qemu/include/qapi/qmp/qstring.h
Eric Blake 55e1819c50 qobject: Simplify QObject
The QObject hierarchy is small enough, and unlikely to grow further
(since we only use it to map to JSON and already cover all JSON
types), that we can simplify things by not tracking a separate
vtable, but just inline the code element of the vtable QType
directly into QObject (renamed to type), and track a separate array
of destroy functions.  We can drop qnull_destroy_obj() in the
process.

The remaining QObject subclasses must export their destructor.

This also has the nice benefit of moving the typename 'QType'
out of the way, so that the next patch can repurpose it for a
nicer name for 'qtype_code'.

The various objects are still the same size (so no change in cache
line pressure), but now have less indirection (although I didn't
bother benchmarking to see if there is a noticeable speedup, as
we don't have hard evidence that this was in a performance hotspot
in the first place).

A future patch could drop the refcnt size to 32 bits for a smaller
struct on 64-bit architectures, if desired (we have limits on the
largest JSON that we are willing to parse, and will probably never
need to take full advantage of a 64-bit refcnt).

Suggested-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <1449033659-25497-2-git-send-email-eblake@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
2015-12-17 08:21:28 +01:00

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/*
* QString Module
*
* Copyright (C) 2009 Red Hat Inc.
*
* Authors:
* Luiz Capitulino <lcapitulino@redhat.com>
*
* 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.
*/
#ifndef QSTRING_H
#define QSTRING_H
#include <stdint.h>
#include "qapi/qmp/qobject.h"
typedef struct QString {
QObject base;
char *string;
size_t length;
size_t capacity;
} QString;
QString *qstring_new(void);
QString *qstring_from_str(const char *str);
QString *qstring_from_substr(const char *str, int start, int end);
size_t qstring_get_length(const QString *qstring);
const char *qstring_get_str(const QString *qstring);
void qstring_append_int(QString *qstring, int64_t value);
void qstring_append(QString *qstring, const char *str);
void qstring_append_chr(QString *qstring, int c);
QString *qobject_to_qstring(const QObject *obj);
void qstring_destroy_obj(QObject *obj);
#endif /* QSTRING_H */