ceph/src/boost/libs/contract/example/mitchell02/counter/decrement_button.hpp

   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 //[mitchell02_decrement_button
   8 #ifndef DECREMENT_BUTTON_HPP_
   9 #define DECREMENT_BUTTON_HPP_
  10
  11 #include "push_button.hpp"
  12 #include "counter.hpp"
  13 #include "../observer/observer.hpp"
  14 #include <boost/contract.hpp>
  15 #include <boost/noncopyable.hpp>
  16
  17 class decrement_button
  18     #define BASES public push_button, public observer, \
  19             private boost::noncopyable
  20     : BASES
  21 {
  22     friend class boost::contract::access;
  23
  24     typedef BOOST_CONTRACT_BASE_TYPES(BASES) base_types;
  25     #undef BASES
  26
  27     BOOST_CONTRACT_OVERRIDES(on_bn_clicked, up_to_date_with_subject, update);
  28
  29 public:
  30     /* Creation */
  31
  32     explicit decrement_button(counter& a_counter) : counter_(a_counter) {
  33         boost::contract::check c = boost::contract::constructor(this)
  34             .postcondition([&] {
  35                 // Enable iff positive value.
  36                 BOOST_CONTRACT_ASSERT(enabled() == (a_counter.value() > 0));
  37             })
  38         ;
  39         counter_.attach(this);
  40     }
  41
  42     // Destroy button.
  43     virtual ~decrement_button() {
  44         // Could have omitted contracts here (nothing to check).
  45         boost::contract::check c = boost::contract::destructor(this);
  46     }
  47
  48     /* Commands */
  49
  50     virtual void on_bn_clicked(boost::contract::virtual_* v = 0)
  51             /* override */ {
  52         boost::contract::old_ptr<int> old_value =
  53                 BOOST_CONTRACT_OLDOF(v, counter_.value());
  54         boost::contract::check c = boost::contract::public_function<
  55             override_on_bn_clicked
  56         >(v, &decrement_button::on_bn_clicked, this)
  57             .postcondition([&] {
  58                 // Counter decremented.
  59                 BOOST_CONTRACT_ASSERT(counter_.value() == *old_value - 1);
  60             })
  61         ;
  62         counter_.decrement();
  63     }
  64
  65     virtual bool up_to_date_with_subject(boost::contract::virtual_* v = 0)
  66             const /* override */ {
  67         bool result;
  68         boost::contract::check c = boost::contract::public_function<
  69             override_up_to_date_with_subject
  70         >(v, result, &decrement_button::up_to_date_with_subject, this);
  71
  72         return result = true; // For simplicity, assume always up-to-date.
  73     }
  74
  75     virtual void update(boost::contract::virtual_* v = 0) /* override */ {
  76         boost::contract::check c = boost::contract::public_function<
  77                 override_update>(v, &decrement_button::update, this)
  78             .postcondition([&] {
  79                 // Enabled iff positive value.
  80                 BOOST_CONTRACT_ASSERT(enabled() == (counter_.value() > 0));
  81             })
  82         ;
  83
  84         if(counter_.value() == 0) disable();
  85         else enable();
  86     }
  87
  88 private:
  89     counter& counter_;
  90 };
  91
  92 #endif // #include guard
  93 //]
  94