[Qemu-devel] [PATCH v2 08/14] qjson: Simplify by using json-output-visitor

[Eric Blake <eblake@redhat.com>]

Instead of rolling our own limited JSON outputter, we can just
wrap the more full-featured JSON output Visitor.

This slightly changes the output (different spacing), but the
result is still equivalent JSON contents.

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

---
v2: rebase to earlier changes

This is alternative 1.  See also patches 10-11 for alternative 2.
---
 qjson.c | 61 ++++++++++++++++++++++---------------------------------------
 1 file changed, 22 insertions(+), 39 deletions(-)

diff --git a/qjson.c b/qjson.c
index 8c93c1b..8874bad 100644
--- a/qjson.c
+++ b/qjson.c
@@ -11,103 +11,86 @@
  *
  */

-#include <qapi/qmp/qstring.h>
 #include <stdbool.h>
-#include <glib.h>
+#include <stdint.h>
 #include <qjson.h>
 #include <qemu/module.h>
 #include <qom/object.h>
+#include "qapi/json-output-visitor.h"

 struct QJSON {
     Object obj;
-    QString *str;
-    bool omit_comma;
+    JsonOutputVisitor *jov;
+    char *str;
 };

 #define QJSON(obj) OBJECT_CHECK(QJSON, (obj), TYPE_QJSON)

-static void json_emit_element(QJSON *json, const char *name)
-{
-    /* Check whether we need to print a , before an element */
-    if (json->omit_comma) {
-        json->omit_comma = false;
-    } else {
-        qstring_append(json->str, ", ");
-    }
-
-    if (name) {
-        qstring_append_json_string(json->str, name);
-        qstring_append(json->str, " : ");
-    }
-}
-
 void json_start_object(QJSON *json, const char *name)
 {
-    json_emit_element(json, name);
-    qstring_append(json->str, "{ ");
-    json->omit_comma = true;
+    Visitor *v = json_output_get_visitor(json->jov);
+    visit_start_struct(v, name, NULL, 0, &error_abort);
 }

 void json_end_object(QJSON *json)
 {
-    qstring_append(json->str, " }");
-    json->omit_comma = false;
+    Visitor *v = json_output_get_visitor(json->jov);
+    visit_check_struct(v, &error_abort);
+    visit_end_struct(v);
 }

 void json_start_array(QJSON *json, const char *name)
 {
-    json_emit_element(json, name);
-    qstring_append(json->str, "[ ");
-    json->omit_comma = true;
+    Visitor *v = json_output_get_visitor(json->jov);
+    visit_start_list(v, name, NULL, 0, &error_abort);
 }

 void json_end_array(QJSON *json)
 {
-    qstring_append(json->str, " ]");
-    json->omit_comma = false;
+    Visitor *v = json_output_get_visitor(json->jov);
+    visit_end_list(v);
 }

 void json_prop_int(QJSON *json, const char *name, int64_t val)
 {
-    json_emit_element(json, name);
-    qstring_append_format(json->str, "%" PRId64, val);
+    Visitor *v = json_output_get_visitor(json->jov);
+    visit_type_int(v, name, &val, &error_abort);
 }

 void json_prop_str(QJSON *json, const char *name, const char *str)
 {
-    json_emit_element(json, name);
-    qstring_append_json_string(json->str, str);
+    Visitor *v = json_output_get_visitor(json->jov);
+    visit_type_str(v, name, (char **)&str, &error_abort);
 }

 const char *qjson_get_str(QJSON *json)
 {
-    return qstring_get_str(json->str);
+    return json->str;
 }

 QJSON *qjson_new(void)
 {
     QJSON *json = QJSON(object_new(TYPE_QJSON));
+    json_start_object(json, NULL);
     return json;
 }

 void qjson_finish(QJSON *json)
 {
     json_end_object(json);
+    json->str = json_output_get_string(json->jov);
 }

 static void qjson_initfn(Object *obj)
 {
     QJSON *json = QJSON(obj);
-
-    json->str = qstring_from_str("{ ");
-    json->omit_comma = true;
+    json->jov = json_output_visitor_new();
 }

 static void qjson_finalizefn(Object *obj)
 {
     QJSON *json = QJSON(obj);
-
-    qobject_decref(QOBJECT(json->str));
+    g_free(json->str);
 }

 static const TypeInfo qjson_type_info = {
-- 
2.4.3