Implemented missing functions for the interpreter

src/field.nim

@@ -213,3 +213,6 @@ func Step*(f: Field, v: tuple[x, y: int], d: tuple[x, y: int]): (int, int) =
     if not f.IsIn(x2, y2):
       return (x, y)
     x = x2; y = y2
+
+func GetSize*(f: Field): (int, int, int, int) =
+  return (f.x, f.y, f.lx, f.ly)

src/stack.nim

@@ -80,3 +80,19 @@ func Discard*(s: var Stack, n: int) =
 
 func Next*(s: Stack): ref Stack =
   return s.next
+
+func GetHeights*(s: Stack): seq[int] =
+  if s.next != nil:
+    result = s.next[].GetHeights()
+    result.add(s.height)
+  else:
+    return @[s.height]
+
+func YCommandPick*(s: var Stack, n, h: int) =
+  if n > s.height:
+    s.height = 1
+    s.data[0] = 0
+  else:
+    let v = s.data[s.height-n]
+    s.height = h
+    s.Push(v)

src/stackStack.nim

@@ -52,8 +52,7 @@ func End*(ss: var StackStack, v: var tuple[x, y: int]): bool =
   let toss = ss.head
   let soss = toss[].Next()
   let n = toss[].Pop()
-  v.y = soss[].Pop()
-  v.x = soss[].Pop()
+  (v.x, v.y) = soss[].PopVector()
   if n > 0:
     soss[].Transfert(toss[], n)
   else:
@@ -61,3 +60,22 @@ func End*(ss: var StackStack, v: var tuple[x, y: int]): bool =
   dec ss.height
   ss.head = soss
   return false
+
+func Under*(ss: var StackStack): bool =
+  if ss.height == 1:
+    return true
+  let soss = ss.head[].Next()
+  let n = ss.Pop()
+  if n > 0:
+    for i in 0..<n:
+      ss.Push(soss[].Pop())
+  else:
+    for i in 0 ..< -n:
+      soss[].Push(ss.Pop())
+  return false
+
+func GetHeights*(ss: StackStack): (int, seq[int]) =
+  return (ss.height, ss.head[].GetHeights)
+
+func YCommandPick*(ss: var StackStack, n, h: int) =
+  ss.head[].YCommandPick(n, h)