read if gay

computer/18/rail.lua

@@ -0,0 +1,65 @@
+_G.facing = "south"
+
+local rightOf = {
+	south = "west",
+	west = "north",
+	north = "east",
+	east = "south"
+}
+
+local leftOf = {
+	west = "south",
+	north = "west",
+	east = "north",
+	south = "east"
+}
+
+local opposite = {
+	west = "east",
+	east = "west",
+	south = "north",
+	north = "south"
+}
+
+function step()
+--	exists, block = turtle.inspectDown()
+	--if not exists then
+		repeat
+			turtle.down()
+			exists, block = turtle.inspectDown()
+		until exists
+--	end
+	if block.name == "minecraft:rail" then
+		shape = block.state.shape
+		if shape  == "ascending_" .. _G.facing then
+			turtle.up()
+			turtle.forward()
+		elseif string.match(shape, _G.facing) or shape == "ascending_" .. opposite[_G.facing] then
+			turtle.forward()
+		elseif string.match(shape, leftOf[_G.facing]) then
+			_G.facing = leftOf[_G.facing]
+			turtle.turnLeft()
+		elseif string.match(shape, rightOf[_G.facing]) then
+			_G.facing = rightOf[_G.facing]
+			turtle.turnRight()
+		else
+			error("i'm lost\n".. shape)
+		end
+		return false
+	elseif block.name == "minecraft:iron_block" then
+		return "done"
+	else
+		return "lost"
+	end
+end
+
+function follow_rail(init_dir)
+	_G.facing = init_dir
+	repeat
+		state = step()
+	until state
+	print(state)
+end
+
+print("what direction am i facing?")
+follow_rail(read())