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//////////////////////////////////////////////////////////////////////////////
//
// (C) Copyright Ion Gaztanaga 2008-2012.
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
//
// See http://www.boost.org/libs/move for documentation.
//
//////////////////////////////////////////////////////////////////////////////
//[file_descriptor_def
#include <boost/move/utility_core.hpp>
#include <stdexcept>
class file_descriptor
{
//<-
int operating_system_open_file(const char *)
{
return 1;
}
void operating_system_close_file(int)
{}
//->
int os_descr_;
private:
BOOST_MOVABLE_BUT_NOT_COPYABLE(file_descriptor)
public:
explicit file_descriptor(const char *filename) //Constructor
: os_descr_(operating_system_open_file(filename))
{
//=if(!os_descr_)
//=throw std::runtime_error("file not found");
}
~file_descriptor() //Destructor
{ if(os_descr_) operating_system_close_file(os_descr_); }
file_descriptor(BOOST_RV_REF(file_descriptor) x) // Move ctor
: os_descr_(x.os_descr_)
{ x.os_descr_ = 0; }
file_descriptor& operator=(BOOST_RV_REF(file_descriptor) x) // Move assign
{
if(os_descr_) operating_system_close_file(os_descr_);
os_descr_ = x.os_descr_;
x.os_descr_ = 0;
return *this;
}
bool empty() const { return os_descr_ == 0; }
};
//]
//[file_descriptor_example
#include <boost/container/vector.hpp>
#include <cassert>
//Remember: 'file_descriptor' is NOT copyable, but it
//can be returned from functions thanks to move semantics
file_descriptor create_file_descriptor(const char *filename)
{ return file_descriptor(filename); }
int main()
{
//Open a file obtaining its descriptor, the temporary
//returned from 'create_file_descriptor' is moved to 'fd'.
file_descriptor fd = create_file_descriptor("filename");
assert(!fd.empty());
//Now move fd into a vector
boost::container::vector<file_descriptor> v;
v.push_back(boost::move(fd));
//Check ownership has been transferred
assert(fd.empty());
assert(!v[0].empty());
//Compilation error if uncommented since file_descriptor is not copyable
//and vector copy construction requires value_type's copy constructor:
//boost::container::vector<file_descriptor> v2(v);
return 0;
}
//]
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