1 /*
2 * A simple JSON writer
3 *
4 * Copyright Alexander Graf
5 *
6 * Authors:
7 * Alexander Graf <agraf@suse.de>
8 *
9 * This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
10 * See the COPYING.LIB file in the top-level directory.
11 *
12 */
13
14 /*
15 * Type QJSON lets you build JSON text. Its interface mirrors (a
16 * subset of) abstract JSON syntax.
17 *
18 * It does *not* detect incorrect use. It happily produces invalid
19 * JSON then. This is what migration wants.
20 *
21 * QAPI output visitors also produce JSON text. However, they do
22 * assert their preconditions and invariants, and therefore abort on
23 * incorrect use.
24 */
25
26 #include "qemu/osdep.h"
27 #include "qapi/qmp/qstring.h"
28 #include "qjson.h"
29
30 struct QJSON {
31 QString *str;
32 bool omit_comma;
33 };
34
json_emit_element(QJSON * json,const char * name)35 static void json_emit_element(QJSON *json, const char *name)
36 {
37 /* Check whether we need to print a , before an element */
38 if (json->omit_comma) {
39 json->omit_comma = false;
40 } else {
41 qstring_append(json->str, ", ");
42 }
43
44 if (name) {
45 qstring_append(json->str, "\"");
46 qstring_append(json->str, name);
47 qstring_append(json->str, "\" : ");
48 }
49 }
50
json_start_object(QJSON * json,const char * name)51 void json_start_object(QJSON *json, const char *name)
52 {
53 json_emit_element(json, name);
54 qstring_append(json->str, "{ ");
55 json->omit_comma = true;
56 }
57
json_end_object(QJSON * json)58 void json_end_object(QJSON *json)
59 {
60 qstring_append(json->str, " }");
61 json->omit_comma = false;
62 }
63
json_start_array(QJSON * json,const char * name)64 void json_start_array(QJSON *json, const char *name)
65 {
66 json_emit_element(json, name);
67 qstring_append(json->str, "[ ");
68 json->omit_comma = true;
69 }
70
json_end_array(QJSON * json)71 void json_end_array(QJSON *json)
72 {
73 qstring_append(json->str, " ]");
74 json->omit_comma = false;
75 }
76
json_prop_int(QJSON * json,const char * name,int64_t val)77 void json_prop_int(QJSON *json, const char *name, int64_t val)
78 {
79 json_emit_element(json, name);
80 qstring_append_int(json->str, val);
81 }
82
json_prop_str(QJSON * json,const char * name,const char * str)83 void json_prop_str(QJSON *json, const char *name, const char *str)
84 {
85 json_emit_element(json, name);
86 qstring_append_chr(json->str, '"');
87 qstring_append(json->str, str);
88 qstring_append_chr(json->str, '"');
89 }
90
qjson_get_str(QJSON * json)91 const char *qjson_get_str(QJSON *json)
92 {
93 return qstring_get_str(json->str);
94 }
95
qjson_new(void)96 QJSON *qjson_new(void)
97 {
98 QJSON *json = g_new0(QJSON, 1);
99
100 json->str = qstring_from_str("{ ");
101 json->omit_comma = true;
102 return json;
103 }
104
qjson_finish(QJSON * json)105 void qjson_finish(QJSON *json)
106 {
107 json_end_object(json);
108 }
109
qjson_destroy(QJSON * json)110 void qjson_destroy(QJSON *json)
111 {
112 qobject_unref(json->str);
113 g_free(json);
114 }
115