RE: Re: command line parsing

From: Vladimir Prus (yg-boost-users_at_[hidden])
Date: 2003-04-17 09:24:12

Hi Ben,

Ben Hutchings wrote:

> A full solution will need to be a little bit more complicated.  There
> isn't a specification of how Windows command-lines should be generated
> or interpreted from an array of strings, but it seems to be sensible to
> interpret them in the same way as Microsoft's run-time library does it:
> 
> * Outside a quoted section, a double-quote begins a quoted section.
> * Outside a quoted section, a string of one or more spaces is a
>   separator if there are non-space characters both before and after it;
>   otherwise it's just padding.
> * Inside a quoted section, a double-quote preceded by an odd number of
>   backslashes (call this n) represents (n-1)/2 backslashes followed by
>   a double-quote.
> * Inside a quoted section, a double-quote preceded by an even number
>   of backslashes (possibly zero; call this n) represents n/2 backslashes
>   and ends the quoted section.
> * All other characters represent themselves.

Thanks for this explanation! Just tried with MinGw, and the argv array
appears to follow the rules you describe. For borland, however, the fancy
rules about backslahes do not apply. Backslash before double quote blocks
its special meaning, and backslash anywhere else has no effect.

(BTW, I really don't understand the point of collapsing "\\" only before
quotes.)

> Note that double-quotes are not separators and backslashes are not
> usually escape characters.  Also note that a quoted section does not
> have to be terminated.
> 
> tokenizer is probably not up to this job.  You could probably use
> regular expressions, but a custom state machine might be the best
> solution.

Yep, the existing tokenizer facilities won't work with this case. I'll see
about implementing either new tokenizing function or state machine.

Thanks,
Volodya