Move QMetaMethod::parameterTypes() implementation to helper function

Because of an upcoming change to the meta-object data format, the
ability to extract parameter types from a signature will be needed by
meta-object builders (such as QMetaObjectBuilder) soon.

Change-Id: I1f21b2be41761a5db2f1a05976fad29eb3aebb03
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/corelib/kernel/qmetaobject.cpp

@@ -1295,25 +1295,10 @@ const char *QMetaMethod::signature() const
 */
 QList<QByteArray> QMetaMethod::parameterTypes() const
 {
-    QList<QByteArray> list;
     if (!mobj)
-        return list;
-    const char *signature = mobj->d.stringdata + mobj->d.data[handle];
-    while (*signature && *signature != '(')
-        ++signature;
-    while (*signature && *signature != ')' && *++signature != ')') {
-        const char *begin = signature;
-        int level = 0;
-        while (*signature && (level > 0 || *signature != ',') && *signature != ')') {
-            if (*signature == '<')
-                ++level;
-            else if (*signature == '>')
-                --level;
-            ++signature;
-        }
-        list += QByteArray(begin, signature - begin);
-    }
-    return list;
+        return QList<QByteArray>();
+    return QMetaObjectPrivate::parameterTypeNamesFromSignature(
+            mobj->d.stringdata + mobj->d.data[handle]);
 }
 
 /*!
@@ -2809,4 +2794,29 @@ int QMetaObjectPrivate::originalClone(const QMetaObject *mobj, int local_method_
     return local_method_index;
 }
 
+/*!
+    \internal
+
+    Returns the parameter type names extracted from the given \a signature.
+*/
+QList<QByteArray> QMetaObjectPrivate::parameterTypeNamesFromSignature(const char *signature)
+{
+    QList<QByteArray> list;
+    while (*signature && *signature != '(')
+        ++signature;
+    while (*signature && *signature != ')' && *++signature != ')') {
+        const char *begin = signature;
+        int level = 0;
+        while (*signature && (level > 0 || *signature != ',') && *signature != ')') {
+            if (*signature == '<')
+                ++level;
+            else if (*signature == '>')
+                --level;
+            ++signature;
+        }
+        list += QByteArray(begin, signature - begin);
+    }
+    return list;
+}
+
 QT_END_NAMESPACE

src/corelib/kernel/qmetaobject_p.h

@@ -134,6 +134,8 @@ struct QMetaObjectPrivate
                            bool normalizeStringData);
     static int originalClone(const QMetaObject *obj, int local_method_index);
 
+    static QList<QByteArray> parameterTypeNamesFromSignature(const char *signature);
+
 #ifndef QT_NO_QOBJECT
     //defined in qobject.cpp
     enum DisconnectType { DisconnectAll, DisconnectOne };