Re: [Qemu-devel] [PATCH 10/22] qapi: qapi.py, make json parser more robust

[Michael Roth <mdroth@linux.vnet.ibm.com>]

On Tue, Jul 24, 2012 at 05:23:33PM -0500, Anthony Liguori wrote:
> Michael Roth <mdroth@linux.vnet.ibm.com> writes:
> 
> > Currently the QAPI JSON parser expects a very particular style of code
> > indentation, the major one being that terminating curly/square brackets are
> > not on placed on a seperate line. This is incompatible with most
> > pretty-print formats, so make it a little more robust by supporting
> > these cases.
> 
> The code was supposed to just expect that all subsequent lines are
> indented.  This was to simplify the parser.  Can you provide an
> problematic example?

The main one was cases like this:

    mdroth@loki:~/w/qemu3.git$ cat example.json 
    {
        'a': 'test'
    }
    mdroth@loki:~/w/qemu3.git$ python scripts/qapi-types.py -o /tmp <example.json 
    Traceback (most recent call last):
      File "scripts/qapi-types.py", line 260, in <module>
        exprs = parse_schema(sys.stdin)
      File "/home/mdroth/dev/kvm/qemu3.git/scripts/qapi.py", line 76, in parse_schema
        expr_eval = evaluate(expr)
      File "/home/mdroth/dev/kvm/qemu3.git/scripts/qapi.py", line 62, in evaluate
        return parse(map(lambda x: x, tokenize(string)))[0]
      File "/home/mdroth/dev/kvm/qemu3.git/scripts/qapi.py", line 42, in parse
        if tokens[0] == ',':
    IndexError: list index out of range

I had it in my queue because it was what was preventing me from pretty-printing
the QIDL-generated schemas in V1, since python's pretty print stuff generally
puts the opening/closing braces at the same indent level. But now we store them
in the binary, and don't pretty-print those, so I don't think this is an issue
WRT this series anymore. Might still make sense to add it for future use-cases
though.

> 
> Regards,
> 
> Anthony Liguori
> [...]
>