text: //////////////////////////////////////////////////////////////////////////
  //
  //  Copyright (c) 2012, John Haddon. All rights reserved.
  //  Copyright (c) 2013, Image Engine Design Inc. 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
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  //  PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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  //////////////////////////////////////////////////////////////////////////
  
  #ifndef GAFFERSCENE_PRIMITIVEVARIABLEPROCESSOR_H
  #define GAFFERSCENE_PRIMITIVEVARIABLEPROCESSOR_H
  
  #include "GafferScene/SceneElementProcessor.h"
  
  namespace GafferScene
  {
  
  /// The PrimitiveVariableProcessor base class simplifies the process of manipulating
  /// primitive variables.
  class PrimitiveVariableProcessor : public SceneElementProcessor
  {
  
  	public :
  
  		PrimitiveVariableProcessor( const std::string &name=defaultName<PrimitiveVariableProcessor>() );
  		virtual ~PrimitiveVariableProcessor();
  
  		IE_CORE_DECLARERUNTIMETYPEDEXTENSION( GafferScene::PrimitiveVariableProcessor, PrimitiveVariableProcessorTypeId, SceneElementProcessor );
  
  		Gaffer::StringPlug *namesPlug();
  		const Gaffer::StringPlug *namesPlug() const;
  
  		Gaffer::BoolPlug *invertNamesPlug();
  		const Gaffer::BoolPlug *invertNamesPlug() const;
  
  		/// Implemented so that namesPlug() affects outPlug()->objectPlug().
  		virtual void affects( const Gaffer::Plug *input, AffectedPlugsContainer &outputs ) const;
  
  	protected :
  
  		/// Implemented to call processPrimitiveVariable() for the appropriate variables of inputObject.
  		virtual bool processesObject() const;
  		virtual void hashProcessedObject( const ScenePath &path, const Gaffer::Context *context, IECore::MurmurHash &h ) const;
  		virtual IECore::ConstObjectPtr computeProcessedObject( const ScenePath &path, const Gaffer::Context *context, IECore::ConstObjectPtr inputObject ) const;
  
  		/// Must be implemented by subclasses to process the primitive variable in place.
  		virtual void processPrimitiveVariable( const ScenePath &path, const Gaffer::Context *context, IECore::ConstPrimitivePtr inputGeometry, IECore::PrimitiveVariable &inputVariable ) const = 0;
  
  	private :
  
  		static size_t g_firstPlugIndex;
  
  };
  
  IE_CORE_DECLAREPTR( PrimitiveVariableProcessor )
  
  } // namespace GafferScene
  
  #endif // GAFFERSCENE_PRIMITIVEVARIABLEPROCESSOR_H
  