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/// \file Kokkos_Parallel.hpp
/// \brief Declaration of parallel operators

#ifndef KOKKOS_PARALLEL_HPP
#define KOKKOS_PARALLEL_HPP

#include <cstddef>
#include <Kokkos_Core_fwd.hpp>
#include <Kokkos_View.hpp>
#include <Kokkos_ExecPolicy.hpp>

#ifdef KOKKOSP_ENABLE_PROFILING
#include <impl/Kokkos_Profiling_Interface.hpp>
#include <typeinfo>
#endif

#include <impl/Kokkos_AllocationTracker.hpp>
#include <impl/Kokkos_Tags.hpp>
#include <impl/Kokkos_Traits.hpp>
#include <impl/Kokkos_FunctorAdapter.hpp>

#ifdef KOKKOS_HAVE_DEBUG
#include<iostream>
#endif

//----------------------------------------------------------------------------
//----------------------------------------------------------------------------

namespace Kokkos {
namespace Impl {

//----------------------------------------------------------------------------
/** \brief  Given a Functor and Execution Policy query an execution space.
 *
 *  if       the Policy has an execution space use that
 *  else if  the Functor has an execution_space use that
 *  else if  the Functor has a device_type use that for backward compatibility
 *  else     use the default
 */
template< class Functor
        , class Policy
        , class EnableFunctor = void
        , class EnablePolicy  = void
        >
struct FunctorPolicyExecutionSpace {
  typedef Kokkos::DefaultExecutionSpace execution_space ;
};

template< class Functor , class Policy >
struct FunctorPolicyExecutionSpace
  < Functor , Policy
  , typename enable_if_type< typename Functor::device_type     >::type
  , typename enable_if_type< typename Policy ::execution_space >::type
  >
{
  typedef typename Policy ::execution_space execution_space ;
};

template< class Functor , class Policy >
struct FunctorPolicyExecutionSpace
  < Functor , Policy
  , typename enable_if_type< typename Functor::execution_space >::type
  , typename enable_if_type< typename Policy ::execution_space >::type
  >
{
  typedef typename Policy ::execution_space execution_space ;
};

template< class Functor , class Policy , class EnableFunctor >
struct FunctorPolicyExecutionSpace
  < Functor , Policy
  , EnableFunctor
  , typename enable_if_type< typename Policy::execution_space >::type
  >
{
  typedef typename Policy ::execution_space execution_space ;
};

template< class Functor , class Policy , class EnablePolicy >
struct FunctorPolicyExecutionSpace
  < Functor , Policy
  , typename enable_if_type< typename Functor::device_type >::type
  , EnablePolicy
  >
{
  typedef typename Functor::device_type execution_space ;
};

template< class Functor , class Policy , class EnablePolicy >
struct FunctorPolicyExecutionSpace
  < Functor , Policy
  , typename enable_if_type< typename Functor::execution_space >::type
  , EnablePolicy
  >
{
  typedef typename Functor::execution_space execution_space ;
};

//----------------------------------------------------------------------------
/// \class ParallelFor
/// \brief Implementation of the ParallelFor operator that has a
///   partial specialization for the device.
///
/// This is an implementation detail of parallel_for.  Users should
/// skip this and go directly to the nonmember function parallel_for.
template< class FunctorType , class ExecPolicy > class ParallelFor ;

/// \class ParallelReduce
/// \brief Implementation detail of parallel_reduce.
///
/// This is an implementation detail of parallel_reduce.  Users should
/// skip this and go directly to the nonmember function parallel_reduce.
template< class FunctorType , class ExecPolicy > class ParallelReduce ;

/// \class ParallelScan
/// \brief Implementation detail of parallel_scan.
///
/// This is an implementation detail of parallel_scan.  Users should
/// skip this and go directly to the documentation of the nonmember
/// template function Kokkos::parallel_scan.
template< class FunctorType , class ExecPolicy > class ParallelScan ;

} // namespace Impl
} // namespace Kokkos

//----------------------------------------------------------------------------
//----------------------------------------------------------------------------

namespace Kokkos {

/** \brief Execute \c functor in parallel according to the execution \c policy.
 *
 * A "functor" is a class containing the function to execute in parallel,
 * data needed for that execution, and an optional \c execution_space
 * typedef.  Here is an example functor for parallel_for:
 *
 * \code
 *  class FunctorType {
 *  public:
 *    typedef  ...  execution_space ;
 *    void operator() ( WorkType iwork ) const ;
 *  };
 * \endcode
 *
 * In the above example, \c WorkType is any integer type for which a
 * valid conversion from \c size_t to \c IntType exists.  Its
 * <tt>operator()</tt> method defines the operation to parallelize,
 * over the range of integer indices <tt>iwork=[0,work_count-1]</tt>.
 * This compares to a single iteration \c iwork of a \c for loop.
 * If \c execution_space is not defined DefaultExecutionSpace will be used.
 */
template< class ExecPolicy , class FunctorType >
inline
void parallel_for( const ExecPolicy  & policy
                 , const FunctorType & functor
                 , const std::string& str = ""
                 , typename Impl::enable_if< ! Impl::is_integral< ExecPolicy >::value >::type * = 0
                 )
{
#ifdef KOKKOSP_ENABLE_PROFILING
    uint64_t kpID = 0;
     if(Kokkos::Experimental::profileLibraryLoaded()) {
     	Kokkos::Experimental::beginParallelFor("" == str ? typeid(FunctorType).name() : str, 0, &kpID);
     }
#endif

    (void) Impl::ParallelFor< FunctorType , ExecPolicy >( Impl::CopyWithoutTracking::apply(functor) , policy );
   
#ifdef KOKKOSP_ENABLE_PROFILING
     if(Kokkos::Experimental::profileLibraryLoaded()) {
        Kokkos::Experimental::endParallelFor(kpID);
     }
#endif
}

template< class FunctorType >
inline
void parallel_for( const size_t        work_count
                 , const FunctorType & functor
                 , const std::string& str = ""
                 )
{
  typedef typename
    Impl::FunctorPolicyExecutionSpace< FunctorType , void >::execution_space
      execution_space ;
  typedef RangePolicy< execution_space > policy ;

#ifdef KOKKOSP_ENABLE_PROFILING
  uint64_t kpID = 0;
     if(Kokkos::Experimental::profileLibraryLoaded()) {
  	Kokkos::Experimental::beginParallelFor("" == str ? typeid(FunctorType).name() : str, 0, &kpID);
     }
#endif
    
  (void) Impl::ParallelFor< FunctorType , policy >( Impl::CopyWithoutTracking::apply(functor) , policy(0,work_count) );

#ifdef KOKKOSP_ENABLE_PROFILING
     if(Kokkos::Experimental::profileLibraryLoaded()) {
	Kokkos::Experimental::endParallelFor(kpID);
     }
#endif
}

template< class ExecPolicy , class FunctorType >
inline
void parallel_for( const std::string & str
                 , const ExecPolicy  & policy
                 , const FunctorType & functor )
{
  #if KOKKOS_ENABLE_DEBUG_PRINT_KERNEL_NAMES
  Kokkos::fence();
  std::cout << "KOKKOS_DEBUG Start parallel_for kernel: " << str << std::endl;
  #endif

  parallel_for(policy,functor,str);

  #if KOKKOS_ENABLE_DEBUG_PRINT_KERNEL_NAMES
  Kokkos::fence();
  std::cout << "KOKKOS_DEBUG End   parallel_for kernel: " << str << std::endl;
  #endif
  (void) str;
}

//----------------------------------------------------------------------------
//----------------------------------------------------------------------------

/** \brief  Parallel reduction
 *
 * Example of a parallel_reduce functor for a POD (plain old data) value type:
 * \code
 *  class FunctorType { // For POD value type
 *  public:
 *    typedef    ...     execution_space ;
 *    typedef <podType>  value_type ;
 *    void operator()( <intType> iwork , <podType> & update ) const ;
 *    void init( <podType> & update ) const ;
 *    void join( volatile       <podType> & update ,
 *               volatile const <podType> & input ) const ;
 *
 *    typedef true_type has_final ;
 *    void final( <podType> & update ) const ;
 *  };
 * \endcode
 *
 * Example of a parallel_reduce functor for an array of POD (plain old data) values:
 * \code
 *  class FunctorType { // For array of POD value
 *  public:
 *    typedef    ...     execution_space ;
 *    typedef <podType>  value_type[] ;
 *    void operator()( <intType> , <podType> update[] ) const ;
 *    void init( <podType> update[] ) const ;
 *    void join( volatile       <podType> update[] ,
 *               volatile const <podType> input[] ) const ;
 *
 *    typedef true_type has_final ;
 *    void final( <podType> update[] ) const ;
 *  };
 * \endcode
 */
template< class ExecPolicy , class FunctorType >
inline
void parallel_reduce( const ExecPolicy  & policy
                    , const FunctorType & functor
                    , const std::string& str = ""
                    , typename Impl::enable_if< ! Impl::is_integral< ExecPolicy >::value >::type * = 0
                    )
{
  // typedef typename
  //   Impl::FunctorPolicyExecutionSpace< FunctorType , ExecPolicy >::execution_space
  //     execution_space ;

  typedef Kokkos::Impl::FunctorValueTraits< FunctorType , typename ExecPolicy::work_tag >  ValueTraits ;

  typedef typename Kokkos::Impl::if_c< (ValueTraits::StaticValueSize != 0)
                                     , typename ValueTraits::value_type
                                     , typename ValueTraits::pointer_type
                                     >::type value_type ;

  Kokkos::View< value_type
              , HostSpace
              , Kokkos::MemoryUnmanaged
              >
    result_view ;

#ifdef KOKKOSP_ENABLE_PROFILING
  uint64_t kpID = 0;
     if(Kokkos::Experimental::profileLibraryLoaded()) {
  	Kokkos::Experimental::beginParallelReduce("" == str ? typeid(FunctorType).name() : str, 0, &kpID);
     }
#endif

     (void) Impl::ParallelReduce< FunctorType , ExecPolicy >( Impl::CopyWithoutTracking::apply(functor) , policy , result_view );

#ifdef KOKKOSP_ENABLE_PROFILING
     if(Kokkos::Experimental::profileLibraryLoaded()) {
	Kokkos::Experimental::endParallelReduce(kpID);
     }
#endif
}

// integral range policy
template< class FunctorType >
inline
void parallel_reduce( const size_t        work_count
                    , const FunctorType & functor
                    , const std::string& str = ""
                    )
{
  typedef typename
    Impl::FunctorPolicyExecutionSpace< FunctorType , void >::execution_space
      execution_space ;

  typedef RangePolicy< execution_space > policy ;

  typedef Kokkos::Impl::FunctorValueTraits< FunctorType , void >  ValueTraits ;

  typedef typename Kokkos::Impl::if_c< (ValueTraits::StaticValueSize != 0)
                                     , typename ValueTraits::value_type
                                     , typename ValueTraits::pointer_type
                                     >::type value_type ;

  Kokkos::View< value_type
              , HostSpace
              , Kokkos::MemoryUnmanaged
              >
    result_view ;

#ifdef KOKKOSP_ENABLE_PROFILING
  uint64_t kpID = 0;
     if(Kokkos::Experimental::profileLibraryLoaded()) {
  	Kokkos::Experimental::beginParallelReduce("" == str ? typeid(FunctorType).name() : str, 0, &kpID);
     }
#endif
    
  (void) Impl::ParallelReduce< FunctorType , policy >( Impl::CopyWithoutTracking::apply(functor) , policy(0,work_count) , result_view );

#ifdef KOKKOSP_ENABLE_PROFILING
     if(Kokkos::Experimental::profileLibraryLoaded()) {
	Kokkos::Experimental::endParallelReduce(kpID);
     }
#endif

}

// general policy and view ouput
template< class ExecPolicy , class FunctorType , class ViewType >
inline
void parallel_reduce( const ExecPolicy  & policy
                    , const FunctorType & functor
                    , const ViewType    & result_view
                    , const std::string& str = ""
                    , typename Impl::enable_if<
                      ( Impl::is_view<ViewType>::value && ! Impl::is_integral< ExecPolicy >::value
#ifdef KOKKOS_HAVE_CUDA
                        && ! Impl::is_same<typename ExecPolicy::execution_space,Kokkos::Cuda>::value
#endif
                      )>::type * = 0 )
{
    
#ifdef KOKKOSP_ENABLE_PROFILING
  uint64_t kpID = 0;
     if(Kokkos::Experimental::profileLibraryLoaded()) {
	Kokkos::Experimental::beginParallelReduce("" == str ? typeid(FunctorType).name() : str, 0, &kpID);
     }
#endif
    
  (void) Impl::ParallelReduce< FunctorType, ExecPolicy >( Impl::CopyWithoutTracking::apply(functor) , policy , Impl::CopyWithoutTracking::apply(result_view) );

#ifdef KOKKOSP_ENABLE_PROFILING
     if(Kokkos::Experimental::profileLibraryLoaded()) {
	Kokkos::Experimental::endParallelReduce(kpID);
     }
#endif

}

// general policy and pod or array of pod output
template< class ExecPolicy , class FunctorType >
void parallel_reduce( const ExecPolicy  & policy
                    , const FunctorType & functor
#ifdef KOKKOS_HAVE_CUDA
                    , typename Impl::enable_if<
                      ( ! Impl::is_integral< ExecPolicy >::value &&
                        ! Impl::is_same<typename ExecPolicy::execution_space,Kokkos::Cuda>::value )
                      , typename Kokkos::Impl::FunctorValueTraits< FunctorType , typename ExecPolicy::work_tag >::reference_type>::type result_ref
                      , const std::string& str = ""
                      , typename Impl::enable_if<! Impl::is_same<typename ExecPolicy::execution_space,Kokkos::Cuda>::value >::type* = 0
                      )
#else
                      , typename Impl::enable_if<
                        ( ! Impl::is_integral< ExecPolicy >::value)
                        , typename Kokkos::Impl::FunctorValueTraits< FunctorType , typename ExecPolicy::work_tag >::reference_type
                        >::type result_ref
                      , const std::string& str = ""
                        )
#endif
{
  typedef Kokkos::Impl::FunctorValueTraits< FunctorType , typename ExecPolicy::work_tag >  ValueTraits ;
  typedef Kokkos::Impl::FunctorValueOps<    FunctorType , typename ExecPolicy::work_tag >  ValueOps ;

  // Wrap the result output request in a view to inform the implementation
  // of the type and memory space.

  typedef typename Kokkos::Impl::if_c< (ValueTraits::StaticValueSize != 0)
                                     , typename ValueTraits::value_type
                                     , typename ValueTraits::pointer_type
                                     >::type value_type ;

  Kokkos::View< value_type
              , HostSpace
              , Kokkos::MemoryUnmanaged
              >
    result_view( ValueOps::pointer( result_ref )
               , ValueTraits::value_count( functor )
               );

#ifdef KOKKOSP_ENABLE_PROFILING
  uint64_t kpID = 0;
     if(Kokkos::Experimental::profileLibraryLoaded()) {
	Kokkos::Experimental::beginParallelReduce("" == str ? typeid(FunctorType).name() : str, 0, &kpID);
     }
#endif
    
  (void) Impl::ParallelReduce< FunctorType, ExecPolicy >( Impl::CopyWithoutTracking::apply(functor) , policy , Impl::CopyWithoutTracking::apply(result_view) );

#ifdef KOKKOSP_ENABLE_PROFILING
     if(Kokkos::Experimental::profileLibraryLoaded()) {
	Kokkos::Experimental::endParallelReduce(kpID);
     }
#endif

}

// integral range policy and view ouput
template< class FunctorType , class ViewType >
inline
void parallel_reduce( const size_t        work_count
                    , const FunctorType & functor
                    , const ViewType    & result_view
                    , const std::string& str = ""
                    , typename Impl::enable_if<( Impl::is_view<ViewType>::value
#ifdef KOKKOS_HAVE_CUDA
                        && ! Impl::is_same<
                          typename Impl::FunctorPolicyExecutionSpace< FunctorType , void >::execution_space,
                          Kokkos::Cuda>::value
#endif
                        )>::type * = 0 )
{
  typedef typename
    Impl::FunctorPolicyExecutionSpace< FunctorType , void >::execution_space
      execution_space ;

  typedef RangePolicy< execution_space > ExecPolicy ;

#ifdef KOKKOSP_ENABLE_PROFILING
  uint64_t kpID = 0;
     if(Kokkos::Experimental::profileLibraryLoaded()) {
	Kokkos::Experimental::beginParallelReduce("" == str ? typeid(FunctorType).name() : str, 0, &kpID);
     }
#endif

  (void) Impl::ParallelReduce< FunctorType, ExecPolicy >( Impl::CopyWithoutTracking::apply(functor) , ExecPolicy(0,work_count) , Impl::CopyWithoutTracking::apply(result_view) );
    
#ifdef KOKKOSP_ENABLE_PROFILING
     if(Kokkos::Experimental::profileLibraryLoaded()) {
	Kokkos::Experimental::endParallelReduce(kpID);
     }
#endif

}

// integral range policy and pod or array of pod output
template< class FunctorType >
inline
void parallel_reduce( const size_t        work_count
                    , const FunctorType & functor
                    , typename Kokkos::Impl::FunctorValueTraits<
                         typename Impl::if_c<Impl::is_execution_policy<FunctorType>::value ||
                                             Impl::is_integral<FunctorType>::value,
                            void,FunctorType>::type
                         , void >::reference_type result
                    , const std::string& str = ""
                    , typename Impl::enable_if< true
#ifdef KOKKOS_HAVE_CUDA
                              && ! Impl::is_same<
                             typename Impl::FunctorPolicyExecutionSpace< FunctorType , void >::execution_space,
                             Kokkos::Cuda>::value
#endif
                     >::type * = 0 )
{
  typedef Kokkos::Impl::FunctorValueTraits< FunctorType , void >  ValueTraits ;
  typedef Kokkos::Impl::FunctorValueOps<    FunctorType , void >  ValueOps ;

  typedef typename
    Kokkos::Impl::FunctorPolicyExecutionSpace< FunctorType , void >::execution_space
      execution_space ;

  typedef Kokkos::RangePolicy< execution_space > policy ;

  // Wrap the result output request in a view to inform the implementation
  // of the type and memory space.

  typedef typename Kokkos::Impl::if_c< (ValueTraits::StaticValueSize != 0)
                                     , typename ValueTraits::value_type
                                     , typename ValueTraits::pointer_type
                                     >::type value_type ;

  Kokkos::View< value_type
              , HostSpace
              , Kokkos::MemoryUnmanaged
              >
    result_view( ValueOps::pointer( result )
               , ValueTraits::value_count( functor )
               );

#ifdef KOKKOSP_ENABLE_PROFILING
  uint64_t kpID = 0;
     if(Kokkos::Experimental::profileLibraryLoaded()) {
	Kokkos::Experimental::beginParallelReduce("" == str ? typeid(FunctorType).name() : str, 0, &kpID);
     }
#endif

  (void) Impl::ParallelReduce< FunctorType , policy >( Impl::CopyWithoutTracking::apply(functor) , policy(0,work_count) , Impl::CopyWithoutTracking::apply(result_view) );

#ifdef KOKKOSP_ENABLE_PROFILING
     if(Kokkos::Experimental::profileLibraryLoaded()) {
	Kokkos::Experimental::endParallelReduce(kpID);
     }
#endif

}

template< class ExecPolicy , class FunctorType , class ResultType >
inline
void parallel_reduce( const std::string & str
                    , const ExecPolicy  & policy
                    , const FunctorType & functor
                    , ResultType * result)
{
  #if KOKKOS_ENABLE_DEBUG_PRINT_KERNEL_NAMES
  Kokkos::fence();
  std::cout << "KOKKOS_DEBUG Start parallel_reduce kernel: " << str << std::endl;
  #endif

  parallel_reduce(policy,functor,result,str);

  #if KOKKOS_ENABLE_DEBUG_PRINT_KERNEL_NAMES
  Kokkos::fence();
  std::cout << "KOKKOS_DEBUG End   parallel_reduce kernel: " << str << std::endl;
  #endif
  (void) str;
}

template< class ExecPolicy , class FunctorType , class ResultType >
inline
void parallel_reduce( const std::string & str
                    , const ExecPolicy  & policy
                    , const FunctorType & functor
                    , ResultType & result)
{
  #if KOKKOS_ENABLE_DEBUG_PRINT_KERNEL_NAMES
  Kokkos::fence();
  std::cout << "KOKKOS_DEBUG Start parallel_reduce kernel: " << str << std::endl;
  #endif

  parallel_reduce(policy,functor,result,str);

  #if KOKKOS_ENABLE_DEBUG_PRINT_KERNEL_NAMES
  Kokkos::fence();
  std::cout << "KOKKOS_DEBUG End   parallel_reduce kernel: " << str << std::endl;
  #endif
  (void) str;
}

template< class ExecPolicy , class FunctorType >
inline
void parallel_reduce( const std::string & str
                    , const ExecPolicy  & policy
                    , const FunctorType & functor)
{
  #if KOKKOS_ENABLE_DEBUG_PRINT_KERNEL_NAMES
  Kokkos::fence();
  std::cout << "KOKKOS_DEBUG Start parallel_reduce kernel: " << str << std::endl;
  #endif

  parallel_reduce(policy,functor,str);

  #if KOKKOS_ENABLE_DEBUG_PRINT_KERNEL_NAMES
  Kokkos::fence();
  std::cout << "KOKKOS_DEBUG End   parallel_reduce kernel: " << str << std::endl;
  #endif
  (void) str;
}


} // namespace Kokkos

//----------------------------------------------------------------------------
//----------------------------------------------------------------------------

namespace Kokkos {

/// \fn parallel_scan
/// \tparam ExecutionPolicy The execution policy type.
/// \tparam FunctorType     The scan functor type.
///
/// \param policy  [in] The execution policy.
/// \param functor [in] The scan functor.
///
/// This function implements a parallel scan pattern.  The scan can
/// be either inclusive or exclusive, depending on how you implement
/// the scan functor.
///
/// A scan functor looks almost exactly like a reduce functor, except
/// that its operator() takes a third \c bool argument, \c final_pass,
/// which indicates whether this is the last pass of the scan
/// operation.  We will show below how to use the \c final_pass
/// argument to control whether the scan is inclusive or exclusive.
///
/// Here is the minimum required interface of a scan functor for a POD
/// (plain old data) value type \c PodType.  That is, the result is a
/// View of zero or more PodType.  It is also possible for the result
/// to be an array of (same-sized) arrays of PodType, but we do not
/// show the required interface for that here.
/// \code
/// template< class ExecPolicy , class FunctorType >
/// class ScanFunctor {
/// public:
///   // The Kokkos device type
///   typedef ... execution_space;
///   // Type of an entry of the array containing the result;
///   // also the type of each of the entries combined using
///   // operator() or join().
///   typedef PodType value_type;
///
///   void operator () (const ExecPolicy::member_type & i, value_type& update, const bool final_pass) const;
///   void init (value_type& update) const;
///   void join (volatile value_type& update, volatile const value_type& input) const
/// };
/// \endcode
///
/// Here is an example of a functor which computes an inclusive plus-scan
/// of an array of \c int, in place.  If given an array [1, 2, 3, 4], this
/// scan will overwrite that array with [1, 3, 6, 10].
///
/// \code
/// template<class SpaceType>
/// class InclScanFunctor {
/// public:
///   typedef SpaceType execution_space;
///   typedef int value_type;
///   typedef typename SpaceType::size_type size_type;
///
///   InclScanFunctor( Kokkos::View<value_type*, execution_space> x
///                  , Kokkos::View<value_type*, execution_space> y ) : m_x(x), m_y(y) {}
///
///   void operator () (const size_type i, value_type& update, const bool final_pass) const {
///     update += m_x(i);
///     if (final_pass) {
///       m_y(i) = update;
///     }
///   }
///   void init (value_type& update) const {
///     update = 0;
///   }
///   void join (volatile value_type& update, volatile const value_type& input) const {
///     update += input;
///   }
///
/// private:
///   Kokkos::View<value_type*, execution_space> m_x;
///   Kokkos::View<value_type*, execution_space> m_y;
/// };
/// \endcode
///
/// Here is an example of a functor which computes an <i>exclusive</i>
/// scan of an array of \c int, in place.  In operator(), note both
/// that the final_pass test and the update have switched places, and
/// the use of a temporary.  If given an array [1, 2, 3, 4], this scan
/// will overwrite that array with [0, 1, 3, 6].
///
/// \code
/// template<class SpaceType>
/// class ExclScanFunctor {
/// public:
///   typedef SpaceType execution_space;
///   typedef int value_type;
///   typedef typename SpaceType::size_type size_type;
///
///   ExclScanFunctor (Kokkos::View<value_type*, execution_space> x) : x_ (x) {}
///
///   void operator () (const size_type i, value_type& update, const bool final_pass) const {
///     const value_type x_i = x_(i);
///     if (final_pass) {
///       x_(i) = update;
///     }
///     update += x_i;
///   }
///   void init (value_type& update) const {
///     update = 0;
///   }
///   void join (volatile value_type& update, volatile const value_type& input) const {
///     update += input;
///   }
///
/// private:
///   Kokkos::View<value_type*, execution_space> x_;
/// };
/// \endcode
///
/// Here is an example of a functor which builds on the above
/// exclusive scan example, to compute an offsets array from a
/// population count array, in place.  We assume that the pop count
/// array has an extra entry at the end to store the final count.  If
/// given an array [1, 2, 3, 4, 0], this scan will overwrite that
/// array with [0, 1, 3, 6, 10].
///
/// \code
/// template<class SpaceType>
/// class OffsetScanFunctor {
/// public:
///   typedef SpaceType execution_space;
///   typedef int value_type;
///   typedef typename SpaceType::size_type size_type;
///
///   // lastIndex_ is the last valid index (zero-based) of x.
///   // If x has length zero, then lastIndex_ won't be used anyway.
///   OffsetScanFunctor( Kokkos::View<value_type*, execution_space> x
///                    , Kokkos::View<value_type*, execution_space> y )
///      : m_x(x), m_y(y), last_index_ (x.dimension_0 () == 0 ? 0 : x.dimension_0 () - 1)
///   {}
///
///   void operator () (const size_type i, int& update, const bool final_pass) const {
///     if (final_pass) {
///       m_y(i) = update;
///     }
///     update += m_x(i);
///     // The last entry of m_y gets the final sum.
///     if (final_pass && i == last_index_) {
///       m_y(i+1) = update;
///     }
///   }
///   void init (value_type& update) const {
///     update = 0;
///   }
///   void join (volatile value_type& update, volatile const value_type& input) const {
///     update += input;
///   }
///
/// private:
///   Kokkos::View<value_type*, execution_space> m_x;
///   Kokkos::View<value_type*, execution_space> m_y;
///   const size_type last_index_;
/// };
/// \endcode
///
template< class ExecutionPolicy , class FunctorType >
inline
void parallel_scan( const ExecutionPolicy & policy
                  , const FunctorType     & functor
                  , const std::string& str = ""
                  , typename Impl::enable_if< ! Impl::is_integral< ExecutionPolicy >::value >::type * = 0
                  )
{
#ifdef KOKKOSP_ENABLE_PROFILING
  uint64_t kpID = 0;
     if(Kokkos::Experimental::profileLibraryLoaded()) {
	Kokkos::Experimental::beginParallelScan("" == str ? typeid(FunctorType).name() : str, 0, &kpID);
     }
#endif

  Impl::ParallelScan< FunctorType , ExecutionPolicy > scan( Impl::CopyWithoutTracking::apply(functor) , policy );

#ifdef KOKKOSP_ENABLE_PROFILING
     if(Kokkos::Experimental::profileLibraryLoaded()) {
	Kokkos::Experimental::endParallelScan(kpID);
     }
#endif

}

template< class FunctorType >
inline
void parallel_scan( const size_t        work_count
                  , const FunctorType & functor
                  , const std::string& str = "" )
{
  typedef typename
    Kokkos::Impl::FunctorPolicyExecutionSpace< FunctorType , void >::execution_space
      execution_space ;

  typedef Kokkos::RangePolicy< execution_space > policy ;

#ifdef KOKKOSP_ENABLE_PROFILING
  uint64_t kpID = 0;
     if(Kokkos::Experimental::profileLibraryLoaded()) {
	Kokkos::Experimental::beginParallelScan("" == str ? typeid(FunctorType).name() : str, 0, &kpID);
     }
#endif
    
  (void) Impl::ParallelScan< FunctorType , policy >( Impl::CopyWithoutTracking::apply(functor) , policy(0,work_count) );

#ifdef KOKKOSP_ENABLE_PROFILING
     if(Kokkos::Experimental::profileLibraryLoaded()) {
	Kokkos::Experimental::endParallelScan(kpID);
     }
#endif

}

template< class ExecutionPolicy , class FunctorType >
inline
void parallel_scan( const std::string& str
                  , const ExecutionPolicy & policy
                  , const FunctorType     & functor)
{
  #if KOKKOS_ENABLE_DEBUG_PRINT_KERNEL_NAMES
  Kokkos::fence();
  std::cout << "KOKKOS_DEBUG Start parallel_scan kernel: " << str << std::endl;
  #endif

  parallel_scan(policy,functor,str);

  #if KOKKOS_ENABLE_DEBUG_PRINT_KERNEL_NAMES
  Kokkos::fence();
  std::cout << "KOKKOS_DEBUG End   parallel_scan kernel: " << str << std::endl;
  #endif
  (void) str;
}

} // namespace Kokkos

//----------------------------------------------------------------------------
//----------------------------------------------------------------------------

namespace Kokkos {
namespace Impl {

template< class FunctorType , class Enable = void >
struct FunctorTeamShmemSize
{
  static inline size_t value( const FunctorType & , int ) { return 0 ; }
};

template< class FunctorType >
struct FunctorTeamShmemSize< FunctorType , typename Impl::enable_if< 0 < sizeof( & FunctorType::team_shmem_size ) >::type >
{
  static inline size_t value( const FunctorType & f , int team_size ) { return f.team_shmem_size( team_size ) ; }
};

template< class FunctorType >
struct FunctorTeamShmemSize< FunctorType , typename Impl::enable_if< 0 < sizeof( & FunctorType::shmem_size ) >::type >
{
  static inline size_t value( const FunctorType & f , int team_size ) { return f.shmem_size( team_size ) ; }
};

} // namespace Impl
} // namespace Kokkos

//----------------------------------------------------------------------------
//----------------------------------------------------------------------------

#endif /* KOKKOS_PARALLEL_HPP */