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  package org.apache.cayenne.di.spi;
  
  import java.util.List;
  
  import org.apache.cayenne.di.Provider;
  import org.apache.cayenne.di.Scope;
  
  /**
   * A binding encapsulates DI provider scoping settings and allows to change them as many
   * times as needed.
   * 
   * @since 3.1
   */
  class Binding<T> {
  
      private Provider<T> original;
      private Provider<T> decorated;
      private Provider<T> scoped;
      private Scope scope;
  
      Binding(Provider<T> provider, Scope initialScope) {
          this.original = provider;
          this.decorated = provider;
          
          changeScope(initialScope);
      }
  
      void changeScope(Scope scope) {
          if (scope == null) {
              scope = NoScope.INSTANCE;
          }
  
          // TODO: what happens to the old scoped value? Seems like this leaks
          // scope event listeners and may cause unexpected events...
          
          this.scoped = scope.scope(original);
          this.scope = scope;
      }
      
      void decorate(Decoration<T> decoration) {
  
          List<DecoratorProvider<T>> decorators = decoration.decorators();
          if (decorators.isEmpty()) {
              return;
          }
  
          Provider<T> provider = this.original;
          for (DecoratorProvider<T> decoratorProvider : decorators) {
              provider = decoratorProvider.get(provider);
          }
  
          this.decorated = provider;
  
          // TODO: what happens to the old scoped value? Seems like this leaks
          // scope event listeners and may cause unexpected events...
  
          this.scoped = scope.scope(decorated);
      }
  
      Provider<T> getOriginal() {
          return original;
      }
  
      Provider<T> getScoped() {
          return scoped;
      }
  }
  