icuSources/common/unifilt.cpp

   1 /*
   2 **********************************************************************
   3 * Copyright (c) 2001-2012, International Business Machines
   4 * Corporation and others.  All Rights Reserved.
   5 **********************************************************************
   6 *   Date        Name        Description
   7 *   07/18/01    aliu        Creation.
   8 **********************************************************************
   9 */
  10
  11 #include "unicode/unifilt.h"
  12 #include "unicode/rep.h"
  13 #include "unicode/utf16.h"
  14
  15 U_NAMESPACE_BEGIN
  16 UOBJECT_DEFINE_ABSTRACT_RTTI_IMPLEMENTATION(UnicodeFilter)
  17
  18
  19 /* Define this here due to the lack of another file.
  20    It can't be defined in the header */
  21 UnicodeMatcher::~UnicodeMatcher() {}
  22
  23 UnicodeFilter::~UnicodeFilter() {}
  24
  25 /**
  26  * UnicodeFunctor API.
  27  *   Note that UnicodeMatcher is a base class of UnicodeFilter.
  28  */
  29 UnicodeMatcher* UnicodeFilter::toMatcher() const {
  30   return const_cast<UnicodeFilter *>(this);
  31 }
  32
  33 void UnicodeFilter::setData(const TransliterationRuleData*) {}
  34
  35 /**
  36  * Default implementation of UnicodeMatcher::matches() for Unicode
  37  * filters.  Matches a single code point at offset (either one or
  38  * two 16-bit code units).
  39  */
  40 UMatchDegree UnicodeFilter::matches(const Replaceable& text,
  41                                     int32_t& offset,
  42                                     int32_t limit,
  43                                     UBool incremental) {
  44     UChar32 c;
  45     if (offset < limit &&
  46         contains(c = text.char32At(offset))) {
  47         offset += U16_LENGTH(c);
  48         return U_MATCH;
  49     }
  50     if (offset > limit &&
  51         contains(c = text.char32At(offset))) {
  52         // Backup offset by 1, unless the preceding character is a
  53         // surrogate pair -- then backup by 2 (keep offset pointing at
  54         // the lead surrogate).
  55         --offset;
  56         if (offset >= 0) {
  57             offset -= U16_LENGTH(text.char32At(offset)) - 1;
  58         }
  59         return U_MATCH;
  60     }
  61     if (incremental && offset == limit) {
  62         return U_PARTIAL_MATCH;
  63     }
  64     return U_MISMATCH;
  65 }
  66
  67 U_NAMESPACE_END
  68
  69 //eof