47 lines
1.7 KiB
Plaintext
47 lines
1.7 KiB
Plaintext
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// Copyright (C) 2009-2012 Lorenzo Caminiti
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// Distributed under the Boost Software License, Version 1.0
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// (see accompanying file LICENSE_1_0.txt or a copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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// Home at http://www.boost.org/libs/utility/identity_type
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/** @file
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Wrap type expressions with round parenthesis so they can be passed to macros
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even if they contain commas.
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*/
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#ifndef BOOST_IDENTITY_TYPE_HPP_
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#define BOOST_IDENTITY_TYPE_HPP_
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#include <boost/type_traits/function_traits.hpp>
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/**
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@brief This macro allows to wrap the specified type expression within extra
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round parenthesis so the type can be passed as a single macro parameter even if
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it contains commas (not already wrapped within round parenthesis).
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@Params
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@Param{parenthesized_type,
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The type expression to be passed as macro parameter wrapped by a single set
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of round parenthesis <c>(...)</c>.
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This type expression can contain an arbitrary number of commas.
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}
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@EndParams
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This macro works on any C++03 compiler (it does not use variadic macros).
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This macro must be prefixed by <c>typename</c> when used within templates.
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Note that the compiler will not be able to automatically determine function
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template parameters when they are wrapped with this macro (these parameters
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need to be explicitly specified when calling the function template).
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On some compilers (like GCC), using this macro on abstract types requires to
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add and remove a reference to the specified type.
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*/
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#define BOOST_IDENTITY_TYPE(parenthesized_type) \
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/* must NOT prefix this with `::` to work with parenthesized syntax */ \
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boost::function_traits< void parenthesized_type >::arg1_type
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#endif // #include guard
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