* 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. *
* The text boundary positions are found according to the rules * described in Unicode Standard Annex #29, Text Boundaries, and * Unicode Standard Annex #14, Line Breaking Properties. These * are available at http://www.unicode.org/reports/tr14/ and * http://www.unicode.org/reports/tr29/. *
* In addition to the C++ API defined in this header file, a * plain C API with equivalent functionality is defined in the * file ubrk.h *
* Code snippets illustrating the use of the Break Iterator APIs * are available in the ICU User Guide, * https://unicode-org.github.io/icu/userguide/boundaryanalysis/ * and in the sample program icu/source/samples/break/break.cpp * */ class U_COMMON_API BreakIterator : public UObject { public: /** * destructor * @stable ICU 2.0 */ 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 ICU 2.0 */ virtual bool operator==(const BreakIterator&) const = 0; /** * Returns the complement of the result of operator== * @param rhs The BreakIterator to be compared for inequality * @return the complement of the result of operator== * @stable ICU 2.0 */ bool operator!=(const BreakIterator& rhs) const { return !operator==(rhs); } /** * Return a polymorphic copy of this object. This is an abstract * method which subclasses implement. * @stable ICU 2.0 */ virtual BreakIterator* clone() const = 0; /** * Return a polymorphic class ID for this object. Different subclasses * will return distinct unequal values. * @stable ICU 2.0 */ virtual UClassID getDynamicClassID(void) const override = 0; /** * Return a CharacterIterator over the text being analyzed. * @stable ICU 2.0 */ virtual CharacterIterator& getText(void) const = 0; /** * Get a UText for the text being analyzed. * The returned UText is a shallow clone of the UText used internally * by the break iterator implementation. It can safely be used to * access the text without impacting any break iterator operations, * but the underlying text itself must not be altered. * * @param fillIn A UText to be filled in. If NULL, a new UText will be * allocated to hold the result. * @param status receives any error codes. * @return The current UText for this break iterator. If an input * UText was provided, it will always be returned. * @stable ICU 3.4 */ virtual UText *getUText(UText *fillIn, UErrorCode &status) const = 0; /** * Change the text over which this operates. The text boundary is * reset to the start. * * The BreakIterator will retain a reference to the supplied string. * The caller must not modify or delete the text while the BreakIterator * retains the reference. * * @param text The UnicodeString used to change the text. * @stable ICU 2.0 */ virtual void setText(const UnicodeString &text) = 0; /** * Reset the break iterator to operate over the text represented by * the UText. The iterator position is reset to the start. * * This function makes a shallow clone of the supplied UText. This means * that the caller is free to immediately close or otherwise reuse the * Utext that was passed as a parameter, but that the underlying text itself * must not be altered while being referenced by the break iterator. * * All index positions returned by break iterator functions are * native indices from the UText. For example, when breaking UTF-8 * encoded text, the break positions returned by next(), previous(), etc. * will be UTF-8 string indices, not UTF-16 positions. * * @param text The UText used to change the text. * @param status receives any error codes. * @stable ICU 3.4 */ virtual void setText(UText *text, UErrorCode &status) = 0; /** * Change the text over which this operates. The text boundary is * reset to the start. * Note that setText(UText *) provides similar functionality to this function, * and is more efficient. * @param it The CharacterIterator used to change the text. * @stable ICU 2.0 */ virtual void adoptText(CharacterIterator* it) = 0; enum { /** * DONE is returned by previous() and next() after all valid * boundaries have been returned. * @stable ICU 2.0 */ DONE = (int32_t)-1 }; /** * Sets the current iteration position to the beginning of the text, position zero. * @return The offset of the beginning of the text, zero. * @stable ICU 2.0 */ virtual int32_t first(void) = 0; /** * Set the iterator position to the index immediately BEYOND the last character in the text being scanned. * @return The index immediately BEYOND the last character in the text being scanned. * @stable ICU 2.0 */ virtual int32_t last(void) = 0; /** * Set the iterator position to the boundary preceding the current boundary. * @return The character index of the previous text boundary or DONE if all * boundaries have been returned. * @stable ICU 2.0 */ virtual int32_t previous(void) = 0; /** * Advance the iterator to the boundary following the current boundary. * @return The character index of the next text boundary or DONE if all * boundaries have been returned. * @stable ICU 2.0 */ virtual int32_t next(void) = 0; /** * Return character index of the current iterator position within the text. * @return The boundary most recently returned. * @stable ICU 2.0 */ virtual int32_t current(void) const = 0; /** * Advance the iterator to 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 ICU 2.0 */ virtual int32_t following(int32_t offset) = 0; /** * Set the iterator position to 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 ICU 2.0 */ virtual int32_t preceding(int32_t offset) = 0; /** * Return true if the specified position is a boundary position. * As a side effect, the current position of the iterator is set * to the first boundary position at or following the specified offset. * @param offset the offset to check. * @return True if "offset" is a boundary position. * @stable ICU 2.0 */ virtual UBool isBoundary(int32_t offset) = 0; /** * Set the iterator position to the nth boundary from the current boundary * @param n the number of boundaries to move by. A value of 0 * does nothing. Negative values move to previous boundaries * and positive values move to later boundaries. * @return The new iterator position, or * DONE if there are fewer than |n| boundaries in the specified direction. * @stable ICU 2.0 */ virtual int32_t next(int32_t n) = 0; /** * For RuleBasedBreakIterators, return the status tag from the break rule * that determined the boundary at the current iteration position. *
* For break iterator types that do not support a rule status, * a default value of 0 is returned. *
* @return the status from the break rule that determined the boundary at * the current iteration position. * @see RuleBaseBreakIterator::getRuleStatus() * @see UWordBreak * @stable ICU 52 */ virtual int32_t getRuleStatus() const; /** * For RuleBasedBreakIterators, get the status (tag) values from the break rule(s) * that determined the boundary at the current iteration position. *
* For break iterator types that do not support rule status, * no values are returned. *
* The returned status value(s) are stored into an array provided by the caller. * The values are stored in sorted (ascending) order. * If the capacity of the output array is insufficient to hold the data, * the output will be truncated to the available length, and a * U_BUFFER_OVERFLOW_ERROR will be signaled. *
* @see RuleBaseBreakIterator::getRuleStatusVec * * @param fillInVec an array to be filled in with the status values. * @param capacity the length of the supplied vector. A length of zero causes * the function to return the number of status values, in the * normal way, without attempting to store any values. * @param status receives error codes. * @return The number of rule status values from rules that determined * the boundary at the current iteration position. * In the event of a U_BUFFER_OVERFLOW_ERROR, the return value * is the total number of status values that were available, * not the reduced number that were actually returned. * @see getRuleStatus * @stable ICU 52 */ virtual int32_t getRuleStatusVec(int32_t *fillInVec, int32_t capacity, UErrorCode &status); /** * 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_WARNING 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_WARNING 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. * @stable ICU 2.0 */ static BreakIterator* U_EXPORT2 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. * @param status The error code. * @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_WARNING 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_WARNING 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. * @stable ICU 2.0 */ static BreakIterator* U_EXPORT2 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. * @param status The error code. * @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_WARNING 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_WARNING 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. * @stable ICU 2.0 */ static BreakIterator* U_EXPORT2 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. * @param status The error code. * @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_WARNING 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_WARNING 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. * @stable ICU 2.0 */ static BreakIterator* U_EXPORT2 createSentenceInstance(const Locale& where, UErrorCode& status); #ifndef U_HIDE_DEPRECATED_API /** * Create BreakIterator for title-casing breaks using the specified locale * Returns an instance of a BreakIterator implementing title breaks. * The iterator returned locates title boundaries as described for * Unicode 3.2 only. For Unicode 4.0 and above title boundary iteration, * please use a word boundary iterator. See {@link #createWordInstance }. * * @param where the locale. * @param status The error code. * @return A BreakIterator for title-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_WARNING 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_WARNING 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. * @deprecated ICU 64 Use createWordInstance instead. */ static BreakIterator* U_EXPORT2 createTitleInstance(const Locale& where, UErrorCode& status); #endif /* U_HIDE_DEPRECATED_API */ /** * Get the set of Locales for which TextBoundaries are installed. *
Note: this will not return locales added through the register * call. To see the registered locales too, use the getAvailableLocales * function that returns a StringEnumeration object
* @param count the output parameter of number of elements in the locale list * @return available locales * @stable ICU 2.0 */ static const Locale* U_EXPORT2 getAvailableLocales(int32_t& count); /** * Get name of the object for the desired Locale, in the desired language. * @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 ICU 2.0 */ static UnicodeString& U_EXPORT2 getDisplayName(const Locale& objectLocale, const Locale& displayLocale, UnicodeString& name); /** * Get name of the object for the desired Locale, in the language 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 ICU 2.0 */ static UnicodeString& U_EXPORT2 getDisplayName(const Locale& objectLocale, UnicodeString& name); #ifndef U_FORCE_HIDE_DEPRECATED_API /** * Deprecated functionality. Use clone() instead. * * Thread safe client-buffer-based cloning operation * Do NOT call delete on a safeclone, since 'new' is not used to create it. * @param stackBuffer user allocated space for the new clone. If NULL new memory will be allocated. * If buffer is not large enough, new memory will be allocated. * @param BufferSize reference to size of allocated space. * If BufferSize == 0, a sufficient size for use in cloning will * be returned ('pre-flighting') * If BufferSize is not enough for a stack-based safe clone, * new memory will be allocated. * @param status to indicate whether the operation went on smoothly or there were errors * An informational status value, U_SAFECLONE_ALLOCATED_ERROR, is used if any allocations were * necessary. * @return pointer to the new clone * * @deprecated ICU 52. Use clone() instead. */ virtual BreakIterator * createBufferClone(void *stackBuffer, int32_t &BufferSize, UErrorCode &status) = 0; #endif // U_FORCE_HIDE_DEPRECATED_API #ifndef U_HIDE_DEPRECATED_API /** * Determine whether the BreakIterator was created in user memory by * createBufferClone(), and thus should not be deleted. Such objects * must be closed by an explicit call to the destructor (not delete). * @deprecated ICU 52. Always delete the BreakIterator. */ inline UBool isBufferClone(void); #endif /* U_HIDE_DEPRECATED_API */ #if !UCONFIG_NO_SERVICE /** * Register a new break iterator of the indicated kind, to use in the given locale. * The break iterator will be adopted. Clones of the iterator will be returned * if a request for a break iterator of the given kind matches or falls back to * this locale. * Because ICU may choose to cache BreakIterators internally, this must * be called at application startup, prior to any calls to * BreakIterator::createXXXInstance to avoid undefined behavior. * @param toAdopt the BreakIterator instance to be adopted * @param locale the Locale for which this instance is to be registered * @param kind the type of iterator for which this instance is to be registered * @param status the in/out status code, no special meanings are assigned * @return a registry key that can be used to unregister this instance * @stable ICU 2.4 */ static URegistryKey U_EXPORT2 registerInstance(BreakIterator* toAdopt, const Locale& locale, UBreakIteratorType kind, UErrorCode& status); /** * Unregister a previously-registered BreakIterator using the key returned from the * register call. Key becomes invalid after a successful call and should not be used again. * The BreakIterator corresponding to the key will be deleted. * Because ICU may choose to cache BreakIterators internally, this should * be called during application shutdown, after all calls to * BreakIterator::createXXXInstance to avoid undefined behavior. * @param key the registry key returned by a previous call to registerInstance * @param status the in/out status code, no special meanings are assigned * @return true if the iterator for the key was successfully unregistered * @stable ICU 2.4 */ static UBool U_EXPORT2 unregister(URegistryKey key, UErrorCode& status); /** * Return a StringEnumeration over the locales available at the time of the call, * including registered locales. * @return a StringEnumeration over the locales available at the time of the call * @stable ICU 2.4 */ static StringEnumeration* U_EXPORT2 getAvailableLocales(void); #endif /** * Returns the locale for this break iterator. Two flavors are available: valid and * actual locale. * @stable ICU 2.8 */ Locale getLocale(ULocDataLocaleType type, UErrorCode& status) const; #ifndef U_HIDE_INTERNAL_API /** Get the locale for this break iterator object. You can choose between valid and actual locale. * @param type type of the locale we're looking for (valid or actual) * @param status error code for the operation * @return the locale * @internal */ const char *getLocaleID(ULocDataLocaleType type, UErrorCode& status) const; #endif /* U_HIDE_INTERNAL_API */ /** * Set the subject text string upon which the break iterator is operating * without changing any other aspect of the matching state. * The new and previous text strings must have the same content. * * This function is intended for use in environments where ICU is operating on * strings that may move around in memory. It provides a mechanism for notifying * ICU that the string has been relocated, and providing a new UText to access the * string in its new position. * * Note that the break iterator implementation never copies the underlying text * of a string being processed, but always operates directly on the original text * provided by the user. Refreshing simply drops the references to the old text * and replaces them with references to the new. * * Caution: this function is normally used only by very specialized, * system-level code. One example use case is with garbage collection that moves * the text in memory. * * @param input The new (moved) text string. * @param status Receives errors detected by this function. * @return *this * * @stable ICU 49 */ virtual BreakIterator &refreshInputText(UText *input, UErrorCode &status) = 0; private: static BreakIterator* buildInstance(const Locale& loc, const char *type, UErrorCode& status); static BreakIterator* createInstance(const Locale& loc, int32_t kind, UErrorCode& status); static BreakIterator* makeInstance(const Locale& loc, int32_t kind, UErrorCode& status); friend class ICUBreakIteratorFactory; friend class ICUBreakIteratorService; protected: // Do not enclose protected default/copy constructors with #ifndef U_HIDE_INTERNAL_API // or else the compiler will create a public ones. /** @internal */ BreakIterator(); /** @internal */ BreakIterator (const BreakIterator &other); #ifndef U_HIDE_INTERNAL_API /** @internal */ BreakIterator (const Locale& valid, const Locale &actual); /** @internal. Assignment Operator, used by RuleBasedBreakIterator. */ BreakIterator &operator = (const BreakIterator &other); #endif /* U_HIDE_INTERNAL_API */ private: /** @internal (private) */ char actualLocale[ULOC_FULLNAME_CAPACITY]; char validLocale[ULOC_FULLNAME_CAPACITY]; }; #ifndef U_HIDE_DEPRECATED_API inline UBool BreakIterator::isBufferClone() { return false; } #endif /* U_HIDE_DEPRECATED_API */ U_NAMESPACE_END #endif /* #if !UCONFIG_NO_BREAK_ITERATION */ #endif /* U_SHOW_CPLUSPLUS_API */ #endif // BRKITER_H //eof