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// 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
#include <boost/contract.hpp>
#include <limits>
#include <cassert>
//[private_protected
class counter {
protected: // Protected functions use `function()` (like non-members).
void set(int n) {
boost::contract::check c = boost::contract::function()
.precondition([&] {
BOOST_CONTRACT_ASSERT(n <= 0);
})
.postcondition([&] {
BOOST_CONTRACT_ASSERT(get() == n);
})
;
n_ = n;
}
private: // Private functions use `function()` (like non-members).
void dec() {
boost::contract::old_ptr<int> old_get = BOOST_CONTRACT_OLDOF(get());
boost::contract::check c = boost::contract::function()
.precondition([&] {
BOOST_CONTRACT_ASSERT(
get() + 1 >= std::numeric_limits<int>::min());
})
.postcondition([&] {
BOOST_CONTRACT_ASSERT(get() == *old_get - 1);
})
;
set(get() - 1);
}
int n_;
/* ... */
//]
public:
int get() const {
int result;
boost::contract::check c = boost::contract::public_function(this)
.postcondition([&] {
BOOST_CONTRACT_ASSERT(result <= 0);
BOOST_CONTRACT_ASSERT(result == n_);
})
;
return result = n_;
}
counter() : n_(0) {} // Should contract constructor and destructor too.
void invariant() const {
BOOST_CONTRACT_ASSERT(get() <= 0);
}
friend int main();
};
int main() {
counter cnt;
assert(cnt.get() == 0);
cnt.dec();
assert(cnt.get() == -1);
return 0;
}
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