juce_Functional.h

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 /*
  ==============================================================================
 
   This file is part of the JUCE library.
   Copyright (c) 2022 - Raw Material Software Limited
 
   JUCE is an open source library subject to commercial or open-source
   licensing.
 
   The code included in this file is provided under the terms of the ISC license
   http://www.isc.org/downloads/software-support-policy/isc-license. Permission
   To use, copy, modify, and/or distribute this software for any purpose with or
   without fee is hereby granted provided that the above copyright notice and
   this permission notice appear in all copies.
 
   JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
   EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
   DISCLAIMED.
 
  ==============================================================================
*/
 
namespace juce
{
 
#ifndef DOXYGEN
namespace detail
{
    template <typename...>
    using Void = void;
 
    template <typename, typename = void>
    constexpr auto equalityComparableToNullptr = false;
 
    template <typename T>
    constexpr auto equalityComparableToNullptr<T, Void<decltype (std::declval<T>() != nullptr)>> = true;
} // namespace detail
#endif
 
//==============================================================================
struct NullCheckedInvocation
{
    template <typename Callable, typename... Args>
    static void invoke (Callable&& fn, Args&&... args)
    {
        if constexpr (detail::equalityComparableToNullptr<Callable>)
        {
            JUCE_BEGIN_IGNORE_WARNINGS_GCC_LIKE ("-Waddress")
 
            if (fn != nullptr)
                fn (std::forward<Args> (args)...);
 
            JUCE_END_IGNORE_WARNINGS_GCC_LIKE
        }
        else
        {
            fn (std::forward<Args> (args)...);
        }
    }
 
    template <typename... Args>
    static void invoke (std::nullptr_t, Args&&...) {}
};
 
template <typename A, typename B>
using DisableIfSameOrDerived = std::enable_if_t<! std::is_base_of_v<A, std::remove_reference_t<B>>>;
 
template <typename Object, typename OtherObject, typename Member, typename Other>
[[nodiscard]] Object withMember (Object copy, Member OtherObject::* member, Other&& value)
{
    copy.*member = std::forward<Other> (value);
    return copy;
}
 
#ifndef DOXYGEN
namespace detail
{
template <typename Functor, typename Return, typename... Args>
static constexpr auto toFnPtr (Functor functor, Return (Functor::*) (Args...) const)
{
    return static_cast<Return (*) (Args...)> (functor);
}
} // namespace detail
#endif
 
template <typename Functor>
static constexpr auto toFnPtr (Functor functor) { return detail::toFnPtr (functor, &Functor::operator()); }
 
} // namespace juce