The Annoyance Filter.pdf - Fourmilab

§130 ANNOYANCE-FILTER MAIL FOLDER 113
130. The nextLine method returns the next line from the mail folder to the caller, while parsing the
mail folder into headers, recognising MIME multi-part messages and their boundaries and encodings.
We wrap a grand while loop around the entire function so code within it can ignore the current input
line (which may, depending on where you are in the process, be the concatenation of header lines with
continuations), with a simple continue.
〈 Class implementations 11 〉 +≡
bool mailFolder ::nextLine (string &s)
{
while (true ) {
bool decoderEOF = false ;
if (lookedAhead ) {
s = lookAheadLine ;
lookedAhead = false ;
}
else {
if (mdp ≠ Λ) {
if ((asp ≠ Λ) ? (¬asp ⃗ nextString (s)) : (¬(mdp ⃗ getDecodedLine (s)))) {
if (asp ≠ Λ) {
if (Annotate (’d’)) {
ostringstream os ;
os ≪ "Closing␣" ≪ asp ⃗ name ( ) ≪ "␣application␣file␣decoder.";
reportParserDiagnostic(os );
}
asp ⃗ close ( );
asp = Λ;
}
s = mdp ⃗ getTerminatorSentinel ( );
decoderEOF = mdp ⃗ isEndOfFile ( );
if (decoderEOF ) {
s = "";
}
if (Annotate (’d’)) {
ostringstream os ;
os ≪ "Closing␣out␣" ≪ mdp ⃗ name ( ) ≪ "␣decoder.␣␣" ≪
mdp ⃗ getEncodedLineCount ( ) ≪ "␣lines␣decoded.";
reportParserDiagnostic(os );
os .str ("");
os ≪ "End␣sentinel:␣" ≪ s;
reportParserDiagnostic(os );
}
〈 Reset MIME decoder state 142 〉;
inPartHeader = ¬((s.substr (0, 2) ≡ "−−") ∧ (s.substr (2,
partBoundary .length ( )) ≡ partBoundary ) ∧ (s.substr (partBoundary .length ( ) + 2,
2) ≡ "−−"));
if ((¬inPartHeader ) ∧ (¬(partBoundaryStack .empty ( )))) {
partBoundary = partBoundaryStack .top( );
partBoundaryStack .pop( );
}
}
}
else {