a double click. Word selection provides correct * interpretation of punctuation marks within and following * words. Characters that are not part of a word, such as symbols or * punctuation marks, have word-breaks on both sides. *
* Character boundary analysis allows users to interact with * characters as they expect to, for example, when moving the cursor * through a text string. Character boundary analysis provides correct * navigation of through character strings, regardless of how the * character is stored. For example, an accented character might be * stored as a base character and a diacritical mark. What users * consider to be a character can differ between languages. *
* This is the interface for all text boundaries. *
* Examples: *
* Helper function to output text *
* . void printTextRange( BreakIterator& iterator, UTextOffset start, UTextOffset end )
* . {
* . UnicodeString textBuffer, temp;
* . CharacterIterator *strIter = iterator.createText();
* . strIter->getText(temp);
* . cout << " " << start << " " << end << " |"
* . << temp.extractBetween(start, end, textBuffer)
* . << "|" << endl;
* . delete strIter;
* . }
*
* Print each element in order:
*
* . void printEachForward( BreakIterator& boundary)
* . {
* . UTextOffset start = boundary.first();
* . for (UTextOffset end = boundary.next();
* . end != BreakIterator::DONE;
* . start = end, end = boundary.next())
* . {
* . printTextRange( boundary, start, end );
* . }
* . }
*
* Print each element in reverse order:
*
* . void printEachBackward( BreakIterator& boundary)
* . {
* . UTextOffset end = boundary.last();
* . for (UTextOffset start = boundary.previous();
* . start != BreakIterator::DONE;
* . end = start, start = boundary.previous())
* . {
* . printTextRange( boundary, start, end );
* . }
* . }
*
* Print first element
*
* . void printFirst(BreakIterator& boundary)
* . {
* . UTextOffset start = boundary.first();
* . UTextOffset end = boundary.next();
* . printTextRange( boundary, start, end );
* . }
*
* Print last element
*
* . void printLast(BreakIterator& boundary)
* . {
* . UTextOffset end = boundary.last();
* . UTextOffset start = boundary.previous();
* . printTextRange( boundary, start, end );
* . }
*
* Print the element at a specified position
*
* . void printAt(BreakIterator &boundary, UTextOffset pos )
* . {
* . UTextOffset end = boundary.following(pos);
* . UTextOffset start = boundary.previous();
* . printTextRange( boundary, start, end );
* . }
*
* Creating and using text boundaries
*
* . void BreakIterator_Example( void )
* . {
* . BreakIterator* boundary;
* . UnicodeString stringToExamine("Aaa bbb ccc. Ddd eee fff.");
* . cout << "Examining: " << stringToExamine << endl;
* .
* . //print each sentence in forward and reverse order
* . boundary = BreakIterator::createSentenceInstance( Locale::US );
* . boundary->setText(stringToExamine);
* . cout << "----- forward: -----------" << endl;
* . printEachForward(*boundary);
* . cout << "----- backward: ----------" << endl;
* . printEachBackward(*boundary);
* . delete boundary;
* .
* . //print each word in order
* . boundary = BreakIterator::createWordInstance();
* . boundary->setText(stringToExamine);
* . cout << "----- forward: -----------" << endl;
* . printEachForward(*boundary);
* . //print first element
* . cout << "----- first: -------------" << endl;
* . printFirst(*boundary);
* . //print last element
* . cout << "----- last: --------------" << endl;
* . printLast(*boundary);
* . //print word at charpos 10
* . cout << "----- at pos 10: ---------" << endl;
* . printAt(*boundary, 10 );
* .
* . delete boundary;
* . }
*
*/
class U_I18N_API BreakIterator {
public:
virtual ~BreakIterator();
/**
* Return true if another object is semantically equal to this
* one. The other object should be an instance of the same subclass of
* BreakIterator. Objects of different subclasses are considered
* unequal.
* * Return true if this BreakIterator is at the same position in the * same text, and is the same class and type (word, line, etc.) of * BreakIterator, as the argument. Text is considered the same if * it contains the same characters, it need not be the same * object, and styles are not considered. * @stable */ virtual UBool operator==(const BreakIterator&) const = 0; /** * Returns the complement of the result of operator== * @stable */ UBool operator!=(const BreakIterator& rhs) const { return !operator==(rhs); } /** * Return a polymorphic copy of this object. This is an abstract * method which subclasses implement. * @stable */ virtual BreakIterator* clone(void) const = 0; /** * Return a polymorphic class ID for this object. Different subclasses * will return distinct unequal values. * @stable */ virtual UClassID getDynamicClassID(void) const = 0; /** * Return a CharacterIterator over the text being analyzed. * @draft */ virtual const CharacterIterator& getText(void) const = 0; /** * Get the text for which this object is finding the boundaries. * @deprecated This will be removed after 2000-Dec-31. Use getText() instead. */ virtual CharacterIterator* createText(void) const = 0; /** * Change the text over which this operates. The text boundary is * reset to the start. * @deprecated Use setText(const UnicodeString&) instead. */ virtual void setText(const UnicodeString* it) = 0; /** * Change the text over which this operates. The text boundary is * reset to the start. * @draft */ virtual void setText(const UnicodeString &text) = 0; /** * Change the text over which this operates. The text boundary is * reset to the start. * @stable */ virtual void adoptText(CharacterIterator* it) = 0; /** * DONE is returned by previous() and next() after all valid * boundaries have been returned. * @stable */ static const UTextOffset DONE; /** * Return the index of the first character in the text being scanned. * @stable */ virtual UTextOffset first(void) = 0; /** * Return the index immediately BEYOND the last character in the text being scanned. * @stable */ virtual UTextOffset last(void) = 0; /** * Return the boundary preceding the current boundary. * @return The character index of the previous text boundary or DONE if all * boundaries have been returned. * @stable */ virtual UTextOffset previous(void) = 0; /** * Return the boundary following the current boundary. * @return The character index of the next text boundary or DONE if all * boundaries have been returned. * @stable */ virtual UTextOffset next(void) = 0; /** * Return character index of the text boundary that was most recently * returned by next(), previous(), first(), or last() * @return The boundary most recently returned. * @stable */ virtual UTextOffset current(void) const = 0; /** * Return the first boundary following the specified offset. * The value returned is always greater than the offset or * the value BreakIterator.DONE * @param offset the offset to begin scanning. * @return The first boundary after the specified offset. * @stable */ virtual UTextOffset following(UTextOffset offset) = 0; /** * Return the first boundary preceding the specified offset. * The value returned is always smaller than the offset or * the value BreakIterator.DONE * @param offset the offset to begin scanning. * @return The first boundary before the specified offset. * @stable */ virtual UTextOffset preceding(UTextOffset offset) = 0; /** * Return true if the specfied position is a boundary position. * @param offset the offset to check. * @return True if "offset" is a boundary position. * @stable */ virtual UBool isBoundary(UTextOffset offset) = 0; /** * Return the nth boundary from the current boundary * @param n which boundary to return. A value of 0 * does nothing. Negative values move to previous boundaries * and positive values move to later boundaries. * @return The index of the nth boundary from the current position, or * DONE if there are fewer than |n| boundaries in the specfied direction. * @stable */ virtual UTextOffset next(int32_t n) = 0; /** * Create BreakIterator for word-breaks using the given locale. * Returns an instance of a BreakIterator implementing word breaks. * WordBreak is useful for word selection (ex. double click) * @param where the locale. * @param status the error code * @return A BreakIterator for word-breaks. The UErrorCode& status * parameter is used to return status information to the user. * To check whether the construction succeeded or not, you should check * the value of U_SUCCESS(err). If you wish more detailed information, you * can check for informational error results which still indicate success. * U_USING_FALLBACK_ERROR indicates that a fall back locale was used. For * example, 'de_CH' was requested, but nothing was found there, so 'de' was * used. U_USING_DEFAULT_ERROR indicates that the default locale data was * used; neither the requested locale nor any of its fall back locales * could be found. * The caller owns the returned object and is responsible for deleting it. * @draft */ static BreakIterator* createWordInstance(const Locale& where, UErrorCode& status); /** * Create BreakIterator for line-breaks using specified locale. * Returns an instance of a BreakIterator implementing line breaks. Line * breaks are logically possible line breaks, actual line breaks are * usually determined based on display width. * LineBreak is useful for word wrapping text. * @param where the locale. . * @return A BreakIterator for line-breaks. The UErrorCode& status * parameter is used to return status information to the user. * To check whether the construction succeeded or not, you should check * the value of U_SUCCESS(err). If you wish more detailed information, you * can check for informational error results which still indicate success. * U_USING_FALLBACK_ERROR indicates that a fall back locale was used. For * example, 'de_CH' was requested, but nothing was found there, so 'de' was * used. U_USING_DEFAULT_ERROR indicates that the default locale data was * used; neither the requested locale nor any of its fall back locales * could be found. * The caller owns the returned object and is responsible for deleting it. * @draft */ static BreakIterator* createLineInstance(const Locale& where, UErrorCode& status); /** * Create BreakIterator for character-breaks using specified locale * Returns an instance of a BreakIterator implementing character breaks. * Character breaks are boundaries of combining character sequences. * @param where the locale. * @return A BreakIterator for character-breaks. The UErrorCode& status * parameter is used to return status information to the user. * To check whether the construction succeeded or not, you should check * the value of U_SUCCESS(err). If you wish more detailed information, you * can check for informational error results which still indicate success. * U_USING_FALLBACK_ERROR indicates that a fall back locale was used. For * example, 'de_CH' was requested, but nothing was found there, so 'de' was * used. U_USING_DEFAULT_ERROR indicates that the default locale data was * used; neither the requested locale nor any of its fall back locales * could be found. * The caller owns the returned object and is responsible for deleting it. * @draft */ static BreakIterator* createCharacterInstance(const Locale& where, UErrorCode& status); /** * Create BreakIterator for sentence-breaks using specified locale * Returns an instance of a BreakIterator implementing sentence breaks. * @param where the locale. * @return A BreakIterator for sentence-breaks. The UErrorCode& status * parameter is used to return status information to the user. * To check whether the construction succeeded or not, you should check * the value of U_SUCCESS(err). If you wish more detailed information, you * can check for informational error results which still indicate success. * U_USING_FALLBACK_ERROR indicates that a fall back locale was used. For * example, 'de_CH' was requested, but nothing was found there, so 'de' was * used. U_USING_DEFAULT_ERROR indicates that the default locale data was * used; neither the requested locale nor any of its fall back locales * could be found. * The caller owns the returned object and is responsible for deleting it. * @draft */ static BreakIterator* createSentenceInstance(const Locale& where, UErrorCode& status); /** * Get the set of Locales for which TextBoundaries are installed * @param count the output parameter of number of elements in the locale list * @return available locales * @stable */ static const Locale* getAvailableLocales(int32_t& count); /** * Get name of the object for the desired Locale, in the desired langauge. * @param objectLocale must be from getAvailableLocales. * @param displayLocale specifies the desired locale for output. * @param name the fill-in parameter of the return value * Uses best match. * @return user-displayable name * @stable */ static UnicodeString& getDisplayName(const Locale& objectLocale, const Locale& displayLocale, UnicodeString& name); /** * Get name of the object for the desired Locale, in the langauge of the * default locale. * @param objectLocale must be from getMatchingLocales * @param name the fill-in parameter of the return value * @return user-displayable name * @stable */ static UnicodeString& getDisplayName(const Locale& objectLocale, UnicodeString& name); protected: BreakIterator(); private: /** * The copy constructor and assignment operator have no real implementation. * They are provided to make the compiler happy. Do not call. */ BreakIterator& operator=(const BreakIterator&) { return *this; } BreakIterator (const BreakIterator&) {} }; #endif // _BRKITER //eof