The Annoyance Filter.pdf - Fourmilab

§84 ANNOYANCE-FILTER UTF-8 UNICODE DECODER 73
}
}
return result ;
}
85. UTF-16 Unicode decoder.
The UTF-16 encoding of Unicode encodes logical characters as sequence of 16 bit codes. Most Unicode
characters are encoded in a single 16 bit quantity, but character codes greater than 65535 are encoded in
a pair of 16 bit values in the surrogate range. Naturally, this encoding can be either big- or little-endian
in byte sequence; we handle either, as set by the setBigEndian method or the constructor.
〈 Class definitions 10 〉 +≡
class UTF 16 Unicode MBCSdecoder : public Unicode MBCSdecoder {
protected:
bool bigEndian ;
int getNextUTF 16Word (void)
{
int c1 = getNextEncodedByte ( );
}
if (c1 < 0) {
return c1 ;
}
int c2 = getNextEncodedByte ( );
if (c2 < 0) {
ostringstream os ;
os ≪ name ( ) ≪ "_MBCSdecoder:␣Premature␣end␣of␣line␣in␣UTF−16␣character.";
reportDecoderDiagnostic(os );
return −1;
}
if (bigEndian ) {
c1 = (c1 ≪ 8) | c2 ;
}
else {
c1 |= (c2 ≪ 8);
}
return c1 ;
public:
UTF 16 Unicode MBCSdecoder(bool isBigEndian = true )
{
setBigEndian (isBigEndian );
}
void setBigEndian (bool isBigEndian = true )
{
bigEndian = isBigEndian ;
}
virtual string name (void)
{
return "UTF_16_Unicode";
}
virtual int getNextDecodedChar (void); /∗ Get next decoded byte ∗/
};