[augeas-devel] [PATCH] List handling shellvars_list lens added.

[Frederik Wagner]

Hi David,

On Sat, May 8, 2010 at 1:04 AM, David Lutterkort <lutter at redhat.com> wrote:
> On Thu, 2010-05-06 at 16:35 +0200, Frederik Wagner wrote:
>> @David: I included all your earlier suggestions about single values
>> w/o quotes and single as well as double quoted lists.
>
> Yes, I am very happy that you got that to work.
>
>> There are still two issues, where somebody might help:
>> 1. escaped characters are not handled (i.e. in a double quoted list
>> backpace escaped whitespaces or double quotes are not possible). This
>> does not work by simply including them in the "dqchar" regexp. Why?!
>
> You need to build a slightly more complicated regexp. For example,
> Shellvars.dquot is
>
>        let dquot = /"([^"\\\n]|\\\\.)*"/
>
> In English: a double quoted string is a string that starts and ends with
> '"', and contains any individual character except for '"' and '\n' or
> any two-character sequence '\.' - might take a little to wrap your head
> around ;)

yes... hmm, but I'm not sure why in '\\\\.' 4 backslashes are needed
for the the ecpade chars (it only works like this, but I don't get it
clear). Can you give me a hint?

>
> For your lens, you'd have to change list to take the full regexp for the
> word you're parsing, e.g. /([^"\\\n]|\\\\.)*/ instead of an individual
> character; something like (warning: not tested)
>
>   let list(word:regexp) =
>      let list_value = store word in
>      ...

Done.
I included your patch and the extended the escaped char handling.
Find attached the two patches on top of my original patch.

>
>> 2. When adding new values, the 'quote' key (defining the type of
>> quotes used) has to be added _before_ any other value. I do not
>> understand why the tree has to be sorted?
>
> The Augeas tree is orderd, i.e. the order in which nodes appear in a
> tree matters - that's a consequence of the fact that the tree reflects a
> file, which itself is ordered.

o.k., so a user has to know some structure of the lens.

> It would sometimes be nice, like in this case, to say "don't worry where
> the 'quote' node appears, always act as if it were the first
> node" (i.e., output the quote character before outputting any 'value'
> nodes), but there's no way to do that in Augeas currently. Would be a
> nice addition though[1] ;)

yes it would, but for the moment I'm happy if I have this running so far :-)

Hope the lens is o.k. now?!

Thanks for the help and bye,
Frederik

>
> David
>
> [1] Boomerang (http://www.seas.upenn.edu/~harmony/) has functionality to
> sort etc.
>
>
>
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