UnicodeMatcher::matches()
+ * indicating the degree of match.
+ * @stable ICU 2.4
+ */
+enum UMatchDegree {
+ /**
+ * Constant returned by matches() indicating a
+ * mismatch between the text and this matcher. The text contains
+ * a character which does not match, or the text does not contain
+ * all desired characters for a non-incremental match.
+ * @stable ICU 2.4
+ */
+ U_MISMATCH,
+
+ /**
+ * Constant returned by matches() indicating a
+ * partial match between the text and this matcher. This value is
+ * only returned for incremental match operations. All characters
+ * of the text match, but more characters are required for a
+ * complete match. Alternatively, for variable-length matchers,
+ * all characters of the text match, and if more characters were
+ * supplied at limit, they might also match.
+ * @stable ICU 2.4
+ */
+ U_PARTIAL_MATCH,
+
+ /**
+ * Constant returned by matches() indicating a
+ * complete match between the text and this matcher. For an
+ * incremental variable-length match, this value is returned if
+ * the given text matches, and it is known that additional
+ * characters would not alter the extent of the match.
+ * @stable ICU 2.4
+ */
+ U_MATCH
+};
+
+/**
+ * UnicodeMatcher defines a protocol for objects that can
+ * match a range of characters in a Replaceable string.
+ * @stable ICU 2.4
+ */
+class U_COMMON_API UnicodeMatcher /* not : public UObject because this is an interface/mixin class */ {
+
+public:
+ /**
+ * Destructor.
+ * @stable ICU 2.4
+ */
+ virtual ~UnicodeMatcher();
+
+ /**
+ * Return a UMatchDegree value indicating the degree of match for
+ * the given text at the given offset. Zero, one, or more
+ * characters may be matched.
+ *
+ * Matching in the forward direction is indicated by limit >
+ * offset. Characters from offset forwards to limit-1 will be
+ * considered for matching.
+ *
+ * Matching in the reverse direction is indicated by limit <
+ * offset. Characters from offset backwards to limit+1 will be
+ * considered for matching.
+ *
+ * If limit == offset then the only match possible is a zero
+ * character match (which subclasses may implement if desired).
+ *
+ * As a side effect, advance the offset parameter to the limit of
+ * the matched substring. In the forward direction, this will be
+ * the index of the last matched character plus one. In the
+ * reverse direction, this will be the index of the last matched
+ * character minus one.
+ *
+ * Note: This method is not const because some classes may + * modify their state as the result of a match. + * + * @param text the text to be matched + * @param offset on input, the index into text at which to begin + * matching. On output, the limit of the matched text. The + * number of matched characters is the output value of offset + * minus the input value. Offset should always point to the + * HIGH SURROGATE (leading code unit) of a pair of surrogates, + * both on entry and upon return. + * @param limit the limit index of text to be matched. Greater + * than offset for a forward direction match, less than offset for + * a backward direction match. The last character to be + * considered for matching will be text.charAt(limit-1) in the + * forward direction or text.charAt(limit+1) in the backward + * direction. + * @param incremental if TRUE, then assume further characters may + * be inserted at limit and check for partial matching. Otherwise + * assume the text as given is complete. + * @return a match degree value indicating a full match, a partial + * match, or a mismatch. If incremental is FALSE then + * U_PARTIAL_MATCH should never be returned. + * @stable ICU 2.4 + */ + virtual UMatchDegree matches(const Replaceable& text, + int32_t& offset, + int32_t limit, + UBool incremental) = 0; + + /** + * Returns a string representation of this matcher. If the result of + * calling this function is passed to the appropriate parser, it + * will produce another matcher that is equal to this one. + * @param result the string to receive the pattern. Previous + * contents will be deleted. + * @param escapeUnprintable if TRUE then convert unprintable + * character to their hex escape representations, \\uxxxx or + * \\Uxxxxxxxx. Unprintable characters are those other than + * U+000A, U+0020..U+007E. + * @stable ICU 2.4 + */ + virtual UnicodeString& toPattern(UnicodeString& result, + UBool escapeUnprintable = FALSE) const = 0; + + /** + * Returns TRUE if this matcher will match a character c, where c + * & 0xFF == v, at offset, in the forward direction (with limit > + * offset). This is used by RuleBasedTransliterator for + * indexing. + * @stable ICU 2.4 + */ + virtual UBool matchesIndexValue(uint8_t v) const = 0; + + /** + * Union the set of all characters that may be matched by this object + * into the given set. + * @param toUnionTo the set into which to union the source characters + * @stable ICU 2.4 + */ + virtual void addMatchSetTo(UnicodeSet& toUnionTo) const = 0; +}; + +U_NAMESPACE_END + +#endif