UnicodeFilter defines a protocol for selecting a
* subset of the full range (U+0000 to U+10FFFF) of Unicode characters.
* Currently, filters are used in conjunction with classes like {@link
* Transliterator} to only process selected characters through a
* transformation.
*
* Note: UnicodeFilter currently stubs out two pure virtual methods
* of its base class, UnicodeMatcher. These methods are toPattern()
* and matchesIndexValue(). This is done so that filter classes that
* are not actually used as matchers -- specifically, those in the
* UnicodeFilterLogic component, and those in tests -- can continue to
* work without defining these methods. As long as a filter is not
* used in an RBT during real transliteration, these methods will not
* be called. However, this breaks the UnicodeMatcher base class
* protocol, and it is not a correct solution.
*
*
In the future we may revisit the UnicodeMatcher / UnicodeFilter
* hierarchy and either redesign it, or simply remove the stubs in
* UnicodeFilter and force subclasses to implement the full
* UnicodeMatcher protocol.
*
* @see UnicodeFilterLogic
* @stable ICU 2.0
*/
class U_COMMON_API UnicodeFilter : public UnicodeFunctor, public UnicodeMatcher {
public:
/**
* Destructor
* @stable ICU 2.0
*/
virtual ~UnicodeFilter();
/**
* Returns true for characters that are in the selected
* subset. In other words, if a character is to be
* filtered, then contains() returns
* false.
* @stable ICU 2.0
*/
virtual UBool contains(UChar32 c) const = 0;
/**
* UnicodeFunctor API. Cast 'this' to a UnicodeMatcher* pointer
* and return the pointer.
* @stable ICU 2.4
*/
virtual UnicodeMatcher* toMatcher() const;
/**
* Implement UnicodeMatcher API.
* @stable ICU 2.4
*/
virtual UMatchDegree matches(const Replaceable& text,
int32_t& offset,
int32_t limit,
UBool incremental);
/**
* UnicodeFunctor API. Nothing to do.
* @stable ICU 2.4
*/
virtual void setData(const TransliterationRuleData*);
/**
* ICU "poor man's RTTI", returns a UClassID for this class.
*
* @stable ICU 2.2
*/
static UClassID U_EXPORT2 getStaticClassID();
protected:
/*
* Since this class has pure virtual functions,
* a constructor can't be used.
* @stable ICU 2.0
*/
/* UnicodeFilter();*/
};
/*inline UnicodeFilter::UnicodeFilter() {}*/
U_NAMESPACE_END
#endif