On 2010-06-07 09:01, Hans-Peter Diettrich wrote:
Adem schrieb:
And finally we'll have to talk about parsing invalid code, during
editing. This can be handled by the same hack as for conditionally
excluded code, so that after an syntax error the parser stops
parsing, and simply returns the tokens provided by the scanner. The
only question: how to make the parser resume parsing, once enough
tokens have been skipped?
OTOH, two approaches come to mind:
First one is, introduce another token kind (or several new token
kinds, if we need to take care of degrees of severity) for error, and
add an 'error node' every time an error occurs and contniue
regardless. Then, let the calling application decide what to do.
Second one could be something like this:
Call an event wherever halting occurs:
The Semantics class will have according method(s).
But when the parser is in an error state, inside some procedure, how
can the parser be instructed to exit this and further procedures in
the call stack? Exception handling could implement such detailed
recovery, but the compiler code does not use SEH for speed reasons.
I haven't studied the actual code, so it is entirely possible that I am
talking through my (or even someone else's) hat.
I expect, in the current code, there are exit points that emit a
reasonably suitable message to the compiler. Could we not replace these
exit points with procedure/function calls to that decides whether (in
the case of compiler use) it should exit immediately or (in the case of
non-compiler use) it should consult with the calling class?
But, then, it's probably not as easy as that.
--
Cheers,
Adem
--
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