Re: [Qemu-devel] [PATCH 01/11] QMP: Introduce specification file

[Anthony Liguori <anthony@codemonkey.ws>]

Filip Navara wrote:
> On Fri, Jun 26, 2009 at 5:02 PM, Anthony Liguori<anthony@codemonkey.ws> wrote:
>   


> It answers some of the issues I had with the original protocol
> proposal (interruption of multi-line responses by asynchronous
> events). What bothers me though is that it's not LL(1) grammar (not a
> big problem, but writing LL parsers by hand is much easier)

Perhaps you mean LR(1) (i.e. something that can be understood by yacc).  
When writing parsers by hand, I tend to prefer recursive decent which 
easily handles LL(k).

Fortunately, this grammar is very simple and can be reasonable converted 
to LR(1).

>  and not
> all floats can be represented (eg. NaN).

I'm not sure that's so important.  JSON doesn't support NaN.

>  String is underdefined - does
> the syntax represent bytes or characters? If characters then the \nnn
> syntax is insufficient.

Strings are UTF-8.  Based on the definition of string, the only thing 
needing escaping is ", \\, and \n.  Anything else is just cosmetic.  My 
intention was for \nnn to be a single octal byte as an escape.  You 
could certainly use multiple escape sequences to encoding a large UTF 
character.

>  There's no syntax for binary data which may
> eventually be required (FDT machine description), but that can be
> relatively easily added with something like
>   

I don't think binary data is a requirement.  An FDT should be 
transmitted as a tree, not as a binary blob.  You could also transmit 
binary as a list of bytes though.

Regards,

Anthony Liguori