qapi: Change visit_start_implicit_struct to visit_start_alternate

After recent changes, the only remaining use of
visit_start_implicit_struct() is for allocating the space needed
when visiting an alternate.  Since the term 'implicit struct' is
hard to explain, rename the function to its current usage.  While
at it, we can merge the functionality of visit_get_next_type()
into the same function, making it more like visit_start_struct().

Generated code is now slightly smaller:

| {
|     Error *err = NULL;
|
|-    visit_start_implicit_struct(v, (void**) obj, sizeof(BlockdevRef), &err);
|+    visit_start_alternate(v, name, (GenericAlternate **)obj, sizeof(**obj),
|+                          true, &err);
|     if (err) {
|         goto out;
|     }
|-    visit_get_next_type(v, name, &(*obj)->type, true, &err);
|-    if (err) {
|-        goto out_obj;
|-    }
|     switch ((*obj)->type) {
|     case QTYPE_QDICT:
|         visit_start_struct(v, name, NULL, 0, &err);
...
|     }
|-out_obj:
|-    visit_end_implicit_struct(v);
|+    visit_end_alternate(v);
| out:
|     error_propagate(errp, err);
| }

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <1455778109-6278-16-git-send-email-eblake@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>

1 files changed, 17 insertions, 23 deletions

diff --git a/qapi/qapi-visit-core.c b/qapi/qapi-visit-core.c
index f7b99807b0..856606b253 100644
--- a/qapi/qapi-visit-core.c
+++ b/qapi/qapi-visit-core.c
@@ -30,21 +30,6 @@ void visit_end_struct(Visitor *v, Error **errp)
     v->end_struct(v, errp);
 }
 
-void visit_start_implicit_struct(Visitor *v, void **obj, size_t size,
-                                 Error **errp)
-{
-    if (v->start_implicit_struct) {
-        v->start_implicit_struct(v, obj, size, errp);
-    }
-}
-
-void visit_end_implicit_struct(Visitor *v)
-{
-    if (v->end_implicit_struct) {
-        v->end_implicit_struct(v);
-    }
-}
-
 void visit_start_list(Visitor *v, const char *name, Error **errp)
 {
     v->start_list(v, name, errp);
@@ -61,20 +46,29 @@ void visit_end_list(Visitor *v)
     v->end_list(v);
 }
 
-bool visit_optional(Visitor *v, const char *name, bool *present)
+void visit_start_alternate(Visitor *v, const char *name,
+                           GenericAlternate **obj, size_t size,
+                           bool promote_int, Error **errp)
 {
-    if (v->optional) {
-        v->optional(v, name, present);
+    assert(obj && size >= sizeof(GenericAlternate));
+    if (v->start_alternate) {
+        v->start_alternate(v, name, obj, size, promote_int, errp);
+    }
+}
+
+void visit_end_alternate(Visitor *v)
+{
+    if (v->end_alternate) {
+        v->end_alternate(v);
     }
-    return *present;
 }
 
-void visit_get_next_type(Visitor *v, const char *name, QType *type,
-                         bool promote_int, Error **errp)
+bool visit_optional(Visitor *v, const char *name, bool *present)
 {
-    if (v->get_next_type) {
-        v->get_next_type(v, name, type, promote_int, errp);
+    if (v->optional) {
+        v->optional(v, name, present);
     }
+    return *present;
 }
 
 void visit_type_enum(Visitor *v, const char *name, int *obj,