add Bits/BitAllocator types

OpenRA.FileFormats/OpenRA.FileFormats.csproj

@@ -1,4 +1,4 @@
-<?xml version="1.0" encoding="utf-8"?>
+<?xml version="1.0" encoding="utf-8"?>
 <Project DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003" ToolsVersion="3.5">
   <PropertyGroup>
     <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
@@ -115,6 +115,7 @@
     <Compile Include="Filesystem\ZipFile.cs" />
     <Compile Include="InstallUtils.cs" />
     <Compile Include="Primitives\Cached.cs" />
+    <Compile Include="Primitives\Bits.cs" />
   </ItemGroup>
   <Import Project="$(MSBuildBinPath)\Microsoft.CSharp.targets" />
   <!-- To modify your build process, add your task inside one of the targets below and uncomment it. 

OpenRA.FileFormats/Primitives/Bits.cs

@@ -0,0 +1,65 @@
+#region Copyright & License Information
+/*
+ * Copyright 2007-2011 The OpenRA Developers (see AUTHORS)
+ * This file is part of OpenRA, which is free software. It is made 
+ * available to you under the terms of the GNU General Public License
+ * as published by the Free Software Foundation. For more information,
+ * see COPYING.
+ */
+#endregion
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+
+namespace OpenRA.FileFormats
+{
+	static class BitAllocator<T> where T : struct
+	{
+		static int nextVal = 1;
+		static Cache<string,int> bits;
+
+		static BitAllocator() {	bits = new Cache<string, int>( _ => Allocate() ); }
+
+		static int Allocate()
+		{
+			if (nextVal == 0)
+				throw new InvalidOperationException(
+					"Too many values in BitAllocator<{0}>".F(typeof(T).Name));
+
+			var val = nextVal;
+			nextVal <<= 1;
+			return val;
+		}
+
+		public static int GetValue(string[] val)
+		{
+			return val.Select( a => bits[a] ).Aggregate( 0, (a,b) => a | b );
+		}
+
+		public static IEnumerable<string> GetStrings(int val)
+		{
+			for( var i = 0; i < 32; i++ )
+			{
+				var x = 1 << i;
+				if ((val & x) != 0)
+					yield return bits.Single( a => a.Value == x ).Key;
+			}
+		}
+	}
+
+	public struct Bits<T> where T : struct
+	{
+		public int Value;
+
+		public Bits(string[] val) { Value = BitAllocator<T>.GetValue(val); }
+		public Bits(Bits<T> other) { Value = other.Value; }
+
+		public override string ToString()
+		{
+			return string.Join(",", BitAllocator<T>.GetStrings(Value).ToArray());
+		}
+
+		public override int GetHashCode() { return Value.GetHashCode(); }
+	}
+}