4 * Based on ideas by Avi Kivity <avi@redhat.com>
6 * Copyright (C) 2009 Red Hat Inc.
9 * Luiz Capitulino <lcapitulino@redhat.com>
11 * This work is licensed under the terms of the GNU GPL, version 2. See
12 * the COPYING file in the top-level directory.
14 * QObject Reference Counts Terminology
15 * ------------------------------------
17 * - Returning references: A function that returns an object may
18 * return it as either a weak or a strong reference. If the reference
19 * is strong, you are responsible for calling QDECREF() on the reference
22 * If the reference is weak, the owner of the reference may free it at
23 * any time in the future. Before storing the reference anywhere, you
24 * should call QINCREF() to make the reference strong.
26 * - Transferring ownership: when you transfer ownership of a reference
27 * by calling a function, you are no longer responsible for calling
28 * QDECREF() when the reference is no longer needed. In other words,
29 * when the function returns you must behave as if the reference to the
30 * passed object was weak.
46 typedef struct QType {
48 void (*destroy)(struct QObject *);
51 typedef struct QObject {
56 /* Objects definitions must include this */
57 #define QObject_HEAD \
60 /* Get the 'base' part of an object */
61 #define QOBJECT(obj) (&obj->base)
63 /* High-level interface for qobject_incref() */
64 #define QINCREF(obj) \
65 assert(obj != NULL); \
66 qobject_incref(QOBJECT(obj))
68 /* High-level interface for qobject_decref() */
69 #define QDECREF(obj) \
70 assert(obj != NULL); \
71 qobject_decref(QOBJECT(obj))
73 /* Initialize an object to default values */
74 #define QOBJECT_INIT(obj, qtype_type) \
75 obj->base.refcnt = 1; \
76 obj->base.type = qtype_type
79 * qobject_incref(): Increment QObject's reference count
81 static inline void qobject_incref(QObject *obj)
87 * qobject_decref(): Decrement QObject's reference count, deallocate
88 * when it reaches zero
90 static inline void qobject_decref(QObject *obj)
92 if (--obj->refcnt == 0) {
93 assert(obj->type != NULL);
94 assert(obj->type->destroy != NULL);
95 obj->type->destroy(obj);
100 * qobject_type(): Return the QObject's type
102 static inline qtype_code qobject_type(const QObject *obj)
104 assert(obj->type != NULL);
105 return obj->type->code;
108 #endif /* QOBJECT_H */