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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 <vector>
#include <cassert>
template<typename T>
class pushable { // Somewhat arbitrary base (used just to show subcontracting).
public:
void invariant() const {
BOOST_CONTRACT_ASSERT(capacity() <= max_size());
}
virtual void push_back(T const& value,
boost::contract::virtual_* v = 0) = 0; // Pure virtual function.
protected:
virtual unsigned capacity() const = 0;
virtual unsigned max_size() const = 0;
};
template<typename T> // Contract for pure virtual function.
void pushable<T>::push_back(T const& value, boost::contract::virtual_* v) {
boost::contract::old_ptr<unsigned> old_capacity =
BOOST_CONTRACT_OLDOF(v, capacity());
boost::contract::check c = boost::contract::public_function(v, this)
.precondition([&] {
BOOST_CONTRACT_ASSERT(capacity() < max_size());
})
.postcondition([&] {
BOOST_CONTRACT_ASSERT(capacity() >= *old_capacity);
})
;
assert(false); // Shall never execute this body.
}
//[introduction_public
template<typename T>
class vector
#define BASES public pushable<T>
: BASES
{
public:
typedef BOOST_CONTRACT_BASE_TYPES(BASES) base_types; // For subcontracting.
#undef BASES
void invariant() const { // Checked in AND with base class invariants.
BOOST_CONTRACT_ASSERT(size() <= capacity());
}
virtual void push_back(T const& value,
boost::contract::virtual_* v = 0) /* override */ { // For virtuals.
boost::contract::old_ptr<unsigned> old_size =
BOOST_CONTRACT_OLDOF(v, size()); // Old values for virtuals.
boost::contract::check c = boost::contract::public_function< // For overrides.
override_push_back>(v, &vector::push_back, this, value)
.precondition([&] { // Checked in OR with base preconditions.
BOOST_CONTRACT_ASSERT(size() < max_size());
})
.postcondition([&] { // Checked in AND with base postconditions.
BOOST_CONTRACT_ASSERT(size() == *old_size + 1);
})
;
vect_.push_back(value);
}
BOOST_CONTRACT_OVERRIDE(push_back) // Define `override_push_back` above.
// Could program contracts for those as well.
unsigned size() const { return vect_.size(); }
unsigned max_size() const { return vect_.max_size(); }
unsigned capacity() const { return vect_.capacity(); }
private:
std::vector<T> vect_;
};
//]
int main() {
vector<int> vect;
vect.push_back(123);
assert(vect.size() == 1);
return 0;
}
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