is_identity.hpp

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// SPDX-License-Identifier: BSD-2-Clause
 
#ifndef pRC_CORE_VALUE_FUNCTIONS_IS_IDENTITY_H
#define pRC_CORE_VALUE_FUNCTIONS_IS_IDENTITY_H
 
#include <prc/core/basic/functions/identity.hpp>
#include <prc/core/functors/is_approx.hpp>
#include <prc/core/value/functions/is_approx.hpp>
#include <prc/core/value/limits.hpp>
 
namespace pRC
{
    template<class X, class R = RemoveReference<X>,
        class TT = typename R::Value, If<IsValue<TT>> = 0,
        If<IsDefined<Identity<R>>> = 0, If<IsInvocable<Identity<R>>> = 0,
        If<IsInvocable<AbsoluteError, X, R>> = 0>
    static inline constexpr auto isIdentity(X &&a,
        TT const &tolerance = NumericLimits<TT>::tolerance())
    {
        return absoluteError(forward<X>(a), identity<R>()) <= tolerance;
    }
}
#endif // pRC_CORE_VALUE_FUNCTIONS_IS_IDENTITY_H