codekingpro/portable-devtools

1// © 2016 and later: Unicode, Inc. and others.
2// License & terms of use: http://www.unicode.org/copyright.html
3/*
4**********************************************************************
5* Copyright (C) 1999-2010, International Business Machines Corporation and others.
6* All Rights Reserved.
7**********************************************************************
8*   Date        Name        Description
9*   11/17/99    aliu        Creation.
10**********************************************************************
11*/
12#ifndef UNIFILT_H
13#define UNIFILT_H
14
15#include "unicode/utypes.h"
16
17#if U_SHOW_CPLUSPLUS_API
18
19#include "unicode/unifunct.h"
20#include "unicode/unimatch.h"
21
22/**
23 * \file 
24 * \brief C++ API: Unicode Filter
25 */
26
27U_NAMESPACE_BEGIN
28
29/**
30 * U_ETHER is used to represent character values for positions outside
31 * a range.  For example, transliterator uses this to represent
32 * characters outside the range contextStart..contextLimit-1.  This
33 * allows explicit matching by rules and UnicodeSets of text outside a
34 * defined range.
35 * @stable ICU 3.0
36 */
37#define U_ETHER ((char16_t)0xFFFF)
38
39/**
40 *
41 * <code>UnicodeFilter</code> defines a protocol for selecting a
42 * subset of the full range (U+0000 to U+10FFFF) of Unicode characters.
43 * Currently, filters are used in conjunction with classes like {@link
44 * Transliterator} to only process selected characters through a
45 * transformation.
46 *
47 * <p>Note: UnicodeFilter currently stubs out two pure virtual methods
48 * of its base class, UnicodeMatcher.  These methods are toPattern()
49 * and matchesIndexValue().  This is done so that filter classes that
50 * are not actually used as matchers -- specifically, those in the
51 * UnicodeFilterLogic component, and those in tests -- can continue to
52 * work without defining these methods.  As long as a filter is not
53 * used in an RBT during real transliteration, these methods will not
54 * be called.  However, this breaks the UnicodeMatcher base class
55 * protocol, and it is not a correct solution.
56 *
57 * <p>In the future we may revisit the UnicodeMatcher / UnicodeFilter
58 * hierarchy and either redesign it, or simply remove the stubs in
59 * UnicodeFilter and force subclasses to implement the full
60 * UnicodeMatcher protocol.
61 *
62 * @see UnicodeFilterLogic
63 * @stable ICU 2.0
64 */
65class U_COMMON_API UnicodeFilter : public UnicodeFunctor, public UnicodeMatcher {
66
67public:
68    /**
69     * Destructor
70     * @stable ICU 2.0
71     */
72    virtual ~UnicodeFilter();
73
74    /**
75     * Clones this object polymorphically.
76     * The caller owns the result and should delete it when done.
77     * @return clone, or nullptr if an error occurred
78     * @stable ICU 2.4
79     */
80    virtual UnicodeFilter* clone() const = 0;
81
82    /**
83     * Returns <tt>true</tt> for characters that are in the selected
84     * subset.  In other words, if a character is <b>to be
85     * filtered</b>, then <tt>contains()</tt> returns
86     * <b><tt>false</tt></b>.
87     * @stable ICU 2.0
88     */
89    virtual UBool contains(UChar32 c) const = 0;
90
91    /**
92     * UnicodeFunctor API.  Cast 'this' to a UnicodeMatcher* pointer
93     * and return the pointer.
94     * @stable ICU 2.4
95     */
96    virtual UnicodeMatcher* toMatcher() const;
97
98    /**
99     * Implement UnicodeMatcher API.
100     * @stable ICU 2.4
101     */
102    virtual UMatchDegree matches(const Replaceable& text,
103                                 int32_t& offset,
104                                 int32_t limit,
105                                 UBool incremental);
106
107    /**
108     * UnicodeFunctor API.  Nothing to do.
109     * @stable ICU 2.4
110     */
111    virtual void setData(const TransliterationRuleData*);
112
113    /**
114     * ICU "poor man's RTTI", returns a UClassID for this class.
115     *
116     * @stable ICU 2.2
117     */
118    static UClassID U_EXPORT2 getStaticClassID();
119
120protected:
121
122    /*
123     * Since this class has pure virtual functions,
124     * a constructor can't be used.
125     * @stable ICU 2.0
126     */
127/*    UnicodeFilter();*/
128};
129
130/*inline UnicodeFilter::UnicodeFilter() {}*/
131
132U_NAMESPACE_END
133
134#endif /* U_SHOW_CPLUSPLUS_API */
135
136#endif
137