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qapi: Share gen_visit_fields()

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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, so that a future
patch can reduce the size of generated code while touching only
one instead of three locations.

There are no changes to the generated marshal code.

The visitor code becomes slightly more verbose, but remains
semantically equivalent, and is actually easier to read as
it follows a more common idiom:

|     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;
|+        }
|+    }

The event code becomes slightly more verbose, but this is
arguably a bug fix: although the visitors are not well
documented, use of an optional member should not be attempted
unless guarded by a prior call to visit_optional().  Works only
because the output qmp 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>
Message-Id: <1443565276-4535-17-git-send-email-eblake@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
This commit is contained in:
Eric Blake 2015-09-29 16:21:14 -06:00 committed by Markus Armbruster
parent 1f35334489
commit 82ca8e4696
4 changed files with 46 additions and 77 deletions
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27
scripts/qapi-commands.py
View File

@ -101,7 +101,6 @@ def gen_marshal_input_visit(arg_type, dealloc=False):
return ret
if dealloc:
errparg = 'NULL'
errarg = None
ret += mcgen('''
qmp_input_visitor_cleanup(qiv);
@ -109,36 +108,12 @@ def gen_marshal_input_visit(arg_type, dealloc=False):
v = qapi_dealloc_get_visitor(qdv);
''')
else:
errparg = '&err'
errarg = 'err'
ret += mcgen('''
v = qmp_input_get_visitor(qiv);
''')
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(err=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(err=errarg)
if memb.optional:
pop_indent()
ret += mcgen('''
}
''')
ret += gen_visit_fields(arg_type.members, errarg=errarg)
if dealloc:
ret += mcgen('''

31
scripts/qapi-event.py
View File

@ -71,36 +71,7 @@ def gen_event_send(name, arg_type):
''',
name=name)
ret += gen_err_check()
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);
''',
cast=cast,
c_name=c_name(memb.name),
c_type=memb.type.c_name(),
name=memb.name)
ret += gen_err_check()
if memb.optional:
pop_indent()
ret += mcgen('''
}
''')
ret += gen_visit_fields(arg_type.members, need_cast=True)
ret += mcgen('''
visit_end_struct(v, &err);
if (err) {

22
scripts/qapi-visit.py
View File

@ -85,27 +85,7 @@ static void visit_type_%(c_name)s_fields(Visitor *v, %(c_name)s **obj, Error **e
c_type=base.c_name(), c_name=c_name('base'))
ret += gen_err_check()
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 += gen_err_check()
ret += gen_visit_fields(members, prefix='(*obj)->')
if re.search('^ *goto out;', ret, re.MULTILINE):
ret += mcgen('''

43
scripts/qapi.py
View File

@ -1548,6 +1548,49 @@ def gen_err_check(err='err', label='out'):
err=err, label=label)
def gen_visit_fields(members, prefix='', need_cast=False, errarg='err'):
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(err=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(err=errarg)
if memb.optional:
pop_indent()
ret += mcgen('''
}
''')
return ret
#
# Common command line parsing
#