迭代器和生成器 实现代码

#任何实现了 __iter__ 和 __next__ 方法的对象都是迭代器,所以生成器是一种特殊的迭代器
#生成器的标志是yied 函数
class Range:
    def __init__(self, start, end=None, step=1):
        if end is None:
            self.end = start
            self.start = 0
        else:
            self.start = start
            self.end = end
        self.step = step

    def __iter__(self):
        return self

    def __next__(self):
        if self.start < self.end:
            current = self.start
            self.start += self.step
            return current
        else:
            raise StopIteration()

 
#定义一个迭代器, 实现斐波那契数列
class Fib:
      def __init__(self, max_value):
          self.prev = 0
          self.curr = 1
          self.max_value = max_value

      def __iter__(self):
          return self

      def __next__(self):
          if self.curr <= self.max_value:
              res = self.curr
              self.prev, self.curr = self.curr, self.prev + self.curr  # 为下一次做准备
              return res
          else:
              raise StopIteration()

# 定义一个生成器函数, 实现斐波那契数列
def fib(max_value):
      prev = 0
      curr = 1
      while curr < max_value:
          yield curr
            
          prev, curr = curr, curr + prev