AsNative.h

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/** @noop License Comment
 *  @file
 *  @copyright
 *  This Source Code is subject to the terms of the Mozilla Public License, v2.0.
 *  If a copy of the MPL was not distributed with this file You can obtain one at
 *  https://mozilla.org/MPL/2.0/
 *  
 *  @author David Mórász
 *  @date 2025
 */
 
#pragma once
 
#include "CoreMinimal.h"
#include "Mcro/FunctionTraits.h"
#include "Mcro/Delegates/Traits.h"
 
namespace Mcro::Delegates
{
    using namespace Mcro::FunctionTraits;
    
    /**
     *  @brief
     *  Creates a native delegate that is bound to the same UFunction as the specified dynamic delegate.
     *  
     *  @note This function can only convert non-multicast delegates.
     *  
     *  The signatures of the functions are checked, so that it is not possible to compile a conversion that would crash
     *  at runtime.
     *  
     *  Example Usage:
     *
     *  @code
     *  using FMyNativeDelegate = TDelegate<void(int32 someParam)>;
     *  DECLARE_DYNAMIC_DELEGATE_OneParam(FMyBlueprintDelegate, int32, someParam);
     *  
     *  void MyNativeDelegateFunction(FMyNativeDelegate delegate)
     *  {
     *      ...
     *  }
     *  
     *  void MyBlueprintDelegateFunction(FMyBlueprintDelegate delegate)
     *  {
     *      MyNativeDelegateFunction(Delegates::AsNative(delegate));
     *  }
     *  @endcode
     *  
     *  @tparam            Dynamic  The origin type, i.e. the dynamic delegate. Will be auto-deduced.
     *  @tparam NativeDelegateType  The target type, i.e. the delegate that you want to produce. Will be auto-deduced from Dynamic.
     *  @param     dynamicDelegate  The dynamic delegate that will be converted
     */
    template <
        CDynamicDelegate Dynamic,
        typename MethodPtrTypeDynamic = TDynamicMethodPtr<Dynamic>,
        typename NativeDelegateType = TDelegate<TFunction_Signature<MethodPtrTypeDynamic>>,
        typename MethodPtrTypeNative = typename TMemFunPtrType<
            false,
            FDeclareOnly,
            typename NativeDelegateType::TFuncType
        >::Type
    >
    requires CSameAsDecayed<MethodPtrTypeDynamic, MethodPtrTypeNative>
    NativeDelegateType AsNative(Dynamic&& dynamicDelegate)
    {
        // The TBaseUFunctionDelegateInstance constructor asserts if the function name is NAME_None. We therefore must check
        // to see if the dynamic delegate is bound at all. If it isn't, return an unbound native delegate.
        if (!dynamicDelegate.IsBound())
        {
            return NativeDelegateType();
        }
 
        return NativeDelegateType::CreateUFunction(dynamicDelegate.GetUObject(), dynamicDelegate.GetFunctionName());
    }
}