解析网络接口配置的正则表达式

Question

我想知道下面的问题是否可以通过一个正则表达式来解决，或者我应该创建标准循环并逐行计算，

当我运行包含的代码时，我得到了['Ethernet0/22', 'Ethernet0/24']，只有结果应该是['Ethernet0/23', 'Ethernet0/25']。

对此有什么建议吗？

 import re

 txt='''#
 interface Ethernet0/22
  stp disable
  broadcast-suppression 5
  mac-address max-mac-count 1
  port access vlan 452
 #
 interface Ethernet0/23
  stp disable
  description BTO
  broadcast-suppression 5
  port access vlan 2421
 #
 interface Ethernet0/24
  stp disable
  description Avaya G700
  broadcast-suppression 5
  port access vlan 452
 #
 interface Ethernet0/25
  stp disable
  description BTO
  broadcast-suppression 5
  port access vlan 2421
 #
 '''

 re1 = '''^interface (.*?$).*?BTO.*?^#$'''

 rg = re.compile(re1,re.IGNORECASE|re.DOTALL|re.MULTILINE)
 m = rg.findall(txt)
 if m:
  print m

Answer 1

您的问题是正则表达式继续在下一组中查找BTO。作为一种快速的解决方法，您可以在接口id中禁用"#“字符(假设这在记录中无效，并且只将它们分开)。

re1 = '''^interface ([^#]*?$)[^#]*?BTO.*?^#$'''

Answer 2

这是一个针对你的文件的小的pyparsing解析器。这不仅显示了直接问题的解决方案，而且解析器为您提供了一组很好的对象，您可以使用这些对象轻松地访问每个接口中的数据。

下面是解析器：

from pyparsing import *

# set up the parser
comment = "#" + Optional(restOfLine)
keyname = Word(alphas,alphanums+'-')
value = Combine(empty + SkipTo(LineEnd() | comment))
INTERFACE = Keyword("interface")
interfaceDef = Group(INTERFACE + value("name") + \
    Dict(OneOrMore(Group(~INTERFACE + keyname + value))))

# ignore comments (could be anywhere)
interfaceDef.ignore(comment)

# parse the source text
ifcdata = OneOrMore(interfaceDef).parseString(txt)

现在如何使用它：

# use dump() to list all of the named fields created at parse time
for ifc in ifcdata:
    print ifc.dump()

# first the answer to the OP's question
print [ifc.name for ifc in ifcdata if ifc.description == "BTO"]

# how to access fields that are not legal Python identifiers
print [(ifc.name,ifc['broadcast-suppression']) for ifc in ifcdata 
    if 'broadcast-suppression' in ifc]

# using names to index into a mapping with string interpolation
print ', '.join(["(%(name)s, '%(port)s')" % ifc for ifc in ifcdata ])

打印输出：

['interface', 'Ethernet0/22', ['stp', 'disable'], ['broadcast-suppression', '5'], ['mac-address', 'max-mac-count 1'], ['port', 'access vlan 452']]
- broadcast-suppression: 5
- mac-address: max-mac-count 1
- name: Ethernet0/22
- port: access vlan 452
- stp: disable
['interface', 'Ethernet0/23', ['stp', 'disable'], ['description', 'BTO'], ['broadcast-suppression', '5'], ['port', 'access vlan 2421']]
- broadcast-suppression: 5
- description: BTO
- name: Ethernet0/23
- port: access vlan 2421
- stp: disable
['interface', 'Ethernet0/24', ['stp', 'disable'], ['description', 'Avaya G700'], ['broadcast-suppression', '5'], ['port', 'access vlan 452']]
- broadcast-suppression: 5
- description: Avaya G700
- name: Ethernet0/24
- port: access vlan 452
- stp: disable
['interface', 'Ethernet0/25', ['stp', 'disable'], ['description', 'BTO'], ['broadcast-suppression', '5'], ['port', 'access vlan 2421']]
- broadcast-suppression: 5
- description: BTO
- name: Ethernet0/25
- port: access vlan 2421
- stp: disable
['Ethernet0/23', 'Ethernet0/25']
[('Ethernet0/22', '5'), ('Ethernet0/23', '5'), ('Ethernet0/24', '5'), ('Ethernet0/25', '5')]
(Ethernet0/22, 'access vlan 452'), (Ethernet0/23, 'access vlan 2421'), (Ethernet0/24, 'access vlan 452'), (Ethernet0/25, 'access vlan 2421')

Answer 3

没有正则表达式的示例：

print [ stanza.split()[0]
        for stanza in txt.split("interface ")
        if stanza.lower().startswith( "ethernet" )
        and stanza.lower().find("bto") > -1 ]

解释：

我发现作文最好是“由内而外”：

for stanza in txt.split("interface ")

在每次出现"interface“时拆分文本(包括以下空格)。生成的节将如下所示：

Ethernet0/22
 stp disable
 broadcast-suppression 5
 mac-address max-mac-count 1
 port access vlan 452
#

接下来，过滤小节：

if stanza.lower().startswith( "ethernet" ) and stanza.lower().find("bto") > -1

这应该是不言而喻的。

stanza.split()[0]

在空格上拆分数学节，并将第一个元素放入结果列表中。这与筛选器startswith一起，将防止IndexError