viewHolder2.kt

class LayoutManager(private val recycler: Recycler) {
    fun getViewForPosition(pos: Int): View {
        return recycler.getView(pos)
    }
}

class RecyclerView(
    private val adapter: Adapter,
    private val recyclerPool: RecyclerPool,
    private val viewCache: ViewCache
) {
    fun getView(pos: Int): View {
        val viewOrNull = viewCache.getOrNull(pos)
        // view found then return view
        if (viewOrNull != null) {
            return viewOrNull
        }
        // if view not found in cache get view type
        val viewType = adapter.getViewType(pos)
        // from view type get viewholder from cache 
        val holderOrNull = recyclerPool.getViewHolderByType(viewType)
        // view holder found -> bind data and return view
        if (holderOrNull != null) {
            adapter.bindViewHolder(holderOrNull, pos)
            return holderOrNull.itemView
        }
        return TODO()
    }
}

class ViewCache {
    private val viewCache = mutableMapOf<Int, View>() // LRU cache
    fun getOrNull(pos: Int): View? = viewCache.get(pos)
}

class RecyclerPool {
    private val cache = mutableMapOf<ViewType, ViewHolder>() // LRU cache
    fun getViewHolderByType(viewType: ViewType): ViewHolder? {
        return cache.get(viewType)
    }
}

abstract class Adapter {
    abstract fun getViewType(pos: Int): ViewType
    abstract fun bindViewHolder(holder: ViewHolder,pos:Int)
}