Helper class to facilitate looking up TypeReference objects for types.

TypeResolver.cs

public class TypeResolver
{
  private readonly TypeDefinition _typeDef;
  private readonly IDictionary<Type, TypeReference> _typeRefs = 
    new Dictionary<Type, TypeReference>();
  private readonly TypeSystem _ts;
  private readonly ModuleDefinition _systemModule;
  private readonly ModuleDefinition _mscorlibModule;

  public TypeResolver(TypeDefinition typeDef)
  {
    _typeDef = typeDef;
    _ts = typeDef.Module.TypeSystem;
    Func<string, ModuleDefinition> getModule = 
      m => typeDef.Module.AssemblyResolver.Resolve(m).MainModule;
    _systemModule = getModule("system");
    _mscorlibModule = getModule("mscorlib");
  }

  public TypeReference Object
  {
    get { return _ts.Object; }
  }

  public TypeReference String
  {
    get { return _ts.String; }
  }

  public TypeReference Void
  {
    get { return _ts.Void; }
  }

  public TypeReference INotifyPropertyChanged
  {
    get { return LookupSystem(typeof(INotifyPropertyChanged)); }
  }

  public TypeReference PropertyChangedEventHandler
  {
    get { return LookupSystem(typeof(PropertyChangedEventHandler)); }
  }

  public TypeReference PropertyChangedEventArgs
  {
    get { return LookupSystem(typeof(PropertyChangedEventArgs)); }
  }

  public TypeReference Delegate
  {
    get { return LookupCore(typeof(Delegate)); }
  }

  public TypeReference Interlocked
  {
    get { return LookupCore(typeof(Interlocked)); }
  }

  private TypeReference LookupCore(Type t)
  {
    return Lookup(t, _mscorlibModule);
  }

  private TypeReference LookupSystem(Type t)
  {
    return Lookup(t, _systemModule);
  }

  private TypeReference Lookup(Type t, ModuleDefinition moduleDef)
  {
    if (!_typeRefs.ContainsKey(t))
    {
      var typeRef = moduleDef.Types.FirstOrDefault(
        td => td.FullName == t.FullName);
      if (typeRef == null)
      {
        return null;
      }
      var importedTypeRef = _typeDef.Module.Import(typeRef);
      _typeRefs[t] = importedTypeRef;
    }
    return _typeRefs[t];
  }
}