regex: java.util.regex companion code (groups, lookarounds, replaceAll lambdas, ReDoS and timeouts)

Co-Authored-By: Claude Sonnet 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01KqJyCidz3ZgRyHABv2GVJh

regex/output/01-basics.txt

@@ -0,0 +1,23 @@
+matches()    = true
+group(0)     = 2026-03-14 ERROR disk /dev/sda1 is 97% full
+group(2)     = ERROR
+level        = ERROR
+start(msg)   = 17, end(msg) = 43
+namedGroups  = {date=1, level=2, msg=3}
+
+matches()    on "order-42 shipped" = false
+lookingAt()  on "order-42 shipped" = false
+find()       on "order-42 shipped" = true
+
+results() over "a1 b22 c333":
+  a1 -> group(1)=1
+  b22 -> group(1)=22
+  c333 -> group(1)=333
+
+no flags            : 0
+CASE_INSENSITIVE    : 0
+MULTILINE           : 1
+MULTILINE|CASE_INS. : 3
+embedded (?im)      : 3
+'.' vs newline      : 0 / DOTALL 1
+COMMENTS            : 1