Added more functionality to the Queue class.

mods/defense/Queue.lua

@@ -1,6 +1,6 @@
 Queue = {}
 function Queue.new ()
-	return {first = 0, last = -1}
+	return {first = 1, last = 0}
 end
 
 function Queue.push (queue, value)
@@ -15,9 +15,52 @@ function Queue.pop (queue)
 	local value = queue[first]
 	queue[first] = nil
 	queue.first = first + 1
+
+	-- resize internal array
+	first = queue.first
+	local last = queue.last
+	if first * 2 > last then
+		for i = first,last do
+			queue[i - first + 1] = queue[i]
+			queue[i] = nil
+		end
+		queue.first = 1
+		queue.last = last - first + 1
+	end
+
 	return value
 end
 
+function Queue.push_back (queue, value)
+	local first = queue.first
+	if first > 1 then
+		first = first - 1
+		queue.first = first
+		queue[first] = value
+	else 
+		-- shift elements to right
+		local last = queue.last
+		for i = last,first,-1 do
+			queue[i + 1] = queue[i]
+		end
+		
+		queue[1] = value
+		queue.first = 1
+		queue.last = last + 1
+	end
+end
+
+function Queue.remove (queue, index)
+	local last = queue.last - 1
+	queue.last = last
+
+	for i = index,last-1 do
+		queue[i] = queue[i + 1]
+	end
+
+	queue[last + 1] = nil
+end
+
 function Queue.size (queue)
 	return queue.last - queue.first + 1
 end