contract/example/mitchell02/counter/decrement_button.hpp
2017-12-10 18:48:50 -08:00

95 lines
2.9 KiB
C++

// Copyright (C) 2008-2018 Lorenzo Caminiti
// Distributed under the Boost Software License, Version 1.0 (see accompanying
// file LICENSE_1_0.txt or a copy at http://www.boost.org/LICENSE_1_0.txt).
// See: http://www.boost.org/doc/libs/release/libs/contract/doc/html/index.html
//[mitchell02_decrement_button
#ifndef DECREMENT_BUTTON_HPP_
#define DECREMENT_BUTTON_HPP_
#include "push_button.hpp"
#include "counter.hpp"
#include "../observer/observer.hpp"
#include <boost/contract.hpp>
#include <boost/noncopyable.hpp>
class decrement_button
#define BASES public push_button, public observer, \
private boost::noncopyable
: BASES
{
friend class boost::contract::access;
typedef BOOST_CONTRACT_BASE_TYPES(BASES) base_types;
#undef BASES
BOOST_CONTRACT_OVERRIDES(on_bn_clicked, up_to_date_with_subject, update);
public:
/* Creation */
explicit decrement_button(counter& a_counter) : counter_(a_counter) {
boost::contract::check c = boost::contract::constructor(this)
.postcondition([&] {
// Enable iff positive value.
BOOST_CONTRACT_ASSERT(enabled() == (a_counter.value() > 0));
})
;
counter_.attach(this);
}
// Destroy button.
virtual ~decrement_button() {
// Could have omitted contracts here (nothing to check).
boost::contract::check c = boost::contract::destructor(this);
}
/* Commands */
virtual void on_bn_clicked(boost::contract::virtual_* v = 0)
/* override */ {
boost::contract::old_ptr<int> old_value =
BOOST_CONTRACT_OLDOF(v, counter_.value());
boost::contract::check c = boost::contract::public_function<
override_on_bn_clicked
>(v, &decrement_button::on_bn_clicked, this)
.postcondition([&] {
// Counter decremented.
BOOST_CONTRACT_ASSERT(counter_.value() == *old_value - 1);
})
;
counter_.decrement();
}
virtual bool up_to_date_with_subject(boost::contract::virtual_* v = 0)
const /* override */ {
bool result;
boost::contract::check c = boost::contract::public_function<
override_up_to_date_with_subject
>(v, result, &decrement_button::up_to_date_with_subject, this);
return result = true; // For simplicity, assume always up-to-date.
}
virtual void update(boost::contract::virtual_* v = 0) /* override */ {
boost::contract::check c = boost::contract::public_function<
override_update>(v, &decrement_button::update, this)
.postcondition([&] {
// Enabled iff positive value.
BOOST_CONTRACT_ASSERT(enabled() == (counter_.value() > 0));
})
;
if(counter_.value() == 0) disable();
else enable();
}
private:
counter& counter_;
};
#endif // #include guard
//]