* 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() const override = 0;
/**
* Return a CharacterIterator over the text being analyzed.
* @stable ICU 2.0
*/
virtual CharacterIterator& getText() 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 nullptr, 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 = static_cast
* 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