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

[Markus Armbruster <armbru@redhat.com>]

Lluís Vilanova <vilanova@ac.upc.edu> writes:

> Adds the "include(...)" primitive to the syntax of QAPI schema files.
>
> Signed-off-by: Lluís Vilanova <vilanova@ac.upc.edu>
> ---
>  docs/qapi-code-gen.txt |    8 ++++++++
>  scripts/qapi.py        |   36 ++++++++++++++++++++++++++++++++++--
>  2 files changed, 42 insertions(+), 2 deletions(-)
>
> diff --git a/docs/qapi-code-gen.txt b/docs/qapi-code-gen.txt
> index 2e9f036..e007807 100644
> --- a/docs/qapi-code-gen.txt
> +++ b/docs/qapi-code-gen.txt
> @@ -40,6 +40,14 @@ enumeration types and union types.
>  Generally speaking, types definitions should always use CamelCase for the type
>  names. Command names should be all lower case with words separated by a hyphen.
>  
> +The QAPI schema definitions can be modularized using the 'include' directive:
> +
> + include("sub-system/qapi.json")

And now it isn't JSON anymore.

To keep it JSON, use syntax like

    { "include": "sub-system/qapi.json" }

If you absolutely must make it non-JSON, you better rename the .json
files.

Hmm, we already are non-JSON, because we use ' instead of " for no sane
reason.

Our JSON parser accepts ' as an extension, to save us quoting in C
strings.  That reason doesn't apply to .json files.

> +
> +All paths are interpreted as relative to the initial input file passed to the
> +QAPI parsing scripts.

Really?

Consider foo.json includes lib/a.json, which wants to include
lib/b.json.

foo.json:       include("lib/a.json")
lib/a.json:     include("lib/b.json")   # relative to foo.json's directory

Now throw in bar/bar.json including lib/a.json:

bar/bar.json:   include("../lib/a.json")
lib/a.json:     include("lib/b.json")   # relative to bar/ -> ENOENT

Make it relative to the file with the include directive.

> +
> +
>  === Complex types ===
>  
>  A complex type is a dictionary containing a single key whose value is a
[...]

Are you aware of Wenchao Xia's "[PATCH V8 00/10] qapi script: support
enum as discriminator and better enum name"?  I'm afraid there's a
(semantic?) conflict.  With include files, "[PATCH V8 03/10] qapi
script: remember line number in schema parsing" needs to remember the
source file, too.

Wenchao's series is likely go in first.  Perhaps you want to base on it
now.