60 lines
1.6 KiB
C++
60 lines
1.6 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_observer
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#ifndef OBSERVER_HPP_
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#define OBSERVER_HPP_
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#include <boost/contract.hpp>
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#include <cassert>
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// Observer.
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class observer {
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friend class subject;
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public:
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// No inv and no bases so contracts optional if no pre, post, and override.
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/* Creation */
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observer() {
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// Could have omitted contracts here (nothing to check).
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boost::contract::check c = boost::contract::constructor(this);
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}
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virtual ~observer() {
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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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// If up-to-date with related subject.
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virtual bool up_to_date_with_subject(boost::contract::virtual_* v = 0)
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const = 0;
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// Update this observer.
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virtual void update(boost::contract::virtual_* v = 0) = 0;
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};
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bool observer::up_to_date_with_subject(boost::contract::virtual_* v) const {
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boost::contract::check c = boost::contract::public_function(v, this);
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assert(false);
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return false;
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}
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void observer::update(boost::contract::virtual_* v) {
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boost::contract::check c = boost::contract::public_function(v, this)
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.postcondition([&] {
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BOOST_CONTRACT_ASSERT(up_to_date_with_subject()); // Up-to-date.
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})
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;
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assert(false);
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}
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#endif // #include guard
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//]
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