////////////////////////////////////////////////////////////////////////////////////////////////////
// NoesisGUI - http://www.noesisengine.com
// Copyright (c) 2013 Noesis Technologies S.L. All Rights Reserved.
////////////////////////////////////////////////////////////////////////////////////////////////////


#ifndef __CORE_IMULTIVALUECONVERTER_H__
#define __CORE_IMULTIVALUECONVERTER_H__


#include <NsCore/Noesis.h>
#include <NsCore/Interface.h>


namespace Noesis
{

class BaseComponent;
template<class T> class Ptr;
template<class T> class ArrayRef;
template<class T> class BaseVector;

////////////////////////////////////////////////////////////////////////////////////////////////////
/// Provides a way to apply custom logic to a MultiBinding.
////////////////////////////////////////////////////////////////////////////////////////////////////
NS_INTERFACE IMultiValueConverter: public Interface
{
    /// Converts source values to a value for the binding target. The data binding engine calls
    /// this method when it propagates the values from source bindings to the binding target.
    ///
    /// Return *DependencyProperty.UnsetValue* to indicate that the converter produced no value and
    /// that the fallback (if available) or default value should be used instead.
    ///
    /// Return *Binding.DoNothing* to indicate that the binding should not transfer the value to the
    /// target property or use the fallback or default value.
    virtual bool TryConvert(ArrayRef<BaseComponent*> values, const Type* targetType,
        BaseComponent* parameter, Ptr<BaseComponent>& result) = 0;

    /// Converts a binding target value to the source binding values. The data binding engine calls
    /// this method when it propagates a value from the binding to the sources.
    ///
    /// If there are more return values than source bindings, the excess portion of return values
    /// will be ignored. If there are more source bindings than return values, the remaining source
    /// bindings will not have any value set to them.
    ///
    /// Types of return values are not verified against targetTypes; the values will be set to
    /// source bindings directly.
    ///
    /// Returning *Binding.DoNothing* in position i indicates that no value should be set on the
    /// source binding at index i.
    ///
    /// Returning *DependencyProperty.UnsetValue* in position i indicates that the converter is
    /// unable to provide a value to the source binding at index i, and no value will be set to it.
    ///
    /// Returning *null* indicates that the conversion could not be performed at all, or that the
    /// backward conversion direction is not supported by the converter.
    virtual bool TryConvertBack(BaseComponent* value, ArrayRef<const Type*> targetTypes,
        BaseComponent* parameter, BaseVector<Ptr<BaseComponent>>& results) = 0;

    NS_IMPLEMENT_INLINE_REFLECTION_(IMultiValueConverter, Interface)
};

}


#endif