diff --git a/OpenRA.FileFormats/ConnectedComponents.cs b/OpenRA.FileFormats/ConnectedComponents.cs
new file mode 100644
index 0000000000..a1216cdb86
--- /dev/null
+++ b/OpenRA.FileFormats/ConnectedComponents.cs
@@ -0,0 +1,36 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+
+namespace OpenRA.FileFormats
+{
+	public static class ConnectedComponents
+	{
+		static readonly int2[] Neighbors 
+			= { new int2(-1, -1), new int2(0, -1), new int2(1, -1), new int2(-1, 0) };
+
+		public static int[,] Extract(Map m, Func<int, int, int> f)
+		{
+			var result = new int[m.MapSize, m.MapSize];
+			var types = new int[m.MapSize, m.MapSize];
+			var d = new Dictionary<int,int>();
+			var n = 1;
+
+			for( var j = m.YOffset; j < m.YOffset + m.Height; j++ )
+				for (var i = m.XOffset; i < m.XOffset + m.Width; i++)
+				{
+					types[i, j] = f(i, j);
+
+					var k = n;
+					foreach (var a in Neighbors)
+						if (types[i + a.X, j + a.Y] == types[i, j] && result[i + a.X, j + a.Y] < k)
+							k = result[i + a.X, j + a.Y];
+
+					// todo: finish this
+				}
+
+			return result;
+		}
+	}
+}
diff --git a/OpenRA.FileFormats/Evaluator.cs b/OpenRA.FileFormats/Evaluator.cs
index 4cec92809a..95b5d435ea 100644
--- a/OpenRA.FileFormats/Evaluator.cs
+++ b/OpenRA.FileFormats/Evaluator.cs
@@ -22,10 +22,10 @@ namespace OpenRA.FileFormats
 			{
 				switch (t[0])
 				{
-					case '+': ApplyBinop(s, (x, y) => x + y); break;
-					case '-': ApplyBinop(s, (x, y) => x - y); break;
-					case '*': ApplyBinop(s, (x, y) => x * y); break;
-					case '/': ApplyBinop(s, (x, y) => x / y); break;
+					case '+': ApplyBinop(s, (x, y) => y + x); break;
+					case '-': ApplyBinop(s, (x, y) => y - x); break;
+					case '*': ApplyBinop(s, (x, y) => y * x); break;
+					case '/': ApplyBinop(s, (x, y) => y / x); break;
 					default: s.Push(int.Parse(t)); break;
 				}
 			}
@@ -65,7 +65,7 @@ namespace OpenRA.FileFormats
 		}
 
 		static readonly Dictionary<string, int> Prec
-			= new Dictionary<string, int> { { "+", 0 }, { "-", 0 }, { "*", 1 }, { "/", 1 } };
+			= new Dictionary<string, int> { { "+", 0 }, { "-", 0 }, { "*", 1 }, { "/", 1 }, { "(", -1 } };
 
 		static IEnumerable<string> Tokens(string expr, string ops)
 		{
diff --git a/OpenRA.FileFormats/OpenRA.FileFormats.csproj b/OpenRA.FileFormats/OpenRA.FileFormats.csproj
index 22932f3639..0f09e98ca2 100644
--- a/OpenRA.FileFormats/OpenRA.FileFormats.csproj
+++ b/OpenRA.FileFormats/OpenRA.FileFormats.csproj
@@ -54,6 +54,7 @@
     <Compile Include="BlowfishKeyProvider.cs" />
     <Compile Include="Cache.cs" />
     <Compile Include="Collections\Set.cs" />
+    <Compile Include="ConnectedComponents.cs" />
     <Compile Include="DisposableAction.cs" />
     <Compile Include="Dune2ShpReader.cs" />
     <Compile Include="Evaluator.cs" />