ceph/src/boost/libs/contract/example/n1962/circle.cpp

   1
   2 // Copyright (C) 2008-2018 Lorenzo Caminiti
   3 // Distributed under the Boost Software License, Version 1.0 (see accompanying
   4 // file LICENSE_1_0.txt or a copy at http://www.boost.org/LICENSE_1_0.txt).
   5 // See: http://www.boost.org/doc/libs/release/libs/contract/doc/html/index.html
   6
   7 //[n1962_circle
   8 #include <boost/contract.hpp>
   9 #include <cassert>
  10
  11 class shape {
  12 public:
  13     virtual ~shape() {}
  14
  15     virtual unsigned compute_area(boost::contract::virtual_* v = 0) const = 0;
  16 };
  17
  18 unsigned shape::compute_area(boost::contract::virtual_* v) const {
  19     unsigned result;
  20     boost::contract::check c = boost::contract::public_function(v, result, this)
  21         .postcondition([&] (int const& result) {
  22             BOOST_CONTRACT_ASSERT(result > 0);
  23         })
  24     ;
  25     assert(false);
  26     return result;
  27 }
  28
  29 class circle
  30     #define BASES public shape
  31     : BASES
  32 {
  33     friend class boost::contract::access;
  34
  35     typedef BOOST_CONTRACT_BASE_TYPES(BASES) base_types;
  36     #undef BASES
  37
  38     BOOST_CONTRACT_OVERRIDE(compute_area);
  39
  40 public:
  41     static int const pi = 3; // Truncated to int from 3.14...
  42
  43     explicit circle(unsigned a_radius) : radius_(a_radius) {
  44         boost::contract::check c = boost::contract::constructor(this)
  45             .postcondition([&] {
  46                 BOOST_CONTRACT_ASSERT(radius() == a_radius);
  47             })
  48         ;
  49     }
  50
  51     virtual unsigned compute_area(boost::contract::virtual_* v = 0) const
  52             /* override */ {
  53         unsigned result;
  54         boost::contract::check c = boost::contract::public_function<
  55                 override_compute_area>(v, result, &circle::compute_area, this)
  56             .postcondition([&] (unsigned const& result) {
  57                 BOOST_CONTRACT_ASSERT(result == pi * radius() * radius());
  58             })
  59         ;
  60
  61         return result = pi * radius() * radius();
  62     }
  63
  64     unsigned radius() const {
  65         boost::contract::check c = boost::contract::public_function(this);
  66         return radius_;
  67     }
  68
  69 private:
  70     unsigned radius_;
  71 };
  72
  73 int main() {
  74     circle c(2);
  75     assert(c.radius() == 2);
  76     assert(c.compute_area() == 12);
  77     return 0;
  78 }
  79 //]
  80