Move ARDOUR::Change into PBD so that Stateful can be aware of

what Change a State reflects.  Hence allow Stateful to do some
of the work of set/get_state in Region.


git-svn-id: svn://localhost/ardour2/branches/3.0@6671 d708f5d6-7413-0410-9779-e7cbd77b26cf

libs/pbd/stateful.cc

@@ -35,6 +35,27 @@ namespace PBD {
 int Stateful::current_state_version = 0;
 int Stateful::loading_state_version = 0;
 
+PBD::Change
+new_change ()
+{
+	Change c;
+	static uint32_t change_bit = 1;
+
+	/* catch out-of-range */
+	if (!change_bit)
+	{
+		fatal << _("programming error: ")
+			<< "change_bit out of range in ARDOUR::new_change()"
+			<< endmsg;
+		/*NOTREACHED*/
+	}
+
+	c = Change (change_bit);
+	change_bit <<= 1;	// if it shifts too far, change_bit == 0
+
+	return c;
+}
+
 Stateful::Stateful ()
 {
 	_extra_xml = 0;
@@ -175,5 +196,32 @@ Stateful::diff ()
 
 	return make_pair (old, current);
 }
+	
+/** Set state of _states from an XML node.
+ *  @param node Node.
+ *  @return Changes made.
+ */
+Change
+Stateful::set_state_using_states (XMLNode const & node)
+{
+	Change c = Change (0);
+	
+	for (list<StateBase*>::iterator i = _states.begin(); i != _states.end(); ++i) {
+		c = Change (c | (*i)->set_state (node));
+	}
+
+	return c;
+}
+
+/** Add state of _states to an XML node.
+ *  @param node Node.
+ */
+void
+Stateful::add_states (XMLNode & node)
+{
+	for (list<StateBase*>::iterator i = _states.begin(); i != _states.end(); ++i) {
+		(*i)->add_state (node);
+	}
+}
 
 } // namespace PBD