Line data    Source code

       1             : #pragma once
       2             : 
       3             : #include <tuple>
       4             : #include <variant>
       5             : #include <optional>
       6             : 
       7             : #include "elsaDefines.h"
       8             : #include "TypeCasts.hpp"
       9             : #include "DataDescriptor.h"
      10             : #include "ExpressionPredicates.h"
      11             : #include "DataHandlerCPU.h"
      12             : #include "DataHandlerMapCPU.h"
      13             : 
      14             : #ifdef ELSA_CUDA_VECTOR
      15             : #include "DataHandlerGPU.h"
      16             : #endif
      17             : 
      18             : namespace elsa
      19             : {
      20             :     /// Compile time switch to select to recursively evaluate for expression type
      21             :     template <bool GPU, class Operand, std::enable_if_t<isExpression<Operand>, int> = 0>
      22           0 :     constexpr auto evaluateOrReturn(Operand const& operand)
      23             :     {
      24           0 :         return operand.template eval<GPU>();
      25             :     }
      26             : 
      27             :     /// Compile time switch to return-by-value of arithmetic types
      28             :     template <bool GPU, class Operand, std::enable_if_t<isArithmetic<Operand>, int> = 0>
      29           0 :     constexpr auto evaluateOrReturn(Operand const operand)
      30             :     {
      31           0 :         return operand;
      32             :     }
      33             : 
      34             :     /// Compile time switch to return data in container
      35             :     template <bool GPU, class Operand, std::enable_if_t<isDataContainer<Operand>, int> = 0>
      36           0 :     constexpr auto evaluateOrReturn(Operand const& operand)
      37             :     {
      38             :         using data_t = typename Operand::value_type;
      39             : 
      40             :         if constexpr (GPU) {
      41             : #ifdef ELSA_CUDA_VECTOR
      42             :             if (auto handler = downcast_safe<DataHandlerGPU<data_t>>(operand._dataHandler.get())) {
      43             :                 return handler->accessData();
      44             :             } else if (auto handler =
      45             :                            downcast_safe<DataHandlerMapGPU<data_t>>(operand._dataHandler.get())) {
      46             :                 return handler->accessData();
      47             :             } else {
      48             :                 throw InternalError("Unknown handler type");
      49             :             }
      50             : #endif
      51             :         } else {
      52           0 :             if (auto handler = downcast_safe<DataHandlerCPU<data_t>>(operand._dataHandler.get())) {
      53           0 :                 return handler->accessData();
      54           0 :             } else if (auto handler =
      55           0 :                            downcast_safe<DataHandlerMapCPU<data_t>>(operand._dataHandler.get())) {
      56           0 :                 return handler->accessData();
      57             :             } else {
      58           0 :                 throw InternalError("Unknown handler type");
      59             :             }
      60             :         }
      61             :     }
      62             : 
      63             :     /// Type trait which decides if const lvalue reference or not
      64             :     template <typename Operand>
      65             :     class ReferenceOrNot
      66             :     {
      67             :     public:
      68             :         using type = typename std::conditional<isExpression<Operand> || isArithmetic<Operand>,
      69             :                                                Operand, const Operand&>::type;
      70             :     };
      71             : 
      72             :     /**
      73             :      * @brief Temporary expression type which enables lazy-evaluation of expression
      74             :      *
      75             :      * @author Jens Petit
      76             :      *
      77             :      * @tparam Callable - the operation to be performed
      78             :      * @tparam Operands - the objects on which the operation is performed
      79             :      *
      80             :      */
      81             :     template <typename Callable, typename... Operands>
      82             :     class Expression
      83             :     {
      84             :     public:
      85             :         /// type which bundles the meta information to create a new DataContainer
      86             :         using MetaInfo_t = std::pair<DataDescriptor const&, DataHandlerType>;
      87             : 
      88             :         /// indicates data type is used in the expression
      89             :         using data_t = typename GetOperandsDataType<Operands...>::data_t;
      90             : 
      91             :         /// Constructor
      92           0 :         Expression(Callable func, Operands const&... args)
      93           0 :             : _callable(func), _args(args...), _dataMetaInfo(initDescriptor(args...))
      94             :         {
      95           0 :         }
      96             : 
      97             :         /// Evaluates the expression
      98             :         template <bool GPU = false>
      99           0 :         auto eval() const
     100             :         {
     101             :             // generic lambda for evaluating tree, we need this to get a pack again out of the tuple
     102           0 :             auto const callCallable = [this](Operands const&... args) {
     103             :                 // here evaluateOrReturn is called on each Operand within args as the unpacking
     104             :                 // takes place after the fcn call
     105             :                 // selects the right callable from the Callables struct with multiple lambdas
     106             :                 if constexpr (GPU) {
     107             :                     return _callable(evaluateOrReturn<GPU>(args)..., GPU);
     108             :                 } else {
     109           0 :                     return _callable(evaluateOrReturn<GPU>(args)...);
     110             :                 }
     111             :             };
     112           0 :             return std::apply(callCallable, _args);
     113             :         }
     114             : 
     115           0 :         MetaInfo_t getDataMetaInfo() const { return _dataMetaInfo; }
     116             : 
     117             :     private:
     118             :         /// The function to call on the operand(s)
     119             :         const Callable _callable;
     120             : 
     121             :         /// Contains all operands saved as const references (DataContainers) or copies
     122             :         /// (Expressions and arithmetic types)
     123             :         std::tuple<typename ReferenceOrNot<Operands>::type...> _args;
     124             : 
     125             :         /// saves the meta information to create a new DataContainer out of an expression
     126             :         const MetaInfo_t _dataMetaInfo;
     127             : 
     128             :         /// correctly returns the DataContainer descriptor based on the operands (either
     129             :         /// expressions or Datacontainers)
     130           0 :         MetaInfo_t initDescriptor(Operands const&... args)
     131             :         {
     132           0 :             if (auto info = getMetaInfoFromContainers(args...); info.has_value()) {
     133           0 :                 return *info;
     134             :             } else {
     135           0 :                 if (auto info = getMetaInfoFromExpressions(args...); info.has_value()) {
     136           0 :                     return *info;
     137             :                 } else {
     138           0 :                     throw LogicError("No meta info available, cannot create expression");
     139             :                 }
     140             :             }
     141             :         }
     142             : 
     143             :         /// base recursive case if no DataContainer as operand
     144           0 :         std::optional<MetaInfo_t> getMetaInfoFromContainers() { return {}; }
     145             : 
     146             :         /// recursive traversal of all contained DataContainers
     147             :         template <class T, class... Ts>
     148           0 :         std::optional<MetaInfo_t> getMetaInfoFromContainers(T& arg, Ts&... args)
     149             :         {
     150             :             if constexpr (isDataContainer<T>) {
     151           0 :                 return MetaInfo_t{arg.getDataDescriptor(), arg.getDataHandlerType()};
     152             :             } else {
     153           0 :                 return getMetaInfoFromContainers(args...);
     154             :             }
     155             :         }
     156             : 
     157             :         /// base recursive case if no Expression as operand
     158           0 :         std::optional<MetaInfo_t> getMetaInfoFromExpressions() { return {}; }
     159             : 
     160             :         /// recursive traversal of all contained Expressions
     161             :         template <class T, class... Ts>
     162           0 :         std::optional<MetaInfo_t> getMetaInfoFromExpressions(T& arg, Ts&... args)
     163             :         {
     164             :             if constexpr (isExpression<T>) {
     165           0 :                 return arg.getDataMetaInfo();
     166             :             } else {
     167           0 :                 return getMetaInfoFromExpressions(args...);
     168             :             }
     169             :         }
     170             :     };
     171             : } // namespace elsa