Re: [Qemu-devel] [PATCH v4 2/3] qapi: Add a primitive to include other files from a QAPI schema file

[Benoît Canet]

The Thursday 13 Mar 2014 à 09:54:15 (-0600), Eric Blake wrote :
> On 03/13/2014 09:33 AM, Benoît Canet wrote:
> 
> >> We certainly can't do without comments.
> >>
> >> JSON is designed for easy data exchange, but we use it as programming
> >> language syntax.  Its restrictions make sense for easy data exchange,
> >> but hurt our use.  We're not the first ones experiencing that pain:
> >> http://json5.org/
> >>
> >> No idea how much momentum this JSON5 thingy has...
> 
> If we 's,#,//,', our comments magically fall in line with JSON5 syntax;
> everything else in our files is already compliant with JSON5.

Not really qapi-schema.json is missing comas between types to be a
valid json file.

The fragment:

{ 'type'  : 'InputBtnEvent',
  'data'  : { 'button'  : 'InputButton',
              'down'    : 'bool' } }

{ 'type'  : 'InputMoveEvent',
  'data'  : { 'axis'    : 'InputAxis',
              'value'   : 'int' } }

Should be:

[

{ 'type'  : 'InputBtnEvent',
  'data'  : { 'button'  : 'InputButton',
              'down'    : 'bool' } },

{ 'type'  : 'InputMoveEvent',
  'data'  : { 'axis'    : 'InputAxis',
              'value'   : 'int' } }

]

to hope being a valid json file.

Best regards

Benoît

> 
> >>
> >> Switch to JSON5 and call it qapi-schema.json5?
> 
> This actually seems like a rather nice idea - but due to our choice of
> comments, it means rewriting the bulk of the file and tweaking our parser.
> 
> >>
> > 
> > Hmm don't we want something that python and other language know how to 
> > parse out
> > of the box ? Or will we write yet another delicate work of art to parse it ?
> 
> Our existing parser would only need to learn a new comment syntax to
> parse the subset of JSON5 that we currently actually use.  Parsing FULL
> JSON5 would mean also learning about trailing commas, unquoted names in
> name:value pairs, multiline strings, and alternative numeric
> representations.  But a point made on the JSON5 page is that ES5
> JavaScript already parses JSON5, just as it already parses original JSON.
> 
> -- 
> Eric Blake   eblake redhat com    +1-919-301-3266
> Libvirt virtualization library http://libvirt.org
>