preprocessor/example/is_integral.cpp

/* Copyright (C) 2002
 * Housemarque Oy
 * http://www.housemarque.com
 *
 * 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.
 *
 * See http://www.boost.org for most recent version.
 */

/* This example demonstrates the usage of preprocessor lists for generating C++ code. */

#include <boost/preprocessor/list/for_each_product.hpp>
#include <boost/preprocessor/list/at.hpp>
#include <boost/preprocessor/tuple/to_list.hpp>
#include <boost/preprocessor/empty.hpp>

/* List of integral types. (Strictly speaking, wchar_t should be on the list.) */
#define INTEGRAL_TYPES\
  BOOST_PP_TUPLE_TO_LIST(9,(char, signed char, unsigned char, short, unsigned short, int, unsigned, long, unsigned long))

/* List of invokeable cv-qualifiers. */
#define CV_QUALIFIERS\
  BOOST_PP_TUPLE_TO_LIST(4,(BOOST_PP_EMPTY, const BOOST_PP_EMPTY, volatile BOOST_PP_EMPTY, const volatile BOOST_PP_EMPTY))

/* Template for testing whether a type is an integral type. */
template<class T> struct is_integral {enum {value = false};};

/* Macro for defining a specialization of is_integral<> template. */
#define IS_INTEGRAL_SPECIALIZATION(R,_,L)\
  template<> struct is_integral<BOOST_PP_LIST_AT(L,1)() BOOST_PP_LIST_AT(L,0)> {enum {value = true};};

BOOST_PP_LIST_FOR_EACH_PRODUCT(IS_INTEGRAL_SPECIALIZATION,_,BOOST_PP_TUPLE_TO_LIST(2,(CV_QUALIFIERS, INTEGRAL_TYPES)))
#undef IS_INTEGRAL_SPECIALIZATION
#undef CV_QUALIFIERS
#undef INTEGRAL_TYPES