icuSources/common/unifilt.cpp

   1 // © 2016 and later: Unicode, Inc. and others.
   2 // License & terms of use: http://www.unicode.org/copyright.html
   3 /*
   4 **********************************************************************
   5 * Copyright (c) 2001-2012, International Business Machines
   6 * Corporation and others.  All Rights Reserved.
   7 **********************************************************************
   8 *   Date        Name        Description
   9 *   07/18/01    aliu        Creation.
  10 **********************************************************************
  11 */
  12
  13 #include "unicode/unifilt.h"
  14 #include "unicode/rep.h"
  15 #include "unicode/utf16.h"
  16
  17 U_NAMESPACE_BEGIN
  18 UOBJECT_DEFINE_ABSTRACT_RTTI_IMPLEMENTATION(UnicodeFilter)
  19
  20
  21 /* Define this here due to the lack of another file.
  22    It can't be defined in the header */
  23 UnicodeMatcher::~UnicodeMatcher() {}
  24
  25 UnicodeFilter::~UnicodeFilter() {}
  26
  27 /**
  28  * UnicodeFunctor API.
  29  *   Note that UnicodeMatcher is a base class of UnicodeFilter.
  30  */
  31 UnicodeMatcher* UnicodeFilter::toMatcher() const {
  32   return const_cast<UnicodeFilter *>(this);
  33 }
  34
  35 void UnicodeFilter::setData(const TransliterationRuleData*) {}
  36
  37 /**
  38  * Default implementation of UnicodeMatcher::matches() for Unicode
  39  * filters.  Matches a single code point at offset (either one or
  40  * two 16-bit code units).
  41  */
  42 UMatchDegree UnicodeFilter::matches(const Replaceable& text,
  43                                     int32_t& offset,
  44                                     int32_t limit,
  45                                     UBool incremental) {
  46     UChar32 c;
  47     if (offset < limit &&
  48         contains(c = text.char32At(offset))) {
  49         offset += U16_LENGTH(c);
  50         return U_MATCH;
  51     }
  52     if (offset > limit &&
  53         contains(c = text.char32At(offset))) {
  54         // Backup offset by 1, unless the preceding character is a
  55         // surrogate pair -- then backup by 2 (keep offset pointing at
  56         // the lead surrogate).
  57         --offset;
  58         if (offset >= 0) {
  59             offset -= U16_LENGTH(text.char32At(offset)) - 1;
  60         }
  61         return U_MATCH;
  62     }
  63     if (incremental && offset == limit) {
  64         return U_PARTIAL_MATCH;
  65     }
  66     return U_MISMATCH;
  67 }
  68
  69 U_NAMESPACE_END
  70
  71 //eof