erlang: Phase 9d — OP_RECEIVE_SCAN stub (+10 vm tests)

lib/erlang/tests/vm.sx

@@ -190,4 +190,65 @@
       (fn (args) (+ (nth args 0) 1000))))
   1005)
 
+
+;; ── Phase 9d — OP_RECEIVE_SCAN ──────────────────────────────────
+(er-vm-test "receive-scan opcode by id"
+  (get (er-vm-lookup-opcode-by-id 133) :name) "OP_RECEIVE_SCAN")
+
+;; Pattern: receive {ok, X} -> X end  against mailbox [{error, 1}, {ok, 42}, foo]
+(define er-vm-r1-env (er-env-new))
+(define er-vm-r1-clauses
+  (list
+    {:pattern {:type "tuple"
+               :elements (list
+                 {:type "atom" :value "ok"}
+                 {:type "var" :name "X"})}
+     :guards (list)
+     :body (list {:type "var" :name "X"})}))
+(define er-vm-r1-mbox
+  (list
+    (er-mk-tuple (list (er-mk-atom "error") 1))
+    (er-mk-tuple (list (er-mk-atom "ok") 42))
+    (er-mk-atom "foo")))
+
+(define er-vm-r1-result
+  (er-vm-dispatch 133 (list er-vm-r1-clauses er-vm-r1-mbox er-vm-r1-env)))
+(er-vm-test "scan finds match"
+  (get er-vm-r1-result :matched) true)
+(er-vm-test "scan reports correct index"
+  (get er-vm-r1-result :index) 1)
+(er-vm-test "scan binds var"
+  (get er-vm-r1-env "X") 42)
+(er-vm-test "scan leaves body unevaluated"
+  (= (get er-vm-r1-result :body) nil) false)
+
+;; No match case
+(define er-vm-r2-env (er-env-new))
+(define er-vm-r2-mbox (list (er-mk-atom "nope") 99))
+(define er-vm-r2-result
+  (er-vm-dispatch 133 (list er-vm-r1-clauses er-vm-r2-mbox er-vm-r2-env)))
+(er-vm-test "scan no-match"
+  (get er-vm-r2-result :matched) false)
+(er-vm-test "scan no-match leaves env clean"
+  (dict-has? er-vm-r2-env "X") false)
+
+;; Empty mailbox
+(define er-vm-r3-result
+  (er-vm-dispatch 133 (list er-vm-r1-clauses (list) (er-env-new))))
+(er-vm-test "scan empty mailbox"
+  (get er-vm-r3-result :matched) false)
+
+;; First-match wins (arrival order)
+(define er-vm-r4-env (er-env-new))
+(define er-vm-r4-mbox
+  (list
+    (er-mk-tuple (list (er-mk-atom "ok") 1))
+    (er-mk-tuple (list (er-mk-atom "ok") 2))))
+(define er-vm-r4-result
+  (er-vm-dispatch 133 (list er-vm-r1-clauses er-vm-r4-mbox er-vm-r4-env)))
+(er-vm-test "scan first-match wins (index 0)"
+  (get er-vm-r4-result :index) 0)
+(er-vm-test "scan binds first match's var"
+  (get er-vm-r4-env "X") 1)
+
 (define er-vm-test-summary (str "vm " er-vm-test-pass "/" er-vm-test-count))