[news.eclipse.technology.imp] Re: IMP LPG editor syntax errors on %optio

[Brian Payton <bpayton@xxxxxxxxxx>]

Thanks.  I agree that the double ParseTable option should be marked as 
an error in the editor.

Robert M. Fuhrer wrote:
> Hi there,
>
> Thanks for the bug reports!
>
> The LPG parser generator and the LPG IDE use different parsers (even 
> slightly
> different grammars), partly since the parser generator hand-rolls its 
> scanner,
> while the IDE uses LPG itself to generate the scanner. This difference 
> shows
> up particularly for the %options directives. In theory, they should be in
> perfect agreement, but obviously they're not quite.
>
> More details below...
>
> Brian Payton wrote:
> > Hi,
> >
> > I'm starting to use the IMP LPG source editor, and I noticed the 
> > editor shows syntax errors on certain input that LPG accepts, 
> > particularly in the %options declarations.  Here's the lines showing 
> > errors, plus the error messages.
> >
> > Line:
> >   %options action=("DB2ZQueryParser.java", "/.", "./")
> > Error:
> >    Multiple messages: misplaced construct(s): "ERROR_TOKEN" {0} is 
> > invalid: "%options action" {0}
> >  expected after this token: "DISJOINTPREDECESSORSETS_KEY"
>
> I'm looking into this.
>
> > Line:
> >   %options ParseTable=%options ParseTable=lpg.lpgjavaruntime.ParseTable
> > (Note: this options line doesn't make much sense to me, so it might be 
> > an error in the source file.  However LPG doesn't complain about it.)
> > Error:
> >   Multiple messages: {0} unexpected token(s) ignored: "ERROR_TOKEN" 
> > {0} is invalid: "%options ParseTable=%options "
>
> Such a line is really two ParseTable options specifications, the first
> with a bogus empty value that gets overridden by the second, which has
> the value "lpg.lpgjavaruntime.ParseTable". You can safely delete the
> initial "%options ParseTable=" prefix.
>
> I don't think it really makes much sense to change the IDE parser to
> accept this (erroneous) options specification. If anything, I'd argue
> that we should change the parser generator to flag it as an error.
>
> > Line:
> >   %options var=nt,automatic_ast,visitor,parent_save
> > Error:
> >   {0} is invalid: "%options var"
>
> You're right - we missed the "var" option. I'll fix that.
>
> > Line:
> >   %options or_marker='|'
> > Error:
> >   {0} is invalid: "%options or_marker='"
>
> In this case, the grammar used by the IDE doesn't seem to permit a
> quoted character. As a workaround, removing the quotes should work.
> Of course, I'll fix the IDE's grammar to allow the quoting.
>
> > I also noticed that the editor doesn't hilight as keywords the "no" 
> > prefix on keywords such as "noserialize", "nogoto_default", and 
> > "noerror-maps"
>
> I'll have to look into this as well.