Question

The regex I currently have is:

"^(?:(\\.\\.)|^([a-z]+[a-z.\\-]*)([\\*]?)[\\[]*([^\\]]*)[\\]]*)$";

It captures either “..” (group 1) with group 2-4 being empty
or:
– a group of lowercase, dots, dashes. starting with lowercase (group 2)
– followed by optional asterisk (group 3)
– followed by optional content within square brackets (group 4)

I’m having a couple problems, first is making it so group2 must end with a letter, I have tried many things including:

"^([a-z]+[a-z.\\-]*[a-z]$)"
"^([a-z]+[a-z.\\-]*[a-z])$"

which kills anything in group 3-4

"^([a-z]+[a-z.\\-]*[a-z])"

which doesn’t seem to do anything different

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The other problem I’m having is group 4, it doesn’t depend on the square brackets (which makes sense as I have the * character for them)… but if I remove that character it will not give me any results for ANY of the groups.

Any help is greatly needed and appreciated.

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In response to comment below, the following should match:
"string" - (group1)(group2)(group3)(group4)

".." - (..)()()()
"blah" - ()(blah)()()
"blah.blah" - ()(blah.blah)()()
"blah.blah*" - ()(blah.blah)(*)()
"blah*" - ()(blah)(*)()
"blah.blah*[foobar] - ()(blah.blah)(*)(foobar)
"blah[foobar] - ()(blah)()(foobar)

The following should not match:

 "."
 "..."
 ".blah"
 "blah."
 ".blah*"
 "blah.*[foobar]

Answer 1

                   ┌ one or more lowercase letters followed by
                   │ 
                   │   ┌ none or several occurrences of ───────────────────────┐
                   │   │     ┌ dot or dash                                     │
                   │   │     │     ┌ followed by one or more lowercase letters │
                   │   │     │     │     ┌─────────────────────────────────────┘
                   │   │     │     │     │ 
                   │   │     │     │     │  ┌ followed by optional asterisk
                   │   │     │     │     │  │
                   │   │     │     │     │  │   ┌ followed by optional square brackets
            ┌ or   │   │     │     │     │  │   │         ┌ with some content inside │
            │      │   │     │     │     │  │   │         │        ┌─────────────────┘
            │      │   │     │     │     │  │   │         │        │
^(?:(\\.\\.)|(?:([a-z]+(?:[.\\-]*[a-z]+)*)(\\*?)(?:\\[([^\\]]*)\\])?))$
│   │      │                                                          │
│   └ two  │                                                          │
│     dots ┘                                                          │
│                                                                     │
└ start of string                                       end of string ┘