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