Re: [Qemu-devel] [PATCH v4 2/4] scripts: qmp-shell: Expand support for QMP expressions

[Eric Blake]

On 04/29/2015 01:14 PM, John Snow wrote:
> This includes support for [] expressions, single-quotes in
> QMP expressions (which is not strictly a part of JSON), and
> the ability to use "True", "False" and "None" literals instead
> of JSON's equivalent true, false, and null literals.
> 
> qmp-shell currently allows you to describe values as
> JSON expressions:
> key={"key":{"key2":"val"}}
> 
> But it does not currently support arrays, which are needed
> for serializing and deserializing transactions:
> key=[{"type":"drive-backup","data":{...}}]
> 
> qmp-shell also only currently accepts doubly quoted strings
> as-per JSON spec, but QMP allows single quotes.
> 
> Lastly, python allows you to utilize "True" or "False" as
> boolean literals, but JSON expects "true" or "false". Expand
> qmp-shell to allow the user to type either, converting to the
> correct type.
> 
> As a consequence of the above, the key=val parsing is also improved
> to give better error messages if a key=val token is not provided.
> 
> CAVEAT: The parser is still extremely rudimentary and does not
> expect to find spaces in {} nor [] expressions. This patch does
> not improve this functionality.
> 
> Signed-off-by: John Snow <address@hidden>
> ---
>  scripts/qmp/qmp-shell | 63 
> ++++++++++++++++++++++++++++++++++++++-------------
>  1 file changed, 47 insertions(+), 16 deletions(-)
> 

>  
> +class FuzzyJSON(ast.NodeTransformer):
> +    '''This extension of ast.NodeTransformer filters literal 
> "true/false/null"
> +    values in an AST and replaces them by proper "True/False/None" values 
> that
> +    Python can properly evaluate.'''
> +    def visit_Name(self, node):
> +        if node.id == 'true':
> +            node.id = 'True'
> +        if node.id == 'false':
> +            node.id = 'False'
> +        if node.id == 'null':
> +            node.id = 'None'
> +        return node

Cute!

Reviewed-by: Eric Blake <address@hidden>

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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