package bluej.utility.javafx.binding;

import java.util.function.Function;
import java.util.stream.Stream;

import javafx.collections.ObservableList;




| Binds a destination list to the concatenation of some observable-list accessor
| on items in an observable list.
|
public class ConcatMapListBinding<DEST, SRC> extends DeepListBinding<DEST>{    
   private final ObservableList<SRC> src;
   
   private final Function<SRC, ObservableList<? extends DEST>> via;

   
   public static  void bind(ObservableList<DEST> dest, ObservableList<SRC> src, Function<SRC, ObservableList<? extends DEST>> via)
   {        
      new ConcatMapListBinding<>(dest, src, via).startListening();     
      }
    
   
   private ConcatMapListBinding(ObservableList<DEST> dest, ObservableList<SRC> src, Function<SRC, ObservableList<? extends DEST>> via)
   {
      super(dest);
       
      this.src = src;
       
      this.via = via;     
      }

   
   @Override
   
   protected Stream> getListenTargets()
   {
      return Stream.concat(Stream.of((ObservableList<?>)src), src.stream().map(via));     
      }

   
   @Override
   
   protected Stream calculateValues()
   {
      return src.stream().map(via).flatMap(ObservableList::stream);     
      } 
   }