The Annoyance Filter.pdf - Fourmilab

128 MAIL FOLDER ANNOYANCE-FILTER §148
148. After decoding the Quoted−Printable or Base64 sequence from the header line, examine its
character set specification. If it is a character set we know how to decode and interpret, instantiate the
appropriate components and replace the decoded sequence with its interpretation. There is no need to
further process ISO−8859 sequences.
〈 Interpret header quoted string if character set known 148 〉 ≡
if (charset .substr (0, 6) ≡ "gb2312") {
EUC MBCSdecoder mbd euc; /∗ EUC decoder ∗/
GB2312 MBCSinterpreter mbi gb2312 ; /∗ GB2312 interpreter ∗/
mbd euc.setMailFolder (this);
mbi gb2312 .setDecoder (mbd euc);
drt = mbi gb2312 .decodeLine (drt );
}
else if (charset ≡ "big5") {
Big5 MBCSdecoder mbd big5 ; /∗ Big5 decoder ∗/
Big5 MBCSinterpreter mbi big5 ; /∗ Big5 interpreter ∗/
mbd big5 .setMailFolder (this);
mbi big5 .setDecoder (mbd big5 );
drt = mbi big5 .decodeLine (drt );
}
else if (charset ≡ "utf−8") {
UTF 8 Unicode MBCSdecoder mbd utf 8 ; /∗ Unicode UTF-8 decoder ∗/
Unicode MBCSinterpreter mbi unicode ; /∗ Unicode interpreter ∗/
mbd utf 8 .setMailFolder (this);
mbi unicode .setDecoder (mbd utf 8 );
drt = mbi unicode .decodeLine (drt );
}
else if (charset ≡ "euc−kr") {
EUC MBCSdecoder mbd euc; /∗ EUC decoder ∗/
KR MBCSinterpreter mbi kr ; /∗ Korean (euc−kr) interpreter ∗/
mbd euc.setMailFolder (this);
mbi kr .setDecoder (mbd euc);
drt = mbi kr .decodeLine (drt );
}
else if ((charset .substr (0, 8) ≡ "iso−8859") ∨ (charset ≡ "us−ascii")) {
/∗ No decoding or interpretation required for ISO-8859 or US-ASCII ∗/
}
else {
ostringstream os ;
}
os ≪ "Header␣line:␣no␣interpreter␣for␣(" ≪ charset ≪ ")␣character␣set.";
reportParserDiagnostic(os .str ( ));
This code is used in section 147.