ext/scintilla/src/DBCS.cxx

   1 // Scintilla source code edit control
   2 /** @file DBCS.cxx
   3  ** Functions to handle DBCS double byte encodings like Shift-JIS.
   4  **/
   5 // Copyright 2017 by Neil Hodgson <neilh@scintilla.org>
   6 // The License.txt file describes the conditions under which this software may be distributed.
   7
   8 #include "DBCS.h"
   9
  10 using namespace Scintilla::Internal;
  11
  12 namespace Scintilla::Internal {
  13
  14 bool DBCSIsLeadByte(int codePage, char ch) noexcept {
  15         // Byte ranges found in Wikipedia articles with relevant search strings in each case
  16         const unsigned char uch = ch;
  17         switch (codePage) {
  18         case 932:
  19                 // Shift_jis
  20                 return ((uch >= 0x81) && (uch <= 0x9F)) ||
  21                         ((uch >= 0xE0) && (uch <= 0xFC));
  22                 // Lead bytes F0 to FC may be a Microsoft addition.
  23         case 936:
  24                 // GBK
  25                 return (uch >= 0x81) && (uch <= 0xFE);
  26         case 949:
  27                 // Korean Wansung KS C-5601-1987
  28                 return (uch >= 0x81) && (uch <= 0xFE);
  29         case 950:
  30                 // Big5
  31                 return (uch >= 0x81) && (uch <= 0xFE);
  32         case 1361:
  33                 // Korean Johab KS C-5601-1992
  34                 return
  35                         ((uch >= 0x84) && (uch <= 0xD3)) ||
  36                         ((uch >= 0xD8) && (uch <= 0xDE)) ||
  37                         ((uch >= 0xE0) && (uch <= 0xF9));
  38         }
  39         return false;
  40 }
  41
  42 bool IsDBCSValidSingleByte(int codePage, int ch) noexcept {
  43         switch (codePage) {
  44         case 932:
  45                 return ch == 0x80
  46                         || (ch >= 0xA0 && ch <= 0xDF)
  47                         || (ch >= 0xFD);
  48
  49         default:
  50                 return false;
  51         }
  52 }
  53
  54 }