gistfile1.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-

"""
Alejandro Santos, alejolp@alejolp.com.ar

Adaptador de un Iterador para saber si el Iterador original tiene
un proximo elemento. Igual que los iteradores de Java:

  http://download.oracle.com/javase/1.5.0/docs/api/java/util/Iterator.html

"""

class HasNextIter(object):
    def __init__(self, it):
        self.it = it.__iter__()
        self.data = None
        self.hn = None

    def __iter__(self):
        return self

    def _fetchOne(self):
        try:
            self.data = self.it.next()
            self.hn = True
        except StopIteration:
            self.hn = False

    def next(self):
        if self.hn is None:
            self._fecthOne()

        if self.hn is False:
            raise StopIteration()
        else:
            self.hn = None
            return self.data

    def hasNext(self):
        if self.hn is None:
            self._fetchOne()
        return bool(self.hn)

x = HasNextIter([True, False, None] * 2)

while x.hasNext():
    print x.next()