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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_virtual_counter
class counter {
// Virtual private and protected functions still declare extra
// `virtual_* = 0` parameter (otherwise they cannot be overridden), but...
protected:
virtual void set(int n, boost::contract::virtual_* = 0) {
boost::contract::check c = boost::contract::function() // ...no `v`.
.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()); // ...no `v`.
boost::contract::check c = boost::contract::function() // ...no `v`.
.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_counter10
class counter10
#define BASES public counter
: BASES
{
public:
typedef BOOST_CONTRACT_BASE_TYPES(BASES) base_types;
#undef BASES
// Overriding from non-public members so no subcontracting, no override_...
virtual void set(int n, boost::contract::virtual_* v = 0) /* override */ {
boost::contract::check c = boost::contract::public_function(v, this)
.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(v, this)
.precondition([&] {
BOOST_CONTRACT_ASSERT(
get() + 10 >= std::numeric_limits<int>::min());
})
.postcondition([&] {
BOOST_CONTRACT_ASSERT(get() == *old_get - 10);
})
;
set(get() - 10);
}
/* ... */
//]
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;
counter& b = cnt10; // Polymorphic calls.
assert(b.get() == 0);
b.dec();
assert(b.get() == -10);
return 0;
}
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