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rvalue.cpp

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This commit is contained in:
Vahagn Khachatryan
2015-01-05 12:43:06 +04:00
parent fca912bbb4
commit c0b2c2f12d
2 changed files with 239 additions and 68 deletions
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239
cpp/rvalue.cpp Normal file
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/*
VIM: let g:lcppflags="-std=c++11 -O2 -pthread"
VIM: let g:wcppflags="/O2 /EHsc /DWIN32"
VIM: let g:argv=""
*/
#include <iostream>
#include <string>
class copy_tracker
{
int v;
public:
copy_tracker()
: v(0)
{
// std::cout << "copy_tracker::copy_tracker()" << std::endl;
}
copy_tracker( const copy_tracker& c )
: v( c.v )
{
std::cout << "copy_tracker::copy_tracker( copy_tracker& c )" << std::endl;
}
int use_object() const
{
return v;
}
void non_const_method()
{
v++;
std::cout << "copy_tracker::non_const_method()" << std::endl;
}
};
/*
* e
*/
#if 0
// uncommenting this will cause compiler error due to ambiguity.
void e ( copy_tracker o )
{
std::cout << "e( ) by value called" << std::endl;
o.use_object();
}
#endif
void e ( copy_tracker& o )
{
std::cout << "e( & ) is called" << std::endl;
o.use_object();
}
void e ( const copy_tracker& o )
{
std::cout << "e( const & ) is called" << std::endl;
o.use_object();
}
void e ( copy_tracker&& o )
{
std::cout << "e( && ) is called" << std::endl;
o.use_object();
}
void e ( const copy_tracker&& o )
{
std::cout << "e( const && ) is called" << std::endl;
o.use_object();
}
/*
* f
*/
void f ( copy_tracker& o )
{
std::cout << "f( & ) is called" << std::endl;
o.use_object();
}
void f ( const copy_tracker& o )
{
std::cout << "f( const & ) is called" << std::endl;
o.use_object();
}
void f ( copy_tracker&& o )
{
std::cout << "f( && ) is called" << std::endl;
o.use_object();
}
/*
* g
*/
void g ( copy_tracker& o )
{
std::cout << "g( & ) is called" << std::endl;
o.use_object();
}
void g ( const copy_tracker& o )
{
std::cout << "g( const & ) is called" << std::endl;
o.use_object();
}
void g ( const copy_tracker&& o )
{
std::cout << "g( const && ) is called" << std::endl;
o.use_object();
}
/*
* h
*/
void h ( copy_tracker& o )
{
std::cout << "h( & ) is called" << std::endl;
o.use_object();
}
void h ( const copy_tracker& o )
{
std::cout << "h( const & ) is called" << std::endl;
o.use_object();
}
/*
*/
void s( const int & )
{
std::cout << "s( const int & ) is called" << std::endl;
}
void s( int && )
{
std::cout << "s( int && ) is called" << std::endl;
}
/*
*/
void aaa( const std::string& s )
{
std::cout << s << std::endl;
}
/*
* rvalue and const_rvalue
*/
copy_tracker rvalue()
{
return copy_tracker();
}
const copy_tracker const_rvalue()
{
return copy_tracker();
}
int main( void )
{
copy_tracker lvalue;
const copy_tracker const_lvalue;
//
//
//
std::cout << "The following modifies an rvalue." << std::endl;
//
rvalue().non_const_method();
//
//
//
std::cout << "e is called for rvalue, const rvalue, lvalue, const lvalue." << std::endl;
//
e( rvalue() );
e( const_rvalue() );
e( lvalue );
e( const_lvalue );
//
// Const rvalue is handled by f( const & )
//
std::cout << "f is called for rvalue, const rvalue, lvalue, const lvalue." << std::endl;
//
f( rvalue() );
f( const_rvalue() );// f( const & )
f( lvalue );
f( const_lvalue );
//
// Rvalue is handled by g( const && )
//
std::cout << "g is called for rvalue, const rvalue, lvalue, const lvalue." << std::endl;
//
g( rvalue() );// g( const && )
g( const_rvalue() );
g( lvalue );
g( const_lvalue );
//
// Pre C++11 handling. h has only & and const & versions.
//
std::cout << "h is called for rvalue, const rvalue, lvalue, const lvalue." << std::endl;
//
h( rvalue() );// h(const &)
h( const_rvalue() );// h(const &)
h( lvalue );
h( const_lvalue );
//
// Try std::move
//
std::cout << "std::move." << std::endl;
//
e( std::move(rvalue()) );// e( && )
e( std::move(const_rvalue()) );// e ( const && )
e( std::move(lvalue) );// e( && )
e( std::move(const_lvalue) );// e ( const && )
#if 0
//
// The following converts lvalue and const lvalue to rvalue and const
// rvalue.
//
std::cout << "std::forward lvalue and const lvalue." << std::endl;
//
e( std::forward(rvalue()) );// e( && )
e( std::move(const_rvalue()) );// e ( const && )
e( std::forward(lvalue) );// e( && )
e( std::move(const_lvalue) );// e ( const && )
#endif
s( 5 );//s(int &&)
aaa( "aaaa");
return 0;
}

68
cpp/test_rvalue_ref.cpp
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@@ -1,68 +0,0 @@
#include <iostream>
#include <string>
class copy_tracker
{
int v;
public:
copy_tracker()
: v(0)
{
std::cout << "copy_tracker::copy_tracker()" << std::endl;
}
copy_tracker( const copy_tracker& c )
: v( c.v )
{
std::cout << "copy_tracker::copy_tracker( copy_tracker& c )" << std::endl;
}
void use_object() const
{
std::cout << v << std::endl;
}
};
copy_tracker create_rvalue()
{
return copy_tracker();
}
const copy_tracker create_const_rvalue()
{
return copy_tracker();
}
void f ( copy_tracker&& o )
{
o.use_object();
}
void f_const ( const copy_tracker&& o )
{
o.use_object();
}
void aaa( const std::string& s )
{
std::cout << s << std::endl;
}
int main( void )
{
f( create_rvalue() );
f_const( create_rvalue() );
f_const( create_const_rvalue() );
copy_tracker lvalue;
f( std::move(lvalue) );
f_const( std::move(lvalue) );
aaa( "aaaa");
return 0;
}