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 KEYWORD_050328_HPP
Chris@16: #define KEYWORD_050328_HPP
Chris@16: 
Chris@16: #include <boost/parameter/aux_/unwrap_cv_reference.hpp>
Chris@16: #include <boost/parameter/aux_/tag.hpp>
Chris@16: #include <boost/parameter/aux_/default.hpp>
Chris@16: 
Chris@16: namespace boost { namespace parameter {
Chris@16: 
Chris@16: // Instances of unique specializations of keyword<...> serve to
Chris@16: // associate arguments with parameter names.  For example:
Chris@16: //
Chris@16: //    struct rate_;           // parameter names
Chris@16: //    struct skew_;
Chris@16: //    namespace
Chris@16: //    {
Chris@16: //      keyword<rate_> rate;  // keywords
Chris@16: //      keyword<skew_> skew;
Chris@16: //    }
Chris@16: //
Chris@16: //    ...
Chris@16: //
Chris@16: //    f(rate = 1, skew = 2.4);
Chris@16: //
Chris@16: template <class Tag>
Chris@16: struct keyword
Chris@16: {
Chris@16:     template <class T>
Chris@16:     typename aux::tag<Tag, T>::type const
Chris@16:     operator=(T& x) const
Chris@16:     {
Chris@16:         typedef typename aux::tag<Tag, T>::type result;
Chris@16:         return result(x);
Chris@16:     }
Chris@16: 
Chris@16:     template <class Default>
Chris@16:     aux::default_<Tag, Default>
Chris@16:     operator|(Default& default_) const
Chris@16:     {
Chris@16:         return aux::default_<Tag, Default>(default_);
Chris@16:     }
Chris@16: 
Chris@16:     template <class Default>
Chris@16:     aux::lazy_default<Tag, Default>
Chris@16:     operator||(Default& default_) const
Chris@16:     {
Chris@16:         return aux::lazy_default<Tag, Default>(default_);
Chris@16:     }
Chris@16: 
Chris@16: #if !BOOST_WORKAROUND(BOOST_MSVC, < 1300)  // avoid partial ordering bugs
Chris@16:     template <class T>
Chris@16:     typename aux::tag<Tag, T const>::type const
Chris@16:     operator=(T const& x) const
Chris@16:     {
Chris@16:         typedef typename aux::tag<Tag, T const>::type result;
Chris@16:         return result(x);
Chris@16:     }
Chris@16: #endif 
Chris@16: 
Chris@16: #if !BOOST_WORKAROUND(BOOST_MSVC, < 1300)  // avoid partial ordering bugs
Chris@16:     template <class Default>
Chris@16:     aux::default_<Tag, const Default>
Chris@16:     operator|(const Default& default_) const
Chris@16: #if BOOST_WORKAROUND(BOOST_MSVC, == 1300)
Chris@16:         volatile
Chris@16: #endif 
Chris@16:     {
Chris@16:         return aux::default_<Tag, const Default>(default_);
Chris@16:     }
Chris@16: 
Chris@16:     template <class Default>
Chris@16:     aux::lazy_default<Tag, Default>
Chris@16:     operator||(Default const& default_) const
Chris@16: #if BOOST_WORKAROUND(BOOST_MSVC, == 1300)
Chris@16:         volatile
Chris@16: #endif 
Chris@16:     {
Chris@16:         return aux::lazy_default<Tag, Default>(default_);
Chris@16:     }
Chris@16: #endif
Chris@16: 
Chris@16:  public: // Insurance against ODR violations
Chris@16:     
Chris@16:     // People will need to define these keywords in header files.  To
Chris@16:     // prevent ODR violations, it's important that the keyword used in
Chris@16:     // every instantiation of a function template is the same object.
Chris@16:     // We provide a reference to a common instance of each keyword
Chris@16:     // object and prevent construction by users.
Chris@16:     static keyword<Tag> const instance;
Chris@16: 
Chris@16:     // This interface is deprecated
Chris@16:     static keyword<Tag>& get()
Chris@16:     {
Chris@16:         return const_cast<keyword<Tag>&>(instance);
Chris@16:     }
Chris@16: };
Chris@16: 
Chris@16: template <class Tag>
Chris@16: keyword<Tag> const keyword<Tag>::instance = {};
Chris@16: 
Chris@16: // Reduces boilerplate required to declare and initialize keywords
Chris@16: // without violating ODR.  Declares a keyword tag type with the given
Chris@16: // name in namespace tag_namespace, and declares and initializes a
Chris@16: // reference in an anonymous namespace to a singleton instance of that
Chris@16: // type.
Chris@16: 
Chris@16: #if BOOST_WORKAROUND(BOOST_MSVC, < 1300)
Chris@16: 
Chris@16: # define BOOST_PARAMETER_KEYWORD(tag_namespace,name)                    \
Chris@16:     namespace tag_namespace                                             \
Chris@16:     {                                                                   \
Chris@16:       struct name                                                       \
Chris@16:       {                                                                 \
Chris@16:           static char const* keyword_name()                             \
Chris@16:           {                                                             \
Chris@16:               return #name;                                             \
Chris@16:           }                                                             \
Chris@16:       };                                                                \
Chris@16:     }                                                                   \
Chris@16:     static ::boost::parameter::keyword<tag_namespace::name> const& name \
Chris@16:        = ::boost::parameter::keyword<tag_namespace::name>::instance;
Chris@16: 
Chris@16: #else
Chris@16: 
Chris@16: #define BOOST_PARAMETER_KEYWORD(tag_namespace,name)                 \
Chris@16:     namespace tag_namespace                                         \
Chris@16:     {                                                               \
Chris@16:       struct name                                                   \
Chris@16:       {                                                             \
Chris@16:           static char const* keyword_name()                         \
Chris@16:           {                                                         \
Chris@16:               return #name;                                         \
Chris@16:           }                                                         \
Chris@16:       };                                                            \
Chris@16:     }                                                               \
Chris@16:     namespace                                                       \
Chris@16:     {                                                               \
Chris@16:        ::boost::parameter::keyword<tag_namespace::name> const& name \
Chris@16:        = ::boost::parameter::keyword<tag_namespace::name>::instance;\
Chris@16:     }
Chris@16: 
Chris@16: #endif
Chris@16: 
Chris@16: }} // namespace boost::parameter
Chris@16: 
Chris@16: #endif // KEYWORD_050328_HPP
Chris@16: