[Qemu-devel] [PATCH v5 10/46] qapi: Merge generation of per-member visits

[Eric Blake <eblake@redhat.com>]

Consolidate the code between visit, command marshalling, and
event generation that iterates over the members of a struct.
It reduces code duplication in the generator, with no change to
generated marshal code, slightly more verbose 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;
|+        }
|+    }

and slightly more verbose event code (recall that the qmp
output visitor has a no-op visit_optional()):

|+    visit_optional(v, &has_offset, "offset", &err);
|+    if (err) {
|+        goto out;
|+    }
|     if (has_offset) {
|         visit_type_int(v, &offset, "offset", &err);

Signed-off-by: Eric Blake <eblake@redhat.com>
---
 scripts/qapi-commands.py | 38 +---------------------------------
 scripts/qapi-event.py    | 35 +++-----------------------------
 scripts/qapi-visit.py    | 26 +-----------------------
 scripts/qapi.py          | 53 ++++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 58 insertions(+), 94 deletions(-)

diff --git a/scripts/qapi-commands.py b/scripts/qapi-commands.py
index 2151120..55287b1 100644
--- a/scripts/qapi-commands.py
+++ b/scripts/qapi-commands.py
@@ -25,17 +25,6 @@ def gen_command_decl(name, arg_type, ret_type):
                  params=gen_params(arg_type, '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, ret_type):
     ret = ''

@@ -119,7 +108,6 @@ def gen_marshal_input_visit(arg_type, dealloc=False):
     push_indent()

     if dealloc:
-        errparg = 'NULL'
         errarg = None
         ret += mcgen('''
 qmp_input_visitor_cleanup(mi);
@@ -127,36 +115,12 @@ md = qapi_dealloc_visitor_new();
 v = qapi_dealloc_get_visitor(md);
 ''')
     else:
-        errparg = '&err'
         errarg = 'err'
         ret += mcgen('''
 v = qmp_input_get_visitor(mi);
 ''')

-    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, '', False, errarg)

     if dealloc:
         ret += mcgen('''
diff --git a/scripts/qapi-event.py b/scripts/qapi-event.py
index b43bbc2..6c70a06 100644
--- a/scripts/qapi-event.py
+++ b/scripts/qapi-event.py
@@ -74,38 +74,9 @@ def gen_event_send(name, arg_type):

 ''',
                      name=name)
-
-        for memb in arg_type.members:
-            if memb.optional:
-                ret += mcgen('''
-    if (has_%(c_name)s) {
-''',
-                             c_name=c_name(memb.name))
-                push_indent()
-
-            # Ugly: need to cast away the const
-            if memb.type.name == "str":
-                cast = '(char **)'
-            else:
-                cast = ''
-
-            ret += mcgen('''
-    visit_type_%(c_type)s(v, %(cast)s&%(c_name)s, "%(name)s", &err);
-    if (err) {
-        goto out;
-    }
-''',
-                         cast=cast,
-                         c_name=c_name(memb.name),
-                         c_type=memb.type.c_name(),
-                         name=memb.name)
-
-            if memb.optional:
-                pop_indent()
-                ret += mcgen('''
-    }
-''')
-
+        push_indent()
+        ret += gen_visit_fields(arg_type.members, '', True, 'err')
+        pop_indent()
         ret += mcgen('''

     visit_end_struct(v, &err);
diff --git a/scripts/qapi-visit.py b/scripts/qapi-visit.py
index 9c0328d..1f287ba 100644
--- a/scripts/qapi-visit.py
+++ b/scripts/qapi-visit.py
@@ -88,31 +88,7 @@ if (err) {
 ''',
                      c_type=base.c_name(), c_name=c_name('base'))

-    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)->', False, 'err')

     pop_indent()
     if re.search('^ *goto out;', ret, re.MULTILINE):
diff --git a/scripts/qapi.py b/scripts/qapi.py
index 6f4e471..7275daa 100644
--- a/scripts/qapi.py
+++ b/scripts/qapi.py
@@ -1531,6 +1531,59 @@ def gen_params(arg_type, 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, need_cast, 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()
+
+        # Ugly: sometimes we need to cast away const
+        if need_cast and memb.type.name == 'str':
+            cast = '(char **)'
+        else:
+            cast = ''
+
+        ret += mcgen('''
+visit_type_%(c_type)s(v, %(cast)s&%(prefix)s%(c_name)s, "%(name)s", %(errp)s);
+''',
+                     c_type=memb.type.c_name(), prefix=prefix, cast=cast,
+                     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