Sandbox/TemplateMetaProgramming.cpp

   1 #include "TemplateMetaProgramming.h"
   2
   3 #include <iostream>
   4 #include <utility>
   5 #include <array>
   6 using namespace std;
   7
   8 #include "Types.h"
   9
  10 // See chapter 28 of "The C++ programming language".
  11
  12 namespace TemplateMetaProgramming
  13 {
  14     template<i64 I>
  15     struct Fib
  16     {
  17         static const i64 val = Fib<I - 1>::val + Fib<I - 2>::val;
  18     };
  19
  20     template<>
  21     struct Fib<0>
  22     {
  23         static const i64 val = 0;
  24     };
  25
  26     template<>
  27     struct Fib<1>
  28     {
  29         static const i64 val = 1;
  30     };
  31
  32     /////
  33
  34     template<i64 ... I>
  35     i64 fib_impl(integer_sequence<i64, I...>, const i64 i)
  36     {
  37         constexpr array<i64, sizeof...(I)> a = { Fib<I>::val... };
  38         return a[i];
  39     }
  40
  41     i64 fib(const i64 i)
  42     {
  43         // Generate all fibonacci sequence from 0 to 80.
  44         return fib_impl(make_integer_sequence<i64, 81>(), i);
  45     }
  46 }
  47
  48 void TemplateMetaProgramming::tests()
  49 {
  50     constexpr i64 n = 80;
  51     cout << "Compile time: fib(" << n << ") = " << Fib<n>::val << endl;
  52
  53     const i64 m = 80;
  54     cout << "Run time: fib(" << m << ") = " << fib(m) << endl;
  55 }