A utility for flattening CISCO 'show system internal l2fm l2dbg macdb' command output

cisco_macdb_flattener

#!/usr/bin/env python3
import regex as re
from sys import argv, exit

macdb_regexpr = r"""
# Some examples matched by this regexp :
#  VLAN: 2324 MAC: d867.d972.0fc3
#   Time                     If/swid    Db Op                    Src Slot  FE  Count
#     Mon Apr  6 20:37:34 2020 0x160003e6 0  INSERT               3    5    7   
#     Mon Apr  6 20:37:59 2020 0x160003e6 0  NON_PI_MOD           3    2    15   6   
#     Mon Apr  6 21:33:03 2020 0x160003e6 0  FLUSH                2    0    15  
# 
#  VLAN: 1982 MAC: d4d2.52ca.931a FE ID: 4
#   Time                     If/swid    Db Op                    Src Slot  FE  Count
#     Tue Apr  7 12:54:21 2020 0x16000024 0  AGE                  3    5    4   
#     Tue Apr  7 16:38:00 2020 0x16000024 0  AGE                  3    6    4   
# 
#  VLAN: 197 MAC: 0000.0c9f.f0c5
#   Time                     If         Db Op                    Src Slot  FE  Local Remote
#    Tue Apr  7 22:20:01 2020 0x090300c5 1  MAC_SMLIST           2    0    15   0     0     
#    Tue Apr  7 22:20:01 2020 0x090300c5 1  GWMAC_SKIP_NO_CHG    2    0    15   0     0     
# Test this regexp here https://regex101.com/r/dA9sQ5/8
(?(DEFINE)
    (?P<vlan_descriptor> # A VLAN descriptor is an header with either a local or a remote descriptor
        (?&vlan_header)
        (?&local_or_remote_vlan)
    )
    (?P<local_or_remote_vlan> # A VLAN can be either local or remote
        (?&local_vlan)
        |
        (?&remote_vlan)
    )
    (?P<local_vlan> # Local VLAN has local column header "Time If/swid Db Op Src Slot  FE  Count" and local columns
        (?&local_vlan_column_header)
        (?&local_vlan_event)+ # and several local style events
    )
    (?P<local_vlan_column_header>\s*Time\s*If\/swid\s*Db\s*Op\s*Src\s*Slot\s*FE\s*Count)
    (?P<local_vlan_event>\s*(?&full_date)\s*(?&ifswid)\s*(?&db)\s*(?&op)\s*(?&src)\s*(?&slot)\s*(?&fe)\s*(?&count)?)
    
    (?P<remote_vlan> # Remote VLAN has remote column header "Time If Db Op Src Slot  FE  Local Remote" and local columns
        (?&remote_vlan_column_header)
        (?&remote_vlan_event)+ # and several remote style events
    )
    (?P<remote_vlan_column_header>\s*Time\s*If\s*Db\s*Op\s*Src\s*Slot\s*FE\s*Local\s*Remote)
    (?P<remote_vlan_event>\s*(?&full_date)\s*(?&ifswid)\s*(?&db)\s*(?&op)\s*(?&src)\s*(?&slot)\s*(?&fe)\s*(?&local)\s*(?&remote))
    
    # VLAN header has VLAN id and MAC address and possibly an FE ID
    (?P<vlan_header>\s*VLAN:\s*(?&vlan_id)\s*MAC:\s*(?&mac_address)\s*(FE\ ID:\s*(?&feid))?)
    (?P<vlan_id>[0-9]+)
    (?P<mac_address>[0-9a-f]{4}.[0-9a-f]{4}.[0-9a-f]{4})
    (?P<feid>[0-9]+)
    
    (?P<full_date>(?&day)\s*(?&month)\s*(?&day_in_month)\s*(?&time)\s*(?&year))
    (?P<day>Mon|Tue|Wed|Thu|Fri|Sat|Sun)
    (?P<day_in_month>[0-9]+)
    (?P<month>Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec)
    (?P<year>[0-9]{4})
    (?P<time>([0-1][0-9]|[2][0-3]):([0-5][0-9]):([0-5][0-9]))
    
    (?P<ifswid>0x[0-9a-f]{8})
    (?P<op>[A-Z]([A-Z_]*))
    (?P<db>[0-9]+)
    (?P<src>[0-9]+)
    (?P<slot>[0-9]+)
    (?P<fe>[0-9]+)
    (?P<count>([0-9]+))
    (?P<local>([0-9]+))
    (?P<remote>([0-9]+))
)
# Match all kind of VLAN descriptors (see above)
(?&vlan_descriptor)
"""

if len(argv) < 2:
    print(f"""Usage :\n\t{__file__} [macdb file]""")
    exit(1)

# Open parameter on command line
buffer = open(argv[1]).read()
expression = re.compile(macdb_regexpr, re.MULTILINE | re.VERBOSE)

# Extract all the matches in the specified file
matches = expression.finditer(buffer)

for match in matches:
    # Returns a dict where each column contents is in a list
    match_dict = match.capturesdict()
    # VLAN type Local or Remote (don't know if useful)
    local_or_remote = "L" if match_dict["local_vlan"] else "R"
    for counter, event in enumerate(match_dict["full_date"], start=0):
        # Output format is VLAN_ID;MAC_ADDR;L or R;Date and time;If/Swid;Op
        print(
            f"{match_dict['vlan_id'][0]};{match_dict['mac_address'][0]};"
            f"{local_or_remote};{match_dict['full_date'][counter]};{match_dict['ifswid'][counter]};"
            f"{match_dict['op'][counter]}"
        )