text: //////////////////////////////////////////////////////////////////////////
  //
  //  Copyright (c) 2019, Cinesite VFX Ltd. All rights reserved.
  //
  //  Redistribution and use in source and binary forms, with or without
  //  modification, are permitted provided that the following conditions are
  //  met:
  //
  //      * Redistributions of source code must retain the above
  //        copyright notice, this list of conditions and the following
  //        disclaimer.
  //
  //      * Redistributions in binary form must reproduce the above
  //        copyright notice, this list of conditions and the following
  //        disclaimer in the documentation and/or other materials provided with
  //        the distribution.
  //
  //      * Neither the name of John Haddon nor the names of
  //        any other contributors to this software may be used to endorse or
  //        promote products derived from this software without specific prior
  //        written permission.
  //
  //  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
  //  IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
  //  THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  //  PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
  //  CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  //  EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  //  PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  //  PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
  //  LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
  //  NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  //  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  //
  //////////////////////////////////////////////////////////////////////////
  
  #include "GafferUI/NoduleLayout.h"
  #include "GafferUI/PlugAdder.h"
  #include "GafferUI/StandardNodeGadget.h"
  
  #include "Gaffer/EditScope.h"
  
  #include "boost/bind.hpp"
  
  using namespace IECore;
  using namespace Gaffer;
  using namespace GafferUI;
  
  namespace
  {
  
  class EditScopePlugAdder : public PlugAdder
  {
  
  	public :
  
  		EditScopePlugAdder( EditScopePtr editScope )
  			:	m_editScope( editScope )
  		{
  			m_editScope->childAddedSignal().connect( boost::bind( &EditScopePlugAdder::childAdded, this ) );
  			m_editScope->childRemovedSignal().connect( boost::bind( &EditScopePlugAdder::childRemoved, this ) );
  			updateVisibility();
  		}
  
  	protected :
  
  		bool canCreateConnection( const Plug *endpoint ) const override
  		{
  			if( !PlugAdder::canCreateConnection( endpoint ) )
  			{
  				return false;
  			}
  
  			if(
  				endpoint->node() == m_editScope ||
  				m_editScope->inPlug()
  			)
  			{
  				return false;
  			}
  
  			return true;
  		}
  
  		void createConnection( Plug *endpoint ) override
  		{
  			m_editScope->setup( endpoint );
  			if( endpoint->direction() == Plug::In )
  			{
  				endpoint->setInput( m_editScope->outPlug() );
  			}
  			else
  			{
  				m_editScope->inPlug()->setInput( endpoint );
  			}
  		}
  
  	private :
  
  		void updateVisibility()
  		{
  			setVisible( !m_editScope->inPlug() );
  		}
  
  		void childAdded()
  		{
  			updateVisibility();
  		}
  
  		void childRemoved()
  		{
  			updateVisibility();
  		}
  
  		EditScopePtr m_editScope;
  
  };
  
  struct Registration
  {
  
  	Registration()
  	{
  		NoduleLayout::registerCustomGadget(
  			"GafferUI.EditScopeUI.PlugAdder",
  			[]( GraphComponentPtr parent ) {
  				if( EditScopePtr editScope = runTimeCast<EditScope>( parent ) )
  				{
  					return new EditScopePlugAdder( editScope );
  				}
  				throw IECore::Exception( "Expected an EditScope" );
  			}
  		);
  	}
  
  };
  
  Registration g_registration;
  
  } // namespace
  
  