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, 10 insertions, 18 deletions

diff --git a/docs/qapi-code-gen.txt b/docs/qapi-code-gen.txt
index 0ae239ad6c..db9d5b6357 100644
--- a/docs/qapi-code-gen.txt
+++ b/docs/qapi-code-gen.txt
@@ -802,32 +802,28 @@ Example:
 
     void qapi_free_UserDefOne(UserDefOne *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_UserDefOne(v, NULL, &obj, NULL);
-        qapi_dealloc_visitor_cleanup(qdv);
+        visit_free(v);
     }
 
     void qapi_free_UserDefOneList(UserDefOneList *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_UserDefOneList(v, NULL, &obj, NULL);
-        qapi_dealloc_visitor_cleanup(qdv);
+        visit_free(v);
     }
 
 === scripts/qapi-visit.py ===
@@ -985,7 +981,6 @@ Example:
     {
         Error *err = NULL;
         QmpOutputVisitor *qov = qmp_output_visitor_new();
-        QapiDeallocVisitor *qdv;
         Visitor *v;
 
         v = qmp_output_get_visitor(qov);
@@ -997,11 +992,10 @@ Example:
 
     out:
         error_propagate(errp, err);
-        qmp_output_visitor_cleanup(qov);
-        qdv = qapi_dealloc_visitor_new();
-        v = qapi_dealloc_get_visitor(qdv);
+        visit_free(v);
+        v = qapi_dealloc_visitor_new();
         visit_type_UserDefOne(v, "unused", &ret_in, NULL);
-        qapi_dealloc_visitor_cleanup(qdv);
+        visit_free(v);
     }
 
     static void qmp_marshal_my_command(QDict *args, QObject **ret, Error **errp)
@@ -1009,7 +1003,6 @@ Example:
         Error *err = NULL;
         UserDefOne *retval;
         QmpInputVisitor *qiv = qmp_input_visitor_new(QOBJECT(args), true);
-        QapiDeallocVisitor *qdv;
         Visitor *v;
         UserDefOneList *arg1 = NULL;
 
@@ -1036,13 +1029,12 @@ Example:
 
     out:
         error_propagate(errp, err);
-        qmp_input_visitor_cleanup(qiv);
-        qdv = qapi_dealloc_visitor_new();
-        v = qapi_dealloc_get_visitor(qdv);
+        visit_free(v);
+        v = qapi_dealloc_visitor_new();
         visit_start_struct(v, NULL, NULL, 0, NULL);
         visit_type_UserDefOneList(v, "arg1", &arg1, NULL);
         visit_end_struct(v, NULL);
-        qapi_dealloc_visitor_cleanup(qdv);
+        visit_free(v);
     }
 
     static void qmp_init_marshal(void)