[antlr-interest] Idea: semantic grammar

[Adam Connelly]

Ok, but do you think it would be fair to say that there is a separation
between the method that you use to identify that an error has occurred, the
method used to generate an error message, and what you then do with that
message?  Also, is it fair to assume that many applications share a very
similar set of errors (I've got no idea about this one since I'm pretty much
only familiar with compiled programming languages)?

Adam

2008/5/22 Loring Craymer <lgcraymer at yahoo.com>:

> Johannes, Adam--
>
> Yes, Yggdrasil will let you do the analysis in a target-independent way.
>  Semantics, however, are application-dependent, not language-dependent.  If
> your application processes a language as a compiler, then it finds compiler
> errors.  On the other hand, if the application is a static analyzer, then
> you have a different set of errors--race condition detection or memory
> leaks, and so forth.
>
> --Loring
>
> ----- Original Message ----
> > From: Johannes Luber <JALuber at gmx.de>
> > To: Adam Connelly <adam.rpconnelly at googlemail.com>;
> antlr-interest at antlr.org
> > Sent: Thursday, May 22, 2008 9:09:53 AM
> > Subject: Re: [antlr-interest] Idea: semantic grammar
> >
> > > Hi,
> > > I don't know if there is anything like this about at the moment, or
> even
> > > if
> > > it's a good idea.  What I've been thinking about is having a grammar
> that
> > > defines the semantics of a language that parsers can then import.  It
> > > would
> > > basically be a list of the possible types of semantic error that could
> > > occur, along with any information necessary to generate an error
> message,
> > > and an action that creates the message.
> > >
> > > >>From this a number of exception classes would be generated, along
> with a
> > > MessageCreator that would generate error messages based on the actions
> > > supplied.  Inside the parser grammar, when semantic predicates are
> > > declared,
> > > the type of error would be indicated, and from this the correct
> exception
> > > would be thrown.  The parser would then ask its ErrorReporter to handle
> > > the
> > > error, which would use the MessageCreator to create the error message,
> and
> > > would then add it to a list / print to the console / whatever.
> > >
> > > >>From this, "catalogs" of pre-defined semantic errors could be
> provided
> > > along
> > > with the correct messages to display for these errors.  Obviously this
> > > wouldn't define the actual semantics of the language (since you'd still
> > > need
> > > to implement this in actions), but it would simplify the error
> reporting
> > > part since users would just import the correct semantics, then indicate
> > > when
> > > a certain semantic error should be thrown.
> > >
> > > Any thoughts?
> > > Adam
> >
> > A nice idea but probably infeasible. There are too many semantic
> differences for
> > basically one thing - recently I read an article about "PHP sucks" and
> saw that
> > references were handled in 4.3, 4.4 and 5 differently. Granted, 4.3 was
> leaky
> > and 4.4 made it too complicated, so restricting options to sensible ones
> has a
> > benefit, but if you want to be able to parse even the most idiotic
> things, you
> > have to able to define arbitrary semantics. And then you can use the
> target
> > language itself.
> >
> > Maybe Yggdrasil of Loring Craymer can do that in target independent
> manner, but
> > it would be basically still Turing equivalent. At least you can do far
> more
> > things target independent in Yggdrasil than in ANTLR - just a shame, that
> he
> > didn't got around to finish it yet.
> >
> > Johannes
> > --
> > Der GMX SmartSurfer hilft bis zu 70% Ihrer Onlinekosten zu sparen!
> > Ideal für Modem und ISDN: http://www.gmx.net/de/go/smartsurfer
>
>
>
>
>
>
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