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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/config.hpp>
#ifdef BOOST_MSVC
// WARNING: MSVC (at least up to VS 2015) gives a compile-time error if SFINAE
// cannot introspect a member because of its private or protected access level.
// That is incorrect, SFINAE should fail in these cases without generating
// compile-time errors like GCC and CLang do. Therefore, currently it is not
// possible to override a member that is public in one base but private or
// protected in other base using this library on MSVC (that can be done instead
// using this library on GCC or CLang).
int main() { return 0; } // Trivial program for MSVC.
#else
#include <boost/contract.hpp>
#include <limits>
#include <cassert>
class counter {
// Virtual private and protected functions still declare extra
// `virtual_* = 0` parameter (otherwise they cannot be overridden).
protected:
virtual void set(int n, boost::contract::virtual_* = 0) {
boost::contract::check c = boost::contract::function()
.precondition([&] {
BOOST_CONTRACT_ASSERT(n <= 0);
})
.postcondition([&] {
BOOST_CONTRACT_ASSERT(get() == n);
})
;
n_ = n;
}
private:
virtual void dec(boost::contract::virtual_* = 0) {
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:
virtual int get(boost::contract::virtual_* v = 0) const {
int result;
boost::contract::check c = boost::contract::public_function(
v, result, this)
.postcondition([&] (int const result) {
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();
};
//[private_protected_virtual_multi_countable
class countable {
public:
void invariant() const {
BOOST_CONTRACT_ASSERT(get() <= 0);
}
virtual void dec(boost::contract::virtual_* v = 0) = 0;
virtual void set(int n, boost::contract::virtual_* v = 0) = 0;
virtual int get(boost::contract::virtual_* v = 0) const = 0;
};
/* ... */
//]
void countable::dec(boost::contract::virtual_* v) {
boost::contract::old_ptr<int> old_get = BOOST_CONTRACT_OLDOF(v, get());
boost::contract::check c = boost::contract::public_function(v, this)
.precondition([&] {
BOOST_CONTRACT_ASSERT(get() > std::numeric_limits<int>::min());
})
.postcondition([&] {
BOOST_CONTRACT_ASSERT(get() < *old_get);
})
;
assert(false); // Never executed by this library.
}
void countable::set(int n, boost::contract::virtual_* v) {
boost::contract::check c = boost::contract::public_function(
v, this)
.precondition([&] {
BOOST_CONTRACT_ASSERT(n <= 0);
})
.postcondition([&] {
BOOST_CONTRACT_ASSERT(get() == n);
})
;
assert(false); // Never executed by this library.
}
int countable::get(boost::contract::virtual_* v) const {
int result;
boost::contract::check c = boost::contract::public_function(
v, result, this);
assert(false); // Never executed by this library.
}
//[private_protected_virtual_multi_counter10
class counter10
#define BASES public countable, public counter // Multiple inheritance.
: BASES
{
public:
typedef BOOST_CONTRACT_BASE_TYPES(BASES) base_types;
#undef BASES
// Overriding from public members from `countable` so use `override_...`.
virtual void set(int n, boost::contract::virtual_* v = 0) /* override */ {
boost::contract::check c = boost::contract::public_function<
override_set>(v, &counter10::set, this, n)
.precondition([&] {
BOOST_CONTRACT_ASSERT(n % 10 == 0);
})
.postcondition([&] {
BOOST_CONTRACT_ASSERT(get() == n);
})
;
counter::set(n);
}
virtual void dec(boost::contract::virtual_* v = 0) /* override */ {
boost::contract::old_ptr<int> old_get = BOOST_CONTRACT_OLDOF(v, get());
boost::contract::check c = boost::contract::public_function<
override_dec>(v, &counter10::dec, this)
.precondition([&] {
BOOST_CONTRACT_ASSERT(
get() + 10 >= std::numeric_limits<int>::min());
})
.postcondition([&] {
BOOST_CONTRACT_ASSERT(get() == *old_get - 10);
})
;
set(get() - 10);
}
BOOST_CONTRACT_OVERRIDES(set, dec)
/* ... */
//]
virtual int get(boost::contract::virtual_* v = 0) const {
int result;
boost::contract::check c = boost::contract::public_function<
override_get>(v, result, &counter10::get, this);
return result = counter::get();
}
BOOST_CONTRACT_OVERRIDE(get)
// Should contract default constructor and destructor too.
void invariant() const {
BOOST_CONTRACT_ASSERT(get() % 10 == 0);
}
};
int main() {
counter cnt;
assert(cnt.get() == 0);
cnt.dec();
assert(cnt.get() == -1);
counter10 cnt10;
countable& b = cnt10; // Polymorphic calls.
assert(b.get() == 0);
b.dec();
assert(b.get() == -10);
return 0;
}
#endif // MSVC
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