如何匹配前面没有特定单词的字符串？

Question

我试图匹配字符串 ARIBABA 仅当 .get 不在它之前时。

示例：

ARIBABA = config.get('SOMETHING', 'ARIBABA').lower()

我试过这个（在下面），但它与任何东西都不匹配。

^(.get)\bARIBABA\b

Answer 1

你可以简单地试试这个：

if 0 =< s.find('.get') < s.find('ARIBABA'):

s.find(substring) returns 以子字符串

开头的 s 的最低索引

完整示例：

s = "config.get('SOMETHING', 'ARIBABA').lower()"
if 0 =< s.find('.get') < s.find('ARIBABA'):
    print('.get comes before ARIBABA')

输出：

.get comes before ARIBABA

编辑：如果 s 中不存在子字符串，find 将 return -1，这就是我添加 0=< 条件

的原因

Answer 2

这是纯正则表达式的解决方案。

pattern = "^(?!.*\.get).*(ARIBABA)"
aribaba = "config.get('SOMETHING', 'ARIBABA').lower()"
try:
    re.search(pattern, aribaba).group(1)
except:
    print("No ARIBABA or get comes before")

Answer 3

您必须在此处使用 PyPi 正则表达式库：

import regex
s = "ARIBABA = config.get('SOMETHING', 'ARIBABA').lower()"
p = r"(?<!\.get\b.*)\bARIBABA\b"
print(regex.findall(p, s))

参见Python proof。

解释

--------------------------------------------------------------------------------
  (?<!                     look behind to see if there is not:
--------------------------------------------------------------------------------
    \.                       '.'
--------------------------------------------------------------------------------
    get                      'get'
--------------------------------------------------------------------------------
    \b                       the boundary between a word char (\w)
                             and something that is not a word char
--------------------------------------------------------------------------------
    .*                       any character except \n (0 or more times
                             (matching the most amount possible))
--------------------------------------------------------------------------------
  )                        end of look-behind
--------------------------------------------------------------------------------
  \b                       the boundary between a word char (\w) and
                           something that is not a word char
--------------------------------------------------------------------------------
  ARIBABA                  'ARIBABA'
--------------------------------------------------------------------------------
  \b                       the boundary between a word char (\w) and
                           something that is not a word char

如何匹配前面没有特定单词的字符串？

How to match a string that a specific word doesn't comes before it?

python

regex

python-re