ceph/src/boost/libs/yap/example/calc2a.cpp

   1 // Copyright (C) 2016-2018 T. Zachary Laine
   2 //
   3 // Distributed under the Boost Software License, Version 1.0. (See
   4 // accompanying file LICENSE_1_0.txt or copy at
   5 // http://www.boost.org/LICENSE_1_0.txt)
   6 //[ calc2a
   7 #include <boost/yap/expression.hpp>
   8
   9 #include <iostream>
  10
  11
  12 int main ()
  13 {
  14     using namespace boost::yap::literals;
  15
  16     auto expr_1 = 1_p + 2.0;
  17
  18     auto expr_1_fn = [expr_1](auto &&... args) {
  19         return evaluate(expr_1, args...);
  20     };
  21
  22     auto expr_2 = 1_p * 2_p;
  23
  24     auto expr_2_fn = [expr_2](auto &&... args) {
  25         return evaluate(expr_2, args...);
  26     };
  27
  28     auto expr_3 = (1_p - 2_p) / 2_p;
  29
  30     auto expr_3_fn = [expr_3](auto &&... args) {
  31         return evaluate(expr_3, args...);
  32     };
  33
  34     // Displays "5"
  35     std::cout << expr_1_fn(3.0) << std::endl;
  36
  37     // Displays "6"
  38     std::cout << expr_2_fn(3.0, 2.0) << std::endl;
  39
  40     // Displays "0.5"
  41     std::cout << expr_3_fn(3.0, 2.0) << std::endl;
  42
  43     return 0;
  44 }
  45 //]