from collections import Iterator
isinstance(obj, Iterator)

from collections import Iterable
from collections import Iterator
import time


class MylistIterator(object):
  """這是Mylist類型的對(duì)應(yīng)迭代器類型 """
  def __init__(self,data):
    # 需要被便利的數(shù)據(jù)
    self.data = data
    # 保存用戶訪問的位置
    self.index = 0

  def __iter__(self):
    """python規(guī)定 迭代器是一種可迭代對(duì)象"""
    return self

  def __next__(self):
    """next(ml_iterator) 相當(dāng)于調(diào)用迭代器對(duì)象的.__next__()"""
    if self.index < len(self.data):
      ret = self.data[self.index]
      self.index += 1
      return ret
    else:
      # 訪問完成 應(yīng)該拋出異常
      raise StopIteration

class Mylist(object):
  """可迭代對(duì)象"""
  def __init__(self):
    self.data = [1,2,3,4,5]

  def __iter__(self):
    """提供迭代器"""
    # 返回迭代器對(duì)象
    mliter = MylistIterator(self.data)
    return mliter

# ml是一個(gè)可迭代類型
ml = Mylist()

# 獲取可迭代對(duì)象的 迭代器對(duì)象
ml_iter = iter(ml)
print(isinstance(ml_iter, Iterator))
for i in ml:
  print(i)
  time.sleep(1)

"""
１　可迭代對(duì)象的本質(zhì)　提供了一個(gè)迭代器(遍歷可迭代對(duì)象中的數(shù)據(jù))

２　如何獲取可迭代對(duì)象中的迭代器　迭代器對(duì)象　= iter(可迭代對(duì)象)
    實(shí)際上相當(dāng)于 可迭代對(duì)象.__iter__()
３　如果通過迭代器訪問可迭代對(duì)象中下一個(gè)元素　元素的值　＝　next(迭代器對(duì)象)
　　　　　　　　　　　　　　　　　　如果迭代器遍歷完成　拋出 停止迭代－異常StopIteration
"""
print(isinstance(ml, Iterable))

"""兔子隊(duì)列 某一項(xiàng)的值是前兩項(xiàng)的和
1 1 2 3 5 8
"""

class Fib(object):
  def __init__(self,n):
    """初始化操作"""
    # n代表數(shù)列的長度
    self.n = n

    # 下標(biāo)記錄
    self.index = 0

    self.number1 = 0
    self.number2 = 1

  def __iter__(self):
    return self

  def __next__(self):
    """ｎｅｘｔ(迭代器)　?。剑剑健?__next__()"""
    if self.index < self.n:
      ret = self.number1
      self.number1,self.number2 = self.number2,self.number2+self.number1
      self.index += 1
      return ret
    else:
      raise StopIteration

# list() tuple()都可以接收迭代器　并且將遍歷到的數(shù)據(jù)存儲(chǔ)到集合中
print(list(Fib(10)))
#
# # 打印斐波那契數(shù)列的前10項(xiàng)的值
# # for i in Fib(10):
# #   print(i)
# # 1 通過iter函數(shù)獲取可迭代對(duì)象 Iterable 的迭代器 iterator
# ml_iterator = iter(Fib(1000))
#
# # 2 在循環(huán)內(nèi)部不斷調(diào)用next(迭代器) 獲取下一個(gè)元素的值
# # 3 如果迭代完成 會(huì)拋出一個(gè)停止迭代的異常StopIteration

# 列表推導(dǎo)式
lis=[x for x in range(10)]
print(lis)

# 生成器表達(dá)式 中括號(hào)變圓括號(hào)
data=(x for x in range(10))
print(data)
# 遍歷data
for i in data:
  print(i)

[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
<generator object <genexpr> at 0x02AE7120>
1
3
5
7
9