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/pbd/stateful.h

@@ -33,13 +33,20 @@ namespace sys {
 	class path;
 }
 
+enum Change {
+	range_guarantee = ~0
+};
+
+Change new_change ();
+
 /** Base (non template) part of State */	
 class StateBase
 {
 public:
-	StateBase (std::string const & p)
+	StateBase (std::string const & p, Change c)
 		: _have_old (false)
 		, _xml_property_name (p)
+		, _change (c)
 	{
 
 	}
@@ -47,6 +54,7 @@ public:
 	StateBase (StateBase const & s)
 		: _have_old (s._have_old)
 		, _xml_property_name (s._xml_property_name)
+		, _change (s._change)
 	{
 
 	}
@@ -57,10 +65,13 @@ public:
 	}
 
 	virtual void diff (XMLNode *, XMLNode *) const = 0;
+	virtual Change set_state (XMLNode const &) = 0;
+	virtual void add_state (XMLNode &) const = 0;
 
 protected:
 	bool _have_old;
 	std::string _xml_property_name;
+	Change _change;
 };
 
 /** Class to represent a single piece of state in a Stateful object */
@@ -68,8 +79,8 @@ template <class T>
 class State : public StateBase
 {
 public:
-	State (std::string const & p, T const & v)
-		: StateBase (p)
+	State (std::string const & p, Change c, T const & v)
+		: StateBase (p, c)
 		, _current (v)
 	{
 
@@ -86,6 +97,7 @@ public:
 		/* XXX: isn't there a nicer place to do this? */
 		_have_old = s._have_old;
 		_xml_property_name = s._xml_property_name;
+		_change = s._change;
 		
 		_current = s._current;
 		_old = s._old;
@@ -112,21 +124,50 @@ public:
 
 	void diff (XMLNode* old, XMLNode* current) const {
 		if (_have_old) {
-			std::stringstream o;
-			o << _old;
-			old->add_property (_xml_property_name.c_str(), o.str().c_str());
-			std::stringstream c;
-			c << _current;
-			current->add_property (_xml_property_name.c_str(), c.str().c_str());
+			old->add_property (_xml_property_name.c_str(), to_string (_old));
+			current->add_property (_xml_property_name.c_str(), to_string (_current));
 		}
 	}
 
+	/** Try to set state from the property of an XML node.
+	 *  @param node XML node.
+	 *  @return Change effected, or 0.
+	 */
+	Change set_state (XMLNode const & node) {
+		XMLProperty const * p = node.property (_xml_property_name.c_str());
+
+		if (p) {
+			std::stringstream s (p->value ());
+			T v;
+			s >> v;
+
+			if (v == _current) {
+				return Change (0);
+			}
+
+			set (v);
+			return _change;
+		}
+
+		return Change (0);
+	}
+
+	void add_state (XMLNode & node) const {
+		node.add_property (_xml_property_name.c_str(), to_string (_current));
+	}
+
 private:
 	void set (T const & v) {
 		_old = _current;
 		_have_old = true;
 		_current = v;
 	}
+
+	std::string to_string (T const & v) const {
+		std::stringstream s;
+		s << v;
+		return s.str ();
+	}
 		
 	T _current;
 	T _old;
@@ -163,6 +204,8 @@ class Stateful {
 
 	void add_instant_xml (XMLNode&, const sys::path& directory_path);
 	XMLNode *instant_xml (const std::string& str, const sys::path& directory_path);
+	Change set_state_using_states (XMLNode const &);
+	void add_states (XMLNode &);
 
 	XMLNode *_extra_xml;
 	XMLNode *_instant_xml;

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