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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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