[857] | 1 | // Copyright Daniel Wallin, David Abrahams 2005. Use, modification and
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| 2 | // distribution is subject to the Boost Software License, Version 1.0. (See
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| 3 | // accompanying file LICENSE_1_0.txt or copy at
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| 4 | // http://www.boost.org/LICENSE_1_0.txt)
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| 5 |
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| 6 | #ifndef TAGGED_ARGUMENT_050328_HPP
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| 7 | #define TAGGED_ARGUMENT_050328_HPP
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| 8 |
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| 9 | #include <boost/parameter/aux_/void.hpp>
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| 10 | #include <boost/parameter/aux_/arg_list.hpp>
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| 11 | #include <boost/detail/is_xxx.hpp>
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| 12 |
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| 13 | namespace boost { namespace parameter { namespace aux {
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| 14 |
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| 15 | // Holds a reference to an argument of type Arg associated with
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| 16 | // keyword Keyword
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| 17 |
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| 18 | template <class Keyword, class Arg>
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| 19 | struct tagged_argument
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| 20 | {
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| 21 | typedef Keyword key_type;
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| 22 | typedef Arg value_type;
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| 23 | typedef Arg& reference;
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| 24 |
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| 25 | tagged_argument(reference x) : value(x) {}
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| 26 |
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| 27 | // Comma operator to compose argument list without using parameters<>.
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| 28 | // Useful for argument lists with undetermined length.
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| 29 | template <class Keyword2, class Arg2>
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| 30 | arg_list<
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| 31 | tagged_argument<Keyword, Arg>
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| 32 | , arg_list<tagged_argument<Keyword2, Arg2> >
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| 33 | >
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| 34 | operator,(tagged_argument<Keyword2, Arg2> x) const
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| 35 | {
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| 36 | return arg_list<
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| 37 | tagged_argument<Keyword, Arg>
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| 38 | , arg_list<tagged_argument<Keyword2, Arg2> >
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| 39 | >(
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| 40 | *this
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| 41 | , arg_list<tagged_argument<Keyword2, Arg2> >(x, empty_arg_list())
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| 42 | );
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| 43 | }
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| 44 |
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| 45 | reference value;
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| 46 | };
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| 47 |
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| 48 | // Defines a metafunction, is_tagged_argument, that identifies
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| 49 | // tagged_argument specializations.
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| 50 | BOOST_DETAIL_IS_XXX_DEF(tagged_argument,tagged_argument,2)
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| 51 |
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| 52 | }}} // namespace boost::parameter::aux
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| 53 |
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| 54 | #endif // TAGGED_ARGUMENT_050328_HPP
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| 55 |
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