/*============================================================================= | |
Copyright (c) 2001-2011 Joel de Guzman | |
Distributed under 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) | |
==============================================================================*/ | |
#if !defined(BOOST_SPIRIT_EXPAND_ARG_FEB_19_2007_1107AM) | |
#define BOOST_SPIRIT_EXPAND_ARG_FEB_19_2007_1107AM | |
#if defined(_MSC_VER) | |
#pragma once | |
#endif | |
#include <boost/mpl/bool.hpp> | |
#include <boost/mpl/or.hpp> | |
#include <boost/mpl/identity.hpp> | |
#include <boost/mpl/eval_if.hpp> | |
#include <boost/utility/result_of.hpp> | |
#include <boost/type_traits/is_scalar.hpp> | |
#include <boost/spirit/home/support/string_traits.hpp> | |
namespace boost { namespace spirit { namespace detail | |
{ | |
/////////////////////////////////////////////////////////////////////////// | |
template <typename Context> | |
struct expand_arg | |
{ | |
template <typename T> | |
struct result_type | |
{ | |
// This is a temporary hack. The better way is to detect if T | |
// can be called given unused context. | |
typedef typename | |
mpl::eval_if< | |
mpl::or_<is_scalar<T>, traits::is_string<T> > | |
, mpl::identity<T const &> | |
, boost::result_of<T(unused_type, Context)> | |
>::type | |
type; | |
}; | |
template <typename T> | |
struct result; | |
template <typename F, typename A0> | |
struct result<F(A0)> | |
: result_type<A0> {}; | |
template <typename F, typename A0> | |
struct result<F(A0&)> | |
: result_type<A0> {}; | |
expand_arg(Context& context) | |
: context(context) | |
{ | |
} | |
template <typename T> | |
typename result_type<T>::type | |
call(T const& f, mpl::false_) const | |
{ | |
return f(unused, context); | |
} | |
template <typename T> | |
typename result_type<T>::type | |
call(T const& val, mpl::true_) const | |
{ | |
return val; | |
} | |
template <typename T> | |
typename result_type<T>::type | |
operator()(T const& x) const | |
{ | |
return call(x, mpl::or_<is_scalar<T>, traits::is_string<T> >()); | |
} | |
Context& context; | |
private: | |
// silence MSVC warning C4512: assignment operator could not be generated | |
expand_arg& operator= (expand_arg const&); | |
}; | |
}}} | |
#endif |