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 character iterator through which this BreakIterator accesses the text + * @internal + */ + CharacterIterator* fText; + + /** + * 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. Normal RBBI iterators don't use it, although the code + * for updating it is live. Dictionary Based break iterators (a subclass + * of us) access this field directly. + * @internal + */ + uint32_t fDictionaryCharCount; + + /** + * Debugging flag. Trace operation of state machine when true. + * @internal + */ + static UBool fTrace; + + +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); + + /** @internal */ + 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. This version + * of this method returns the actual CharacterIterator we're using internally. + * Changing the state of this iterator can have undefined consequences. If + * you need to change it, clone it first. + * @return An iterator over the text being analyzed. + * @stable ICU 2.0 + */ + virtual const 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. + * (i.e., the CharacterIterator's starting offset). + * @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. + * (i.e., the CharacterIterator's ending offset). + * @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 + * @draft 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 + //======================================================================= + /** + * 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. + * @internal + */ + virtual int32_t handleNext(void); + + /** + * 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.) + * @internal + */ + virtual int32_t handlePrevious(void); + + /** + * Dumps caches and performs other actions associated with a complete change + * in text or iteration position. This function is a no-op in RuleBasedBreakIterator, + * but subclasses can and do override it. + * @internal + */ + virtual void reset(void); + + /** + * 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); + + /** + * 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); + + /** + * @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