icuSources/common/unicode/unifilt.h

   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
  27 U_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  */
  65 class U_COMMON_API UnicodeFilter : public UnicodeFunctor, public UnicodeMatcher {
  66
  67 public:
  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
 120 protected:
 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
 132 U_NAMESPACE_END
 133
 134 #endif /* U_SHOW_CPLUSPLUS_API */
 135
 136 #endif