Hi
On Fri, May 21, 2021 at 3:58 PM Markus Armbruster <arm...@redhat.com> wrote:
> marcandre.lur...@redhat.com writes:
>
> > From: Marc-André Lureau <marcandre.lur...@redhat.com>
> >
> > Signed-off-by: Marc-André Lureau <marcandre.lur...@redhat.com>
> > Reviewed-by: Stefan Hajnoczi <stefa...@redhat.com>
> > Tested-by: John Snow <js...@redhat.com>
> > ---
> > docs/devel/qapi-code-gen.txt | 27 ++++++++++++++++-----------
> > 1 file changed, 16 insertions(+), 11 deletions(-)
> >
> > diff --git a/docs/devel/qapi-code-gen.txt b/docs/devel/qapi-code-gen.txt
> > index edaaf7ec40..4a3fd02723 100644
> > --- a/docs/devel/qapi-code-gen.txt
> > +++ b/docs/devel/qapi-code-gen.txt
> > @@ -780,26 +780,31 @@ downstream command __com.redhat_drive-mirror.
> > === Configuring the schema ===
> >
> > Syntax:
> > - COND = STRING
> > - | [ STRING, ... ]
> > + COND = CFG-ID
> > + | [ COND, ... ]
> > + | { 'all: [ COND, ... ] }
> > + | { 'any: [ COND, ... ] }
> > + | { 'not': COND }
> >
> > -All definitions take an optional 'if' member. Its value must be a
> > -string or a list of strings. A string is shorthand for a list
> > -containing just that string. The code generated for the definition
> > -will then be guarded by #if STRING for each STRING in the COND list.
> > + CFG-ID = STRING
> > +
> > +All definitions take an optional 'if' member. Its value must be a
> string, a list
> > +of strings or an object with a single member 'all', 'any' or 'not'. A
> string is
> > +shorthand for a list containing just that string. A list is a shorthand
> for a
> > +'all'-member object. The C code generated for the definition will then
> be guarded
>
> Please try to make your changes blend into the existing text: limit line
> length to 70 characters, and put two spaces between sentences.
>
ok
> I doubt the CFG-ID non-terminal is useful. Elsewhere, we do without,
> e.g. ENUM-VALUE, ALTERNATIVE, FEATURE.
>
> Sure the [ COND, ... ] sugar is worth the bother?
>
Maybe not
> Perhaps
>
> COND = STRING
> | { 'all: [ COND, ... ] }
> | { 'any: [ COND, ... ] }
> | { 'not': COND }
>
> All definitions take an optional 'if' member. The form STRING is
> shorthand for { 'any': [ STRING ] }. The C code generated ...
>
ok
> > +by an #if precessor expression generated from that condition: 'all':
> [COND, ...]
> > +will generate '(COND && ...)', 'any': [COND, ...] '(COND || ...)',
> 'not': COND '!COND'.
>
> The technical term is "#if preprocessing directive". Let's use it.
>
ok
> I find the last part unnecessarily hard to read. What about:
>
> ... generated from that condition:
>
> * { 'all': [COND, ...] } will generate #if (COND && ...)
> * { 'any': [COND, ...] } will generate #if (COND || ...)
> * { 'not': COND } will generate #if !COND
>
>
Yes!
>
> > Example: a conditional struct
> >
> > { 'struct': 'IfStruct', 'data': { 'foo': 'int' },
> > - 'if': ['CONFIG_FOO', 'HAVE_BAR'] }
> > + 'if': { 'all': [ 'CONFIG_FOO', 'HAVE_BAR' ] } }
> >
> > gets its generated code guarded like this:
> >
> > - #if defined(CONFIG_FOO)
> > - #if defined(HAVE_BAR)
> > + #if defined(CONFIG_FOO) && defined(HAVE_BAR)
> > ... generated code ...
> > - #endif /* defined(HAVE_BAR) */
> > - #endif /* defined(CONFIG_FOO) */
> > + #endif /* defined(HAVE_BAR) && defined(CONFIG_FOO) */
> >
> > Individual members of complex types, commands arguments, and
> > event-specific data can also be made conditional. This requires the
>
>
>
thanks
--
Marc-André Lureau
