Proper whitespace formatting in mini_xml_karma.cpp example code

Do you want pretty printing? Or do you want whitespace preservation, as
you seemingly say.

Regardless of the choice there, stateful pretty printing in  karma isn't
my favorite pastime. I always find that writing a visitor myself is less
work.

There's an old thread here:
http://boost.2283326.n4.nabble.com/Indentation-on-Karma-td2677502.html
that discusses a mechanism for inclusion in the library.

Related sample directives are here:
https://stackoverflow.com/questions/18085020/boostspiritkarma-how-to-get-current-position-of-output
(the answers are by llonesmiz from this list, usually recommendable).

I thought I'd have tackled this problem on SO myself once or twicewith
varying degrees of success. See e.g. this answer:
https://stackoverflow.com/a/46854802/85371 which is a followup to my
earlier answer that didn't use Karma. The topic is similar, but about
pretty-printing Json instead. In that answer I show how to do "the same"
but without karma, and you can see the difference. As I remember the
end-result wasn't as bad as I anticipated, so you might find it
perfectly viable :) I just glanced it over and I think it didn't go all
the way and left proper indenting as an "exercise for the reader".

Hope the info helps you,

Seth

 



On 17-04-18 08:52, Maarten Verhage wrote:
> Dear people,
>
> I'm using some CAD software tool that produces output that looks a bit like 
> xml. Certain values that are produced in these files are undesired in my 
> perspective. So I wish to change them automatically. Therefore I was 
> thinking that the mini_xml_karma example code of Spirit 2.5.3 is a good 
> starting point to write such an utility program. Correct?
>
> I've done some stuff with Spirit in the past but you still should consider 
> me a novice on this topic.
>
> Regarding the mini_xml_karma example code I managed to write the result to a 
> file. However the whitespace is removed from it, as was the case with the 
> original output to std::cout.
>
> My next objective is to generate proper whitespace. I've no need the 
> preserve the original line numbers so I can define my own formatting style 
> for this. I think something like the formatting of the "3.toyxml" file would 
> be fine. So, top hierarchy start tags should have a line feed directly after 
> it. Any line that follows should have indentation of some spaces until the 
> end tag. Subsequent start/end tags should be on the same line.
>
> Do you know of some example code that shows behavior like this? Or which 
> Spirit and/or Karma facilities should I be using to implement this?
>
> Thank you very much for your attention and time!
>
> Best regards,
> Maarten Verhage 
>
>
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