Groovy regex enhancement with conditional handling

Question

I need to enhance the regex for this application to satisfy the following.

The current regex looks like this

^[CDFGIMP][^_\\s]*_\\S*$

and the following code will be valid

C_12345

https://regex101.com/r/x2jUnt/2

it needs to be adapted to accept the following cases

The new ReGex format should contain at least 2 underscores
Exception: if the code begin with 'M' then it only must contain at least one underscore
FKT12965_I20_GB215_01
FKN16250_I26_GB215_03
FKT12808_I09_GB215_01
CQ425441_I09_GB214_01

(^[CDFGIP][^_\\s]*_\\S*$)(^[M][^_\\s]*) - tried to group it as such — The Old County, Nov 01 '18 at 10:57
(_){2} - something like this to ensure there are two underscores? — The Old County, Nov 01 '18 at 10:59
Its nearly there -- if it is CDFGIP - then it needs to contain at least TWO underscores — The Old County, Nov 01 '18 at 11:31
But it does require 2 underscores then. Check https://ideone.com/iFP1Jx. Note you do not need anchors and grouping if you use `==~` operator as it requires a full string match. — Wiktor Stribiżew, Nov 01 '18 at 11:33

score 0 · Answer 1 · answered Nov 01 '18 at 23:45

Just a slight variation to the answer from @tim-yates and with comments:

def regex = /(?x)           # to enable whitespace and comments
             ^              # match from beginning
               (            # start of alternative 1
                 [CDFGIP]   # starts with one of CDFGIP
                 [^_\s]*    # zero or more non-underscore non-whitespace chars
                 _          # an underscore
                 [^_\s]*    # zero or more non-underscore non-whitespace chars
                 _          # an underscore
                 \S*        # zero or more non-whitespace chars
               |            # start of alternative 2
                 M          # starts with M
                 [^_\s]*    # zero or more non-underscore non-whitespace chars
                 _          # an underscore
                 \S*        # zero or more non-whitespace chars
               )            # end of alternatives
             $              # match to end
/

assert "FKT12965_I20_GB215_01".matches(regex)
assert "MKT12965_I20".matches(regex)
assert !"C_12345".matches(regex)

score -1 · Answer 2 · answered Nov 01 '18 at 11:08

I believe you could use this:

def regex = /^([CDFGIP][^_\s]+_[^_\s]+_\S+|M[^_\s]+_\S+)$/

assert "FKT12965_I20_GB215_01".matches(regex)
assert "MKT12965_I20".matches(regex)
assert !"C_12345".matches(regex)

I tend to prefer to pull this sort of thing out into actual code though, as the next person who has to look at this code will have thoughts of violence

Groovy regex enhancement with conditional handling

2 Answers2