Re: Support for "break *ADDRESS thread THREADNO"

["Maciej W. Rozycki" <macro@mips.com>]

On Wed, 13 Apr 2005, Daniel Jacobowitz wrote:

> > > I assume so.  It is parsed as an expression, not just an address; for
> > > instance "break *thread" would actually work if thread is a pointer to
> > > a function.
> > 
> >  I think the actual problem is the expression parser cannot be told to 
> > stop successfully on an unparseable token as long as the expression 
> > collected so far is valid and let the caller deal with that.  AFAICS the 
> > parser can only stop on a string terminator or optionally a comma, 
> > otherwise it issues an error.
> 
> And - can yacc do that?

 No idea.  With bison, according to documentation, the special "error" 
token might be a way of implementing that.  But I haven't done any real 
lex/yacc coding for years, so I'd have to refresh my dusty memory.

> Are you sure that there's no C expression that's valid with and without
> a trailing identifier, by the way?  I certainly find that believable,
> but I haven't thought about it too hard.

 Well, with C it seems to be true -- I can't recall any expression where a 
trailing identifier would be valid if not preceded by either a type cast, 
which by itself is not a valid expression, or an operator that accepts a 
right-side operand, which cannot be left dangling either.  But I'd have to 
have a look at the grammar spec to be sure I don't miss any obscure corner 
case.

  Maciej