Add a utility command to output an actor's MiniYaml tree

Possibly taking in a path (to a .zip/.oramap/directory).

OpenRA.Mods.Common/OpenRA.Mods.Common.csproj

@@ -755,6 +755,7 @@
     <Compile Include="UtilityCommands\ListMixContentsCommand.cs" />
     <Compile Include="UtilityCommands\ListMSCabContentsCommand.cs" />
     <Compile Include="FileFormats\MSCabCompression.cs" />
+    <Compile Include="UtilityCommands\OutputActorMiniYamlCommand.cs" />
   </ItemGroup>
   <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
   <PropertyGroup>

OpenRA.Mods.Common/UtilityCommands/OutputActorMiniYamlCommand.cs

@@ -0,0 +1,51 @@
+using System;
+using System.IO;
+using System.Linq;
+
+namespace OpenRA.Mods.Common.UtilityCommands
+{
+	public class OutputActorMiniYamlCommand : IUtilityCommand
+	{
+		string IUtilityCommand.Name { get { return "--actor-yaml"; } }
+
+		bool IUtilityCommand.ValidateArguments(string[] args)
+		{
+			return args.Length == 2 || args.Length == 3;
+		}
+
+		[Desc("ACTOR-TYPE [PATH/TO/MAP]", "Display the finalized, merged MiniYaml tree for the given actor type. Input values are case-sensitive.")]
+		void IUtilityCommand.Run(ModData modData, string[] args)
+		{
+			// HACK: The engine code assumes that Game.modData is set.
+			Game.ModData = modData;
+
+			var actorType = args[1];
+			string mapPath = null;
+
+			Map map = null;
+			if (args.Length == 3)
+				try
+				{
+					mapPath = args[2];
+					map = new Map(modData, modData.ModFiles.OpenPackage(mapPath));
+				}
+				catch (InvalidDataException)
+				{
+					Console.WriteLine("Could not load map '{0}'.", mapPath);
+					Environment.Exit(2);
+				}
+
+			var fs = map ?? modData.DefaultFileSystem;
+			var topLevelNodes = MiniYaml.Load(fs, modData.Manifest.Rules, map == null ? null : map.RuleDefinitions);
+
+			var result = topLevelNodes.FirstOrDefault(n => n.Key == actorType);
+			if (result == null)
+			{
+				Console.WriteLine("Could not find actor '{0}' (name is case-sensitive).", actorType);
+				Environment.Exit(1);
+			}
+
+			Console.WriteLine(result.Value.Nodes.WriteToString());
+		}
+	}
+}