1// Copyright (C) 2016 and later: Unicode, Inc. and others.
2// License & terms of use: http://www.unicode.org/copyright.html
3/*
4* Copyright (C) 2001-2005, International Business Machines Corporation and others. All Rights Reserved.
5**********************************************************************
6*   Date        Name        Description
7*   07/18/01    aliu        Creation.
8**********************************************************************
9*/
10#ifndef UNIMATCH_H
11#define UNIMATCH_H
12
13#include "unicode/utypes.h"
14
15/**
16 * \file
17 * \brief C++ API: Unicode Matcher
18 */
19
20
21U_NAMESPACE_BEGIN
22
23class Replaceable;
24class UnicodeString;
25class UnicodeSet;
26
27/**
28 * Constants returned by <code>UnicodeMatcher::matches()</code>
29 * indicating the degree of match.
30 * @stable ICU 2.4
31 */
32enum UMatchDegree {
33    /**
34     * Constant returned by <code>matches()</code> indicating a
35     * mismatch between the text and this matcher.  The text contains
36     * a character which does not match, or the text does not contain
37     * all desired characters for a non-incremental match.
38     * @stable ICU 2.4
39     */
40    U_MISMATCH,
41
42    /**
43     * Constant returned by <code>matches()</code> indicating a
44     * partial match between the text and this matcher.  This value is
45     * only returned for incremental match operations.  All characters
46     * of the text match, but more characters are required for a
47     * complete match.  Alternatively, for variable-length matchers,
48     * all characters of the text match, and if more characters were
49     * supplied at limit, they might also match.
50     * @stable ICU 2.4
51     */
52    U_PARTIAL_MATCH,
53
54    /**
55     * Constant returned by <code>matches()</code> indicating a
56     * complete match between the text and this matcher.  For an
57     * incremental variable-length match, this value is returned if
58     * the given text matches, and it is known that additional
59     * characters would not alter the extent of the match.
60     * @stable ICU 2.4
61     */
62    U_MATCH
63};
64
65/**
66 * <code>UnicodeMatcher</code> defines a protocol for objects that can
67 * match a range of characters in a Replaceable string.
68 * @stable ICU 2.4
69 */
70class U_COMMON_API UnicodeMatcher /* not : public UObject because this is an interface/mixin class */ {
71
72public:
73    /**
74     * Destructor.
75     * @stable ICU 2.4
76     */
77    virtual ~UnicodeMatcher();
78
79    /**
80     * Return a UMatchDegree value indicating the degree of match for
81     * the given text at the given offset.  Zero, one, or more
82     * characters may be matched.
83     *
84     * Matching in the forward direction is indicated by limit >
85     * offset.  Characters from offset forwards to limit-1 will be
86     * considered for matching.
87     *
88     * Matching in the reverse direction is indicated by limit <
89     * offset.  Characters from offset backwards to limit+1 will be
90     * considered for matching.
91     *
92     * If limit == offset then the only match possible is a zero
93     * character match (which subclasses may implement if desired).
94     *
95     * As a side effect, advance the offset parameter to the limit of
96     * the matched substring.  In the forward direction, this will be
97     * the index of the last matched character plus one.  In the
98     * reverse direction, this will be the index of the last matched
99     * character minus one.
100     *
101     * <p>Note:  This method is not const because some classes may
102     * modify their state as the result of a match.
103     *
104     * @param text the text to be matched
105     * @param offset on input, the index into text at which to begin
106     * matching.  On output, the limit of the matched text.  The
107     * number of matched characters is the output value of offset
108     * minus the input value.  Offset should always point to the
109     * HIGH SURROGATE (leading code unit) of a pair of surrogates,
110     * both on entry and upon return.
111     * @param limit the limit index of text to be matched.  Greater
112     * than offset for a forward direction match, less than offset for
113     * a backward direction match.  The last character to be
114     * considered for matching will be text.charAt(limit-1) in the
115     * forward direction or text.charAt(limit+1) in the backward
116     * direction.
117     * @param incremental if TRUE, then assume further characters may
118     * be inserted at limit and check for partial matching.  Otherwise
119     * assume the text as given is complete.
120     * @return a match degree value indicating a full match, a partial
121     * match, or a mismatch.  If incremental is FALSE then
122     * U_PARTIAL_MATCH should never be returned.
123     * @stable ICU 2.4
124     */
125    virtual UMatchDegree matches(const Replaceable& text,
126                                 int32_t& offset,
127                                 int32_t limit,
128                                 UBool incremental) = 0;
129
130    /**
131     * Returns a string representation of this matcher.  If the result of
132     * calling this function is passed to the appropriate parser, it
133     * will produce another matcher that is equal to this one.
134     * @param result the string to receive the pattern.  Previous
135     * contents will be deleted.
136     * @param escapeUnprintable if TRUE then convert unprintable
137     * character to their hex escape representations, \\uxxxx or
138     * \\Uxxxxxxxx.  Unprintable characters are those other than
139     * U+000A, U+0020..U+007E.
140     * @stable ICU 2.4
141     */
142    virtual UnicodeString& toPattern(UnicodeString& result,
143                                     UBool escapeUnprintable = FALSE) const = 0;
144
145    /**
146     * Returns TRUE if this matcher will match a character c, where c
147     * & 0xFF == v, at offset, in the forward direction (with limit >
148     * offset).  This is used by <tt>RuleBasedTransliterator</tt> for
149     * indexing.
150     * @stable ICU 2.4
151     */
152    virtual UBool matchesIndexValue(uint8_t v) const = 0;
153
154    /**
155     * Union the set of all characters that may be matched by this object
156     * into the given set.
157     * @param toUnionTo the set into which to union the source characters
158     * @stable ICU 2.4
159     */
160    virtual void addMatchSetTo(UnicodeSet& toUnionTo) const = 0;
161};
162
163U_NAMESPACE_END
164
165#endif
166