DelegateFilter.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreTypes.h"
#include "Misc/AssertionMacros.h"
#include "Templates/SharedPointer.h"
#include "Delegates/Delegate.h"
#include "Misc/IFilter.h"
 
/**
 *  A generic filter designed to call a predicate provided on construction to filter
 */
template< typename ItemType >
class TDelegateFilter
    : public IFilter< ItemType >, public TSharedFromThis< TDelegateFilter< ItemType > >
{
public:
 
    DECLARE_DELEGATE_RetVal_OneParam( bool, FPredicate, ItemType );
 
    /** 
     *  TDelegateFilter Constructor
     *  
     * @param   InPredicate     A required delegate called to determine if an Item passes the filter
     */
    TDelegateFilter( FPredicate InPredicate )
        : Predicate( InPredicate )
    {
        check( Predicate.IsBound() );
    }
 
    DECLARE_DERIVED_EVENT( TDelegateFilter, IFilter<ItemType>::FChangedEvent, FChangedEvent );
    virtual FChangedEvent& OnChanged() override { return ChangedEvent; }
 
    /** 
     * Returns whether the specified Item passes the Filter's restrictions 
     *
     *  @param  InItem  The Item is check 
     *  @return         Whether the specified Item passed the filter
     */
    virtual bool PassesFilter( ItemType InItem ) const override
    {
        return Predicate.Execute( InItem );
    }
 
    /** Broadcasts the OnChanged event for this filter */
    void BroadcastChanged()
    {
        ChangedEvent.Broadcast();
    }
 
private:
 
    /** The delegate called to determine if an Item passes the filter */
    FPredicate Predicate;
 
    /** Fires whenever the filter changes */
    FChangedEvent ChangedEvent;
};