Instances of this class are most commonly created by the factory methods of * BreakIterator::createWordInstance(), BreakIterator::createLineInstance(), etc., * and then used via the abstract API in class BreakIterator
* *See the ICU User Guide for information on Break Iterator Rules.
* *This class is not intended to be subclassed. (Class DictionaryBasedBreakIterator * is a subclass, but that relationship is effectively internal to the ICU * implementation. The subclassing interface to RulesBasedBreakIterator is * not part of the ICU API, and may not remain stable.
* */ class U_COMMON_API RuleBasedBreakIterator : public BreakIterator { protected: /** * The UText through which this BreakIterator accesses the text * @internal */ UText *fText; /** * A character iterator that refers to the same text as the UText, above. * Only included for compatibility with old API, which was based on CharacterIterators. * Value may be adopted from outside, or one of fSCharIter or fDCharIter, below. */ CharacterIterator *fCharIter; /** * When the input text is provided by a UnicodeString, this will point to * a characterIterator that wraps that data. Needed only for the * implementation of getText(), a backwards compatibility issue. */ StringCharacterIterator *fSCharIter; /** * When the input text is provided by a UText, this * dummy CharacterIterator over an empty string will * be returned from getText() */ UCharCharacterIterator *fDCharIter; /** * The rule data for this BreakIterator instance * @internal */ RBBIDataWrapper *fData; /** Index of the Rule {tag} values for the most recent match. * @internal */ int32_t fLastRuleStatusIndex; /** * Rule tag value valid flag. * Some iterator operations don't intrinsically set the correct tag value. * This flag lets us lazily compute the value if we are ever asked for it. * @internal */ UBool fLastStatusIndexValid; /** * Counter for the number of characters encountered with the "dictionary" * flag set. * @internal */ uint32_t fDictionaryCharCount; /** * When a range of characters is divided up using the dictionary, the break * positions that are discovered are stored here, preventing us from having * to use either the dictionary or the state table again until the iterator * leaves this range of text. Has the most impact for line breaking. * @internal */ int32_t* fCachedBreakPositions; /** * The number of elements in fCachedBreakPositions * @internal */ int32_t fNumCachedBreakPositions; /** * if fCachedBreakPositions is not null, this indicates which item in the * cache the current iteration position refers to * @internal */ int32_t fPositionInCache; /** * * If present, UStack of LanguageBreakEngine objects that might handle * dictionary characters. Searched from top to bottom to find an object to * handle a given character. * @internal */ UStack *fLanguageBreakEngines; /** * * If present, the special LanguageBreakEngine used for handling * characters that are in the dictionary set, but not handled by any * LangugageBreakEngine. * @internal */ UnhandledEngine *fUnhandledBreakEngine; /** * * The type of the break iterator, or -1 if it has not been set. * @internal */ int32_t fBreakType; protected: //======================================================================= // constructors //======================================================================= /** * Constructor from a flattened set of RBBI data in malloced memory. * RulesBasedBreakIterators built from a custom set of rules * are created via this constructor; the rules are compiled * into memory, then the break iterator is constructed here. * * The break iterator adopts the memory, and will * free it when done. * @internal */ RuleBasedBreakIterator(RBBIDataHeader* data, UErrorCode &status); friend class RBBIRuleBuilder; /** @internal */ friend class BreakIterator; public: /** Default constructor. Creates an empty shell of an iterator, with no * rules or text to iterate over. Object can subsequently be assigned to. * @stable ICU 2.2 */ RuleBasedBreakIterator(); /** * Copy constructor. Will produce a break iterator with the same behavior, * and which iterates over the same text, as the one passed in. * @param that The RuleBasedBreakIterator passed to be copied * @stable ICU 2.0 */ RuleBasedBreakIterator(const RuleBasedBreakIterator& that); /** * Construct a RuleBasedBreakIterator from a set of rules supplied as a string. * @param rules The break rules to be used. * @param parseError In the event of a syntax error in the rules, provides the location * within the rules of the problem. * @param status Information on any errors encountered. * @stable ICU 2.2 */ RuleBasedBreakIterator( const UnicodeString &rules, UParseError &parseError, UErrorCode &status); /** * This constructor uses the udata interface to create a BreakIterator * whose internal tables live in a memory-mapped file. "image" is an * ICU UDataMemory handle for the pre-compiled break iterator tables. * @param image handle to the memory image for the break iterator data. * Ownership of the UDataMemory handle passes to the Break Iterator, * which will be responsible for closing it when it is no longer needed. * @param status Information on any errors encountered. * @see udata_open * @see #getBinaryRules * @stable ICU 2.8 */ RuleBasedBreakIterator(UDataMemory* image, UErrorCode &status); /** * Destructor * @stable ICU 2.0 */ virtual ~RuleBasedBreakIterator(); /** * Assignment operator. Sets this iterator to have the same behavior, * and iterate over the same text, as the one passed in. * @param that The RuleBasedBreakItertor passed in * @return the newly created RuleBasedBreakIterator * @stable ICU 2.0 */ RuleBasedBreakIterator& operator=(const RuleBasedBreakIterator& that); /** * Equality operator. Returns TRUE if both BreakIterators are of the * same class, have the same behavior, and iterate over the same text. * @param that The BreakIterator to be compared for equality * @return TRUE if both BreakIterators are of the * same class, have the same behavior, and iterate over the same text. * @stable ICU 2.0 */ virtual UBool operator==(const BreakIterator& that) const; /** * Not-equal operator. If operator== returns TRUE, this returns FALSE, * and vice versa. * @param that The BreakIterator to be compared for inequality * @return TRUE if both BreakIterators are not same. * @stable ICU 2.0 */ UBool operator!=(const BreakIterator& that) const; /** * Returns a newly-constructed RuleBasedBreakIterator with the same * behavior, and iterating over the same text, as this one. * Differs from the copy constructor in that it is polymorphic, and * will correctly clone (copy) a derived class. * clone() is thread safe. Multiple threads may simultaeneously * clone the same source break iterator. * @return a newly-constructed RuleBasedBreakIterator * @stable ICU 2.0 */ virtual BreakIterator* clone() const; /** * Compute a hash code for this BreakIterator * @return A hash code * @stable ICU 2.0 */ virtual int32_t hashCode(void) const; /** * Returns the description used to create this iterator * @return the description used to create this iterator * @stable ICU 2.0 */ virtual const UnicodeString& getRules(void) const; //======================================================================= // BreakIterator overrides //======================================================================= /** ** Return a CharacterIterator over the text being analyzed. * The returned character iterator is owned by the break iterator, and must * not be deleted by the caller. Repeated calls to this function may * return the same CharacterIterator. *
** The returned character iterator must not be used concurrently with * the break iterator. If concurrent operation is needed, clone the * returned character iterator first and operate on the clone. *
** When the break iterator is operating on text supplied via a UText, * this function will fail. Lacking any way to signal failures, it * returns an CharacterIterator containing no text. * The function getUText() provides similar functionality, * is reliable, and is more efficient. *
* * TODO: deprecate this function? * * @return An iterator over the text being analyzed. * @stable ICU 2.0 */ virtual CharacterIterator& getText(void) const; /** * 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. * @draft ICU 3.4 */ virtual UText *getUText(UText *fillIn, UErrorCode &status) const; /** * Set the iterator to analyze a new piece of text. This function resets * the current iteration position to the beginning of the text. * @param newText An iterator over the text to analyze. The BreakIterator * takes ownership of the character iterator. The caller MUST NOT delete it! * @stable ICU 2.0 */ virtual void adoptText(CharacterIterator* newText); /** * Set the iterator to analyze a new piece of text. This function resets * the current iteration position to the beginning of the text. * @param newText The text to analyze. * @stable ICU 2.0 */ virtual void setText(const UnicodeString& newText); /** * 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. * * @param text The UText used to change the text. * @param status Receives any error codes. * @draft ICU 3.4 */ virtual void setText(UText *text, UErrorCode &status); /** * Sets the current iteration position to the beginning of the text. * @return The offset of the beginning of the text. * @stable ICU 2.0 */ virtual int32_t first(void); /** * Sets the current iteration position to the end of the text. * @return The text's past-the-end offset. * @stable ICU 2.0 */ virtual int32_t last(void); /** * Advances the iterator either forward or backward the specified number of steps. * Negative values move backward, and positive values move forward. This is * equivalent to repeatedly calling next() or previous(). * @param n The number of steps to move. The sign indicates the direction * (negative is backwards, and positive is forwards). * @return The character offset of the boundary position n boundaries away from * the current one. * @stable ICU 2.0 */ virtual int32_t next(int32_t n); /** * Advances the iterator to the next boundary position. * @return The position of the first boundary after this one. * @stable ICU 2.0 */ virtual int32_t next(void); /** * Moves the iterator backwards, to the last boundary preceding this one. * @return The position of the last boundary position preceding this one. * @stable ICU 2.0 */ virtual int32_t previous(void); /** * Sets the iterator to refer to the first boundary position following * the specified position. * @param offset The position from which to begin searching for a break position. * @return The position of the first break after the current position. * @stable ICU 2.0 */ virtual int32_t following(int32_t offset); /** * Sets the iterator to refer to the last boundary position before the * specified position. * @param offset The position to begin searching for a break from. * @return The position of the last boundary before the starting position. * @stable ICU 2.0 */ virtual int32_t preceding(int32_t offset); /** * 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 offset the offset to check. * @return True if "offset" is a boundary position. * @stable ICU 2.0 */ virtual UBool isBoundary(int32_t offset); /** * Returns the current iteration position. * @return The current iteration position. * @stable ICU 2.0 */ virtual int32_t current(void) const; /** * Return the status tag from the break rule that determined the most recently * returned break position. For break rules that do not specify a * status, a default value of 0 is returned. If more than one break rule * would cause a boundary to be located at some position in the text, * the numerically largest of the applicable status values is returned. ** Of the standard types of ICU break iterators, only word break and * line break provide status values. The values are defined in * the header file ubrk.h. For Word breaks, the status allows distinguishing between words * that contain alphabetic letters, "words" that appear to be numbers, * punctuation and spaces, words containing ideographic characters, and * more. For Line Break, the status distinguishes between hard (mandatory) breaks * and soft (potential) break positions. *
* getRuleStatus() can be called after obtaining a boundary
* position from next(), previous(), or
* any other break iterator functions that returns a boundary position.
*
* When creating custom break rules, one is free to define whatever * status values may be convenient for the application. *
* Note: this function is not thread safe. It should not have been * declared const, and the const remains only for compatibility * reasons. (The function is logically const, but not bit-wise const). *
* @return the status from the break rule that determined the most recently * returned break position. * * @see UWordBreak * @stable ICU 2.2 */ virtual int32_t getRuleStatus() const; /** * Get the status (tag) values from the break rule(s) that determined the most * recently returned break position. *
* 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. * * @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. * 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 3.0 */ virtual int32_t getRuleStatusVec(int32_t *fillInVec, int32_t capacity, UErrorCode &status); /** * Returns a unique class ID POLYMORPHICALLY. Pure virtual override. * This method is to implement a simple version of RTTI, since not all * C++ compilers support genuine RTTI. Polymorphic operator==() and * clone() methods call this method. * * @return The class ID for this object. All objects of a * given class have the same class ID. Objects of * other classes have different class IDs. * @stable ICU 2.0 */ virtual UClassID getDynamicClassID(void) const; /** * Returns the class ID for this class. This is useful only for * comparing to a return value from getDynamicClassID(). For example: * * Base* polymorphic_pointer = createPolymorphicObject(); * if (polymorphic_pointer->getDynamicClassID() == * Derived::getStaticClassID()) ... * * @return The class ID for all objects of this class. * @stable ICU 2.0 */ static UClassID U_EXPORT2 getStaticClassID(void); /* * Create a clone (copy) of this break iterator in memory provided * by the caller. The idea is to increase performance by avoiding * a storage allocation. Use of this functoin is NOT RECOMMENDED. * Performance gains are minimal, and correct buffer management is * tricky. Use clone() instead. * * @param stackBuffer The pointer to the memory into which the cloned object * should be placed. If NULL, allocate heap memory * for the cloned object. * @param BufferSize The size of the buffer. If zero, return the required * buffer size, but do not clone the object. If the * size was too small (but not zero), allocate heap * storage for the cloned object. * * @param status Error status. U_SAFECLONE_ALLOCATED_WARNING will be * returned if the the provided buffer was too small, and * the clone was therefore put on the heap. * * @return Pointer to the clone object. This may differ from the stackBuffer * address if the byte alignment of the stack buffer was not suitable * or if the stackBuffer was too small to hold the clone. * @stable ICU 2.0 */ virtual BreakIterator * createBufferClone(void *stackBuffer, int32_t &BufferSize, UErrorCode &status); /** * Return the binary form of compiled break rules, * which can then be used to create a new break iterator at some * time in the future. Creating a break iterator from pre-compiled rules * is much faster than building one from the source form of the * break rules. * * The binary data can only be used with the same version of ICU * and on the same platform type (processor endian-ness) * * @param length Returns the length of the binary data. (Out paramter.) * * @return A pointer to the binary (compiled) rule data. The storage * belongs to the RulesBasedBreakIterator object, not the * caller, and must not be modified or deleted. * @internal */ virtual const uint8_t *getBinaryRules(uint32_t &length); protected: //======================================================================= // implementation //======================================================================= /** * Dumps caches and performs other actions associated with a complete change * in text or iteration position. * @internal */ virtual void reset(void); #if 0 /** * Return true if the category lookup for this char * indicates that it is in the set of dictionary lookup chars. * This function is intended for use by dictionary based break iterators. * @return true if the category lookup for this char * indicates that it is in the set of dictionary lookup chars. * @internal */ virtual UBool isDictionaryChar(UChar32); /** * Get the type of the break iterator. * @internal */ virtual int32_t getBreakType() const; #endif /** * Set the type of the break iterator. * @internal */ virtual void setBreakType(int32_t type); /** * Common initialization function, used by constructors and bufferClone. * (Also used by DictionaryBasedBreakIterator::createBufferClone().) * @internal */ void init(); private: /** * This method backs the iterator back up to a "safe position" in the text. * This is a position that we know, without any context, must be a break position. * The various calling methods then iterate forward from this safe position to * the appropriate position to return. (For more information, see the description * of buildBackwardsStateTable() in RuleBasedBreakIterator.Builder.) * @param statetable state table used of moving backwards * @internal */ int32_t handlePrevious(const RBBIStateTable *statetable); /** * This method is the actual implementation of the next() method. All iteration * vectors through here. This method initializes the state machine to state 1 * and advances through the text character by character until we reach the end * of the text or the state machine transitions to state 0. We update our return * value every time the state machine passes through a possible end state. * @param statetable state table used of moving forwards * @internal */ int32_t handleNext(const RBBIStateTable *statetable); protected: /** * This is the function that actually implements dictionary-based * breaking. Covering at least the range from startPos to endPos, * it checks for dictionary characters, and if it finds them determines * the appropriate object to deal with them. It may cache found breaks in * fCachedBreakPositions as it goes. It may well also look at text outside * the range startPos to endPos. * If going forward, endPos is the normal Unicode break result, and * if goind in reverse, startPos is the normal Unicode break result * @param startPos The start position of a range of text * @param endPos The end position of a range of text * @param reverse The call is for the reverse direction * @internal */ int32_t checkDictionary(int32_t startPos, int32_t endPos, UBool reverse); private: /** * This function returns the appropriate LanguageBreakEngine for a * given character c. * @param c A character in the dictionary set * @internal */ const LanguageBreakEngine *getLanguageBreakEngine(UChar32 c); /** * @internal */ void makeRuleStatusValid(); }; //------------------------------------------------------------------------------ // // Inline Functions Definitions ... // //------------------------------------------------------------------------------ inline UBool RuleBasedBreakIterator::operator!=(const BreakIterator& that) const { return !operator==(that); } U_NAMESPACE_END #endif /* #if !UCONFIG_NO_BREAK_ITERATION */ #endif