Python使用正則表達式為此模式查找文本

Question

我想根據以下文本中db access出現來分隔文本，

db access alpha customer1
 deny bla bla
db access beta customer99
 permit bla bla
 permit bla bla
 permit bla bla
 permit bla bla
db access game customer14
 permit no
!

（實際文本在Linux上以\\r\\n開頭）。 我想要

db access alpha customer1
 deny bla bla

和

db access beta customer99
 permit bla bla
 permit bla bla
 permit bla bla
 permit bla bla

和

db access game customer14
 permit no

作為單獨的元素。 我最能得到的是

>>> re.findall('db\s+access.*?db\s+access',txt,re.M|re.S)
['db access alpha customer1\n     deny bla bla\n    db access']

和

>>> re.findall('db\s+access.*?!',txt,re.M|re.S)
['db access alpha customer1\n     deny bla bla\n    db access beta customer99\n     permit bla bla\n     permit bla bla\n     permit bla bla\n     permit bla bla\n    db access game customer14\n     permit no\n    !']

任何建議都會有所幫助。

Answer 1

如果您確實想使用正則表達式，則可以使用正向前行：

>>> txt = '''
... 
... db access alpha customer1
...  deny bla bla
... db access beta customer99
...  permit bla bla
...  permit bla bla
...  permit bla bla
...  permit bla bla
... db access game customer14
...  permit no
... !'''
>>> re.findall('db\s+access.*?(?=db\s+access|!)',s,re.M|re.S)
['db access alpha customer1\n deny bla bla\n', 'db access beta customer99\n permit bla bla\n permit bla bla\n permit bla bla\n permit bla bla\n', 'db access game customer14\n permit no\n']