Is there a way to Continue with the same line in State changes in TextFSM?

Question

I know that I can't combine state transitions with a continue statement.

I'm trying to parse network configuration with ansible where the only clear end of row its the beginning of the next one.

For example I want to parse configs like follows:

line vty 0 4
 exec-timeout 30 0
 authorization exec MIRADIUS
 accounting connection MIRADIUS
 accounting exec MIRADIUS
 login authentication MIRADIUS
line vty 5 16
 access-class 95 in vrf-also
 exec-timeout 30 0
 authorization exec MIRADIUS
 accounting connection MIRADIUS
 accounting exec MIRADIUS
 login authentication MIRADIUS
 history size 25
 transport input ssh
line vty 15 116
 access-class 95 in
 exec-timeout 30 0
 authorization exec MIRADIUS
 accounting connection MIRADIUS
 accounting exec MIRADIUS
 login authentication MIRADIUS
 history size 25

Template I'm using:

Value Required LINE (\d+\s+\d+)
Value vtyAcl (\d+|\w+)
Value aclDir (\w+)
Value vrfAlso (\w+-\w+)

Start
  ^\s+access-class\s+${vtyAcl}\s+${aclDir}\s+${vrfAlso}.*$$
  ^\s+access-class\s+${vtyAcl}\s+${aclDir}.*$$
  ^line vty ${LINE}.*$$ -> Continue.Record

So the only certain way I have to know I'm done with the vty 0 4 for example is that the vty 5 16 starts.

so, it is possible to keep continue with the line in order to save the new vty? Currently my template is saving the config of previous row in the nextone. I have no way to know the which will be the lasts lines possibilities.

Current result:
[
    {
        "LINE": "0 4",
        "aclDir": "",
        "vrfAlso": "",
        "vtyAcl": ""
    },
    {
        "LINE": "5 16",
        "aclDir": "",
        "vrfAlso": "",
        "vtyAcl": ""
    },
    {
        "LINE": "15 116",
        "aclDir": "in",
        "vrfAlso": "vrf-also",
        "vtyAcl": "95"
    }
]

Desired Result:
[
    {
        "LINE": "0 4",
        "aclDir": "",
        "vrfAlso": "",
        "vtyAcl": ""
    },
    {
        "LINE": "5 16",
        "aclDir": "in",
        "vrfAlso": "vrf-also",
        "vtyAcl": "95"
    },
    {
        "LINE": "15 116",
        "aclDir": "in",
        "vrfAlso": "",
        "vtyAcl": "95"
    }
]

UPDATE : Here the update with solution for this particular issue. Thanks.

Value Required LINE (\d+\s+\d+)
Value vtyAcl (\d+|\w+)
Value aclDir (\w+)
Value vrfAlso (\w+-\w+)

Start
  ^line vty -> Continue.Record
  ^\s+access-class\s+${vtyAcl}\s+${aclDir}\s+${vrfAlso}.*$$
  ^\s+access-class\s+${vtyAcl}\s+${aclDir}.*$$
  ^line vty ${LINE}.*$$ 

Answer 1

I have been looking an answer for the same question but have not found it (found just your question:)). AFAIK:

1. TextFSM does NOT support Lookahead/Lookbehind regex features.
2. As you already wrote, TextFSM does NOT support Record+Continue (state change) as it is stated in their docs: "Note that the Continue action does not accept a state transition. This ensures that state machines are loop free."
3. If there was an empty string (or any other delimiter for information blocks) BEFORE the line "line vty XY" we could use TextFSM's states.

What workaround I'm using now - I'm using several templates consequently, a template extract VTY-number and ONE parameter for this line. Then combine the results together.

BUT in your case you have only ONE "interesting" line per "line vty XY" block and this line is NOT the last line in the "line vty XY" block, so you may use just the right REGEX (I slightly correct your template - vrfAlso "may be" or "may be not" exist) and a little TextFSM trick. :)

Value Required LINE (\d+\s+\d+)
Value vtyAcl (\d+|\w+)
Value aclDir (\w+)
Value vrfAlso (\w+-\w+)

Start
  ^line vty ${LINE}.*$$
  ^\s+access-class\s+${vtyAcl}\s+${aclDir}\s*(${vrfAlso})?.*$$ -> Record
  ^.* -> Record

EOF

Here, we are using "^.* -> Record" in order to Record the lines that do NOT have "interesting" string.

And you will get your desired result (I presume):

LINE    vtyAcl    aclDir    vrfAlso
------  --------  --------  ---------
0 4
5 16    95        in        vrf-also
15 116  95        in

Unfortunately, in my case, I have multiple "interesting" strings and they may be the last in a block, so it will not work for me. :(

UPDATE: I accidentally found a TextFSM's way of looking ahead. It gave me an idea how to find a solution for my task and the main idea is described here: https://github.com/google/textfsm/issues/22