Consolidate plugin API to access parent insert

Previously this was special cased only for VST for callbacks
from the plugin (e.g. check pin connections), but it is generally
useful.

libs/ardour/ardour/plugin.h

@@ -24,6 +24,7 @@
 #define __ardour_plugin_h__
 
 #include <boost/shared_ptr.hpp>
+
 #include <set>
 #include <string>
 
@@ -84,6 +85,14 @@ public:
 	virtual void set_insert_id (PBD::ID id) {}
 	virtual void set_state_dir (const std::string& d = "") {}
 
+	void set_insert (PluginInsert* pi, uint32_t num) {
+		_pi = pi;
+		_num = num;
+	}
+
+	PluginInsert* plugin_insert () const { return _pi; }
+	uint32_t plugin_number () const { return _num; }
+
 	virtual std::string unique_id () const                   = 0;
 	virtual const char* label () const                       = 0;
 	virtual const char* name () const                        = 0;
@@ -412,6 +421,9 @@ private:
 
 	void invalidate_preset_cache (std::string const&, Plugin*, bool);
 	void resolve_midi ();
+
+	PluginInsert* _pi;
+	uint32_t      _num;
 };
 
 struct PluginPreset {

libs/ardour/ardour/plugin_insert.h

@@ -28,6 +28,7 @@
 #include <string>
 
 #include <boost/weak_ptr.hpp>
+#include <boost/enable_shared_from_this.hpp>
 
 #include "pbd/stack_allocator.h"
 #include "pbd/timing.h"
@@ -57,7 +58,7 @@ class Plugin;
 
 /** Plugin inserts: send data through a plugin
  */
-class LIBARDOUR_API PluginInsert : public Processor, public PlugInsertBase
+class LIBARDOUR_API PluginInsert : public Processor, public PlugInsertBase, public boost::enable_shared_from_this <PluginInsert>
 {
 public:
 	PluginInsert (Session&, Temporal::TimeDomain td, boost::shared_ptr<Plugin> = boost::shared_ptr<Plugin>());
@@ -65,6 +66,10 @@ public:
 
 	void drop_references ();
 
+	boost::weak_ptr<PluginInsert> weak_ptr () {
+		return shared_from_this();
+	}
+
 	static const std::string port_automation_node_name;
 
 	int set_state(const XMLNode&, int version);

libs/ardour/ardour/vst_plugin.h

@@ -98,9 +98,6 @@ public:
 
 	int first_user_preset_index () const;
 
-	void set_insert (PluginInsert* pi, uint32_t num) { _pi = pi; _num = num; }
-	PluginInsert* plugin_insert () const { return _pi; }
-	uint32_t plugin_number () const { return _num; }
 	VstTimeInfo* timeinfo () { return &_timeInfo; }
 	samplepos_t transport_sample () const { return _transport_sample; }
 	float transport_speed () const { return _transport_speed; }
@@ -125,8 +122,6 @@ protected:
 	VSTHandle* _handle;
 	VSTState*  _state;
 	AEffect*   _plugin;
-	PluginInsert* _pi;
-	uint32_t      _num;
 
 	MidiBuffer* _midi_out_buf;
 	VstTimeInfo _timeInfo;

libs/ardour/plugin.cc

@@ -95,6 +95,8 @@ Plugin::Plugin (AudioEngine& e, Session& s)
 	, _have_pending_stop_events (false)
 	, _parameter_changed_since_last_preset (false)
 	, _immediate_events(6096) // FIXME: size?
+	, _pi (0)
+	, _num (0)
 {
 	_pending_stop_events.ensure_buffers (DataType::MIDI, 1, 4096);
 	PresetsChanged.connect_same_thread(_preset_connection, boost::bind (&Plugin::invalidate_preset_cache, this, _1, _2, _3));
@@ -114,6 +116,8 @@ Plugin::Plugin (const Plugin& other)
 	, _last_preset (other._last_preset)
 	, _parameter_changed_since_last_preset (false)
 	, _immediate_events(6096) // FIXME: size?
+	, _pi (other._pi)
+	, _num (other._num)
 {
 	_pending_stop_events.ensure_buffers (DataType::MIDI, 1, 4096);
 

libs/ardour/plugin_insert.cc

@@ -3127,12 +3127,8 @@ PluginInsert::add_plugin (boost::shared_ptr<Plugin> plugin)
 			}
 		}
 	}
-#if (defined WINDOWS_VST_SUPPORT || defined LXVST_SUPPORT || defined MACVST_SUPPORT)
-	boost::shared_ptr<VSTPlugin> vst = boost::dynamic_pointer_cast<VSTPlugin> (plugin);
-	if (vst) {
-		vst->set_insert (this, _plugins.size ());
-	}
-#endif
+
+	plugin->set_insert (this, _plugins.size ());
 
 	_plugins.push_back (plugin);
 

libs/ardour/vst_plugin.cc

@@ -52,8 +52,6 @@ VSTPlugin::VSTPlugin (AudioEngine& engine, Session& session, VSTHandle* handle)
 	, _handle (handle)
 	, _state (0)
 	, _plugin (0)
-	, _pi (0)
-	, _num (0)
 	, _transport_sample (0)
 	, _transport_speed (0.f)
 	, _eff_bypassed (false)
@@ -66,8 +64,6 @@ VSTPlugin::VSTPlugin (const VSTPlugin& other)
 	, _handle (other._handle)
 	, _state (other._state)
 	, _plugin (other._plugin)
-	, _pi (other._pi)
-	, _num (other._num)
 	, _midi_out_buf (other._midi_out_buf)
 	, _transport_sample (0)
 	, _transport_speed (0.f)