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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>
//[pure_virtual_public_base_begin
template<typename Iterator>
class range {
public:
// Pure virtual function declaration (contract in definition below).
virtual Iterator begin(boost::contract::virtual_* v = 0) = 0;
//]
// Could program class invariants and contracts for the following too.
virtual Iterator end() = 0;
virtual bool empty() const = 0;
//[pure_virtual_public_base_end
/* ... */
};
//]
//[pure_virtual_public_base_impl
// Pure virtual function default implementation (out-of-line in C++).
template<typename Iterator>
Iterator range<Iterator>::begin(boost::contract::virtual_* v) {
Iterator result; // As usual, virtual pass `result` right after `v`...
boost::contract::check c = boost::contract::public_function(v, result, this)
.postcondition([&] (Iterator const& result) {
if(empty()) BOOST_CONTRACT_ASSERT(result == end());
})
;
// Pure function body (never executed by this library).
assert(false);
return result;
}
//]
template<typename T>
class vector
#define BASES public range<typename std::vector<T>::iterator>
: BASES
{
public:
typedef BOOST_CONTRACT_BASE_TYPES(BASES) base_types;
#undef BASES
typedef typename std::vector<T>::iterator iterator;
iterator begin(boost::contract::virtual_* v = 0) /* override */ {
iterator result;
// Again, pass result right after `v`...
boost::contract::check c = boost::contract::public_function<
override_begin>(v, result, &vector::begin, this)
// ...plus postconditions take `result` as parameter (not capture).
.postcondition([&] (iterator const& result) {
if(!empty()) BOOST_CONTRACT_ASSERT(*result == front());
})
;
return result = vect_.begin();
}
BOOST_CONTRACT_OVERRIDE(begin)
// Could program class invariants and contracts for the following too.
iterator end() { return vect_.end(); }
bool empty() const { return vect_.empty(); }
T const& front() const { return vect_.front(); }
void push_back(T const& value) { vect_.push_back(value); }
private:
std::vector<T> vect_;
};
int main() {
vector<int> v;
v.push_back(1);
v.push_back(2);
v.push_back(3);
range<std::vector<int>::iterator>& r = v;
assert(*(r.begin()) == 1);
return 0;
}
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