LXR qemu/migration/qjson.c

   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 "migration/qjson.h"
  29
  30struct QJSON {
  31    QString *str;
  32    bool omit_comma;
  33};
  34
  35static 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
  51void 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
  58void json_end_object(QJSON *json)
  59{
  60    qstring_append(json->str, " }");
  61    json->omit_comma = false;
  62}
  63
  64void 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
  71void json_end_array(QJSON *json)
  72{
  73    qstring_append(json->str, " ]");
  74    json->omit_comma = false;
  75}
  76
  77void 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
  83void 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
  91const char *qjson_get_str(QJSON *json)
  92{
  93    return qstring_get_str(json->str);
  94}
  95
  96QJSON *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
 105void qjson_finish(QJSON *json)
 106{
 107    json_end_object(json);
 108}
 109
 110void qjson_destroy(QJSON *json)
 111{
 112    g_free(json);
 113}
 114