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