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