icuSources/common/unicode/unifilt.h

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