text: //////////////////////////////////////////////////////////////////////////
  //
  //  Copyright (c) 2012, John Haddon. 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 "Gaffer/ContextVariables.h"
  
  #include "Gaffer/Context.h"
  
  #include "IECore/SimpleTypedData.h"
  
  using namespace Gaffer;
  
  GAFFER_NODE_DEFINE_TYPE( ContextVariables );
  
  size_t ContextVariables::g_firstPlugIndex;
  
  ContextVariables::ContextVariables( const std::string &name )
  	:	ContextProcessor( name )
  {
  	storeIndexOfNextChild( g_firstPlugIndex );
  	addChild( new CompoundDataPlug( "variables" ) );
  	addChild( new AtomicCompoundDataPlug( "extraVariables", Plug::In, new IECore::CompoundData ) );
  }
  
  ContextVariables::~ContextVariables()
  {
  }
  
  CompoundDataPlug *ContextVariables::variablesPlug()
  {
  	return getChild<CompoundDataPlug>( g_firstPlugIndex );
  }
  
  const CompoundDataPlug *ContextVariables::variablesPlug() const
  {
  	return getChild<CompoundDataPlug>( g_firstPlugIndex );
  }
  
  AtomicCompoundDataPlug *ContextVariables::extraVariablesPlug()
  {
  	return getChild<AtomicCompoundDataPlug>( g_firstPlugIndex + 1 );
  }
  
  const AtomicCompoundDataPlug *ContextVariables::extraVariablesPlug() const
  {
  	return getChild<AtomicCompoundDataPlug>( g_firstPlugIndex + 1 );
  }
  
  bool ContextVariables::affectsContext( const Plug *input ) const
  {
  	return variablesPlug()->isAncestorOf( input ) || input == extraVariablesPlug();
  }
  
  void ContextVariables::processContext( Context::EditableScope &context ) const
  {
  	std::string name;
  	for( NameValuePlugIterator it( variablesPlug() ); !it.done(); ++it )
  	{
  		IECore::DataPtr data = variablesPlug()->memberDataAndName( it->get(), name );
  		if( data )
  		{
  			context.set( name, data.get() );
  		}
  	}
  	IECore::ConstCompoundDataPtr extraVariablesData = extraVariablesPlug()->getValue();
  	const IECore::CompoundDataMap &extraVariables = extraVariablesData->readable();
  	for( IECore::CompoundDataMap::const_iterator it = extraVariables.begin(), eIt = extraVariables.end(); it != eIt; ++it )
  	{
  		context.set( it->first, it->second.get() );
  	}
  }
  