libs/contract/example/features/lambda.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 #include <vector>
   9 #include <algorithm>
  10 #include <limits>
  11
  12 int main() {
  13     std::vector<int> v;
  14     v.push_back(1);
  15     v.push_back(2);
  16     v.push_back(3);
  17
  18     //[lambda
  19     int total = 0;
  20     std::for_each(v.cbegin(), v.cend(),
  21         // Contract for a lambda function.
  22         [&total] (int const x) {
  23             boost::contract::old_ptr<int> old_total =
  24                     BOOST_CONTRACT_OLDOF(total);
  25             boost::contract::check c = boost::contract::function()
  26                 .precondition([&] {
  27                     BOOST_CONTRACT_ASSERT(
  28                             total < std::numeric_limits<int>::max() - x);
  29                 })
  30                 .postcondition([&] {
  31                     BOOST_CONTRACT_ASSERT(total == *old_total + x);
  32                 })
  33             ;
  34
  35             total += x; // Lambda function body.
  36         }
  37     );
  38     //]
  39
  40     assert(total == 6);
  41     return 0;
  42 }
  43