s/\.\K[^.]*$/txt/;
####
Compiling REx "(?<=[.])[^.]*$"
Final program:
1: IFMATCH[-1] (7)
3: EXACT <.> (5)
5: SUCCEED (0)
6: TAIL (7)
7: STAR (19)
8: ANYOF[\0-\-/-\377{unicode_all}] (0)
19: EOL (20)
20: END (0)
floating ""$ at 0..2147483647 (checking floating) minlen 0
Guessing start of match in sv for REx "(?<=[.])[^.]*$" against "xyz.foo"
Found floating substr ""$ at offset 7...
Guessed: match at offset 0
Matching REx "(?<=[.])[^.]*$" against "xyz.foo"
0 <> | 1:IFMATCH[-1](7)
failed...
1 | 1:IFMATCH[-1](7)
0 <> | 3: EXACT <.>(5)
failed...
failed...
2 | 1:IFMATCH[-1](7)
1 | 3: EXACT <.>(5)
failed...
failed...
3 <.foo> | 1:IFMATCH[-1](7)
2 | 3: EXACT <.>(5)
failed...
failed...
4 | 1:IFMATCH[-1](7)
3 <.foo> | 3: EXACT <.>(5)
4 | 5: SUCCEED(0)
subpattern success...
4 | 7:STAR(19)
ANYOF[\0-\-/-\377{unicode_all}] can match 3 times out of 2147483647...
7 <> | 19: EOL(20)
7 <> | 20: END(0)
Match successful!
####
Compiling REx "\.\K[^.]*$"
Final program:
1: EXACT <.> (3)
3: KEEPS (4)
4: STAR (16)
5: ANYOF[\0-\-/-\377{unicode_all}] (0)
16: EOL (17)
17: END (0)
anchored "." at 0 floating ""$ at 1..2147483647 (checking anchored) minlen 1
Guessing start of match in sv for REx "\.\K[^.]*$" against "xyz.foo"
Found anchored substr "." at offset 3...
Found floating substr ""$ at offset 7...
Starting position does not contradict /^/m...
Guessed: match at offset 3
Matching REx "\.\K[^.]*$" against ".foo"
3 <.foo> | 1:EXACT <.>(3)
4 | 3:KEEPS(4)
4 | 4: STAR(16)
ANYOF[\0-\-/-\377{unicode_all}] can match 3 times out of 2147483647...
7 <> | 16: EOL(17)
7 <> | 17: END(0)
Match successful!