Message ID | 20210517163040.2308926-10-marcandre.lureau@redhat.com (mailing list archive) |
---|---|
State | New, archived |
Headers | show |
Series | qapi: untie 'if' conditions from C preprocessor | expand |
marcandre.lureau@redhat.com writes: > From: Marc-André Lureau <marcandre.lureau@redhat.com> > > Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com> > Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> > Tested-by: John Snow <jsnow@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. 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? 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 ... > +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. 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 > > 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
Hi On Fri, May 21, 2021 at 3:58 PM Markus Armbruster <armbru@redhat.com> wrote: > marcandre.lureau@redhat.com writes: > > > From: Marc-André Lureau <marcandre.lureau@redhat.com> > > > > Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com> > > Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> > > Tested-by: John Snow <jsnow@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
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 +by an #if precessor expression generated from that condition: 'all': [COND, ...] +will generate '(COND && ...)', 'any': [COND, ...] '(COND || ...)', 'not': COND '!COND'. 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