Tier 4 · Enchanterreplace

Name Your Groups

Rewrite a log line "DATE TIME LEVEL MESSAGE" as "[LEVEL] MESSAGE (TIME on DATE)".

Four fields, all reordered. You can do this with $1 to $4, and you will miscount at least once. Name them instead: (?<level>\w+) creates a group called level, and $<level> puts it in the replacement. Same regex, same cost at runtime, and the replacement string now says what it means — which is the whole point, because a pattern is read far more often than it is written.

groups named-groups replace

Your pattern0 chars · par 88

Flags

Replacement — $1, $2 refer to your capture groups

Start typing — tests run as you go.

Test cases

2026-08-13 14:22:31 ERROR database timeout→ "[ERROR] database timeout (14:22:31 on 2026-08-13)"
2026-01-01 00:00:00 INFO started→ "[INFO] started (00:00:00 on 2026-01-01)"
2025-12-31 23:59:59 WARN disk almost full→ "[WARN] disk almost full (23:59:59 on 2025-12-31)"

+ 3 hidden tests, checked when you submit. They are what stops a pattern that only fits the examples above.