third_party/boost/type_traits/doc/disjunction.qbk

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Copyright 2020 Glen Joseph Fernandes
(glenjofe@gmail.com)

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).
]

[section:disjunction disjunction]

    template<class... T>
    struct disjunction;

__inherit Inherits from the first type `U` in the list for which
`bool(U::value)` is `true`, or the last type in the list if there is no such
type. If `sizeof...(T)` is `0` then inherits from `__false_type`.

__header `#include <boost/type_traits/disjunction.hpp>`

[all_compilers] In the absence of variadic-template support, `disjunction` has
only 2 parameters.

__examples

[:Given: `template<int N> struct Int { static const int value = N };` ]

[:`disjunction<>` inherits from `__false_type`.]

[:`disjunction<Int<1> >` inherits from `Int<1>`.]

[:`disjunction<Int<1>, Int<2>, Int<3> >` inherits from `Int<1>`.]

[:`disjunction<Int<0>, Int<2>, Int<3> >` inherits from `Int<2>`.]

[endsect]