88 lines
3.1 KiB
C++
88 lines
3.1 KiB
C++
|
// boost/identifier.hpp ----------------------------------------------------//
|
||
|
|
|
||
|
|
// Copyright Beman Dawes 2006
|
||
|
|
|
||
|
|
// 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 documentation at http://www.boost.org/libs/utility
|
||
|
|
|
||
|
|
#ifndef BOOST_IDENTIFIER_HPP
|
||
|
|
#define BOOST_IDENTIFIER_HPP
|
||
|
|
|
||
|
|
#include <boost/utility/enable_if.hpp>
|
||
|
|
#include <boost/type_traits/is_base_of.hpp>
|
||
|
|
#include <iosfwd>
|
||
|
|
|
||
|
|
namespace boost
|
||
|
|
{
|
||
|
|
namespace detail
|
||
|
|
{
|
||
|
|
// class template identifier ---------------------------------------------//
|
||
|
|
|
||
|
|
// Always used as a base class so that different instantiations result in
|
||
|
|
// different class types even if instantiated with the same value type T.
|
||
|
|
|
||
|
|
// Expected usage is that T is often an integer type, best passed by
|
||
|
|
// value. There is no reason why T can't be a possibly larger class such as
|
||
|
|
// std::string, best passed by const reference.
|
||
|
|
|
||
|
|
// This implementation uses pass by value, based on expected common uses.
|
||
|
|
|
||
|
|
template <typename T, typename D>
|
||
|
|
class identifier
|
||
|
|
{
|
||
|
|
public:
|
||
|
|
typedef T value_type;
|
||
|
|
|
||
|
|
const value_type value() const { return m_value; }
|
||
|
|
void assign( value_type v ) { m_value = v; }
|
||
|
|
|
||
|
|
bool operator==( const D & rhs ) const { return m_value == rhs.m_value; }
|
||
|
|
bool operator!=( const D & rhs ) const { return m_value != rhs.m_value; }
|
||
|
|
bool operator< ( const D & rhs ) const { return m_value < rhs.m_value; }
|
||
|
|
bool operator<=( const D & rhs ) const { return m_value <= rhs.m_value; }
|
||
|
|
bool operator> ( const D & rhs ) const { return m_value > rhs.m_value; }
|
||
|
|
bool operator>=( const D & rhs ) const { return m_value >= rhs.m_value; }
|
||
|
|
|
||
|
|
typedef void (*unspecified_bool_type)(D); // without the D, unspecified_bool_type
|
||
|
|
static void unspecified_bool_true(D){} // conversion allows relational operators
|
||
|
|
// between different identifier types
|
||
|
|
|
||
|
|
operator unspecified_bool_type() const { return m_value == value_type() ? 0 : unspecified_bool_true; }
|
||
|
|
bool operator!() const { return m_value == value_type(); }
|
||
|
|
|
||
|
|
// constructors are protected so that class can only be used as a base class
|
||
|
|
protected:
|
||
|
|
identifier() {}
|
||
|
|
explicit identifier( value_type v ) : m_value(v) {}
|
||
|
|
|
||
|
|
private:
|
||
|
|
T m_value;
|
||
|
|
};
|
||
|
|
|
||
|
|
//#ifndef BOOST_NO_SFINAE
|
||
|
|
|
||
|
|
// template <class Ostream, class Id>
|
||
|
|
// typename enable_if< is_base_of< identifier< typename Id::value_type, Id >, Id >,
|
||
|
|
// Ostream & >::type operator<<( Ostream & os, const Id & id )
|
||
|
|
// {
|
||
|
|
// return os << id.value();
|
||
|
|
// }
|
||
|
|
|
||
|
|
// template <class Istream, class Id>
|
||
|
|
// typename enable_if< is_base_of< identifier< typename Id::value_type, Id >, Id >,
|
||
|
|
// Istream & >::type operator>>( Istream & is, Id & id )
|
||
|
|
// {
|
||
|
|
// typename Id::value_type v;
|
||
|
|
// is >> v;
|
||
|
|
// id.value( v );
|
||
|
|
// return is;
|
||
|
|
// }
|
||
|
|
//#endif
|
||
|
|
|
||
|
|
} // namespace detail
|
||
|
|
} // namespace boost
|
||
|
|
|
||
|
|
#endif // BOOST_IDENTIFIER_HPP
|