Lazy Evaluation

lazy.java

Operation
  Result apply(Object element)
  void  stack(Operation operation)

Result
  void apply(Collection c)


Chain.evaluate()
  Collection c = Create.newCollection()
  for e : elements 
    Result r = operation.apply(e)
    r.apply(c) 
  return c

Chain.transform(Function f)
  this.operation.stack(new TransformOperation(f))
  return this

TransformOperation implements Operation
  Operation stack;
  Result apply(Object element)
    Object v = this.function.apply(element)
    if(stack == null)
      return new AddResult(v)
    else return stack.apply(v)

AddResult implements Result
  final Object v
  void apply(Collection c)
    c.add(v)
  
Chain.filter(Predicate p)
  this.operation.stack(new FilterOperation(p))
  return this

FilterOperation
  final Predicate p
  Result apply(Object e)
    b = this.p.apply(e)
    if(!b) return new NoOpResult()
    else if(stack == null) return new AddResult(e);
    return stack.apply(e)

Chain.flatten(Function f)
  this.operation.stack(new FlatternOperation(f)
  return this

FlattenOperation
  final Function f
  Result apply(Object e)
    Collection c = f.apply(e)
    Collection t = Create.newList()
    if(stack == null) return new AddAllResult(c)
    for o : c
      r = stack.apply(o)
      r.apply(t)
    return new AddAllResult(t)


Chain.detect(Predicate p)
  this.operation.stack(new DetectOperation(p))
  try {
  this.evaluate()
  } catch(DetectionDetectedException e) {
      return e.get()
  }
  return null;
  
DetectOperation
  final Predicate p
  Result apply(Object e) throws DetectionDetectedException
    if(p.apply(e)) throw new DetectionDetectedException(e)
    return new NoOpResult()