1/*
2* Copyright (C) 2001-2005, International Business Machines Corporation and others. All Rights Reserved.
3**********************************************************************
4*   Date        Name        Description
5*   07/18/01    aliu        Creation.
6**********************************************************************
7*/
8#ifndef UNIMATCH_H
9#define UNIMATCH_H
10
11#include "unicode/utypes.h"
12
13/**
14 * \file
15 * \brief C++ API: Unicode Matcher
16 */
17
18
19U_NAMESPACE_BEGIN
20
21class Replaceable;
22class UnicodeString;
23class UnicodeSet;
24
25/**
26 * Constants returned by <code>UnicodeMatcher::matches()</code>
27 * indicating the degree of match.
28 * @stable ICU 2.4
29 */
30enum UMatchDegree {
31    /**
32     * Constant returned by <code>matches()</code> indicating a
33     * mismatch between the text and this matcher.  The text contains
34     * a character which does not match, or the text does not contain
35     * all desired characters for a non-incremental match.
36     * @stable ICU 2.4
37     */
38    U_MISMATCH,
39
40    /**
41     * Constant returned by <code>matches()</code> indicating a
42     * partial match between the text and this matcher.  This value is
43     * only returned for incremental match operations.  All characters
44     * of the text match, but more characters are required for a
45     * complete match.  Alternatively, for variable-length matchers,
46     * all characters of the text match, and if more characters were
47     * supplied at limit, they might also match.
48     * @stable ICU 2.4
49     */
50    U_PARTIAL_MATCH,
51
52    /**
53     * Constant returned by <code>matches()</code> indicating a
54     * complete match between the text and this matcher.  For an
55     * incremental variable-length match, this value is returned if
56     * the given text matches, and it is known that additional
57     * characters would not alter the extent of the match.
58     * @stable ICU 2.4
59     */
60    U_MATCH
61};
62
63/**
64 * <code>UnicodeMatcher</code> defines a protocol for objects that can
65 * match a range of characters in a Replaceable string.
66 * @stable ICU 2.4
67 */
68class U_COMMON_API UnicodeMatcher /* not : public UObject because this is an interface/mixin class */ {
69
70public:
71    /**
72     * Destructor.
73     * @stable ICU 2.4
74     */
75    virtual ~UnicodeMatcher();
76
77    /**
78     * Return a UMatchDegree value indicating the degree of match for
79     * the given text at the given offset.  Zero, one, or more
80     * characters may be matched.
81     *
82     * Matching in the forward direction is indicated by limit >
83     * offset.  Characters from offset forwards to limit-1 will be
84     * considered for matching.
85     *
86     * Matching in the reverse direction is indicated by limit <
87     * offset.  Characters from offset backwards to limit+1 will be
88     * considered for matching.
89     *
90     * If limit == offset then the only match possible is a zero
91     * character match (which subclasses may implement if desired).
92     *
93     * As a side effect, advance the offset parameter to the limit of
94     * the matched substring.  In the forward direction, this will be
95     * the index of the last matched character plus one.  In the
96     * reverse direction, this will be the index of the last matched
97     * character minus one.
98     *
99     * <p>Note:  This method is not const because some classes may
100     * modify their state as the result of a match.
101     *
102     * @param text the text to be matched
103     * @param offset on input, the index into text at which to begin
104     * matching.  On output, the limit of the matched text.  The
105     * number of matched characters is the output value of offset
106     * minus the input value.  Offset should always point to the
107     * HIGH SURROGATE (leading code unit) of a pair of surrogates,
108     * both on entry and upon return.
109     * @param limit the limit index of text to be matched.  Greater
110     * than offset for a forward direction match, less than offset for
111     * a backward direction match.  The last character to be
112     * considered for matching will be text.charAt(limit-1) in the
113     * forward direction or text.charAt(limit+1) in the backward
114     * direction.
115     * @param incremental if TRUE, then assume further characters may
116     * be inserted at limit and check for partial matching.  Otherwise
117     * assume the text as given is complete.
118     * @return a match degree value indicating a full match, a partial
119     * match, or a mismatch.  If incremental is FALSE then
120     * U_PARTIAL_MATCH should never be returned.
121     * @stable ICU 2.4
122     */
123    virtual UMatchDegree matches(const Replaceable& text,
124                                 int32_t& offset,
125                                 int32_t limit,
126                                 UBool incremental) = 0;
127
128    /**
129     * Returns a string representation of this matcher.  If the result of
130     * calling this function is passed to the appropriate parser, it
131     * will produce another matcher that is equal to this one.
132     * @param result the string to receive the pattern.  Previous
133     * contents will be deleted.
134     * @param escapeUnprintable if TRUE then convert unprintable
135     * character to their hex escape representations, \\uxxxx or
136     * \\Uxxxxxxxx.  Unprintable characters are those other than
137     * U+000A, U+0020..U+007E.
138     * @stable ICU 2.4
139     */
140    virtual UnicodeString& toPattern(UnicodeString& result,
141                                     UBool escapeUnprintable = FALSE) const = 0;
142
143    /**
144     * Returns TRUE if this matcher will match a character c, where c
145     * & 0xFF == v, at offset, in the forward direction (with limit >
146     * offset).  This is used by <tt>RuleBasedTransliterator</tt> for
147     * indexing.
148     * @stable ICU 2.4
149     */
150    virtual UBool matchesIndexValue(uint8_t v) const = 0;
151
152    /**
153     * Union the set of all characters that may be matched by this object
154     * into the given set.
155     * @param toUnionTo the set into which to union the source characters
156     * @stable ICU 2.4
157     */
158    virtual void addMatchSetTo(UnicodeSet& toUnionTo) const = 0;
159};
160
161U_NAMESPACE_END
162
163#endif
164