python - 正则表达式向前看和向后看

Question

我正在尝试正则表达式使用前瞻和后视向后提取数据。
在下面，我只对 column store error 感兴趣，即模式为 : search table error: , 我需要提取字符串直到上一个 : .

Error processing. Reason: Exception: Job aborted due to failure: xxxxx (asasdasd): com.db.jdbc.exceptions.JDBCDriverException: DBTech JDBC: [2048]: column store error: search table error:  [123]

我目前被困在 (?<=:)(.*?)(?=(: search table error)) .这是从第一次出现 : 中提取的从开始。
感谢您的任何帮助。

Answer 1

用

:\s*([^:]*?)\s*: search table error

见 regex proof .
说明

--------------------------------------------------------------------------------
  :                        ':'
--------------------------------------------------------------------------------
  \s*                      whitespace (\n, \r, \t, \f, and " ") (0 or
                           more times (matching the most amount
                           possible))
--------------------------------------------------------------------------------
  (                        group and capture to \1:
--------------------------------------------------------------------------------
    [^:]*?                   any character except: ':' (0 or more
                             times (matching the least amount
                             possible))
--------------------------------------------------------------------------------
  )                        end of \1
--------------------------------------------------------------------------------
  \s*                      whitespace (\n, \r, \t, \f, and " ") (0 or
                           more times (matching the most amount
                           possible))
--------------------------------------------------------------------------------
  : search table error     ': search table error'

Python code :

import re
regex = r":\s*([^:]*?)\s*: search table error"
test_str = "Error processing. Reason: Exception: Job aborted due to failure: xxxxx (asasdasd): com.db.jdbc.exceptions.JDBCDriverException: DBTech JDBC: [2048]: column store error: search table error:  [123]"
match = re.search(regex, test_str)
if match:
    print(match.group(1))

结果 : column store error
还:

(?<=:)[^:]*(?=:\s+search\s+table\s+error:)

见 this regex proof .
说明

--------------------------------------------------------------------------------
  (?<=                     look behind to see if there is:
--------------------------------------------------------------------------------
    :                        ':'
--------------------------------------------------------------------------------
  )                        end of look-behind
--------------------------------------------------------------------------------
  [^:]*                    any character except: ':' (0 or more times
                           (matching the most amount possible))
--------------------------------------------------------------------------------
  (?=                      look ahead to see if there is:
--------------------------------------------------------------------------------
    :                        ':'
--------------------------------------------------------------------------------
    \s+                      whitespace (\n, \r, \t, \f, and " ") (1
                             or more times (matching the most amount
                             possible))
--------------------------------------------------------------------------------
    search                   'search'
--------------------------------------------------------------------------------
    \s+                      whitespace (\n, \r, \t, \f, and " ") (1
                             or more times (matching the most amount
                             possible))
--------------------------------------------------------------------------------
    table                    'table'
--------------------------------------------------------------------------------
    \s+                      whitespace (\n, \r, \t, \f, and " ") (1
                             or more times (matching the most amount
                             possible))
--------------------------------------------------------------------------------
    error:                   'error:'
--------------------------------------------------------------------------------
  )                        end of look-ahead

与 Python code 喜欢

import re
regex = r"(?<=:)[^:]*(?=:\s+search\s+table\s+error:)"
test_str = "Error processing. Reason: Exception: Job aborted due to failure: xxxxx (asasdasd): com.db.jdbc.exceptions.JDBCDriverException: DBTech JDBC: [2048]: column store error: search table error:  [123]"
match = re.search(regex, test_str)
if match:
    print(match.group().strip())