ModuleObserver.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "Modules/ModuleManager.h"
 
class FModuleObserver
{
public:
 
    FModuleObserver(FName InModuleName, FSimpleDelegate InOnModuleLoaded, FSimpleDelegate InOnModuleUnloaded)
        : ModuleName(InModuleName)
        , OnModuleLoaded(InOnModuleLoaded)
        , OnModuleUnloaded(InOnModuleUnloaded)
    {
        FModuleManager& ModuleManager = FModuleManager::Get();
 
        if (ModuleManager.IsModuleLoaded(ModuleName))
        {
            OnModuleLoaded.ExecuteIfBound();
        }
 
        ModuleManager.OnModulesChanged().AddRaw(this, &FModuleObserver::OnModulesChanged);
    }
 
    ~FModuleObserver()
    {
        FModuleManager& ModuleManager = FModuleManager::Get();
        
        if (ModuleManager.IsModuleLoaded(ModuleName))
        {
            OnModuleUnloaded.ExecuteIfBound();
        }
 
        ModuleManager.OnModulesChanged().RemoveAll(this);
    }
 
private:
 
    void OnModulesChanged(FName InModuleName, EModuleChangeReason Reason)
    {
        if (InModuleName != ModuleName || Reason == EModuleChangeReason::PluginDirectoryChanged)
        {
            return;
        }
 
        switch (Reason)
        {
            case EModuleChangeReason::ModuleLoaded:     OnModuleLoaded.ExecuteIfBound();        break;
            case EModuleChangeReason::ModuleUnloaded:   OnModuleUnloaded.ExecuteIfBound();      break;
        }
    }
 
private:
    FName ModuleName;
    FSimpleDelegate OnModuleLoaded;
    FSimpleDelegate OnModuleUnloaded;
};