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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 <algorithm>
#include <cassert>
//[public_class_begin
class unique_identifiers :
private boost::contract::constructor_precondition<unique_identifiers>
{
public:
void invariant() const {
BOOST_CONTRACT_ASSERT(size() >= 0);
}
//]
//[public_constructor
public:
// Contract for a constructor.
unique_identifiers(int from, int to) :
boost::contract::constructor_precondition<unique_identifiers>([&] {
BOOST_CONTRACT_ASSERT(from >= 0);
BOOST_CONTRACT_ASSERT(to >= from);
})
{
boost::contract::check c = boost::contract::constructor(this)
.postcondition([&] {
BOOST_CONTRACT_ASSERT(size() == (to - from + 1));
})
;
// Constructor body.
for(int id = from; id <= to; ++id) vect_.push_back(id);
}
//]
//[public_destructor
public:
// Contract for a destructor.
virtual ~unique_identifiers() {
// Following contract checks class invariants.
boost::contract::check c = boost::contract::destructor(this);
// Destructor body here... (do nothing in this example).
}
//]
int size() const {
// Following contract checks invariants.
boost::contract::check c = boost::contract::public_function(this);
return vect_.size();
}
//[public_function
public:
// Contract for a public function (but no static, virtual, or override).
bool find(int id) const {
bool result;
boost::contract::check c = boost::contract::public_function(this)
.precondition([&] {
BOOST_CONTRACT_ASSERT(id >= 0);
})
.postcondition([&] {
if(size() == 0) BOOST_CONTRACT_ASSERT(!result);
})
;
// Function body.
return result = std::find(vect_.begin(), vect_.end(), id) !=
vect_.end();
}
//]
//[public_virtual_function
public:
// Contract for a public virtual function (but no override).
virtual int push_back(int id, boost::contract::virtual_* v = 0) { // Extra `v`.
int result;
boost::contract::old_ptr<bool> old_find =
BOOST_CONTRACT_OLDOF(v, find(id)); // Pass `v`.
boost::contract::old_ptr<int> old_size =
BOOST_CONTRACT_OLDOF(v, size()); // Pass `v`.
boost::contract::check c = boost::contract::public_function(
v, result, this) // Pass `v` and `result`.
.precondition([&] {
BOOST_CONTRACT_ASSERT(id >= 0);
BOOST_CONTRACT_ASSERT(!find(id)); // ID cannot be already present.
})
.postcondition([&] (int const result) {
if(!*old_find) {
BOOST_CONTRACT_ASSERT(find(id));
BOOST_CONTRACT_ASSERT(size() == *old_size + 1);
}
BOOST_CONTRACT_ASSERT(result == id);
})
;
// Function body.
vect_.push_back(id);
return result = id;
}
//]
private:
std::vector<int> vect_;
//[public_class_end
/* ... */
};
//]
//[public_derived_class_begin
class identifiers
#define BASES public unique_identifiers
: BASES
{
public:
typedef BOOST_CONTRACT_BASE_TYPES(BASES) base_types; // Bases typedef.
#undef BASES
void invariant() const { // Check in AND with bases.
BOOST_CONTRACT_ASSERT(empty() == (size() == 0));
}
//]
//[public_function_override
public:
// Contract for a public function override.
int push_back(int id, boost::contract::virtual_* v = 0) /* override */ {
int result;
boost::contract::old_ptr<bool> old_find =
BOOST_CONTRACT_OLDOF(v, find(id));
boost::contract::old_ptr<int> old_size =
BOOST_CONTRACT_OLDOF(v, size());
boost::contract::check c = boost::contract::public_function<
override_push_back // Pass override type plus below function pointer...
>(v, result, &identifiers::push_back, this, id) // ...and arguments.
.precondition([&] { // Check in OR with bases.
BOOST_CONTRACT_ASSERT(id >= 0);
BOOST_CONTRACT_ASSERT(find(id)); // ID can be already present.
})
.postcondition([&] (int const result) { // Check in AND with bases.
if(*old_find) BOOST_CONTRACT_ASSERT(size() == *old_size);
})
;
// Function body.
if(!find(id)) unique_identifiers::push_back(id); // Else, do nothing.
return result = id;
}
BOOST_CONTRACT_OVERRIDE(push_back) // Define `override_push_back`.
//]
bool empty() const {
// Following contract checks invariants.
boost::contract::check c = boost::contract::public_function(this);
return size() == 0;
}
identifiers(int from, int to) : unique_identifiers(from, to) {
// Following contract checks invariants.
boost::contract::check c = boost::contract::constructor(this);
}
//[public_derived_class_end
/* ... */
};
//]
int main() {
unique_identifiers uids(1, 4);
assert(uids.find(2));
assert(!uids.find(5));
uids.push_back(5);
assert(uids.find(5));
identifiers ids(10, 40);
assert(!ids.find(50));
ids.push_back(50);
ids.push_back(50);
assert(ids.find(50));
return 0;
}
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