[augeas-devel] httpd.conf and beyond

[Francis Giraldeau]

lutter at redhat.com wrote:
> This series of patches adds support for context-free lenses, which means
> that Augeas can now process funky stuff like the Apache config.
>   

That's great! I looked at test lenses, and it seems really exciting.

> Patch 15/16 contains a generic lens for JSON[1] files, which is a very
> pleasant file format.
>   

I tried to load the lens without success. Here is what I got with
release 0.7.0 :

augtool> load
augtool: get.c:952: rec_process: Assertion `lens->tag == L_REC &&
lens->jmt != ((void *)0)' failed.

Will try with git tree before filling a bug...
> Strictly speaking, recursive lenses only support context-free languages in
> the get direction, i.e. the string -> tree direction. The put direction
> from tree to string is still based on regular trees - the tree language is
> expressive enough that it didn't seem to warrant an extension.
>   

What is exactly the implied limitation about the fact that put direction
is based on regular trees?

I saw that there is now an earley parser for recursive lens, is it used
only for context free lenses or for regular ones too? I remember that
regular expressions based parsing, even with regular approximations, was
a show stopper to support context free languages. Does the regular
approximation used only for ambiguity analysis?

Cheer,

Francis Giraldeau