ceph/src/boost/libs/contract/example/features/check.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 #include <boost/contract.hpp>
   8
   9 int gcd(int const a, int const b) {
  10     int result;
  11     boost::contract::check c = boost::contract::function()
  12         .precondition([&] {
  13             BOOST_CONTRACT_ASSERT(a > 0);
  14             BOOST_CONTRACT_ASSERT(b > 0);
  15         })
  16         .postcondition([&] {
  17             BOOST_CONTRACT_ASSERT(result <= a);
  18             BOOST_CONTRACT_ASSERT(result <= b);
  19         })
  20     ;
  21
  22     int x = a, y = b;
  23     while(x != y) {
  24         if(x > y) x = x - y;
  25         else y = y - x;
  26     }
  27     return result = x;
  28 }
  29
  30 //[check
  31 int main() {
  32     // Implementation checks (via nullary functor).
  33     boost::contract::check c = [&] {
  34         BOOST_CONTRACT_ASSERT(gcd(12, 28) == 4);
  35         BOOST_CONTRACT_ASSERT(gcd(4, 14) == 2);
  36     };
  37
  38     return 0;
  39 }
  40 //]
  41