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; /** Rule {tag} value for the most recent match. * @internal */ int32_t fLastBreakTag; /** * 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 fLastBreakTagValid; /** * 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); 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 * @draft 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. * @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; /** * 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); /** * 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. 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. *
* Of the standard types of ICU break iterators, only the word break
* iterator provides status values. The values are defined in
*
* @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;
/**
* 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 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);
};
//------------------------------------------------------------------------------
//
// Inline Functions Definitions ...
//
//------------------------------------------------------------------------------
inline UBool RuleBasedBreakIterator::operator!=(const BreakIterator& that) const {
return !operator==(that);
}
U_NAMESPACE_END
#endif /* #if !UCONFIG_NO_BREAK_ITERATION */
#endif
enum UWordBreak, and allow distinguishing between words
* that contain alphabetic letters, "words" that appear to be numbers,
* punctuation and spaces, words containing ideographic characters, and
* more. Call getRuleStatus after obtaining a boundary
* position from next(), previous(), or
* any other break iterator functions that returns a boundary position.
*