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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 <string>
#include <cassert>
//[friend_byte
class buffer;
class byte {
friend bool operator==(buffer const& left, byte const& right);
private:
char value_;
/* ... */
//]
public:
// Could program invariants and contracts for following too.
explicit byte(char value) : value_(value) {}
bool empty() const { return value_ == '\0'; }
};
//[friend_buffer
class buffer {
// Friend functions are not member functions...
friend bool operator==(buffer const& left, byte const& right) {
// ...so check contracts via `function` (which won't check invariants).
boost::contract::check c = boost::contract::function()
.precondition([&] {
BOOST_CONTRACT_ASSERT(!left.empty());
BOOST_CONTRACT_ASSERT(!right.empty());
})
;
for(char const* x = left.values_.c_str(); *x != '\0'; ++x) {
if(*x != right.value_) return false;
}
return true;
}
private:
std::string values_;
/* ... */
//]
public:
// Could program invariants and contracts for following too.
explicit buffer(std::string const& values) : values_(values) {}
bool empty() const { return values_ == ""; }
};
int main() {
buffer p("aaa");
byte a('a');
assert(p == a);
buffer q("aba");
assert(!(q == a)); // No operator!=.
return 0;
}
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