135 lines
3.8 KiB
C++
135 lines
3.8 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
|
|
|
|
#include <boost/contract.hpp>
|
|
#include <boost/config.hpp>
|
|
#include <cassert>
|
|
|
|
#ifdef BOOST_GCC // G++ does not support static union members yet.
|
|
int instances_ = 0;
|
|
#endif
|
|
|
|
//[union
|
|
union positive {
|
|
public:
|
|
static void static_invariant() { // Static class invariants (as usual).
|
|
BOOST_CONTRACT_ASSERT(instances() >= 0);
|
|
}
|
|
|
|
void invariant() const { // Class invariants (as usual).
|
|
BOOST_CONTRACT_ASSERT(i_ > 0);
|
|
BOOST_CONTRACT_ASSERT(d_ > 0);
|
|
}
|
|
|
|
// Contracts for constructor, as usual but...
|
|
explicit positive(int x) : d_(0) {
|
|
// ...unions cannot have bases so constructor preconditions here.
|
|
boost::contract::constructor_precondition<positive> pre([&] {
|
|
BOOST_CONTRACT_ASSERT(x > 0);
|
|
});
|
|
boost::contract::old_ptr<int> old_instances =
|
|
BOOST_CONTRACT_OLDOF(instances());
|
|
boost::contract::check c = boost::contract::constructor(this)
|
|
.postcondition([&] {
|
|
{ int y; get(y); BOOST_CONTRACT_ASSERT(y == x); }
|
|
BOOST_CONTRACT_ASSERT(instances() == *old_instances + 1);
|
|
})
|
|
;
|
|
|
|
i_ = x;
|
|
++instances_;
|
|
}
|
|
|
|
// Contracts for destructor (as usual).
|
|
~positive() {
|
|
boost::contract::old_ptr<int> old_instances =
|
|
BOOST_CONTRACT_OLDOF(instances());
|
|
boost::contract::check c = boost::contract::destructor(this)
|
|
.postcondition([&] {
|
|
BOOST_CONTRACT_ASSERT(instances() == *old_instances - 1);
|
|
})
|
|
;
|
|
|
|
--instances_;
|
|
}
|
|
|
|
// Contracts for public function (as usual, but no virtual or override).
|
|
void get(int& x) const {
|
|
boost::contract::check c = boost::contract::public_function(this)
|
|
.postcondition([&] {
|
|
BOOST_CONTRACT_ASSERT(x > 0);
|
|
})
|
|
;
|
|
|
|
x = i_;
|
|
}
|
|
|
|
// Contracts for static public function (as usual).
|
|
static int instances() {
|
|
boost::contract::check c = boost::contract::public_function<positive>();
|
|
return instances_;
|
|
}
|
|
|
|
private:
|
|
int i_;
|
|
double d_;
|
|
|
|
/* ... */
|
|
//]
|
|
|
|
public:
|
|
explicit positive(double x) : d_(0) {
|
|
// Unions cannot have bases so constructor preconditions here.
|
|
boost::contract::constructor_precondition<positive> pre([&] {
|
|
BOOST_CONTRACT_ASSERT(x > 0);
|
|
});
|
|
boost::contract::old_ptr<int> old_instances =
|
|
BOOST_CONTRACT_OLDOF(instances());
|
|
boost::contract::check c = boost::contract::constructor(this)
|
|
.postcondition([&] {
|
|
{ double y; get(y); BOOST_CONTRACT_ASSERT(y == x); }
|
|
BOOST_CONTRACT_ASSERT(instances() == *old_instances + 1);
|
|
})
|
|
;
|
|
|
|
d_ = x;
|
|
++instances_;
|
|
}
|
|
|
|
void get(double& x) const {
|
|
boost::contract::check c = boost::contract::public_function(this)
|
|
.postcondition([&] {
|
|
BOOST_CONTRACT_ASSERT(x > 0);
|
|
})
|
|
;
|
|
|
|
x = d_;
|
|
}
|
|
|
|
#ifndef BOOST_GCC // G++ does not support static union members yet.
|
|
static int instances_;
|
|
#endif
|
|
};
|
|
|
|
#ifndef BOOST_GCC // G++ does not support static union members yet.
|
|
int positive::instances_ = 0;
|
|
#endif
|
|
|
|
int main() {
|
|
{
|
|
positive p(123);
|
|
assert(p.instances() == 1);
|
|
{ int y = -456; p.get(y); assert(y == 123); }
|
|
|
|
positive q(1.23);
|
|
assert(q.instances() == 2);
|
|
{ double y = -4.56; q.get(y); assert(y == 1.23); }
|
|
}
|
|
assert(positive::instances() == 0);
|
|
return 0;
|
|
}
|
|
|