[Qemu-devel] [RFC PATCH v7 17/18] qapi: Simplify gen_visit_fields() error handling

[Eric Blake <eblake@redhat.com>]

Since we have consolidated all generated code to use 'err' as
the name of the local variable for error detection, we can
simplify the decision on whether to skip error detection (useful
for deallocation paths) to be a boolean.

This requires the python 2.5 ternary syntax.

Signed-off-by: Eric Blake <eblake@redhat.com>

---
v7: new patch; rfc as it depends on Markus' configure change to
require python 2.6
---
 scripts/qapi-commands.py |  4 +---
 scripts/qapi.py          | 23 ++++++++++-------------
 2 files changed, 11 insertions(+), 16 deletions(-)

diff --git a/scripts/qapi-commands.py b/scripts/qapi-commands.py
index 9d214a6..43a893b 100644
--- a/scripts/qapi-commands.py
+++ b/scripts/qapi-commands.py
@@ -101,19 +101,17 @@ def gen_marshal_input_visit(arg_type, dealloc=False):
         return ret

     if dealloc:
-        errarg = None
         ret += mcgen('''
     qmp_input_visitor_cleanup(qiv);
     qdv = qapi_dealloc_visitor_new();
     v = qapi_dealloc_get_visitor(qdv);
 ''')
     else:
-        errarg = 'err'
         ret += mcgen('''
     v = qmp_input_get_visitor(qiv);
 ''')

-    ret += gen_visit_fields(arg_type.members, errarg=errarg)
+    ret += gen_visit_fields(arg_type.members, skiperr=dealloc)

     if dealloc:
         ret += mcgen('''
diff --git a/scripts/qapi.py b/scripts/qapi.py
index ada6380..7761b4b 100644
--- a/scripts/qapi.py
+++ b/scripts/qapi.py
@@ -1537,23 +1537,19 @@ def gen_params(arg_type, extra):
     return ret


-def gen_err_check(err='err', label='out'):
-    if not err:
+def gen_err_check(label='out', skiperr=False):
+    if skiperr:
         return ''
     return mcgen('''
-    if (%(err)s) {
+    if (err) {
         goto %(label)s;
     }
 ''',
-                 err=err, label=label)
+                 label=label)


-def gen_visit_fields(members, prefix='', need_cast=False, errarg='err'):
+def gen_visit_fields(members, prefix='', need_cast=False, skiperr=False):
     ret = ''
-    if errarg:
-        errparg = '&' + errarg
-    else:
-        errparg = 'NULL'

     for memb in members:
         if memb.optional:
@@ -1561,8 +1557,9 @@ def gen_visit_fields(members, prefix='', need_cast=False, errarg='err'):
     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(err=errarg)
+                         name=memb.name,
+                         errp='&err' if not skiperr else 'NULL')
+            ret += gen_err_check(skiperr=skiperr)
             ret += mcgen('''
     if (%(prefix)shas_%(c_name)s) {
 ''',
@@ -1580,8 +1577,8 @@ def gen_visit_fields(members, prefix='', need_cast=False, errarg='err'):
 ''',
                      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(err=errarg)
+                     errp='&err' if not skiperr else 'NULL')
+        ret += gen_err_check(skiperr=skiperr)

         if memb.optional:
             pop_indent()
-- 
2.4.3