// Macro-expand a macro argument 'arg' to create 'expandedArg'.
// Does not replace 'arg'.
// Returns nullptr if no expanded argument is created.
TPpContext::TokenStream* TPpContext::PrescanMacroArg(TokenStream& arg, TPpToken* ppToken, bool newLineOkay)
{
// expand the argument
TokenStream* expandedArg = new TokenStream;
pushInput(new tMarkerInput(this));
pushTokenStreamInput(arg);
int token;
while ((token = scanToken(ppToken)) != tMarkerInput::marker && token != EndOfInput) {
token = tokenPaste(token, *ppToken);
if (token == tMarkerInput::marker || token == EndOfInput)
break;
if (token == PpAtomIdentifier && MacroExpand(ppToken, false, newLineOkay) != 0)
continue;
expandedArg->putToken(token, ppToken);
}
if (token == EndOfInput) {
// MacroExpand ate the marker, so had bad input, recover
delete expandedArg;
expandedArg = nullptr;
} else {
// remove the marker
popInput();
}
return expandedArg;
}
// Macro-expand a macro argument 'arg' to create 'expandedArg'.
// Does not replace 'arg'.
// Returns nullptr if no expanded argument is created.
TPpContext::TokenStream* TPpContext::PrescanMacroArg(TokenStream& arg, TPpToken* ppToken, bool newLineOkay)
{
// expand the argument
TokenStream* expandedArg = new TokenStream;
pushInput(new tMarkerInput(this));
pushTokenStreamInput(arg);
int token;
while ((token = scanToken(ppToken)) != tMarkerInput::marker && token != EndOfInput) {
token = tokenPaste(token, *ppToken);
if (token == PpAtomIdentifier) {
switch (MacroExpand(ppToken, false, newLineOkay)) {
case MacroExpandNotStarted:
break;
case MacroExpandError:
// toss the rest of the pushed-input argument by scanning until tMarkerInput
while ((token = scanToken(ppToken)) != tMarkerInput::marker && token != EndOfInput)
;
break;
case MacroExpandStarted:
case MacroExpandUndef:
continue;
}
}
if (token == tMarkerInput::marker || token == EndOfInput)
break;
expandedArg->putToken(token, ppToken);
}
if (token != tMarkerInput::marker) {
// Error, or MacroExpand ate the marker, so had bad input, recover
delete expandedArg;
expandedArg = nullptr;
}
return expandedArg;
}