X-Git-Url: https://main.carlh.net/gitweb/?a=blobdiff_plain;f=libs%2Fpbd%2Fpbd%2Fmemento_command.h;h=d22561ab217985fe8c12d48755518f504a9a139b;hb=8d0ec2403f3444e3a53d16b21f2f8557abd71b55;hp=b1347c169d827054719e653ace891019bf7d8e88;hpb=3b89d9eaa03406a5e03648f47734211f09b89d62;p=ardour.git

diff --git a/libs/pbd/pbd/memento_command.h b/libs/pbd/pbd/memento_command.h
index b1347c169d..d22561ab21 100644
--- a/libs/pbd/pbd/memento_command.h
+++ b/libs/pbd/pbd/memento_command.h
@@ -23,44 +23,120 @@
 
 #include <iostream>
 
+#include "pbd/libpbd_visibility.h"
 #include "pbd/command.h"
 #include "pbd/stacktrace.h"
 #include "pbd/xml++.h"
-#include "pbd/shiva.h"
+#include "pbd/demangle.h"
 
 #include <sigc++/slot.h>
 #include <typeinfo>
 
+/** A class that can return a Stateful object which is the subject of a MementoCommand.
+ *
+ *  The existence of this class means that the undo record can refer to objects which
+ *  don't exist in the session file.  Currently this is used for
+ *
+ *  1.  MIDI automation; when MIDI automation is edited, undo records are
+ *  written for the AutomationList being changed.  However this AutomationList
+ *  is a temporary structure, built by a MidiModel, which doesn't get written
+ *  to the session file.  Hence we need to be able to go from a MidiSource and
+ *  Parameter to an AutomationList.  This Binder mechanism allows this through
+ *  MidiAutomationListBinder; the undo record stores the source and parameter,
+ *  and these are bound to an AutomationList by the Binder.
+ *
+ *  2.  Crossfades; unlike regions, these are completely removed from a session
+ *  when they are deleted.  This means that the undo record can contain
+ *  references to non-existant crossfades.  To get around this, CrossfadeBinder
+ *  can do `just-in-time' binding from the crossfade ID.
+ */
+template <class obj_T>
+class LIBPBD_TEMPLATE_API MementoCommandBinder : public PBD::Destructible
+{
+public:
+	/** @return Stateful object to operate on */
+	virtual obj_T* get () const = 0;
+
+	/** @return Name of our type */
+	virtual std::string type_name () const {
+		return PBD::demangled_name (*get ());
+	}
+
+	/** Add our own state to an XMLNode */
+	virtual void add_state (XMLNode *) = 0;
+};
+
+/** A simple MementoCommandBinder which binds directly to an object */
+template <class obj_T>
+class LIBPBD_TEMPLATE_API SimpleMementoCommandBinder : public MementoCommandBinder<obj_T>
+{
+public:
+	SimpleMementoCommandBinder (obj_T& o)
+		: _object (o)
+	{
+		_object.Destroyed.connect_same_thread (_object_death_connection, boost::bind (&SimpleMementoCommandBinder::object_died, this));
+	}
+
+	obj_T* get () const {
+		return &_object;
+	}
+
+	void add_state (XMLNode* node) {
+		node->add_property ("obj_id", _object.id().to_s());
+	}
+	
+	void object_died () {
+		/* The object we are binding died, so drop references to ourselves */
+		this->drop_references ();
+	}
+
+private:
+	obj_T& _object;
+	PBD::ScopedConnection _object_death_connection;
+};
+
 /** This command class is initialized with before and after mementos 
  * (from Stateful::get_state()), so undo becomes restoring the before
  * memento, and redo is restoring the after memento.
  */
 template <class obj_T>
-class MementoCommand : public Command
+class LIBPBD_TEMPLATE_API MementoCommand : public Command
 {
 public:
-	MementoCommand(obj_T& a_object, XMLNode* a_before, XMLNode* a_after) 
-		: obj(a_object), before(a_before), after(a_after)
+	MementoCommand (obj_T& a_object, XMLNode* a_before, XMLNode* a_after) 
+		: _binder (new SimpleMementoCommandBinder<obj_T> (a_object)), before (a_before), after (a_after)
 	{
-		/* catch destruction of the object */
-		new PBD::PairedShiva< obj_T,MementoCommand<obj_T> > (obj, *this);
+		/* The binder's object died, so we must die */
+		_binder->DropReferences.connect_same_thread (_binder_death_connection, boost::bind (&MementoCommand::binder_dying, this));
 	}
 
+	MementoCommand (MementoCommandBinder<obj_T>* b, XMLNode* a_before, XMLNode* a_after) 
+		: _binder (b), before (a_before), after (a_after)
+	{
+		/* The binder's object died, so we must die */
+		_binder->DropReferences.connect_same_thread (_binder_death_connection, boost::bind (&MementoCommand::binder_dying, this));
+	}
+	
 	~MementoCommand () {
-		GoingAway(); /* EMIT SIGNAL */
+		drop_references ();
 		delete before;
 		delete after;
+		delete _binder;
+	}
+
+	void binder_dying () {
+		delete this;
 	}
 
 	void operator() () {
 		if (after) {
-			obj.set_state(*after); 
+			_binder->get()->set_state(*after, Stateful::current_state_version); 
 		}
 	}
 
 	void undo() { 
 		if (before) {
-			obj.set_state(*before); 
+			_binder->get()->set_state(*before, Stateful::current_state_version); 
 		}
 	}
 
@@ -75,9 +151,9 @@ public:
 		}
 
 		XMLNode* node = new XMLNode(name);
-
-		node->add_property("obj_id", obj.id().to_s());
-		node->add_property("type_name", typeid(obj).name());
+		_binder->add_state (node);
+		
+		node->add_property ("type_name", _binder->type_name ());
 
 		if (before) {
 			node->add_child_copy(*before);
@@ -91,9 +167,10 @@ public:
 	}
 
 protected:
-	obj_T&   obj;
+	MementoCommandBinder<obj_T>* _binder;
 	XMLNode* before;
 	XMLNode* after;
+	PBD::ScopedConnection _binder_death_connection;
 };
 
 #endif // __lib_pbd_memento_h__