92 lines
2.5 KiB
C++
92 lines
2.5 KiB
C++
/*=============================================================================
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Copyright (c) 2001-2011 Joel de Guzman
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Distributed under the Boost Software License, Version 1.0. (See accompanying
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file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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==============================================================================*/
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#if !defined(BOOST_SPIRIT_EXPAND_ARG_FEB_19_2007_1107AM)
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#define BOOST_SPIRIT_EXPAND_ARG_FEB_19_2007_1107AM
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#if defined(_MSC_VER)
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#pragma once
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#endif
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#include <boost/mpl/bool.hpp>
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#include <boost/mpl/or.hpp>
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#include <boost/mpl/identity.hpp>
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#include <boost/mpl/eval_if.hpp>
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#include <boost/utility/result_of.hpp>
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#include <boost/type_traits/is_scalar.hpp>
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#include <boost/spirit/home/support/string_traits.hpp>
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namespace boost { namespace spirit { namespace detail
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{
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///////////////////////////////////////////////////////////////////////////
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#ifdef _MSC_VER
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# pragma warning(push)
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# pragma warning(disable: 4512) // assignment operator could not be generated.
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#endif
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template <typename Context>
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struct expand_arg
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{
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template <typename T>
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struct result_type
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{
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// This is a temporary hack. The better way is to detect if T
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// can be called given unused context.
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typedef typename
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mpl::eval_if<
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mpl::or_<is_scalar<T>, traits::is_string<T> >
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, mpl::identity<T const &>
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, boost::result_of<T(unused_type, Context)>
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>::type
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type;
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};
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template <typename T>
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struct result;
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template <typename F, typename A0>
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struct result<F(A0)>
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: result_type<A0> {};
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template <typename F, typename A0>
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struct result<F(A0&)>
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: result_type<A0> {};
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expand_arg(Context& context_)
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: context(context_)
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{
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}
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template <typename T>
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typename result_type<T>::type
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call(T const& f, mpl::false_) const
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{
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return f(unused, context);
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}
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template <typename T>
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typename result_type<T>::type
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call(T const& val, mpl::true_) const
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{
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return val;
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}
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template <typename T>
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typename result_type<T>::type
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operator()(T const& x) const
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{
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return call(x, mpl::or_<is_scalar<T>, traits::is_string<T> >());
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}
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Context& context;
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};
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#ifdef _MSC_VER
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# pragma warning(pop)
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#endif
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}}}
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#endif
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