Re: [Opencxx-users] parse error on valid code

[Shigeru C. <ch...@is...>]

From: Gabriel Dos Reis <gd...@in...>
Subject: Re: [Opencxx-users] parse error on valid code
Date: 27 Jul 2004 13:20:13 +0200

> | So my solution when I wrote OpenC++ was to write a LL(k) parser, which
> | is a LL parser that may perform backtracking.  Then, since LL(k)
> | parser is really powerful, a LL(k) parser does not need to maintain a
> | type-name table for parsing the C++ grammar at that time.  That's why
> | the OpenC++ parser does not maintain a type-name table.
> 
> Pardon my ignorance, but:  Did you really handle full C++ (at the
> time), or a specific subset.  The reason I'm asking is that if you do
> not know which names are type-names, e.g.
> 
>     f(a);
> 
> ?

The answer depends on what a parser should do. :)

The OpenC++ parser accepts the statement above as a correct program
but never gives the semantics of that statement since it does not
know whether or not f is a type name.  ClassWalker traverses on a syntax
tree to maintain a type-name table and give the semantics to statements.

So maybe I should say the OpenC++ parser is not a complete parser.  It
accepts not only correct C++ programs but also some wrong ones and
produces a syntax tree.  Error messages for the wrong programs are
reported by ClassWalker etc (at the next stage).

The grammar dealt with by the OpenC++ parser is a bit looser than the
correct(?) one.  But I think the border between syntax and semantics
is ambiguous at least from the implementation viewpoint.

Chiba