From e25370368e98e6d8766e50b7f13e3543e1c3ef9b Mon Sep 17 00:00:00 2001
From: Kevin Wolf <kwolf@redhat.com>
Date: Mon, 9 Sep 2013 14:28:12 +0200
Subject: [PATCH 21/38] qapi: Flat unions with arbitrary discriminator
RH-Author: Kevin Wolf <kwolf@redhat.com>
Message-id: <1378736903-18489-22-git-send-email-kwolf@redhat.com>
Patchwork-id: 54208
O-Subject: [RHEL-7.0 qemu-kvm PATCH 21/32] qapi: Flat unions with arbitrary discriminator
Bugzilla: 1005818
RH-Acked-by: Fam Zheng <famz@redhat.com>
RH-Acked-by: Max Reitz <mreitz@redhat.com>
RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>
Bugzilla: 1005818
Instead of the rather verbose syntax that distinguishes base and
subclass fields...
{ "type": "file",
"read-only": true,
"data": {
"filename": "test"
} }
...we can now have both in the same namespace, allowing a more direct
mapping of the command line, and moving fields between the common base
and subclasses without breaking the API:
{ "driver": "file",
"read-only": true,
"filename": "test" }
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
(cherry picked from commit 50f2bdc75c5ee00617ad874c9ceac2cea660aa1e)
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
docs/qapi-code-gen.txt | 22 ++++++++++++
scripts/qapi-types.py | 11 ++++--
scripts/qapi-visit.py | 90 +++++++++++++++++++++++++++++++++++++-------------
3 files changed, 98 insertions(+), 25 deletions(-)
Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
---
docs/qapi-code-gen.txt | 22 ++++++++++++
scripts/qapi-types.py | 11 +++++-
scripts/qapi-visit.py | 90 +++++++++++++++++++++++++++++++++++------------
3 files changed, 98 insertions(+), 25 deletions(-)
diff --git a/docs/qapi-code-gen.txt b/docs/qapi-code-gen.txt
index f6f8d33..11f19cf 100644
--- a/docs/qapi-code-gen.txt
+++ b/docs/qapi-code-gen.txt
@@ -103,6 +103,28 @@ And it looks like this on the wire:
"data" : { "backing-file": "/some/place/my-image",
"lazy-refcounts": true } }
+
+Flat union types avoid the nesting on the wire. They are used whenever a
+specific field of the base type is declared as the discriminator ('type' is
+then no longer generated). The discriminator must always be a string field.
+The above example can then be modified as follows:
+
+ { 'type': 'BlockdevCommonOptions',
+ 'data': { 'driver': 'str', 'readonly': 'bool' } }
+ { 'union': 'BlockdevOptions',
+ 'base': 'BlockdevCommonOptions',
+ 'discriminator': 'driver',
+ 'data': { 'raw': 'RawOptions',
+ 'qcow2': 'Qcow2Options' } }
+
+Resulting in this JSON object:
+
+ { "driver": "qcow2",
+ "readonly": false,
+ "backing-file": "/some/place/my-image",
+ "lazy-refcounts": true }
+
+
=== Commands ===
Commands are defined by using a list containing three members. The first
diff --git a/scripts/qapi-types.py b/scripts/qapi-types.py
index c0684a7..f139bfe 100644
--- a/scripts/qapi-types.py
+++ b/scripts/qapi-types.py
@@ -135,7 +135,9 @@ def generate_union(expr):
name = expr['union']
typeinfo = expr['data']
+
base = expr.get('base')
+ discriminator = expr.get('discriminator')
ret = mcgen('''
struct %(name)s
@@ -158,8 +160,13 @@ struct %(name)s
''')
if base:
- struct = find_struct(base)
- ret += generate_struct_fields(struct['data'])
+ base_fields = find_struct(base)['data']
+ if discriminator:
+ base_fields = base_fields.copy()
+ del base_fields[discriminator]
+ ret += generate_struct_fields(base_fields)
+ else:
+ assert not discriminator
ret += mcgen('''
};
diff --git a/scripts/qapi-visit.py b/scripts/qapi-visit.py
index be56ba4..b1c1ad6 100644
--- a/scripts/qapi-visit.py
+++ b/scripts/qapi-visit.py
@@ -17,8 +17,30 @@ import os
import getopt
import errno
-def generate_visit_struct_fields(field_prefix, members):
+def generate_visit_struct_fields(name, field_prefix, fn_prefix, members):
+ substructs = []
ret = ''
+ full_name = name if not fn_prefix else "%s_%s" % (name, fn_prefix)
+
+ for argname, argentry, optional, structured in parse_args(members):
+ if structured:
+ if not fn_prefix:
+ nested_fn_prefix = argname
+ else:
+ nested_fn_prefix = "%s_%s" % (fn_prefix, argname)
+
+ nested_field_prefix = "%s%s." % (field_prefix, argname)
+ ret += generate_visit_struct_fields(name, nested_field_prefix,
+ nested_fn_prefix, argentry)
+
+ ret += mcgen('''
+
+static void visit_type_%(full_name)s_fields(Visitor *m, %(name)s ** obj, Error **errp)
+{
+ Error *err = NULL;
+''',
+ name=name, full_name=full_name)
+ push_indent()
for argname, argentry, optional, structured in parse_args(members):
if optional:
@@ -31,7 +53,7 @@ if (obj && (*obj)->%(prefix)shas_%(c_name)s) {
push_indent()
if structured:
- ret += generate_visit_struct_body(field_prefix + argname, argname, argentry)
+ ret += generate_visit_struct_body(full_name, argname, argentry)
else:
ret += mcgen('''
visit_type_%(type)s(m, obj ? &(*obj)->%(c_prefix)s%(c_name)s : NULL, "%(name)s", &err);
@@ -47,6 +69,12 @@ visit_type_%(type)s(m, obj ? &(*obj)->%(c_prefix)s%(c_name)s : NULL, "%(name)s",
visit_end_optional(m, &err);
''')
+ pop_indent()
+ ret += mcgen('''
+
+ error_propagate(errp, err);
+}
+''')
return ret
@@ -56,8 +84,9 @@ if (!error_is_set(errp)) {
''')
push_indent()
+ full_name = name if not field_prefix else "%s_%s" % (field_prefix, name)
+
if len(field_prefix):
- field_prefix = field_prefix + "."
ret += mcgen('''
Error **errp = &err; /* from outer scope */
Error *err = NULL;
@@ -74,20 +103,14 @@ visit_start_struct(m, (void **)obj, "%(name)s", name, sizeof(%(name)s), &err);
ret += mcgen('''
if (!err) {
if (!obj || *obj) {
-''')
- push_indent()
- push_indent()
-
- ret += generate_visit_struct_fields(field_prefix, members)
- pop_indent()
- ret += mcgen('''
- error_propagate(errp, err);
- err = NULL;
-}
-''')
+ visit_type_%(name)s_fields(m, obj, &err);
+ error_propagate(errp, err);
+ err = NULL;
+ }
+''',
+ name=full_name)
pop_indent()
- pop_indent()
ret += mcgen('''
/* Always call end_struct if start_struct succeeded. */
visit_end_struct(m, &err);
@@ -98,7 +121,9 @@ if (!err) {
return ret
def generate_visit_struct(name, members):
- ret = mcgen('''
+ ret = generate_visit_struct_fields(name, "", "", members)
+
+ ret += mcgen('''
void visit_type_%(name)s(Visitor *m, %(name)s ** obj, const char *name, Error **errp)
{
@@ -157,9 +182,17 @@ def generate_visit_union(expr):
members = expr['data']
base = expr.get('base')
+ discriminator = expr.get('discriminator')
ret = generate_visit_enum('%sKind' % name, members.keys())
+ if base:
+ base_fields = find_struct(base)['data']
+ if discriminator:
+ base_fields = base_fields.copy()
+ del base_fields[discriminator]
+ ret += generate_visit_struct_fields(name, "", "", base_fields)
+
ret += mcgen('''
void visit_type_%(name)s(Visitor *m, %(name)s ** obj, const char *name, Error **errp)
@@ -179,23 +212,34 @@ void visit_type_%(name)s(Visitor *m, %(name)s ** obj, const char *name, Error **
push_indent()
if base:
- struct = find_struct(base)
- push_indent()
- ret += generate_visit_struct_fields("", struct['data'])
- pop_indent()
+ ret += mcgen('''
+ visit_type_%(name)s_fields(m, obj, &err);
+''',
+ name=name)
pop_indent()
ret += mcgen('''
- visit_type_%(name)sKind(m, &(*obj)->kind, "type", &err);
+ visit_type_%(name)sKind(m, &(*obj)->kind, "%(type)s", &err);
if (!err) {
switch ((*obj)->kind) {
''',
- name=name)
+ name=name, type="type" if not discriminator else discriminator)
for key in members:
+ if not discriminator:
+ fmt = 'visit_type_%(c_type)s(m, &(*obj)->%(c_name)s, "data", &err);'
+ else:
+ fmt = '''visit_start_implicit_struct(m, (void**) &(*obj)->%(c_name)s, sizeof(%(c_type)s), &err);
+ if (!err) {
+ visit_type_%(c_type)s_fields(m, &(*obj)->%(c_name)s, &err);
+ error_propagate(errp, err);
+ err = NULL;
+ visit_end_implicit_struct(m, &err);
+ }'''
+
ret += mcgen('''
case %(abbrev)s_KIND_%(enum)s:
- visit_type_%(c_type)s(m, &(*obj)->%(c_name)s, "data", &err);
+ ''' + fmt + '''
break;
''',
abbrev = de_camel_case(name).upper(),
--
1.7.1