113 lines
3.4 KiB
C++
113 lines
3.4 KiB
C++
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///////////////////////////////////////////////////////////////////////////////
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/// \file literal.hpp
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/// The literal\<\> terminal wrapper, and the proto::lit() function for
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/// creating literal\<\> wrappers.
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//
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// Copyright 2008 Eric Niebler. Distributed under the Boost
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// Software License, Version 1.0. (See accompanying file
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// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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#ifndef BOOST_PROTO_LITERAL_HPP_EAN_01_03_2007
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#define BOOST_PROTO_LITERAL_HPP_EAN_01_03_2007
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#include <boost/config.hpp>
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#include <boost/proto/proto_fwd.hpp>
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#include <boost/proto/expr.hpp>
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#include <boost/proto/traits.hpp>
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#include <boost/proto/extends.hpp>
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namespace boost { namespace proto
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{
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namespace utility
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{
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/// \brief A simple wrapper for a terminal, provided for
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/// ease of use.
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///
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/// A simple wrapper for a terminal, provided for
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/// ease of use. In all cases, <tt>literal\<X\> l(x);</tt>
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/// is equivalent to <tt>terminal\<X\>::type l = {x};</tt>.
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///
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/// The \c Domain template parameter defaults to
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/// \c proto::default_domain.
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template<
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typename T
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, typename Domain // = default_domain
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>
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struct literal
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: extends<basic_expr<tag::terminal, term<T>, 0>, literal<T, Domain>, Domain>
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{
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private:
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typedef basic_expr<tag::terminal, term<T>, 0> terminal_type;
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typedef extends<terminal_type, literal<T, Domain>, Domain> base_type;
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typedef literal<T, Domain> literal_t;
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public:
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typedef typename detail::term_traits<T>::value_type value_type;
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typedef typename detail::term_traits<T>::reference reference;
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typedef typename detail::term_traits<T>::const_reference const_reference;
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literal()
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: base_type(terminal_type::make(T()))
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{}
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template<typename U>
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literal(U &u)
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: base_type(terminal_type::make(u))
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{}
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template<typename U>
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literal(U const &u)
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: base_type(terminal_type::make(u))
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{}
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template<typename U>
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literal(literal<U, Domain> const &u)
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: base_type(terminal_type::make(u.get()))
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{}
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BOOST_PROTO_EXTENDS_USING_ASSIGN(literal_t)
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reference get()
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{
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return proto::value(*this);
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}
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const_reference get() const
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{
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return proto::value(*this);
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}
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};
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}
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/// \brief A helper function for creating a \c literal\<\> wrapper.
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/// \param t The object to wrap.
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/// \return literal\<T &\>(t)
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/// \attention The returned value holds the argument by reference.
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/// \throw nothrow
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template<typename T>
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inline literal<T &> const lit(T &t)
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{
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return literal<T &>(t);
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}
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/// \overload
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///
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template<typename T>
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inline literal<T const &> const lit(T const &t)
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{
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#ifdef BOOST_MSVC
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#pragma warning(push)
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#pragma warning(disable: 4180) // warning C4180: qualifier applied to function type has no meaning; ignored
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#endif
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return literal<T const &>(t);
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#ifdef BOOST_MSVC
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#pragma warning(pop)
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#endif
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}
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}}
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#endif
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