Re: Implementing an Ada compiler and libraries.

[Lucretia <lucretia9@lycos.co.uk>]

On May 11, 11:06 pm, Robert A Duff <bobd...@shell01.TheWorld.com>
wrote:
> Lucretia <lucret...@lycos.co.uk> writes:
> > True, but how would a compiler that didn't impose limits (are there
> > any?) manage to find compilation units with'd?
>
> Here's one way:
>
> I presume the way one invokes the compiler is via a "build" tool of some
> sort (something like gnatmake or adabuild).
>
> Keep a data structure that tells which compilation units are in which
> source files.  Whenever the build tool is invoked, it first parses all
> the files that changed since last time, and updates this data structure.
> If any files are new, they need to be parsed.  If any files have been
> deleted, all information about them in the data structure should be
> deleted.  You can store this data structure on disk, if you like.

So, essentially you're saying create a project file which lists which
compilation units are in which files then the build tool will know
where they are?

> At this point, give an error if there are duplicate names (unless the
> user has explicitly requested that one should override the other).
>
> Now you have all the information you need to run the rest of the
> compiler phases (after parsing) on everything in the right order
> (or partially in parallel).
>
> I know this method can be implemented efficiently, because I've done it
> several times (not for Ada compilers, but for other language processing
> tools (Ada and non-Ada)).
>
> >... At least with GNAT it
> > uses package name => filename, so that's easy to implement, but with
> > multiple compilation units per file, it's much more tricky. I've
> > basically thought the only way to partially do it is to compile the
> > source into a parse tree, then traverse it to generate the AST,
>
> Generate the AST from the parse tree?  I normally generate the syntax
> tree directly during parsing.

Well, I was thinking that as you didn't know which compilation units
were in which files, then building a tree without checking, you can
then parse the tree and when you hit a "with" node, you then start
looking for other compilation units.

Just a thought ;D

Thanks,
Luke.