File size: 1,109 Bytes
8ae5fc5 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 | #ifndef METAL_LAMBDA_TRAIT_HPP
#define METAL_LAMBDA_TRAIT_HPP
#include "../config.hpp"
#include "../lambda/bind.hpp"
#include "../lambda/lambda.hpp"
#include "../number/number.hpp"
namespace metal {
/// \ingroup lambda
///
/// ### Description
/// Constructs a _predicate_ out of a _trait_, that is a \lambda that
/// evaluates to a \number, out of an \expression that defines a nested
/// integral constant `value` convertible to metal::int_.
///
/// ### Usage
/// For any \expression `expr`
/// \code
/// using result = metal::trait<expr>;
/// \endcode
///
/// \returns: \lambda
/// \semantics:
/// Equivalent to
/// \code
/// using result = metal::lambda<pred>;
/// \endcode
/// where `pred` is an \expression such that
/// \code
/// template<class... args>
/// using pred = metal::number<expr<args...>::value>;
/// \endcode
///
/// ### Example
/// \snippet lambda.cpp trait
///
/// ### See Also
/// \see lambda, number
template <template <class...> class expr>
using trait = metal::bind<metal::lambda<metal::as_number>, metal::lambda<expr>>;
}
#endif
|