qemu/migration/qjson.c

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/*
* A simple JSON writer
*
* Copyright Alexander Graf
*
* Authors:
* Alexander Graf <agraf@suse.de>
*
* 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.
*
*/
/*
* Type QJSON lets you build JSON text. Its interface mirrors (a
* subset of) abstract JSON syntax.
*
* It does *not* detect incorrect use. It happily produces invalid
* JSON then. This is what migration wants.
*
* QAPI output visitors also produce JSON text. However, they do
* assert their preconditions and invariants, and therefore abort on
* incorrect use.
*/
#include "qemu/osdep.h"
#include "qapi/qmp/qstring.h"
#include "migration/qjson.h"
struct QJSON {
QString *str;
bool omit_comma;
};
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->str, "\"");
qstring_append(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;
}
void json_end_object(QJSON *json)
{
qstring_append(json->str, " }");
json->omit_comma = false;
}
void json_start_array(QJSON *json, const char *name)
{
json_emit_element(json, name);
qstring_append(json->str, "[ ");
json->omit_comma = true;
}
void json_end_array(QJSON *json)
{
qstring_append(json->str, " ]");
json->omit_comma = false;
}
void json_prop_int(QJSON *json, const char *name, int64_t val)
{
json_emit_element(json, name);
qstring_append_int(json->str, val);
}
void json_prop_str(QJSON *json, const char *name, const char *str)
{
json_emit_element(json, name);
qstring_append_chr(json->str, '"');
qstring_append(json->str, str);
qstring_append_chr(json->str, '"');
}
const char *qjson_get_str(QJSON *json)
{
return qstring_get_str(json->str);
}
QJSON *qjson_new(void)
{
QJSON *json = g_new0(QJSON, 1);
json->str = qstring_from_str("{ ");
json->omit_comma = true;
return json;
}
void qjson_finish(QJSON *json)
{
json_end_object(json);
}
void qjson_destroy(QJSON *json)
{
QDECREF(json->str);
g_free(json);
}