Add a Utils.Where function to lua for filtering collections

OpenRA.Mods.Common/Scripting/Global/UtilsGlobal.cs

@@ -9,6 +9,7 @@
  */
 #endregion
 
+using System.Collections;
 using System.Linq;
 using Eluant;
 using OpenRA.Scripting;
@@ -54,6 +55,20 @@ namespace OpenRA.Mods.Common.Scripting
 			return true;
 		}
 
+		[Desc("Returns the original collection filtered with the func.")]
+		public LuaTable Where(LuaValue[] collection, LuaFunction func)
+		{
+			var t = Context.CreateTable();
+
+			foreach (var c in collection)
+				using (var ret = func.Call(c))
+				using (var result = ret.FirstOrDefault())
+					if (result != null && result.ToBoolean())
+						t.Add(t.Count + 1, c);
+
+			return t;
+		}
+
 		[Desc("Returns the first n values from a collection.")]
 		public LuaValue[] Take(int n, LuaValue[] source)
 		{