Chris@16: // Copyright Daniel Wallin 2006. Use, modification and distribution is
Chris@16: // subject to the Boost Software License, Version 1.0. (See accompanying
Chris@16: // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
Chris@16: 
Chris@16: #ifndef BOOST_PARAMETER_CAST_060902_HPP
Chris@16: # define BOOST_PARAMETER_CAST_060902_HPP
Chris@16: 
Chris@16: # include <boost/detail/workaround.hpp>
Chris@16: 
Chris@16: # if !defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION) \
Chris@16:   && !BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x564))
Chris@16: #  include <boost/type_traits/add_reference.hpp>
Chris@16: #  include <boost/type_traits/remove_const.hpp>
Chris@16: # endif
Chris@16: 
Chris@16: namespace boost { namespace parameter { namespace aux {
Chris@16: 
Chris@16: struct use_default_tag {};
Chris@16: 
Chris@16: # if defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION) \
Chris@16:   || BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x564))
Chris@16: 
Chris@16: #  define BOOST_PARAMETER_FUNCTION_CAST(value, predicate) value
Chris@16: 
Chris@16: # else
Chris@16: 
Chris@16: // Handles possible implicit casts. Used by preprocessor.hpp to
Chris@16: // normalize user input.
Chris@16: //
Chris@16: // cast<void*>::execute() is identity
Chris@16: // cast<void*(X)>::execute() is identity
Chris@16: // cast<void(X)>::execute() casts to X
Chris@16: //
Chris@16: // preprocessor.hpp uses this like this:
Chris@16: //
Chris@16: //   #define X(value, predicate)
Chris@16: //      cast<void predicate>::execute(value)
Chris@16: //
Chris@16: //   X(something, *)
Chris@16: //   X(something, *(predicate))
Chris@16: //   X(something, (int))
Chris@16: 
Chris@16: template <class T, class Args>
Chris@16: struct cast;
Chris@16: 
Chris@16: template <class Args>
Chris@16: struct cast<void*, Args>
Chris@16: {
Chris@16:     static use_default_tag execute(use_default_tag)
Chris@16:     {
Chris@16:         return use_default_tag();
Chris@16:     }
Chris@16: 
Chris@16:     static use_default_tag remove_const(use_default_tag)
Chris@16:     {
Chris@16:         return use_default_tag();
Chris@16:     }
Chris@16: 
Chris@16:     template <class U>
Chris@16:     static U& execute(U& value)
Chris@16:     {
Chris@16:         return value;
Chris@16:     }
Chris@16: 
Chris@16:     template <class U>
Chris@16:     static U& remove_const(U& x)
Chris@16:     {
Chris@16:         return x;
Chris@16:     }
Chris@16: };
Chris@16: 
Chris@16: #if BOOST_WORKAROUND(__SUNPRO_CC, BOOST_TESTED_AT(0x580))
Chris@16: 
Chris@16: typedef void* voidstar;
Chris@16: 
Chris@16: template <class T, class Args>
Chris@16: struct cast<voidstar(T), Args>
Chris@16:   : cast<void*, Args>
Chris@16: {
Chris@16: };
Chris@16: 
Chris@16: #else
Chris@16: 
Chris@16: template <class T, class Args>
Chris@16: struct cast<void*(T), Args>
Chris@16:   : cast<void*, Args>
Chris@16: {
Chris@16: };
Chris@16: 
Chris@16: #endif
Chris@16: 
Chris@16: // This is a hack used in cast<> to turn the user supplied type,
Chris@16: // which may or may not be a placeholder expression into one, so
Chris@16: // that it will be properly evaluated by mpl::apply.
Chris@16: template <class T, class Dummy = mpl::_1>
Chris@16: struct as_placeholder_expr
Chris@16: {
Chris@16:     typedef T type;
Chris@16: };
Chris@16: 
Chris@16: template <class T, class Args>
Chris@16: struct cast<void(T), Args>
Chris@16: {
Chris@16:     typedef typename mpl::apply2<
Chris@16:         as_placeholder_expr<T>, Args, Args>::type type0;
Chris@16: 
Chris@16:     typedef typename boost::add_reference<
Chris@16:         typename boost::remove_const<type0>::type 
Chris@16:     >::type reference;
Chris@16: 
Chris@16:     static use_default_tag execute(use_default_tag)
Chris@16:     {
Chris@16:         return use_default_tag();
Chris@16:     }
Chris@16: 
Chris@16:     static use_default_tag remove_const(use_default_tag)
Chris@16:     {
Chris@16:         return use_default_tag();
Chris@16:     }
Chris@16: 
Chris@16:     static type0 execute(type0 value)
Chris@16:     {
Chris@16:         return value;
Chris@16:     }
Chris@16: 
Chris@16:     template <class U>
Chris@16:     static reference remove_const(U const& x)
Chris@16:     {
Chris@16:         return const_cast<reference>(x);
Chris@16:     }
Chris@16: };
Chris@16: 
Chris@16: #  define BOOST_PARAMETER_FUNCTION_CAST(value, predicate, args) \
Chris@16:     boost::parameter::aux::cast<void predicate, args>::remove_const( \
Chris@16:         boost::parameter::aux::cast<void predicate, args>::execute(value) \
Chris@16:     )
Chris@16: 
Chris@16: # endif
Chris@16: 
Chris@16: }}} // namespace boost::parameter::aux
Chris@16: 
Chris@16: #endif // BOOST_PARAMETER_CAST_060902_HPP
Chris@16: