resolve merge with master (?)

[ardour.git] / libs / pbd / pbd / memento_command.h

diff --git a/libs/pbd/pbd/memento_command.h b/libs/pbd/pbd/memento_command.h
index b1347c169d827054719e653ace891019bf7d8e88..45cb100a36e6d967e28771b6f935b565ad1d465e 100644 (file)
--- a/libs/pbd/pbd/memento_command.h
+++ b/libs/pbd/pbd/memento_command.h
@@ -26,11 +26,74 @@
 #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 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 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.
@@ -39,28 +102,40 @@ template <class obj_T>
 class 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 +150,9 @@ 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 +166,10 @@ public:
        }
 
 protected:
-       obj_T&   obj;
+       MementoCommandBinder<obj_T>* _binder;
        XMLNode* before;
        XMLNode* after;
+       PBD::ScopedConnection _binder_death_connection;
 };
 
 #endif // __lib_pbd_memento_h__