Eric Blake <ebl...@redhat.com> writes: > None of the visitor callbacks would set an error when testing > if an optional field was present; make this part of the interface > contract by eliminating the errp argument. Then, for less code, > reflect the determined boolean value back to the caller instead > of making the caller read the boolean after the fact. > > The resulting generated code has a nice diff: > > |- visit_optional(v, &has_fdset_id, "fdset-id", &err); > |- if (err) { > |- goto out; > |- } > |- if (has_fdset_id) { > |+ if (visit_optional(v, &has_fdset_id, "fdset-id")) { > | visit_type_int(v, &fdset_id, "fdset-id", &err); > | if (err) { > | goto out; > | } > | }
Any particular reason not to do has_fdset_id = visit_optional(v, "fdset-id"); if (has_fdset_id) { visit_type_int(v, &fdset_id, "fdset-id", &err); if (err) { goto out; } } ? > Signed-off-by: Eric Blake <ebl...@redhat.com> > > --- > v11 (no v10): no change > v9: no change > v8: no change > v7: rebase to no member.c_name() > v6: rebase onto earlier testsuite and gen_err_check() improvements > --- > include/qapi/visitor-impl.h | 5 ++--- > include/qapi/visitor.h | 10 ++++++++-- > qapi/opts-visitor.c | 2 +- > qapi/qapi-visit-core.c | 6 +++--- > qapi/qmp-input-visitor.c | 3 +-- > qapi/string-input-visitor.c | 3 +-- > scripts/qapi.py | 7 +------ > 7 files changed, 17 insertions(+), 19 deletions(-) > > diff --git a/include/qapi/visitor-impl.h b/include/qapi/visitor-impl.h > index ac6c17e..81d1aa0 100644 > --- a/include/qapi/visitor-impl.h > +++ b/include/qapi/visitor-impl.h > @@ -44,9 +44,8 @@ struct Visitor > void (*type_any)(Visitor *v, QObject **obj, const char *name, > Error **errp); > > - /* May be NULL */ > - void (*optional)(Visitor *v, bool *present, const char *name, > - Error **errp); > + /* May be NULL; most useful for input visitors. */ > + void (*optional)(Visitor *v, bool *present, const char *name); > > void (*type_uint8)(Visitor *v, uint8_t *obj, const char *name, Error > **errp); > void (*type_uint16)(Visitor *v, uint16_t *obj, const char *name, Error > **errp); > diff --git a/include/qapi/visitor.h b/include/qapi/visitor.h > index 250e8e1..dd4f0b3 100644 > --- a/include/qapi/visitor.h > +++ b/include/qapi/visitor.h > @@ -39,8 +39,14 @@ void visit_end_implicit_struct(Visitor *v, Error **errp); > void visit_start_list(Visitor *v, const char *name, Error **errp); > GenericList *visit_next_list(Visitor *v, GenericList **list, Error **errp); > void visit_end_list(Visitor *v, Error **errp); > -void visit_optional(Visitor *v, bool *present, const char *name, > - Error **errp); > + > +/** > + * Check if an optional member @name of an object needs visiting. > + * For input visitors, set *@present according to whether the > + * corresponding visit_type_*() needs calling; for other visitors, > + * leave *@present unchanged. Return *@present for convenience. > + */ > +bool visit_optional(Visitor *v, bool *present, const char *name); > > /** > * Determine the qtype of the item @name in the current object visit. > diff --git a/qapi/opts-visitor.c b/qapi/opts-visitor.c > index cd10392..ef5fb8b 100644 > --- a/qapi/opts-visitor.c > +++ b/qapi/opts-visitor.c > @@ -488,7 +488,7 @@ opts_type_size(Visitor *v, uint64_t *obj, const char > *name, Error **errp) > > > static void > -opts_optional(Visitor *v, bool *present, const char *name, Error **errp) > +opts_optional(Visitor *v, bool *present, const char *name) > { > OptsVisitor *ov = DO_UPCAST(OptsVisitor, visitor, v); > > diff --git a/qapi/qapi-visit-core.c b/qapi/qapi-visit-core.c > index 52c132a..daaa3af 100644 > --- a/qapi/qapi-visit-core.c > +++ b/qapi/qapi-visit-core.c > @@ -73,12 +73,12 @@ void visit_end_union(Visitor *v, bool data_present, Error > **errp) > } > } > > -void visit_optional(Visitor *v, bool *present, const char *name, > - Error **errp) > +bool visit_optional(Visitor *v, bool *present, const char *name) > { > if (v->optional) { > - v->optional(v, present, name, errp); > + v->optional(v, present, name); > } > + return *present; > } Slightly ugly: struct Visitor method optional returns void, but the wrapper returns bool. > > void visit_get_next_type(Visitor *v, QTypeCode *type, bool promote_int, > diff --git a/qapi/qmp-input-visitor.c b/qapi/qmp-input-visitor.c > index 4238faf..9f0ed69 100644 > --- a/qapi/qmp-input-visitor.c > +++ b/qapi/qmp-input-visitor.c > @@ -304,8 +304,7 @@ static void qmp_input_type_any(Visitor *v, QObject **obj, > const char *name, > *obj = qobj; > } > > -static void qmp_input_optional(Visitor *v, bool *present, const char *name, > - Error **errp) > +static void qmp_input_optional(Visitor *v, bool *present, const char *name) > { > QmpInputVisitor *qiv = to_qiv(v); > QObject *qobj = qmp_input_get_object(qiv, name, true); > diff --git a/qapi/string-input-visitor.c b/qapi/string-input-visitor.c > index bbd6a54..dee780a 100644 > --- a/qapi/string-input-visitor.c > +++ b/qapi/string-input-visitor.c > @@ -299,8 +299,7 @@ static void parse_type_number(Visitor *v, double *obj, > const char *name, > *obj = val; > } > > -static void parse_optional(Visitor *v, bool *present, const char *name, > - Error **errp) > +static void parse_optional(Visitor *v, bool *present, const char *name) > { > StringInputVisitor *siv = DO_UPCAST(StringInputVisitor, visitor, v); > > diff --git a/scripts/qapi.py b/scripts/qapi.py > index 1790e8f..b17f843 100644 > --- a/scripts/qapi.py > +++ b/scripts/qapi.py > @@ -1656,15 +1656,10 @@ def gen_visit_fields(members, prefix='', > need_cast=False, skiperr=False): > for memb in members: > if memb.optional: > ret += mcgen(''' > - visit_optional(v, &%(prefix)shas_%(c_name)s, "%(name)s", %(errp)s); > + if (visit_optional(v, &%(prefix)shas_%(c_name)s, "%(name)s")) { > ''', > prefix=prefix, c_name=c_name(memb.name), > name=memb.name, errp=errparg) > - ret += gen_err_check(skiperr=skiperr) > - ret += mcgen(''' > - if (%(prefix)shas_%(c_name)s) { > -''', > - prefix=prefix, c_name=c_name(memb.name)) > push_indent() > > # Ugly: sometimes we need to cast away const