forgot to commit openos

data/openos/lib/sides.lua

@@ -0,0 +1,62 @@
+local sides = {
+  [0] = "bottom",
+  [1] = "top",
+  [2] = "back",
+  [3] = "front",
+  [4] = "right",
+  [5] = "left",
+  [6] = "unknown",
+
+  bottom = 0,
+  top = 1,
+  back = 2,
+  front = 3,
+  right = 4,
+  left = 5,
+  unknown = 6,
+
+  down = 0,
+  up = 1,
+  north = 2,
+  south = 3,
+  west = 4,
+  east = 5,
+
+  negy = 0,
+  posy = 1,
+  negz = 2,
+  posz = 3,
+  negx = 4,
+  posx = 5,
+
+  forward = 3
+}
+
+local metatable = getmetatable(sides) or {}
+
+-- sides[0..5] are mapped to itertable[1..6].
+local itertable = {
+  sides[0],
+  sides[1],
+  sides[2],
+  sides[3],
+  sides[4],
+  sides[5]
+}
+
+-- Future-proofing against the possible introduction of additional
+-- logical sides (e.g. [7] = "all", [8] = "none", etc.).
+function metatable.__len(sides)
+  return #itertable
+end
+
+-- Allow `sides` to be iterated over like a normal (1-based) array.
+function metatable.__ipairs(sides)
+  return ipairs(itertable)
+end
+
+setmetatable(sides, metatable)
+
+-------------------------------------------------------------------------------
+
+return sides