Add ^switched-emitter, test in level 4

modules/game/actors.scm

@@ -6,6 +6,7 @@
             ^wall
             ^block
             ^clock-emitter
+            ^switched-emitter
             ^floor-switch
             ^gate
             ^gem
@@ -145,6 +146,39 @@
     (('describe) `(clock-emitter ,position))
     (('collide other offset grid-info) #f)))
 
+(define (^switched-emitter bcom x y interval)
+  (define timer (spawn ^cell -1))
+  (define on? (spawn ^cell))
+  (define position (vector x y 0))
+  (match-lambda*
+    (('type) 'switched-emitter)
+    (('position) position)
+    (('tick grid-info)
+     (when ($ on?)
+       ($ timer (+ ($ timer) 1))))
+    (('post-tick grid-info) #f)
+    (('enter obj grid-info) #f)
+    (('exit obj grid-info) #f)
+    (('activate grid-info)
+     ($ on? #t)
+     ($ timer 0))
+    (('deactivate grid-info) ($ on? #f))
+    (('wire-state grid-info)
+     (when ($ on?)
+       (let ((t ($ timer)))
+         (cond
+          ((= (modulo t interval) 0)
+           'electron-head)
+          ((= (modulo t interval) 1)
+           'electron-tail)
+          (else
+           'copper)))))
+    (('update-wire-state grid-info) #f)
+    (('alive?) #t)
+    (('on?) ($ on?))
+    (('describe) `(switched-emitter ,position ,($ on?)))
+    (('collide other offset grid-info) #f)))
+
 (define (first-non-player-occupant grid-info x y)
   (let lp ((objs ($ grid-info 'occupants x y)))
     (match objs