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  1. /*!
  2.  * @file GenericImage_typeDispatch.cpp
  3.  * @brief
  4.  * @author vectra
  5.  * @date 16/05/19
  6.  */
  7.  
  8. #include <iostream>
  9. #include <vector>
  10. #include <exception>
  11. #include <array>
  12.  
  13.  
  14. using namespace std;
  15.  
  16.  
  17. // =============================================================================
  18. // type helpers
  19. // =============================================================================
  20.  
  21.  
  22. template < typename T >
  23. void showType(T var)
  24. { throw; }
  25.  
  26. template <>
  27. void showType(double var)
  28. { cout << "double"; }
  29.  
  30. template <>
  31. void showType(int var)
  32. { cout << "int"; }
  33.  
  34. template <>
  35. void showType(float var)
  36. { cout << "float"; }
  37.  
  38.  
  39.  
  40. // =============================================================================
  41. // dummy typed image class (implemented likewise by many real image libs)
  42. // =============================================================================
  43.  
  44.  
  45. class Image
  46. {
  47.  public:
  48.  
  49.   enum class Type
  50.   {
  51.     Float64,
  52.     Float32,
  53.     Int32,
  54.   } type_;
  55.  
  56.   std::size_t voxel_count_;
  57.   void        *data_ptr_ = nullptr;
  58.  
  59.   Image()
  60.   {}
  61.  
  62.   void
  63.   allocate(Image::Type t, size_t voxel_count)
  64.   {
  65.     type_        = t;
  66.     voxel_count_ = voxel_count;
  67.  
  68.     switch (t)
  69.       {
  70.         case Image::Type::Float64:
  71.           data_ptr_ = static_cast<void *>(new double[voxel_count]);
  72.         break;
  73.         case Image::Type::Int32:
  74.           data_ptr_ = static_cast<void *>(new int[voxel_count]);
  75.         break;
  76.         default:
  77.           throw;
  78.       }
  79.   }
  80.  
  81.   void
  82.   set_data(Image::Type t, void *data)
  83.   {
  84.     if ( data_ptr_ != nullptr ) throw;
  85.     type_     = t;
  86.     data_ptr_ = data;
  87.   }
  88. };
  89.  
  90.  
  91. // =============================================================================
  92. // Dispatcher mother, where all ropes are hidden from the user
  93. // =============================================================================
  94.  
  95.  
  96. template < class Derived >
  97. class ExecutorMother
  98. {
  99.  public:
  100.   Image *img_ = nullptr;
  101.  
  102.   ExecutorMother(Image *img) : img_(img)
  103.   {}
  104.  
  105.  
  106.   // This code compiles but does not work as expected (int filter function always called)
  107.   template < class ... ArgsType >
  108.   void
  109.   operator()(ArgsType ... arguments)
  110.   {
  111.     if ( ExecutorMother::img_ -> data_ptr_ == nullptr ) throw;
  112.     Derived &derived = static_cast<Derived &>(*this);
  113.  
  114.     switch (ExecutorMother::img_ -> type_)
  115.       {
  116.         case Image::Type::Float64:
  117.           {
  118.             derived . filter_function(arguments ...);
  119.             //derived . filter_function<double>(arguments ...); // auugh! why!!
  120.             break;
  121.           }
  122.         case Image::Type::Float32:
  123.           {
  124.             derived . filter_function(arguments ...);
  125.             //derived . filter_function<float>(arguments ...); // auugh! why!!
  126.             break;
  127.           }
  128.         case Image::Type::Int32:
  129.           {
  130.             derived . filter_function(arguments ...);
  131.             //derived . filter_function<int>(arguments ...); // auugh! why!!
  132.             break;
  133.           }
  134.         default:
  135.           throw;// std::bad_exception;
  136.       }
  137.   }
  138.  
  139.  
  140. };
  141.  
  142.  
  143. // =============================================================================
  144. // Dispatcher mother, where all ropes are hidden from the user
  145. // =============================================================================
  146.  
  147.  
  148. class CustomDispatcher : public ExecutorMother<CustomDispatcher>
  149. {
  150.  public:
  151.  
  152.   CustomDispatcher(Image *img) : ExecutorMother(img)
  153.   {}
  154.  
  155.  
  156.   template < typename ImgDataType >
  157.   void
  158.   filter_function(ImgDataType trigger_val, int iters, float dummy)
  159.   {
  160.     ImgDataType *data = static_cast<ImgDataType *>(ExecutorMother::img_ -> data_ptr_);
  161.  
  162.     cout << endl << "Types for filter: ";
  163.     showType(data[0]);
  164.     cout << " / arg1: ";
  165.     showType(trigger_val);
  166.     cout << " / arg2: ";
  167.     showType(iters);
  168.     cout << " / arg3: ";
  169.     showType(dummy);
  170.  
  171.  
  172.     for (size_t i = 0; i < ExecutorMother::img_ -> voxel_count_; i ++)
  173.       {
  174.         if ( data[i] == trigger_val )
  175.           data[i] = data[i] + iters;
  176.       }
  177.   }
  178.  
  179.  
  180.   /*
  181.    * @brief this code works 100% fine; but would like it hidden in motherclass
  182.    */
  183.    /*
  184.   template < class ... ArgsType >
  185.   void
  186.   operator()(ArgsType ... arguments)
  187.   {
  188.     if ( ExecutorMother::img_ -> data_ptr_ == nullptr ) throw;
  189.     
  190.     switch (ExecutorMother::img_ -> type_)
  191.       {
  192.         case Image::Type::Float64:
  193.           {
  194.             filter_function<double>(arguments ...);
  195.             break;
  196.           }
  197.         case Image::Type::Float32:
  198.           {
  199.             filter_function<float>(arguments ...);
  200.             break;
  201.           }
  202.         case Image::Type::Int32:
  203.           {
  204.             \
  205.           filter_function<int>(arguments ...);
  206.             break;
  207.           }
  208.         default:
  209.           throw;// std::bad_exception;
  210.       }
  211.   }
  212.   */
  213.  
  214. };
  215.  
  216.  
  217. int main()
  218. {
  219.   std::array<int, 8> data = {1, 2, 3, - 32768, 5, 6, 7, 8};
  220.  
  221.   Image imgd;
  222.   imgd . allocate(Image::Type::Float64, 2 * 4);
  223.   Image imgi;
  224.   imgi . allocate(Image::Type::Int32, 2 * 4);
  225.  
  226.  
  227.   CustomDispatcher execd(&imgd);
  228.   execd(- 32768, 32000, 3.14);
  229.   cout << endl << "double attendu pour type filtre";
  230.   CustomDispatcher execi(&imgi);
  231.   execi(- 32768, 32000, 3.14);
  232.   cout << endl << "int attendu pour type filtre";
  233.  
  234.  
  235.   return 0;
  236. }
Success #stdin #stdout 0s 15240KB
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Standard input is empty
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Types for filter: int / arg1: int / arg2: int / arg3: float
double attendu pour type filtre
Types for filter: int / arg1: int / arg2: int / arg3: float
int attendu pour type filtre
https://ideone.com/WGiGPa
language:
C++ (gcc 8.3)
created:
4 years ago
visibility:
public

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