Re: Ada grammar

[Geoff Bull <gbull@acenet.com.au>]

Ray Blaak wrote:
> 
> Geoff Bull <gbull@acenet.com.au> writes:
> > I can't see why they would have to use the clients compiler.
> > Couldn't they just bundle gnat with their application?
> 
> Assuming the product is a commercial one, is one even allowed to do this under
> copyleft?

So long as you don't try to hoard any modifications to gnat.
The GPL is fairly easy to read.

> Gnat is  pretty big, and its installation is not completely trivial.

Ok, it is big.
But I would argue that the instalation IS completely trivial.
(especially since the user of such a tool can be expected to
 have a reasonable level of competency).


> The parser was a third-party tool,
> used precisely to save on the effort of developing one from scratch. It also
> was the major source of bugs, not because of errors in the parser
> implementation, but because its design did not fit well with the needs of the
> tool that was using it. 
> We ended up writing a Java parser from scratch anyways
> so as to have complete control over how information was extracted from the
> source files.

I don't see how you can extend this experience to reject the use 
of ASIS out of hand. ASIS was specifically designed for tools
such as the originally poster had in mind.

> 
> Once you have done a number of parsers for a number of languages, 
> writing another one is less of a daunting task than one would think.

I wrote a VHDL parser and I have had a good look at the gnat source.
I still find the idea of writing an Ada parser daunting.

> Note too, that there are better technologies than lex/yacc that 
> are more powerful, allowing for grammars that are easier to write
> and faster development times.

It is beyond me why people use lex for other than quick and dirty jobs,
writing custom lexers is so easy (and they are sooo much faster!)


> If you want a challenging task, try writing a Delphi parser sometime. The
> quirks and irregularities of that language make the grammars interesting to
> say the least. 
This is especially daunting since , TMK, Delphi's grammar is not
formally defined and changes at the whim of the owner's of that
language (as does the name of their company!).