forth: BEGIN/UNTIL/WHILE/REPEAT/AGAIN (+9)

lib/forth/tests/test-phase3.sx

@@ -106,6 +106,51 @@
       ": Q -1 IF 1 THEN -1 IF 2 THEN ; Q"
       (list 1 2))))
 
+(define
+  forth-p3-loop-tests
+  (fn
+    ()
+    (forth-p3-check-stack
+      "BEGIN UNTIL (countdown to zero)"
+      ": CD BEGIN 1- DUP 0 = UNTIL ; 3 CD"
+      (list 0))
+    (forth-p3-check-stack
+      "BEGIN UNTIL — single pass (UNTIL true immediately)"
+      ": Q BEGIN -1 UNTIL 42 ; Q"
+      (list 42))
+    (forth-p3-check-stack
+      "BEGIN UNTIL — accumulate sum 1+2+3"
+      ": SUM3 0 3 BEGIN TUCK + SWAP 1- DUP 0 = UNTIL DROP ; SUM3"
+      (list 6))
+    (forth-p3-check-stack
+      "BEGIN WHILE REPEAT — triangular sum 5"
+      ": TRI 0 5 BEGIN DUP 0 > WHILE TUCK + SWAP 1- REPEAT DROP ; TRI"
+      (list 15))
+    (forth-p3-check-stack
+      "BEGIN WHILE REPEAT — zero iterations"
+      ": TRI 0 0 BEGIN DUP 0 > WHILE TUCK + SWAP 1- REPEAT DROP ; TRI"
+      (list 0))
+    (forth-p3-check-stack
+      "BEGIN WHILE REPEAT — one iteration"
+      ": TRI 0 1 BEGIN DUP 0 > WHILE TUCK + SWAP 1- REPEAT DROP ; TRI"
+      (list 1))
+    (forth-p3-check-stack
+      "nested BEGIN UNTIL"
+      ": INNER BEGIN 1- DUP 0 = UNTIL DROP ;
+       : OUTER BEGIN 3 INNER 1- DUP 0 = UNTIL ;
+       2 OUTER"
+      (list 0))
+    (forth-p3-check-stack
+      "BEGIN UNTIL after colon prefix"
+      ": TEN 10 ;
+       : CD TEN BEGIN 1- DUP 0 = UNTIL ;
+       CD"
+      (list 0))
+    (forth-p3-check-stack
+      "WHILE inside IF branch"
+      ": Q 1 IF 0 3 BEGIN DUP 0 > WHILE TUCK + SWAP 1- REPEAT DROP ELSE 99 THEN ; Q"
+      (list 6))))
+
 (define
   forth-p3-run-all
   (fn
@@ -114,6 +159,7 @@
     (set! forth-p3-failed 0)
     (set! forth-p3-failures (list))
     (forth-p3-if-tests)
+    (forth-p3-loop-tests)
     (dict
       "passed"
       forth-p3-passed