Chris@16: // Copyright Daniel Wallin, David Abrahams 2005. Use, modification and
Chris@16: // distribution is subject to the Boost Software License, Version 1.0. (See
Chris@16: // accompanying file LICENSE_1_0.txt or copy at
Chris@16: // http://www.boost.org/LICENSE_1_0.txt)
Chris@16: 
Chris@16: #ifndef DEFAULT_050329_HPP
Chris@16: # define DEFAULT_050329_HPP
Chris@16: 
Chris@16: # include <boost/detail/workaround.hpp>
Chris@16: 
Chris@16: namespace boost { namespace parameter { namespace aux {
Chris@16: 
Chris@16: // A wrapper for the default value passed by the user when resolving
Chris@16: // the value of the parameter with the given Keyword
Chris@16: template <class Keyword, class Value>
Chris@16: struct default_
Chris@16: {
Chris@16:     default_(Value& x)
Chris@16:       : value(x)
Chris@16:     {}
Chris@16: 
Chris@16:     Value& value;
Chris@16: };
Chris@16: 
Chris@16: //
Chris@16: // lazy_default -- 
Chris@16: //
Chris@16: //    A wrapper for the default value computation function passed by
Chris@16: //    the user when resolving the value of the parameter with the
Chris@16: //    given keyword
Chris@16: //
Chris@16: # if BOOST_WORKAROUND(__EDG_VERSION__, <= 300)
Chris@16: // These compilers need a little extra help with overload
Chris@16: // resolution; we have empty_arg_list's operator[] accept a base
Chris@16: // class to make that overload less preferable.
Chris@16: template <class KW, class DefaultComputer>
Chris@16: struct lazy_default_base
Chris@16: {
Chris@16:     lazy_default_base(DefaultComputer const& x)
Chris@16:       : compute_default(x)
Chris@16:     {}
Chris@16:     DefaultComputer const& compute_default;
Chris@16: };
Chris@16: 
Chris@16: template <class KW, class DefaultComputer>
Chris@16: struct lazy_default
Chris@16:   : lazy_default_base<KW,DefaultComputer>
Chris@16:   {
Chris@16:       lazy_default(DefaultComputer const & x)
Chris@16:         : lazy_default_base<KW,DefaultComputer>(x)
Chris@16:       {}
Chris@16:   };
Chris@16: #  define BOOST_PARAMETER_lazy_default_fallback lazy_default_base
Chris@16: # else 
Chris@16: template <class KW, class DefaultComputer>
Chris@16: struct lazy_default
Chris@16: {
Chris@16:     lazy_default(const DefaultComputer& x)
Chris@16:       : compute_default(x)
Chris@16:     {}
Chris@16:     DefaultComputer const& compute_default;
Chris@16: };
Chris@16: #  define BOOST_PARAMETER_lazy_default_fallback lazy_default
Chris@16: # endif 
Chris@16: 
Chris@16: }}} // namespace boost::parameter::aux
Chris@16: 
Chris@16: #endif // DEFAULT_050329_HPP
Chris@16: