.. _program_listing_file_src_pcms_field_field_data.h:

Program Listing for File field_data.h
=====================================

|exhale_lsh| :ref:`Return to documentation for file <file_src_pcms_field_field_data.h>` (``src/pcms/field/field_data.h``)

.. |exhale_lsh| unicode:: U+021B0 .. UPWARDS ARROW WITH TIP LEFTWARDS

.. code-block:: cpp

   #ifndef PCMS_FIELD_DATA_H
   #define PCMS_FIELD_DATA_H
   
   #include "pcms/field/value_view.hpp"
   #include "pcms/utility/arrays.h"
   #include "pcms/utility/memory_spaces.h"
   #include <memory>
   #include <variant>
   
   namespace pcms
   {
   
   // DOFAccess<T> is the optional capability of field data whose values PCMS can
   // read and write directly: the values of the DOF holders this rank owns, shaped
   // [owned DOF holder][component] in the layout's order. Coupler exchanges and
   // transfer targets use it; evaluation never needs it.
   template <typename T>
   class DOFAccess
   {
   public:
     // Valid until the field data is next written or destroyed.
     virtual Rank2View<const T, DeviceMemorySpace> GetOwnedValues() const = 0;
   
     // Writes the owned values, then brings any other copies the backend keeps
     // (ghosts, replicas on other ranks) up to date. Collective over the ranks
     // that share those copies.
     virtual void SetOwnedValues(Rank2View<const T, DeviceMemorySpace> values) = 0;
   
     virtual ~DOFAccess() noexcept = default;
   };
   
   // FieldData<T> holds whatever a backend needs to represent a field. It is
   // opaque. It should only be directly used by the type that created it.
   template <typename T>
   class FieldData
   {
   public:
     using value_type = T;
   
     virtual FieldValueType GetValueType() const = 0;
     virtual const ValueBasis& GetValueBasis() const = 0;
   
     virtual const DOFAccess<T>* GetDOFAccess() const noexcept { return nullptr; }
     virtual DOFAccess<T>* GetDOFAccess() noexcept { return nullptr; }
   
     virtual ~FieldData() noexcept = default;
   };
   
   using FieldDataVariant = std::variant<
     std::unique_ptr<FieldData<int8_t>>, std::unique_ptr<FieldData<int32_t>>,
     std::unique_ptr<FieldData<int64_t>>, std::unique_ptr<FieldData<float>>,
     std::unique_ptr<FieldData<double>>>;
   
   } // namespace pcms
   
   #endif // PCMS_FIELD_DATA_H