Eric Blake <ebl...@redhat.com> writes: > From: Markus Armbruster <arm...@redhat.com> > > For a simple union SU, gen_visit_union() generates a visit of its > single tag member, like this: > > visit_type_SUKind(v, "type", &(*obj)->type, &err); > > For a flat union FU with base B, it generates a visit of its base > fields: > > visit_type_B_fields(v, (B **)obj, &err); > > Instead, we can simply visit the common members using the same fields > visit function we use for structs, generated with > gen_visit_struct_fields(). This function visits the base if any, then > the local members. > > For a simple union SU, visit_type_SU_fields() contains exactly the old > tag member visit, because there is no base, and the tag member is the > only member. For instance, the code generated for qapi-schema.json's > KeyValue changes like this: > > +static void visit_type_KeyValue_fields(Visitor *v, KeyValue **obj, Error > **errp) > +{ > + Error *err = NULL; > + > + visit_type_KeyValueKind(v, "type", &(*obj)->type, &err); > + error_propagate(errp, err); > +} > + > void visit_type_KeyValue(Visitor *v, const char *name, KeyValue **obj, > Error **errp) > { > Error *err = NULL; > @@ -4863,7 +4911,7 @@ void visit_type_KeyValue(Visitor *v, con > if (!*obj) { > goto out_obj; > } > - visit_type_KeyValueKind(v, "type", &(*obj)->type, &err); > + visit_type_KeyValue_fields(v, obj, &err); > if (err) { > goto out_obj; > } > > For a flat union FU, visit_type_FU_fields() contains exactly the old > base fields visit, because there is a base, but no members. For > instance, the code generated for qapi-schema.json's CpuInfo changes > like this: > > static void visit_type_CpuInfoBase_fields(Visitor *v, CpuInfoBase **obj, > Error **errp); > > +static void visit_type_CpuInfo_fields(Visitor *v, CpuInfo **obj, Error > **errp) > +{ > + Error *err = NULL; > + > + visit_type_CpuInfoBase_fields(v, (CpuInfoBase **)obj, &err); > + error_propagate(errp, err); > +} > + > static void visit_type_CpuInfoX86_fields(Visitor *v, CpuInfoX86 **obj, > Error **errp) > ... > @@ -3485,7 +3509,7 @@ void visit_type_CpuInfo(Visitor *v, cons > if (!*obj) { > goto out_obj; > } > - visit_type_CpuInfoBase_fields(v, (CpuInfoBase **)obj, &err); > + visit_type_CpuInfo_fields(v, obj, &err); > if (err) { > goto out_obj; > } > > As you see, the generated code grows a bit, but in practice, it's lost > in the noise: qapi-schema.json's qapi-visit.c gains roughly 1%. > > This simplification became possible with commit 441cbac "qapi-visit: > Convert to QAPISchemaVisitor, fixing bugs". It's a step towards > unifying gen_struct() and gen_union(). > > Signed-off-by: Markus Armbruster <arm...@redhat.com> > Message-Id: <1453902888-20457-2-git-send-email-arm...@redhat.com> > [rebase to avoid pointless gotos in new code]
Also: examples in commit message replaced by better ones :) > Signed-off-by: Eric Blake <ebl...@redhat.com>