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//        Phalanx: A Partial Differential Equation Field Evaluation 
//       Kernel for Flexible Management of Complex Dependency Chains
//                    Copyright 2008 Sandia Corporation
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#ifndef PHX_DATA_LAYOUT
#define PHX_DATA_LAYOUT

#include <iostream>
#include <vector>
#include <string>
#include "Phalanx_KokkosDeviceTypes.hpp"

namespace PHX{


  /*! \brief A pure virtual class to distinguish a unique data layout in a cell.

      The DataLayout class is used to (1) specify the array size of a
      an algebraic type in a single cell, and (2) to differentiate
      FieldTags that have the same name, but have different
      DataLayouts in the FieldManager.  For example suppose we want to
      store density at both the nodes and the quadrature points in a
      cell.  If we use the same string name for the FieldTag, the
      DataLayout will differentiate the objects.  We could probably
      just use an enumerated type here, but the DataLayout class
      allows users to derive and pass in auxiliary data via the tag.
  */
  class DataLayout {

  public:

    // typedef long unsigned int size_type;
    typedef PHX::Device::size_type size_type;

    DataLayout() {}

    virtual ~DataLayout() {}

    virtual PHX::Device::size_type rank() const = 0; 

    virtual PHX::Device::size_type dimension(size_type ordinal) const = 0; 

    virtual PHX::Device::size_type extent(size_type ordinal) const = 0; 

    virtual int extent_int(size_type ordinal) const = 0; 

    virtual void 
    dimensions(std::vector<PHX::Device::size_type>& dim) const = 0; 

    //! Returns the name of the input ordinal
    virtual std::string name(size_type ordinal) const = 0;

    //! Returns the names of all ordinals in a vector
    virtual void names(std::vector<std::string>& names) const = 0; 

    virtual PHX::Device::size_type size() const = 0;

    virtual bool operator==(const DataLayout& left) const = 0;

    virtual bool operator!=(const DataLayout& left) const
    { return !(*this == left); }

    //! Unique name identifier that can be used for strict weak ordering in stl std::map keys.
    virtual std::string identifier() const = 0;

    virtual void print(std::ostream& os, int indent = 0) const = 0;

  };

  std::ostream& operator<<(std::ostream& os, const PHX::DataLayout& t);
  
}

#endif
