//
//  Enumerator.java
//  
//
//  Created by Maria Eugenia Occhiuto on Fri Jul 04 2003.
//  Copyright (c) 2003 __MyCompanyName__. All rights reserved.
//
import java.util.*;
import java.lang.reflect.*;
import java.lang.*;

public abstract class Enumerator  {
public abstract boolean hasMoreElements();
public abstract Object nextElement() throws NoSuchElementException;
    
public void forall (Object o,Method f){
    while (hasMoreElements()) {    
                Object [] Parm={nextElement()};
                try{f.invoke(o,Parm);}
                catch(Exception e){System.out.println("forall error"+e);}}
    }
public Enumerator map (String f){return new MapEnumerator(f,this);}
public Enumerator takeWhile(String s){return new TakeWhileEnumerator(s,this);}
public Enumerator dropWhile(String s){return new DropWhileEnumerator(s,this);}
public Enumerator filter(String s){return new FilterEnumerator(s,this);}

public Object reduceRight(Object z, String s){
 if (hasMoreElements()){
    Class [] ParTy={z.getClass()};
    Object next=nextElement();
    Object [] Parm={reduceRight(z,s)};
    try{ Method m=next.getClass().getMethod(s,ParTy);
        z=m.invoke(next,Parm);}
    catch(Exception e){System.out.println("reduce error"+e);}}
    return z;}


public Object reduceLeft (Object z, String s){
    if (hasMoreElements()){
        Class [] ParTy={z.getClass()};
        Object [] Parm ={z};
        try{Object next=nextElement();
            Method m=next.getClass().getMethod(s,ParTy);
            z=reduceLeft(m.invoke(next,Parm),s);
      }
        catch(Exception e){System.out.println("reduceLeft error"+e);}}
        return z;}

}