Cecil Metadata Resolver for WinRT

gistfile1.cs

class WinRTMetadataResolver : MetadataResolver
{
    public WinRTMetadataResolver(IAssemblyResolver resolver)
        : base(resolver)
    {
    }

    IDictionary<string, ModuleDefinition> _loadedModules = new Dictionary<string, ModuleDefinition>();

    public override TypeDefinition Resolve(TypeReference type)
    {
        if (type.Scope.MetadataScopeType == MetadataScopeType.AssemblyNameReference && ((AssemblyNameReference)type.Scope).IsWindowsRuntime)
        {
            var tuple = ResolveTypeName(type.GetElementType().FullName);
            var filename = tuple.Item1.ToLowerInvariant();

            ModuleDefinition module;

            if (_loadedModules.ContainsKey(filename))
            {
                module = _loadedModules[filename];
            }
            else 
            {
                module = ModuleDefinition.ReadModule(
                    filename, 
                    new ReaderParameters { MetadataResolver = this, });
                _loadedModules.Add(filename, module);
            }
                
            return (TypeDefinition)module.LookupToken((int)tuple.Item2);
        }

        return base.Resolve(type);
    }

    //note, this wrapper funtion returns the metadata file name and token
    //it immediately releases the importer pointer
    static Tuple<string, UInt32> ResolveTypeName(string typename)
    {
        string path;
        object importer = null;
        UInt32 token;

        try
        {
            var hr = RoGetMetaDataFile(typename, IntPtr.Zero, out path, out importer, out token);

            //TODO: check HR for error

            return Tuple.Create(path, token);
        }
        finally
        {
            Marshal.ReleaseComObject(importer);
        }
    }

    [DllImport("WinTypes.dll")]
    static extern UInt32 RoGetMetaDataFile(
        [MarshalAs(UnmanagedType.HString)] string name,
        IntPtr metaDataDispenser,
        [MarshalAs(UnmanagedType.HString)] out string metaDataFilePath,
        [MarshalAs(UnmanagedType.Interface)] out object metaDataImport,
        out UInt32 typeDefToken);
}