Add some misc table util functions

maps/includes/base.lua

@@ -7,6 +7,7 @@
 -- Do not change this file.
 -----------------------------------------------------------------------------
 
+require "util.utils"
 Class = require "util.class"
 Collection = require "util.collection"
 

maps/includes/util/utils.lua

@@ -0,0 +1,28 @@
+
+function table.clear(tbl)
+	for k in pairs(tbl) do
+		tbl[k] = nil
+	end
+end
+
+function table.contains(tbl, element)
+	if tbl == nil then return false end
+	for _, value in pairs(tbl) do
+		if value == element then
+			return true
+		end
+	end
+	return false
+end
+
+function table.contains_any(tbl, elements)
+	if tbl == nil or elements == nil then return false end
+	for _, value in pairs(tbl) do
+		for _, element in pairs(elements) do
+			if value == element then
+				return true
+			end
+		end
+	end
+	return false
+end