qapi: Add qobject_is_equal()

This generic function (along with its implementations for different
types) determines whether two QObjects are equal.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Message-id: 20171114180128.17076-4-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>

include/qapi/qmp/qbool.h

@@ -24,6 +24,7 @@ typedef struct QBool {
 QBool *qbool_from_bool(bool value);
 bool qbool_get_bool(const QBool *qb);
 QBool *qobject_to_qbool(const QObject *obj);
+bool qbool_is_equal(const QObject *x, const QObject *y);
 void qbool_destroy_obj(QObject *obj);
 
 #endif /* QBOOL_H */

include/qapi/qmp/qdict.h

@@ -43,6 +43,7 @@ void qdict_del(QDict *qdict, const char *key);
 int qdict_haskey(const QDict *qdict, const char *key);
 QObject *qdict_get(const QDict *qdict, const char *key);
 QDict *qobject_to_qdict(const QObject *obj);
+bool qdict_is_equal(const QObject *x, const QObject *y);
 void qdict_iter(const QDict *qdict,
                 void (*iter)(const char *key, QObject *obj, void *opaque),
                 void *opaque);

include/qapi/qmp/qlist.h

@@ -61,6 +61,7 @@ QObject *qlist_peek(QList *qlist);
 int qlist_empty(const QList *qlist);
 size_t qlist_size(const QList *qlist);
 QList *qobject_to_qlist(const QObject *obj);
+bool qlist_is_equal(const QObject *x, const QObject *y);
 void qlist_destroy_obj(QObject *obj);
 
 static inline const QListEntry *qlist_first(const QList *qlist)

include/qapi/qmp/qnull.h

@@ -27,4 +27,6 @@ static inline QNull *qnull(void)
     return &qnull_;
 }
 
+bool qnull_is_equal(const QObject *x, const QObject *y);
+
 #endif /* QNULL_H */

include/qapi/qmp/qnum.h

@@ -69,6 +69,7 @@ double qnum_get_double(QNum *qn);
 char *qnum_to_string(QNum *qn);
 
 QNum *qobject_to_qnum(const QObject *obj);
+bool qnum_is_equal(const QObject *x, const QObject *y);
 void qnum_destroy_obj(QObject *obj);
 
 #endif /* QNUM_H */

include/qapi/qmp/qobject.h

@@ -67,6 +67,15 @@ static inline void qobject_incref(QObject *obj)
         obj->refcnt++;
 }
 
+/**
+ * qobject_is_equal(): Return whether the two objects are equal.
+ *
+ * Any of the pointers may be NULL; return true if both are.  Always
+ * return false if only one is (therefore a QNull object is not
+ * considered equal to a NULL pointer).
+ */
+bool qobject_is_equal(const QObject *x, const QObject *y);
+
 /**
  * qobject_destroy(): Free resources used by the object
  */

include/qapi/qmp/qstring.h

@@ -31,6 +31,7 @@ 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);
+bool qstring_is_equal(const QObject *x, const QObject *y);
 void qstring_destroy_obj(QObject *obj);
 
 #endif /* QSTRING_H */