typeop.hpp

C++ Templates 完全导引范例

/* The following code example is taken from the book
 * "C++ Templates - The Complete Guide"
 * by David Vandevoorde and Nicolai M. Josuttis, Addison-Wesley, 2002
 *
 * (C) Copyright David Vandevoorde and Nicolai M. Josuttis 2002.
 * Permission to copy, use, modify, sell and distribute this software
 * is granted provided this copyright notice appears in all copies.
 * This software is provided "as is" without express or implied
 * warranty, and with no claim as to its suitability for any purpose.
 */
#ifndef TYPEOP_HPP
#define TYPEOP_HPP

// primary template
/**********************************
 * typeop1.hpp:
 **********************************/
template <typename T>
class TypeOp {            // primary template
  public:
    typedef T         ArgT;
    typedef T         BareT;
    typedef T const   ConstT;
    typedef T &       RefT;
    typedef T &       RefBareT;
    typedef T const & RefConstT;
};
/**** end of typeop1.hpp ****/

// partial specialization for const
/**********************************
 * typeop2.hpp:
 **********************************/
template <typename T>
class TypeOp <T const> {  // partial specialization for const types
  public:
    typedef T const   ArgT;
    typedef T         BareT;
    typedef T const   ConstT;
    typedef T const & RefT;
    typedef T &       RefBareT;
    typedef T const & RefConstT;
};
/**** end of typeop2.hpp ****/

// partial specialization for references
/**********************************
 * typeop3.hpp:
 **********************************/
template <typename T>
class TypeOp <T&> {       // partial specialization for references
  public:
    typedef T &                         ArgT;
    typedef typename TypeOp<T>::BareT   BareT;
    typedef T const                     ConstT;
    typedef T &                         RefT;
    typedef typename TypeOp<T>::BareT & RefBareT;
    typedef T const &                   RefConstT;
};
/**** end of typeop3.hpp ****/

// full specialization for void
/**********************************
 * typeop4.hpp:
 **********************************/
template<>
class TypeOp <void> {     // full specialization for void
  public:
    typedef void       ArgT;
    typedef void       BareT;
    typedef void const ConstT;
    typedef void       RefT;
    typedef void       RefBareT;
    typedef void       RefConstT;
};
/**** end of typeop4.hpp ****/

#endif // TYPEOP_HPP