qapi: Add new visit_free() function

Making each visitor provide its own (awkwardly-named) FOO_cleanup()
is unusual, when we can instead have a polymorphic visit_free()
interface.  Over the next few patches, we can use the polymorphic
functions to eliminate the need for a FOO_get_visitor() function
for accessing specific visitor functionality, once everything can
be accessed directly through the Visitor* interfaces.

The dealloc visitor is the first one converted to completely use
the new entry point, since qapi_dealloc_visitor_cleanup() was the
only reason that qapi_dealloc_get_visitor() existed, and only
generated and testsuite code was even using it.  With the new
visit_free() entry point in place, we no longer need to expose
the QapiDeallocVisitor subtype through qapi_dealloc_visitor_new(),
and can get by with less generated code, with diffs that look like:

| void qapi_free_ACPIOSTInfo(ACPIOSTInfo *obj)
| {
|-    QapiDeallocVisitor *qdv;
|     Visitor *v;
|
|     if (!obj) {
|         return;
|     }
|
|-    qdv = qapi_dealloc_visitor_new();
|-    v = qapi_dealloc_get_visitor(qdv);
|+    v = qapi_dealloc_visitor_new();
|     visit_type_ACPIOSTInfo(v, NULL, &obj, NULL);
|-    qapi_dealloc_visitor_cleanup(qdv);
|+    visit_free(v);
|}

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <1465490926-28625-5-git-send-email-eblake@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>

1 files changed, 3 insertions, 3 deletions

diff --git a/tests/test-visitor-serialization.c b/tests/test-visitor-serialization.c
index db781c0a79..bcbfd2aeb7 100644
--- a/tests/test-visitor-serialization.c
+++ b/tests/test-visitor-serialization.c
@@ -89,11 +89,11 @@ typedef void (*VisitorFunc)(Visitor *v, void **native, Error **errp);
 
 static void dealloc_helper(void *native_in, VisitorFunc visit, Error **errp)
 {
-    QapiDeallocVisitor *qdv = qapi_dealloc_visitor_new();
+    Visitor *v = qapi_dealloc_visitor_new();
 
-    visit(qapi_dealloc_get_visitor(qdv), &native_in, errp);
+    visit(v, &native_in, errp);
 
-    qapi_dealloc_visitor_cleanup(qdv);
+    visit_free(v);
 }
 
 static void visit_primitive_type(Visitor *v, void **native, Error **errp)