ext-boost/boost/variant/get.hpp

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//-----------------------------------------------------------------------------
// boost variant/get.hpp header file
// See http://www.boost.org for updates, documentation, and revision history.
//-----------------------------------------------------------------------------
//
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// Copyright (c) 2003 Eric Friedman, Itay Maman
// Copyright (c) 2014 Antony Polukhin
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//
// 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)
#ifndef BOOST_VARIANT_GET_HPP
#define BOOST_VARIANT_GET_HPP
#include <exception>
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#include <boost/config.hpp>
#include <boost/detail/workaround.hpp>
#include <boost/static_assert.hpp>
#include <boost/throw_exception.hpp>
#include <boost/utility/addressof.hpp>
#include <boost/variant/variant_fwd.hpp>
#include <boost/variant/detail/element_index.hpp>
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#include <boost/variant/detail/move.hpp>
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#include <boost/type_traits/add_reference.hpp>
#include <boost/type_traits/add_pointer.hpp>
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#include <boost/type_traits/is_lvalue_reference.hpp>
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namespace boost {
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#if defined(BOOST_CLANG)
# pragma clang diagnostic push
# pragma clang diagnostic ignored "-Wweak-vtables"
#endif
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//////////////////////////////////////////////////////////////////////////
// class bad_get
//
// The exception thrown in the event of a failed get of a value.
//
class BOOST_SYMBOL_VISIBLE bad_get
: public std::exception
{
public: // std::exception implementation
virtual const char * what() const BOOST_NOEXCEPT_OR_NOTHROW
{
return "boost::bad_get: "
"failed value get using boost::get";
}
};
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#if defined(BOOST_CLANG)
# pragma clang diagnostic pop
#endif
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//////////////////////////////////////////////////////////////////////////
// function template get<T>
//
// Retrieves content of given variant object if content is of type T.
// Otherwise: pointer ver. returns 0; reference ver. throws bad_get.
//
namespace detail { namespace variant {
// (detail) class template get_visitor
//
// Generic static visitor that: if the value is of the specified type,
// returns a pointer to the value it visits; else a null pointer.
//
template <typename T>
struct get_visitor
{
private: // private typedefs
typedef typename add_pointer<T>::type pointer;
typedef typename add_reference<T>::type reference;
public: // visitor typedefs
typedef pointer result_type;
public: // visitor interfaces
pointer operator()(reference operand) const BOOST_NOEXCEPT
{
return boost::addressof(operand);
}
template <typename U>
pointer operator()(const U&) const BOOST_NOEXCEPT
{
return static_cast<pointer>(0);
}
};
}} // namespace detail::variant
#ifndef BOOST_VARIANT_AUX_GET_EXPLICIT_TEMPLATE_TYPE
# if !BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x0551))
# define BOOST_VARIANT_AUX_GET_EXPLICIT_TEMPLATE_TYPE(t)
# else
# define BOOST_VARIANT_AUX_GET_EXPLICIT_TEMPLATE_TYPE(t) \
, t* = 0
# endif
#endif
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/////////////////////////////////////////////////////////////////////////////////////////////////////////////
// relaxed_get<U>(variant) methods
//
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template <typename U, BOOST_VARIANT_ENUM_PARAMS(typename T) >
inline
typename add_pointer<U>::type
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relaxed_get(
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boost::variant< BOOST_VARIANT_ENUM_PARAMS(T) >* operand
BOOST_VARIANT_AUX_GET_EXPLICIT_TEMPLATE_TYPE(U)
) BOOST_NOEXCEPT
{
typedef typename add_pointer<U>::type U_ptr;
if (!operand) return static_cast<U_ptr>(0);
detail::variant::get_visitor<U> v;
return operand->apply_visitor(v);
}
template <typename U, BOOST_VARIANT_ENUM_PARAMS(typename T) >
inline
typename add_pointer<const U>::type
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relaxed_get(
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const boost::variant< BOOST_VARIANT_ENUM_PARAMS(T) >* operand
BOOST_VARIANT_AUX_GET_EXPLICIT_TEMPLATE_TYPE(U)
) BOOST_NOEXCEPT
{
typedef typename add_pointer<const U>::type U_ptr;
if (!operand) return static_cast<U_ptr>(0);
detail::variant::get_visitor<const U> v;
return operand->apply_visitor(v);
}
template <typename U, BOOST_VARIANT_ENUM_PARAMS(typename T) >
inline
typename add_reference<U>::type
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relaxed_get(
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boost::variant< BOOST_VARIANT_ENUM_PARAMS(T) >& operand
BOOST_VARIANT_AUX_GET_EXPLICIT_TEMPLATE_TYPE(U)
)
{
typedef typename add_pointer<U>::type U_ptr;
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U_ptr result = relaxed_get<U>(boost::addressof(operand));
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if (!result)
boost::throw_exception(bad_get());
return *result;
}
template <typename U, BOOST_VARIANT_ENUM_PARAMS(typename T) >
inline
typename add_reference<const U>::type
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relaxed_get(
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const boost::variant< BOOST_VARIANT_ENUM_PARAMS(T) >& operand
BOOST_VARIANT_AUX_GET_EXPLICIT_TEMPLATE_TYPE(U)
)
{
typedef typename add_pointer<const U>::type U_ptr;
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U_ptr result = relaxed_get<const U>(boost::addressof(operand));
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if (!result)
boost::throw_exception(bad_get());
return *result;
}
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#ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
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#if defined(BOOST_MSVC) && (_MSC_VER < 1900) // MSVC-2014 has fixed the incorrect diagnostics.
# pragma warning(push)
# pragma warning(disable: 4172) // returning address of local variable or temporary
#endif
template <typename U, BOOST_VARIANT_ENUM_PARAMS(typename T) >
inline
U&&
relaxed_get(
boost::variant< BOOST_VARIANT_ENUM_PARAMS(T) >&& operand
BOOST_VARIANT_AUX_GET_EXPLICIT_TEMPLATE_TYPE(U)
)
{
typedef typename add_pointer<U>::type U_ptr;
U_ptr result = relaxed_get<U>(boost::addressof(operand));
if (!result)
boost::throw_exception(bad_get());
return static_cast<U&&>(*result);
}
#if defined(BOOST_MSVC) && (_MSC_VER < 1900)
# pragma warning(pop)
#endif
#endif
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/////////////////////////////////////////////////////////////////////////////////////////////////////////////
// strict_get<U>(variant) methods
//
template <typename U, BOOST_VARIANT_ENUM_PARAMS(typename T) >
inline
typename add_pointer<U>::type
strict_get(
boost::variant< BOOST_VARIANT_ENUM_PARAMS(T) >* operand
BOOST_VARIANT_AUX_GET_EXPLICIT_TEMPLATE_TYPE(U)
) BOOST_NOEXCEPT
{
BOOST_STATIC_ASSERT_MSG(
(boost::detail::variant::holds_element<boost::variant< BOOST_VARIANT_ENUM_PARAMS(T) >, U >::value),
"boost::variant does not contain specified type U, "
"call to boost::get<U>(boost::variant<T...>*) will always return NULL"
);
return relaxed_get<U>(operand);
}
template <typename U, BOOST_VARIANT_ENUM_PARAMS(typename T) >
inline
typename add_pointer<const U>::type
strict_get(
const boost::variant< BOOST_VARIANT_ENUM_PARAMS(T) >* operand
BOOST_VARIANT_AUX_GET_EXPLICIT_TEMPLATE_TYPE(U)
) BOOST_NOEXCEPT
{
BOOST_STATIC_ASSERT_MSG(
(boost::detail::variant::holds_element<boost::variant< BOOST_VARIANT_ENUM_PARAMS(T) >, const U >::value),
"boost::variant does not contain specified type U, "
"call to boost::get<U>(const boost::variant<T...>*) will always return NULL"
);
return relaxed_get<U>(operand);
}
template <typename U, BOOST_VARIANT_ENUM_PARAMS(typename T) >
inline
typename add_reference<U>::type
strict_get(
boost::variant< BOOST_VARIANT_ENUM_PARAMS(T) >& operand
BOOST_VARIANT_AUX_GET_EXPLICIT_TEMPLATE_TYPE(U)
)
{
BOOST_STATIC_ASSERT_MSG(
(boost::detail::variant::holds_element<boost::variant< BOOST_VARIANT_ENUM_PARAMS(T) >, U >::value),
"boost::variant does not contain specified type U, "
"call to boost::get<U>(boost::variant<T...>&) will always throw boost::bad_get exception"
);
return relaxed_get<U>(operand);
}
template <typename U, BOOST_VARIANT_ENUM_PARAMS(typename T) >
inline
typename add_reference<const U>::type
strict_get(
const boost::variant< BOOST_VARIANT_ENUM_PARAMS(T) >& operand
BOOST_VARIANT_AUX_GET_EXPLICIT_TEMPLATE_TYPE(U)
)
{
BOOST_STATIC_ASSERT_MSG(
(boost::detail::variant::holds_element<boost::variant< BOOST_VARIANT_ENUM_PARAMS(T) >, const U >::value),
"boost::variant does not contain specified type U, "
"call to boost::get<U>(const boost::variant<T...>&) will always throw boost::bad_get exception"
);
return relaxed_get<U>(operand);
}
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#ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
template <typename U, BOOST_VARIANT_ENUM_PARAMS(typename T) >
inline
U&&
strict_get(
boost::variant< BOOST_VARIANT_ENUM_PARAMS(T) >&& operand
BOOST_VARIANT_AUX_GET_EXPLICIT_TEMPLATE_TYPE(U)
)
{
BOOST_STATIC_ASSERT_MSG(
(!boost::is_lvalue_reference<U>::value),
"remove ampersand '&' from template type U in boost::get<U>(boost::variant<T...>&&) "
);
BOOST_STATIC_ASSERT_MSG(
(boost::detail::variant::holds_element<boost::variant< BOOST_VARIANT_ENUM_PARAMS(T) >, U >::value),
"boost::variant does not contain specified type U, "
"call to boost::get<U>(const boost::variant<T...>&) will always throw boost::bad_get exception"
);
return relaxed_get<U>(detail::variant::move(operand));
}
#endif
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/////////////////////////////////////////////////////////////////////////////////////////////////////////////
// get<U>(variant) methods
//
template <typename U, BOOST_VARIANT_ENUM_PARAMS(typename T) >
inline
typename add_pointer<U>::type
get(
boost::variant< BOOST_VARIANT_ENUM_PARAMS(T) >* operand
BOOST_VARIANT_AUX_GET_EXPLICIT_TEMPLATE_TYPE(U)
) BOOST_NOEXCEPT
{
#ifdef BOOST_VARIANT_USE_RELAXED_GET_BY_DEFAULT
return relaxed_get<U>(operand);
#else
return strict_get<U>(operand);
#endif
}
template <typename U, BOOST_VARIANT_ENUM_PARAMS(typename T) >
inline
typename add_pointer<const U>::type
get(
const boost::variant< BOOST_VARIANT_ENUM_PARAMS(T) >* operand
BOOST_VARIANT_AUX_GET_EXPLICIT_TEMPLATE_TYPE(U)
) BOOST_NOEXCEPT
{
#ifdef BOOST_VARIANT_USE_RELAXED_GET_BY_DEFAULT
return relaxed_get<U>(operand);
#else
return strict_get<U>(operand);
#endif
}
template <typename U, BOOST_VARIANT_ENUM_PARAMS(typename T) >
inline
typename add_reference<U>::type
get(
boost::variant< BOOST_VARIANT_ENUM_PARAMS(T) >& operand
BOOST_VARIANT_AUX_GET_EXPLICIT_TEMPLATE_TYPE(U)
)
{
#ifdef BOOST_VARIANT_USE_RELAXED_GET_BY_DEFAULT
return relaxed_get<U>(operand);
#else
return strict_get<U>(operand);
#endif
}
template <typename U, BOOST_VARIANT_ENUM_PARAMS(typename T) >
inline
typename add_reference<const U>::type
get(
const boost::variant< BOOST_VARIANT_ENUM_PARAMS(T) >& operand
BOOST_VARIANT_AUX_GET_EXPLICIT_TEMPLATE_TYPE(U)
)
{
#ifdef BOOST_VARIANT_USE_RELAXED_GET_BY_DEFAULT
return relaxed_get<U>(operand);
#else
return strict_get<U>(operand);
#endif
}
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#ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
template <typename U, BOOST_VARIANT_ENUM_PARAMS(typename T) >
inline
U&&
get(
boost::variant< BOOST_VARIANT_ENUM_PARAMS(T) >&& operand
BOOST_VARIANT_AUX_GET_EXPLICIT_TEMPLATE_TYPE(U)
)
{
#ifdef BOOST_VARIANT_USE_RELAXED_GET_BY_DEFAULT
return relaxed_get<U>(detail::variant::move(operand));
#else
return strict_get<U>(detail::variant::move(operand));
#endif
}
#endif
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} // namespace boost
#endif // BOOST_VARIANT_GET_HPP