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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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