如何将缺失的值与regex匹配

Question

我有一个表(在本例中是字符串)，如下所示：

Community            Group / Access      context    acl_filter
---------            --------------      -------    ----------
Community_test-1      network-operator    C0n_text!  T3st-ACL#$
WEWORK                network-operator
RW                    network-admin       _C0n              
YANKS                 network-admin                  my_acl

我必须使用单个regex来匹配和解析所有值，而不需要使用额外的代码，但是编写正则表达式匹配缺少的值也有问题。

现在，让我们忽略前两行，关注实际值：

import re
import pprint

show_snmp_community = """
Community_test-1      network-operator    C0n_text!  T3st-ACL#$
WEWORK                network-operator
RW                    network-admin       _C0n              
YANKS                 network-admin                  my_acl"""

show_snmp_community_regex = "(?P<community>\S+)\s+(?P<group_access>\S+)\s+(?P<context>\S+)\s+(?P<acl>\S+)"
show_snmp_community_split = show_snmp_community.split('\n')
final_dict = {}
i = 0
for line in show_snmp_community_split:
    snmp_dict = {}
    match_snmp = re.match(show_snmp_community_regex, line)
    group_snmp = match_snmp.groupdict()
    community = group_snmp["community"]
    snmp_dict["community"] = community
    group_access = group_snmp["group_access"]
    snmp_dict["group_access"] = group_access
    context = group_snmp["context"]
    snmp_dict["context"] = context
    acl = group_snmp["context"]
    snmp_dict["acl"] = acl
    final_dict[i] = snmp_dict
    i += 1
pretty = pprint.PrettyPrinter(indent=2, depth=10).pprint
pretty(final_dict)

显然，这导致：

Traceback (most recent call last):
  File "C:\Users\Gabriele\Desktop\prova.py", line 18, in <module>
    group_snmp = match_snmp.groupdict()
AttributeError: 'NoneType' object has no attribute 'groupdict'

这就是我想要达到的目标：

{ 0: { 'acl': 'C0n_text!',
       'community': 'Community_test-1',
       'context': 'C0n_text!',
       'group_access': 'network-operator'}
1: { 'acl': '',
       'community': 'WEWORK',
       'context': '',
       'group_access': 'network-operator'}
2: { 'acl': '',
       'community': 'RW',
       'context': '_C0n',
       'group_access': 'network-admin'}
3: { 'acl': 'my_acl',
       'community': 'YANKS',
       'context': '',
       'group_access': 'network-admin'}}

我用不同的正则表达式尝试过许多东西，但没有成功：

Answer 1

引发此错误是因为，当您将原始字符串拆分为show_snmp_community_split时，第一个元素是一个空字符串：''。与re.match一起使用时，这将返回None。

在循环中使用if-语句：

for line in show_snmp_community_split:
    snmp_dict = {}
    match_snmp = re.match(show_snmp_community_regex, line)
    if not match_snmp:
        continue
    group_snmp = match_snmp.groupdict()
    community = group_snmp["community"]
    snmp_dict["community"] = community
    group_access = group_snmp["group_access"]
    snmp_dict["group_access"] = group_access
    context = group_snmp["context"]
    snmp_dict["context"] = context
    acl = group_snmp["context"]
    snmp_dict["acl"] = acl
    final_dict[i] = snmp_dict
    i += 1

接下来，由于acl和context可能会出现空列，所以模式中的\S+匹配将失败。更新模式如下：

show_snmp_community_regex = "^(?P<community>\S+)\s+(?P<group_access>\S+)\s*(?P<context>\S*)\s*(?P<acl>\S*)$"

在本地测试时的输出：

┌─[hjpotter92]─[Oct 29, 2015]─[Programming]
└──$ temp.py
{ 0: { 'acl': 'C0n_text!',
       'community': 'Community_test-1',
       'context': 'C0n_text!',
       'group_access': 'network-operator'},
  1: { 'acl': '',
       'community': 'WEWORK',
       'context': '',
       'group_access': 'network-operator'},
  2: { 'acl': '_C0n',
       'community': 'RW',
       'context': '_C0n',
       'group_access': 'network-admin'},
  3: { 'acl': 'my_acl',
       'community': 'YANKS',
       'context': 'my_acl',
       'group_access': 'network-admin'}}