* 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 identifies the boundaries of * "Extended Grapheme Clusters", which are groupings of codepoints * that should be treated as character-like units for many text operations. * Please see Unicode Standard Annex #29, Unicode Text Segmentation, * http://www.unicode.org/reports/tr29/ for additional information * on grapheme clusters and guidelines on their use. *
* Title boundary analysis locates all positions, * typically starts of words, that should be set to Title Case * when title casing the text. *
* 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 plain C API defined in this header file, an * object oriented C++ API with equivalent functionality is defined in the * file brkiter.h. *
* Code snippets illustrating the use of the Break Iterator APIs * are available in the ICU User Guide, * http://icu-project.org/userguide/boundaryAnalysis.html * and in the sample program icu/source/samples/break/break.cpp */ /** The possible types of text boundaries. @stable ICU 2.0 */ typedef enum UBreakIteratorType { /** Character breaks @stable ICU 2.0 */ UBRK_CHARACTER = 0, /** Word breaks @stable ICU 2.0 */ UBRK_WORD = 1, /** Line breaks @stable ICU 2.0 */ UBRK_LINE = 2, /** Sentence breaks @stable ICU 2.0 */ UBRK_SENTENCE = 3, #ifndef U_HIDE_DEPRECATED_API /** * Title Case breaks * The iterator created using this type locates title boundaries as described for * Unicode 3.2 only. For Unicode 4.0 and above title boundary iteration, * please use Word Boundary iterator. * * @deprecated ICU 2.8 Use the word break iterator for titlecasing for Unicode 4 and later. */ UBRK_TITLE = 4, #endif /* U_HIDE_DEPRECATED_API */ UBRK_COUNT = 5 } UBreakIteratorType; /** Value indicating all text boundaries have been returned. * @stable ICU 2.0 */ #define UBRK_DONE ((int32_t) -1) /** * Enum constants for the word break tags returned by * getRuleStatus(). A range of values is defined for each category of * word, to allow for further subdivisions of a category in future releases. * Applications should check for tag values falling within the range, rather * than for single individual values. * @stable ICU 2.2 */ typedef enum UWordBreak { /** Tag value for "words" that do not fit into any of other categories. * Includes spaces and most punctuation. */ UBRK_WORD_NONE = 0, /** Upper bound for tags for uncategorized words. */ UBRK_WORD_NONE_LIMIT = 100, /** Tag value for words that appear to be numbers, lower limit. */ UBRK_WORD_NUMBER = 100, /** Tag value for words that appear to be numbers, upper limit. */ UBRK_WORD_NUMBER_LIMIT = 200, /** Tag value for words that contain letters, excluding * hiragana, katakana or ideographic characters, lower limit. */ UBRK_WORD_LETTER = 200, /** Tag value for words containing letters, upper limit */ UBRK_WORD_LETTER_LIMIT = 300, /** Tag value for words containing kana characters, lower limit */ UBRK_WORD_KANA = 300, /** Tag value for words containing kana characters, upper limit */ UBRK_WORD_KANA_LIMIT = 400, /** Tag value for words containing ideographic characters, lower limit */ UBRK_WORD_IDEO = 400, /** Tag value for words containing ideographic characters, upper limit */ UBRK_WORD_IDEO_LIMIT = 500 } UWordBreak; /** * Enum constants for the line break tags returned by getRuleStatus(). * A range of values is defined for each category of * word, to allow for further subdivisions of a category in future releases. * Applications should check for tag values falling within the range, rather * than for single individual values. * @stable ICU 2.8 */ typedef enum ULineBreakTag { /** Tag value for soft line breaks, positions at which a line break * is acceptable but not required */ UBRK_LINE_SOFT = 0, /** Upper bound for soft line breaks. */ UBRK_LINE_SOFT_LIMIT = 100, /** Tag value for a hard, or mandatory line break */ UBRK_LINE_HARD = 100, /** Upper bound for hard line breaks. */ UBRK_LINE_HARD_LIMIT = 200 } ULineBreakTag; /** * Enum constants for the sentence break tags returned by getRuleStatus(). * A range of values is defined for each category of * sentence, to allow for further subdivisions of a category in future releases. * Applications should check for tag values falling within the range, rather * than for single individual values. * @stable ICU 2.8 */ typedef enum USentenceBreakTag { /** Tag value for for sentences ending with a sentence terminator * ('.', '?', '!', etc.) character, possibly followed by a * hard separator (CR, LF, PS, etc.) */ UBRK_SENTENCE_TERM = 0, /** Upper bound for tags for sentences ended by sentence terminators. */ UBRK_SENTENCE_TERM_LIMIT = 100, /** Tag value for for sentences that do not contain an ending * sentence terminator ('.', '?', '!', etc.) character, but * are ended only by a hard separator (CR, LF, PS, etc.) or end of input. */ UBRK_SENTENCE_SEP = 100, /** Upper bound for tags for sentences ended by a separator. */ UBRK_SENTENCE_SEP_LIMIT = 200 /** Tag value for a hard, or mandatory line break */ } USentenceBreakTag; /** * Open a new UBreakIterator for locating text boundaries for a specified locale. * A UBreakIterator may be used for detecting character, line, word, * and sentence breaks in text. * @param type The type of UBreakIterator to open: one of UBRK_CHARACTER, UBRK_WORD, * UBRK_LINE, UBRK_SENTENCE * @param locale The locale specifying the text-breaking conventions. * @param text The text to be iterated over. * @param textLength The number of characters in text, or -1 if null-terminated. * @param status A UErrorCode to receive any errors. * @return A UBreakIterator for the specified locale. * @see ubrk_openRules * @stable ICU 2.0 */ U_STABLE UBreakIterator* U_EXPORT2 ubrk_open(UBreakIteratorType type, const char *locale, const UChar *text, int32_t textLength, UErrorCode *status); /** * Open a new UBreakIterator for locating text boundaries using specified breaking rules. * The rule syntax is ... (TBD) * @param rules A set of rules specifying the text breaking conventions. * @param rulesLength The number of characters in rules, or -1 if null-terminated. * @param text The text to be iterated over. May be null, in which case ubrk_setText() is * used to specify the text to be iterated. * @param textLength The number of characters in text, or -1 if null-terminated. * @param parseErr Receives position and context information for any syntax errors * detected while parsing the rules. * @param status A UErrorCode to receive any errors. * @return A UBreakIterator for the specified rules. * @see ubrk_open * @stable ICU 2.2 */ U_STABLE UBreakIterator* U_EXPORT2 ubrk_openRules(const UChar *rules, int32_t rulesLength, const UChar *text, int32_t textLength, UParseError *parseErr, UErrorCode *status); /** * Thread safe cloning operation * @param bi iterator to be cloned * @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. * Clients can use the U_BRK_SAFECLONE_BUFFERSIZE. This will probably be enough to avoid memory allocations. * @param pBufferSize pointer to size of allocated space. * If *pBufferSize == 0, a sufficient size for use in cloning will * be returned ('pre-flighting') * If *pBufferSize 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 * @stable ICU 2.0 */ U_STABLE UBreakIterator * U_EXPORT2 ubrk_safeClone( const UBreakIterator *bi, void *stackBuffer, int32_t *pBufferSize, UErrorCode *status); /** * A recommended size (in bytes) for the memory buffer to be passed to ubrk_saveClone(). * @stable ICU 2.0 */ #define U_BRK_SAFECLONE_BUFFERSIZE 512 /** * Close a UBreakIterator. * Once closed, a UBreakIterator may no longer be used. * @param bi The break iterator to close. * @stable ICU 2.0 */ U_STABLE void U_EXPORT2 ubrk_close(UBreakIterator *bi); #if U_SHOW_CPLUSPLUS_API U_NAMESPACE_BEGIN /** * \class LocalUBreakIteratorPointer * "Smart pointer" class, closes a UBreakIterator via ubrk_close(). * For most methods see the LocalPointerBase base class. * * @see LocalPointerBase * @see LocalPointer * @stable ICU 4.4 */ U_DEFINE_LOCAL_OPEN_POINTER(LocalUBreakIteratorPointer, UBreakIterator, ubrk_close); U_NAMESPACE_END #endif /** * Sets an existing iterator to point to a new piece of text * @param bi The iterator to use * @param text The text to be set * @param textLength The length of the text * @param status The error code * @stable ICU 2.0 */ U_STABLE void U_EXPORT2 ubrk_setText(UBreakIterator* bi, const UChar* text, int32_t textLength, UErrorCode* status); /** * Sets an existing iterator to point to a new piece of text * @param bi The iterator to use * @param text The text to be set. * 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. * @param status The error code * @stable ICU 3.4 */ U_STABLE void U_EXPORT2 ubrk_setUText(UBreakIterator* bi, UText* text, UErrorCode* status); /** * Determine the most recently-returned text boundary. * * @param bi The break iterator to use. * @return The character index most recently returned by \ref ubrk_next, \ref ubrk_previous, * \ref ubrk_first, or \ref ubrk_last. * @stable ICU 2.0 */ U_STABLE int32_t U_EXPORT2 ubrk_current(const UBreakIterator *bi); /** * Determine the text boundary following the current text boundary. * * @param bi The break iterator to use. * @return The character index of the next text boundary, or UBRK_DONE * if all text boundaries have been returned. * @see ubrk_previous * @stable ICU 2.0 */ U_STABLE int32_t U_EXPORT2 ubrk_next(UBreakIterator *bi); /** * Determine the text boundary preceding the current text boundary. * * @param bi The break iterator to use. * @return The character index of the preceding text boundary, or UBRK_DONE * if all text boundaries have been returned. * @see ubrk_next * @stable ICU 2.0 */ U_STABLE int32_t U_EXPORT2 ubrk_previous(UBreakIterator *bi); /** * Determine the index of the first character in the text being scanned. * This is not always the same as index 0 of the text. * @param bi The break iterator to use. * @return The character index of the first character in the text being scanned. * @see ubrk_last * @stable ICU 2.0 */ U_STABLE int32_t U_EXPORT2 ubrk_first(UBreakIterator *bi); /** * Determine the index immediately beyond the last character in the text being * scanned. * This is not the same as the last character. * @param bi The break iterator to use. * @return The character offset immediately beyond the last character in the * text being scanned. * @see ubrk_first * @stable ICU 2.0 */ U_STABLE int32_t U_EXPORT2 ubrk_last(UBreakIterator *bi); /** * Determine the text boundary preceding the specified offset. * The value returned is always smaller than offset, or UBRK_DONE. * @param bi The break iterator to use. * @param offset The offset to begin scanning. * @return The text boundary preceding offset, or UBRK_DONE. * @see ubrk_following * @stable ICU 2.0 */ U_STABLE int32_t U_EXPORT2 ubrk_preceding(UBreakIterator *bi, int32_t offset); /** * Determine the text boundary following the specified offset. * The value returned is always greater than offset, or UBRK_DONE. * @param bi The break iterator to use. * @param offset The offset to begin scanning. * @return The text boundary following offset, or UBRK_DONE. * @see ubrk_preceding * @stable ICU 2.0 */ U_STABLE int32_t U_EXPORT2 ubrk_following(UBreakIterator *bi, int32_t offset); /** * Get a locale for which text breaking information is available. * A UBreakIterator in a locale returned by this function will perform the correct * text breaking for the locale. * @param index The index of the desired locale. * @return A locale for which number text breaking information is available, or 0 if none. * @see ubrk_countAvailable * @stable ICU 2.0 */ U_STABLE const char* U_EXPORT2 ubrk_getAvailable(int32_t index); /** * Determine how many locales have text breaking information available. * This function is most useful as determining the loop ending condition for * calls to \ref ubrk_getAvailable. * @return The number of locales for which text breaking information is available. * @see ubrk_getAvailable * @stable ICU 2.0 */ U_STABLE int32_t U_EXPORT2 ubrk_countAvailable(void); /** * Returns true if the specfied position is a boundary position. As a side * effect, leaves the iterator pointing to the first boundary position at * or after "offset". * @param bi The break iterator to use. * @param offset the offset to check. * @return True if "offset" is a boundary position. * @stable ICU 2.0 */ U_STABLE UBool U_EXPORT2 ubrk_isBoundary(UBreakIterator *bi, int32_t offset); /** * Return the status from the break rule that determined the most recently * returned break position. The values appear in the rule source * within brackets, {123}, for example. For rules that do not specify a * status, a default value of 0 is returned. *
* For word break iterators, the possible values are defined in enum UWordBreak. * @stable ICU 2.2 */ U_STABLE int32_t U_EXPORT2 ubrk_getRuleStatus(UBreakIterator *bi); /** * Get the statuses from the break rules that determined the most recently * returned break position. The values appear in the rule source * within brackets, {123}, for example. The default status value for rules * that do not explicitly provide one is zero. *
* For word break iterators, the possible values are defined in enum UWordBreak. * @param bi The break iterator to use * @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 attemtping to store any values. * @param status receives error codes. * @return The number of rule status values from rules that determined * the most recent boundary returned by the break iterator. * @stable ICU 3.0 */ U_STABLE int32_t U_EXPORT2 ubrk_getRuleStatusVec(UBreakIterator *bi, int32_t *fillInVec, int32_t capacity, UErrorCode *status); /** * Return the locale of the break iterator. You can choose between the valid and * the actual locale. * @param bi break iterator * @param type locale type (valid or actual) * @param status error code * @return locale string * @stable ICU 2.8 */ U_STABLE const char* U_EXPORT2 ubrk_getLocaleByType(const UBreakIterator *bi, ULocDataLocaleType type, UErrorCode* status); #endif /* #if !UCONFIG_NO_BREAK_ITERATION */ #endif