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A delegate to update RecycletView's adapter data with DiffUtil
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class DiffUtilDelegate<T, VH : RecyclerView.ViewHolder, A : RecyclerView.Adapter<VH>>( | |
initialValue: List<T>, | |
private val callbackFactory: (List<T>, List<T>) -> DiffUtil.Callback = | |
{ old, new -> SimpleCallback(old, new) } | |
) { | |
private var currentValue: List<T> = initialValue | |
operator fun setValue(thisRef: A?, property: KProperty<*>, value: List<T>) { | |
val callback = callbackFactory(currentValue, value) | |
val diff = DiffUtil.calculateDiff(callback) | |
thisRef?.let { diff.dispatchUpdatesTo(it) } | |
currentValue = value | |
} | |
operator fun getValue(thisRef: Any?, property: KProperty<*>): List<T> = currentValue | |
} | |
class SimpleCallback<T>( | |
private val oldList: List<T>, | |
private val newList: List<T>, | |
private val areItemsTheSame: ((oldItem: T, newItem: T) -> Boolean)? = null, | |
private val areContentsTheSame: ((oldItem: T, newItem: T) -> Boolean)? = null, | |
private val getChangePayload: ((oldItem: T, newItem: T) -> Any?)? = null | |
) : DiffUtil.Callback() { | |
override fun areItemsTheSame(oldItemPosition: Int, newItemPosition: Int): Boolean { | |
return areItemsTheSame?.invoke( | |
oldList[oldItemPosition], | |
newList[newItemPosition] | |
) ?: oldList[oldItemPosition] == newList[newItemPosition] | |
} | |
override fun areContentsTheSame(oldItemPosition: Int, newItemPosition: Int): Boolean { | |
return areContentsTheSame?.invoke( | |
oldList[oldItemPosition], | |
newList[newItemPosition] | |
) ?: oldList[oldItemPosition] == newList[newItemPosition] | |
} | |
override fun getChangePayload(oldItemPosition: Int, newItemPosition: Int): Any? { | |
return getChangePayload?.invoke(oldList[oldItemPosition], newList[newItemPosition]) | |
} | |
override fun getOldListSize(): Int = oldList.size | |
override fun getNewListSize(): Int = newList.size | |
} |
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