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authorMarkus Armbruster <armbru@redhat.com>2015-04-29 15:35:05 -0600
committerLuiz Capitulino <lcapitulino@redhat.com>2015-05-11 08:59:07 -0400
commit481b002cc81ed7fc7b06e32e9d4d495d81739d14 (patch)
tree20dbf5ec82cf594cdfeefe5db655d411fb55b78d /qobject
parenta7c31816288a8f20fc387d69d441413e7a8c9ff1 (diff)
qobject: Add a special null QObject
I'm going to fix the JSON parser to recognize null. The obvious representation of JSON null as (QObject *)NULL doesn't work, because the parser already uses it as an error value. Perhaps we should change it to free NULL for null, but that's more than I can do right now. Create a special null QObject instead. The existing QDict, QList, and QString all represent something that is a pointer in C and could therefore be associated with NULL. But right now, all three of these sub-types are always non-null once created, so the new null sentinel object is intentionally unrelated to them. Signed-off-by: Markus Armbruster <armbru@redhat.com> Signed-off-by: Eric Blake <eblake@redhat.com> Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Diffstat (limited to 'qobject')
-rw-r--r--qobject/Makefile.objs2
-rw-r--r--qobject/qjson.c3
-rw-r--r--qobject/qnull.c29
3 files changed, 33 insertions, 1 deletions
diff --git a/qobject/Makefile.objs b/qobject/Makefile.objs
index c9ff59c6cc..f7595f56fe 100644
--- a/qobject/Makefile.objs
+++ b/qobject/Makefile.objs
@@ -1,3 +1,3 @@
-util-obj-y = qint.o qstring.o qdict.o qlist.o qfloat.o qbool.o
+util-obj-y = qnull.o qint.o qstring.o qdict.o qlist.o qfloat.o qbool.o
util-obj-y += qjson.o json-lexer.o json-streamer.o json-parser.o
util-obj-y += qerror.o
diff --git a/qobject/qjson.c b/qobject/qjson.c
index f2857c13ea..846733dafb 100644
--- a/qobject/qjson.c
+++ b/qobject/qjson.c
@@ -127,6 +127,9 @@ static void to_json_list_iter(QObject *obj, void *opaque)
static void to_json(const QObject *obj, QString *str, int pretty, int indent)
{
switch (qobject_type(obj)) {
+ case QTYPE_QNULL:
+ qstring_append(str, "null");
+ break;
case QTYPE_QINT: {
QInt *val = qobject_to_qint(obj);
char buffer[1024];
diff --git a/qobject/qnull.c b/qobject/qnull.c
new file mode 100644
index 0000000000..9873e266e6
--- /dev/null
+++ b/qobject/qnull.c
@@ -0,0 +1,29 @@
+/*
+ * QNull
+ *
+ * Copyright (C) 2015 Red Hat, Inc.
+ *
+ * Authors:
+ * Markus Armbruster <armbru@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU LGPL, version 2.1
+ * or later. See the COPYING.LIB file in the top-level directory.
+ */
+
+#include "qemu-common.h"
+#include "qapi/qmp/qobject.h"
+
+static void qnull_destroy_obj(QObject *obj)
+{
+ assert(0);
+}
+
+static const QType qnull_type = {
+ .code = QTYPE_QNULL,
+ .destroy = qnull_destroy_obj,
+};
+
+QObject qnull_ = {
+ .type = &qnull_type,
+ .refcnt = 1,
+};