[Qemu-devel] [PATCH RFC 3/5] qapi: Merge generation of per-member visits

[Eric Blake <eblake@redhat.com>]

Consolidate the code between visit and command marshalling that
iterates over the members of a struct.  It reduces code duplication
in the generator, with no change to generated marshal code, and
slightly more verbose (but no semantic change) in the generated
visit code:

|     visit_optional(v, &(*obj)->has_device, "device", &err);
|-    if (!err && (*obj)->has_device) {
|-        visit_type_str(v, &(*obj)->device, "device", &err);
|-    }
|     if (err) {
|         goto out;
|     }
|+    if ((*obj)->has_device) {
|+        visit_type_str(v, &(*obj)->device, "device", &err);
|+        if (err) {
|+            goto out;
|+        }
|+    }

Signed-off-by: Eric Blake <eblake@redhat.com>
---
 scripts/qapi-commands.py | 35 +----------------------------------
 scripts/qapi-visit.py    | 26 +-------------------------
 scripts/qapi.py          | 45 +++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 47 insertions(+), 59 deletions(-)

diff --git a/scripts/qapi-commands.py b/scripts/qapi-commands.py
index a30f79a..3eb3704 100644
--- a/scripts/qapi-commands.py
+++ b/scripts/qapi-commands.py
@@ -23,16 +23,6 @@ def gen_command_decl(name, arg_type, box, ret_type):
                  c_name=c_name(name),
                  params=gen_params(arg_type, box, 'Error **errp'))

-def gen_err_check(err):
-    if not err:
-        return ''
-    return mcgen('''
-if (%(err)s) {
-    goto out;
-}
-''',
-                 err=err)
-
 def gen_call(name, arg_type, box, ret_type):
     ret = ''

@@ -145,30 +135,7 @@ visit_type_%(c_name)s(v, &arg, NULL, %(errp)s);
                      c_name=arg_type.c_name(), errp=errparg)
         ret += gen_err_check(errarg)
     else:
-        for memb in arg_type.members:
-            if memb.optional:
-                ret += mcgen('''
-visit_optional(v, &has_%(c_name)s, "%(name)s", %(errp)s);
-''',
-                             c_name=c_name(memb.name), name=memb.name,
-                             errp=errparg)
-                ret += gen_err_check(errarg)
-                ret += mcgen('''
-if (has_%(c_name)s) {
-''',
-                             c_name=c_name(memb.name))
-                push_indent()
-            ret += mcgen('''
-visit_type_%(c_type)s(v, &%(c_name)s, "%(name)s", %(errp)s);
-''',
-                         c_name=c_name(memb.name), name=memb.name,
-                         c_type=memb.type.c_name(), errp=errparg)
-            ret += gen_err_check(errarg)
-            if memb.optional:
-                pop_indent()
-                ret += mcgen('''
-}
-''')
+        ret += gen_visit_fields(arg_type.members, '', errarg)

     if dealloc:
         ret += mcgen('''
diff --git a/scripts/qapi-visit.py b/scripts/qapi-visit.py
index 1fe6c64..edf97cb 100644
--- a/scripts/qapi-visit.py
+++ b/scripts/qapi-visit.py
@@ -95,31 +95,7 @@ if (err) {
 ''',
                      c_type=base.c_name())

-    for memb in members:
-        if memb.optional:
-            ret += mcgen('''
-visit_optional(v, &(*obj)->has_%(c_name)s, "%(name)s", &err);
-if (!err && (*obj)->has_%(c_name)s) {
-''',
-                         c_name=c_name(memb.name), name=memb.name)
-            push_indent()
-
-        ret += mcgen('''
-visit_type_%(c_type)s(v, &(*obj)->%(c_name)s, "%(name)s", &err);
-''',
-                     c_type=memb.type.c_name(), c_name=c_name(memb.name),
-                     name=memb.name)
-
-        if memb.optional:
-            pop_indent()
-            ret += mcgen('''
-}
-''')
-        ret += mcgen('''
-if (err) {
-    goto out;
-}
-''')
+    ret += gen_visit_fields(members, '(*obj)->', 'err')

     pop_indent()
     if base or members:
diff --git a/scripts/qapi.py b/scripts/qapi.py
index ac6d7f6..063d299 100644
--- a/scripts/qapi.py
+++ b/scripts/qapi.py
@@ -1456,6 +1456,51 @@ def gen_params(arg_type, box, extra):
         ret += sep + extra
     return ret

+def gen_err_check(err):
+    if not err:
+        return ''
+    return mcgen('''
+if (%(err)s) {
+    goto out;
+}
+''',
+                 err=err)
+
+def gen_visit_fields(members, prefix, errarg):
+    ret = ''
+    if errarg:
+        errparg = '&' + errarg
+    else:
+        errparg = 'NULL';
+    for memb in members:
+        if memb.optional:
+            ret += mcgen('''
+visit_optional(v, &%(prefix)shas_%(c_name)s, "%(name)s", %(errp)s);
+''',
+                         prefix=prefix, c_name=c_name(memb.name),
+                         name=memb.name, errp=errparg)
+            ret += gen_err_check(errarg)
+            ret += mcgen('''
+if (%(prefix)shas_%(c_name)s) {
+''',
+                         prefix=prefix, c_name=c_name(memb.name))
+            push_indent()
+
+        ret += mcgen('''
+visit_type_%(c_type)s(v, &%(prefix)s%(c_name)s, "%(name)s", %(errp)s);
+''',
+                     c_type=memb.type.c_name(), prefix=prefix,
+                     c_name=c_name(memb.name), name=memb.name,
+                     errp=errparg)
+        ret += gen_err_check(errarg)
+
+        if memb.optional:
+            pop_indent()
+            ret += mcgen('''
+}
+''')
+    return ret
+
 #
 # Common command line parsing
 #
-- 
2.4.3