TCL Regular Expression

问题

I have two types of interfaces "Ethernet9/12/1 and Ethernet8/34". I wanted to parse both type of interfaces using single regular expression.

I was trying to achieve this in the below manner:

set int "Ethernet9/12/1"
regexp -nocase "(.*t)((\\d+)\/(\\d+)/\(\\d+))" $int - int_type int_num mod_num port broken_port
puts $int_type
puts $int_num
puts $mod_num
puts $port
puts $broken_port

This code works for Ethernet9/12/1. But, the same regexp does not work for Ethernet8/34. I need help to achieve this in the single regexp using TCL.

Kindly help.

回答1:

You need to make the last part optional with a non-capturing group:

regexp -nocase "(.*t)((\\d+)\/(\\d+)(?:/(\\d+))?)" $int - int_type int_num mod_num port broken_port
                                    ^^^       ^^

See IDEONE Tcl demo

Output:

Ethernet
8/34
8
34

A non-capturing group is only meant to group subpatterns and does not interfere with the capturing groups you already defined to be used later.

回答2:

Just make the second part optional with ?:

(.*t)((\d+)\/(\d+)(?:\/(\d+))?) 

Tested on regex101

NOTE: I escaped your / characters with a \ but that might flavor specific.

回答3:

The code becomes a lot more manageable if one doesn't concentrate all processing within the regular expressions.

set int Ethernet9/12/1

regexp -nocase {(.+t)(.*)} $int -> int_type int_num
lassign [split $int_num /] mod_num port broken_port

puts [list $int_type $int_num $mod_num $port $broken_port]
# -> Ethernet 9/12/1 9 12 1

set int Ethernet8/34

regexp -nocase {(.+t)(.*)} $int -> int_type int_num
lassign [split $int_num /] mod_num port broken_port

puts [list $int_type $int_num $mod_num $port $broken_port]
# -> Ethernet 8/34 8 34 {}

Documentation: lassign, list, puts, regexp, set, split, Syntax of Tcl regular expressions

来源：https://stackoverflow.com/questions/38255800/tcl-regular-expression