[2/4] qapi: Add qobject_is_equal()

diff --git a/include/qapi/qmp/qbool.h b/include/qapi/qmp/qbool.h
index a41111c..f77ea86 100644
--- a/include/qapi/qmp/qbool.h
+++ b/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 */
diff --git a/include/qapi/qmp/qdict.h b/include/qapi/qmp/qdict.h
index 188440a..134a526 100644
--- a/include/qapi/qmp/qdict.h
+++ b/include/qapi/qmp/qdict.h
@@ -41,6 +41,7 @@  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);
diff --git a/include/qapi/qmp/qfloat.h b/include/qapi/qmp/qfloat.h
index b5d1583..318e91e 100644
--- a/include/qapi/qmp/qfloat.h
+++ b/include/qapi/qmp/qfloat.h
@@ -24,6 +24,7 @@  typedef struct QFloat {
 QFloat *qfloat_from_double(double value);
 double qfloat_get_double(const QFloat *qi);
 QFloat *qobject_to_qfloat(const QObject *obj);
+bool qfloat_is_equal(const QObject *x, const QObject *y);
 void qfloat_destroy_obj(QObject *obj);
 
 #endif /* QFLOAT_H */
diff --git a/include/qapi/qmp/qint.h b/include/qapi/qmp/qint.h
index 3aaff76..20975da 100644
--- a/include/qapi/qmp/qint.h
+++ b/include/qapi/qmp/qint.h
@@ -23,6 +23,7 @@  typedef struct QInt {
 QInt *qint_from_int(int64_t value);
 int64_t qint_get_int(const QInt *qi);
 QInt *qobject_to_qint(const QObject *obj);
+bool qint_is_equal(const QObject *x, const QObject *y);
 void qint_destroy_obj(QObject *obj);
 
 #endif /* QINT_H */
diff --git a/include/qapi/qmp/qlist.h b/include/qapi/qmp/qlist.h
index 5dc4ed9..4380a5b 100644
--- a/include/qapi/qmp/qlist.h
+++ b/include/qapi/qmp/qlist.h
@@ -57,6 +57,7 @@  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)
diff --git a/include/qapi/qmp/qnull.h b/include/qapi/qmp/qnull.h
index 69555ac..9299683 100644
--- a/include/qapi/qmp/qnull.h
+++ b/include/qapi/qmp/qnull.h
@@ -23,4 +23,6 @@  static inline QObject *qnull(void)
     return &qnull_;
 }
 
+bool qnull_is_equal(const QObject *x, const QObject *y);
+
 #endif /* QNULL_H */
diff --git a/include/qapi/qmp/qobject.h b/include/qapi/qmp/qobject.h
index ef1d1a9..cac72e3 100644
--- a/include/qapi/qmp/qobject.h
+++ b/include/qapi/qmp/qobject.h
@@ -68,6 +68,15 @@  static inline void qobject_incref(QObject *obj)
 }
 
 /**
+ * qobject_is_equal(): Returns whether the two objects are equal.
+ *
+ * Any of the pointers may be NULL; will return true if both are. Will 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
  */
 void qobject_destroy(QObject *obj);
diff --git a/include/qapi/qmp/qstring.h b/include/qapi/qmp/qstring.h
index 10076b7..65c05a9 100644
--- a/include/qapi/qmp/qstring.h
+++ b/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 */
diff --git a/qobject/qbool.c b/qobject/qbool.c
index 0606bbd..f1d1719 100644
--- a/qobject/qbool.c
+++ b/qobject/qbool.c
@@ -52,6 +52,14 @@  QBool *qobject_to_qbool(const QObject *obj)
 }
 
 /**
+ * qbool_is_equal(): Tests whether the two QBools are equal
+ */
+bool qbool_is_equal(const QObject *x, const QObject *y)
+{
+    return qobject_to_qbool(x)->value == qobject_to_qbool(y)->value;
+}
+
+/**
  * qbool_destroy_obj(): Free all memory allocated by a
  * QBool object
  */
diff --git a/qobject/qdict.c b/qobject/qdict.c
index 88e2ecd..2ed57ca 100644
--- a/qobject/qdict.c
+++ b/qobject/qdict.c
@@ -410,6 +410,30 @@  void qdict_del(QDict *qdict, const char *key)
 }
 
 /**
+ * qdict_is_equal(): Tests whether the two QDicts are equal
+ */
+bool qdict_is_equal(const QObject *x, const QObject *y)
+{
+    const QDict *dict_x = qobject_to_qdict(x), *dict_y = qobject_to_qdict(y);
+    const QDictEntry *e;
+
+    if (qdict_size(dict_x) != qdict_size(dict_y)) {
+        return false;
+    }
+
+    for (e = qdict_first(dict_x); e; e = qdict_next(dict_x, e)) {
+        const QObject *obj_x = qdict_entry_value(e);
+        const QObject *obj_y = qdict_get(dict_y, qdict_entry_key(e));
+
+        if (!qobject_is_equal(obj_x, obj_y)) {
+            return false;
+        }
+    }
+
+    return true;
+}
+
+/**
  * qdict_destroy_obj(): Free all the memory allocated by a QDict
  */
 void qdict_destroy_obj(QObject *obj)
diff --git a/qobject/qfloat.c b/qobject/qfloat.c
index d5da847..291ecc4 100644
--- a/qobject/qfloat.c
+++ b/qobject/qfloat.c
@@ -52,6 +52,14 @@  QFloat *qobject_to_qfloat(const QObject *obj)
 }
 
 /**
+ * qfloat_is_equal(): Tests whether the two QFloats are equal
+ */
+bool qfloat_is_equal(const QObject *x, const QObject *y)
+{
+    return qobject_to_qfloat(x)->value == qobject_to_qfloat(y)->value;
+}
+
+/**
  * qfloat_destroy_obj(): Free all memory allocated by a
  * QFloat object
  */
diff --git a/qobject/qint.c b/qobject/qint.c
index d7d1b30..f638cb7 100644
--- a/qobject/qint.c
+++ b/qobject/qint.c
@@ -51,6 +51,14 @@  QInt *qobject_to_qint(const QObject *obj)
 }
 
 /**
+ * qint_is_equal(): Tests whether the two QInts are equal
+ */
+bool qint_is_equal(const QObject *x, const QObject *y)
+{
+    return qobject_to_qint(x)->value == qobject_to_qint(y)->value;
+}
+
+/**
  * qint_destroy_obj(): Free all memory allocated by a
  * QInt object
  */
diff --git a/qobject/qlist.c b/qobject/qlist.c
index 86b60cb..b3033c6 100644
--- a/qobject/qlist.c
+++ b/qobject/qlist.c
@@ -140,6 +140,31 @@  QList *qobject_to_qlist(const QObject *obj)
 }
 
 /**
+ * qlist_is_equal(): Tests whether the two QLists are equal
+ */
+bool qlist_is_equal(const QObject *x, const QObject *y)
+{
+    const QList *list_x = qobject_to_qlist(x), *list_y = qobject_to_qlist(y);
+    const QListEntry *entry_x, *entry_y;
+
+    entry_x = qlist_first(list_x);
+    entry_y = qlist_first(list_y);
+
+    while (entry_x && entry_y) {
+        if (!qobject_is_equal(qlist_entry_obj(entry_x),
+                              qlist_entry_obj(entry_y)))
+        {
+            return false;
+        }
+
+        entry_x = qlist_next(entry_x);
+        entry_y = qlist_next(entry_y);
+    }
+
+    return !entry_x && !entry_y;
+}
+
+/**
  * qlist_destroy_obj(): Free all the memory allocated by a QList
  */
 void qlist_destroy_obj(QObject *obj)
diff --git a/qobject/qnull.c b/qobject/qnull.c
index b3cc85e..af5453d 100644
--- a/qobject/qnull.c
+++ b/qobject/qnull.c
@@ -19,3 +19,8 @@  QObject qnull_ = {
     .type = QTYPE_QNULL,
     .refcnt = 1,
 };
+
+bool qnull_is_equal(const QObject *x, const QObject *y)
+{
+    return true;
+}
diff --git a/qobject/qobject.c b/qobject/qobject.c
index fe4fa10..af2869a 100644
--- a/qobject/qobject.c
+++ b/qobject/qobject.c
@@ -28,3 +28,33 @@  void qobject_destroy(QObject *obj)
     assert(QTYPE_QNULL < obj->type && obj->type < QTYPE__MAX);
     qdestroy[obj->type](obj);
 }
+
+
+static bool (*qis_equal[QTYPE__MAX])(const QObject *, const QObject *) = {
+    [QTYPE_NONE] = NULL,               /* No such object exists */
+    [QTYPE_QNULL] = qnull_is_equal,
+    [QTYPE_QINT] = qint_is_equal,
+    [QTYPE_QSTRING] = qstring_is_equal,
+    [QTYPE_QDICT] = qdict_is_equal,
+    [QTYPE_QLIST] = qlist_is_equal,
+    [QTYPE_QFLOAT] = qfloat_is_equal,
+    [QTYPE_QBOOL] = qbool_is_equal,
+};
+
+bool qobject_is_equal(const QObject *x, const QObject *y)
+{
+    /* We cannot test x == y because an object does not need to be equal to
+     * itself (e.g. NaN floats are not). */
+
+    if (!x && !y) {
+        return true;
+    }
+
+    if (!x || !y || x->type != y->type) {
+        return false;
+    }
+
+    assert(QTYPE_NONE < x->type && x->type < QTYPE__MAX);
+
+    return qis_equal[x->type](x, y);
+}
diff --git a/qobject/qstring.c b/qobject/qstring.c
index 5da7b5f..a2b51fa 100644
--- a/qobject/qstring.c
+++ b/qobject/qstring.c
@@ -129,6 +129,15 @@  const char *qstring_get_str(const QString *qstring)
 }
 
 /**
+ * qstring_is_equal(): Tests whether the two QStrings are equal
+ */
+bool qstring_is_equal(const QObject *x, const QObject *y)
+{
+    return !strcmp(qobject_to_qstring(x)->string,
+                   qobject_to_qstring(y)->string);
+}
+
+/**
  * qstring_destroy_obj(): Free all memory allocated by a QString
  * object
  */