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qobject: Factor JSON writer out of qobject_to_json()

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We have two JSON writers written in C: qobject/qjson.c provides
qobject_to_json(), and migration/qjson.c provides a more low level
imperative interface.  They don't share code.  The latter tacitly
limits numbers to int64_t, and strings contents to characters that
don't need escaping.

Factor out qobject_to_json()'s JSON writer as qobject/json-writer.c.
Straightforward, except for numbers: since the writer is to be
independent of QObject, it can't use qnum_to_string().  Open-code it
instead.  This is actually an improvement of sorts, because it
liberates qnum_to_string() from JSON's needs: its JSON-related FIXMEs
move to the JSON writer, where they belong.

The next commit will replace migration/qjson.c.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20201211171152.146877-16-armbru@redhat.com>
This commit is contained in:
Markus Armbruster 2020-12-11 18:11:47 +01:00
parent 91f54d92c7
commit 998da0b158
5 changed files with 318 additions and 101 deletions
Download patch file Download diff file Expand all files Collapse all files

125
qobject/qjson.c
View file

@ -14,13 +14,13 @@
#include "qemu/osdep.h"
#include "qapi/error.h"
#include "qapi/qmp/json-parser.h"
#include "qapi/qmp/json-writer.h"
#include "qapi/qmp/qjson.h"
#include "qapi/qmp/qbool.h"
#include "qapi/qmp/qdict.h"
#include "qapi/qmp/qlist.h"
#include "qapi/qmp/qnum.h"
#include "qapi/qmp/qstring.h"
#include "qemu/unicode.h"
typedef struct JSONParsingState
{
@ -149,132 +149,69 @@ QDict *qdict_from_jsonf_nofail(const char *string, ...)
return qdict;
}
static void json_pretty_newline(GString *accu, bool pretty, int indent)
{
if (pretty) {
g_string_append_printf(accu, "\n%*s", indent * 4, "");
}
}
static void quoted_str(const char *str, GString *accu)
{
const char *ptr;
int cp;
char *end;
g_string_append_c(accu, '"');
for (ptr = str; *ptr; ptr = end) {
cp = mod_utf8_codepoint(ptr, 6, &end);
switch (cp) {
case '\"':
g_string_append(accu, "\\\"");
break;
case '\\':
g_string_append(accu, "\\\\");
break;
case '\b':
g_string_append(accu, "\\b");
break;
case '\f':
g_string_append(accu, "\\f");
break;
case '\n':
g_string_append(accu, "\\n");
break;
case '\r':
g_string_append(accu, "\\r");
break;
case '\t':
g_string_append(accu, "\\t");
break;
default:
if (cp < 0) {
cp = 0xFFFD; /* replacement character */
}
if (cp > 0xFFFF) {
/* beyond BMP; need a surrogate pair */
g_string_append_printf(accu, "\\u%04X\\u%04X",
0xD800 + ((cp - 0x10000) >> 10),
0xDC00 + ((cp - 0x10000) & 0x3FF));
} else if (cp < 0x20 || cp >= 0x7F) {
g_string_append_printf(accu, "\\u%04X", cp);
} else {
g_string_append_c(accu, cp);
}
}
};
g_string_append_c(accu, '"');
}
static void to_json(const QObject *obj, GString *accu, bool pretty, int indent)
static void to_json(JSONWriter *writer, const char *name,
const QObject *obj)
{
switch (qobject_type(obj)) {
case QTYPE_QNULL:
g_string_append(accu, "null");
json_writer_null(writer, name);
break;
case QTYPE_QNUM: {
QNum *val = qobject_to(QNum, obj);
char *buffer = qnum_to_string(val);
g_string_append(accu, buffer);
g_free(buffer);
switch (val->kind) {
case QNUM_I64:
json_writer_int64(writer, name, val->u.i64);
break;
case QNUM_U64:
json_writer_uint64(writer, name, val->u.u64);
break;
case QNUM_DOUBLE:
json_writer_double(writer, name, val->u.dbl);
break;
default:
abort();
}
break;
}
case QTYPE_QSTRING: {
quoted_str(qstring_get_str(qobject_to(QString, obj)), accu);
QString *val = qobject_to(QString, obj);
json_writer_str(writer, name, qstring_get_str(val));
break;
}
case QTYPE_QDICT: {
QDict *val = qobject_to(QDict, obj);
const char *comma = pretty ? "," : ", ";
const char *sep = "";
const QDictEntry *entry;
g_string_append_c(accu, '{');
json_writer_start_object(writer, name);
for (entry = qdict_first(val);
entry;
entry = qdict_next(val, entry)) {
g_string_append(accu, sep);
json_pretty_newline(accu, pretty, indent + 1);
quoted_str(qdict_entry_key(entry), accu);
g_string_append(accu, ": ");
to_json(qdict_entry_value(entry), accu, pretty, indent + 1);
sep = comma;
to_json(writer, qdict_entry_key(entry), qdict_entry_value(entry));
}
json_pretty_newline(accu, pretty, indent);
g_string_append_c(accu, '}');
json_writer_end_object(writer);
break;
}
case QTYPE_QLIST: {
QList *val = qobject_to(QList, obj);
const char *comma = pretty ? "," : ", ";
const char *sep = "";
QListEntry *entry;
g_string_append_c(accu, '[');
json_writer_start_array(writer, name);
QLIST_FOREACH_ENTRY(val, entry) {
g_string_append(accu, sep);
json_pretty_newline(accu, pretty, indent + 1);
to_json(qlist_entry_obj(entry), accu, pretty, indent + 1);
sep = comma;
to_json(writer, NULL, qlist_entry_obj(entry));
}
json_pretty_newline(accu, pretty, indent);
g_string_append_c(accu, ']');
json_writer_end_array(writer);
break;
}
case QTYPE_QBOOL: {
QBool *val = qobject_to(QBool, obj);
if (qbool_get_bool(val)) {
g_string_append(accu, "true");
} else {
g_string_append(accu, "false");
}
json_writer_bool(writer, name, qbool_get_bool(val));
break;
}
default:
@ -284,10 +221,10 @@ static void to_json(const QObject *obj, GString *accu, bool pretty, int indent)
GString *qobject_to_json_pretty(const QObject *obj, bool pretty)
{
GString *accu = g_string_new(NULL);
JSONWriter *writer = json_writer_new(pretty);
to_json(obj, accu, pretty, 0);
return accu;
to_json(writer, NULL, obj);
return json_writer_get_and_free(writer);
}
GString *qobject_to_json(const QObject *obj)