using System;
using System.Collections.Generic;
using System.ComponentModel.Composition.Hosting;
using System.ComponentModel.Composition.Primitives;
using System.Linq;
using System.Reflection;
namespace MediaBrowser.Common.Mef
{
///
/// Class MefUtils
///
public static class MefUtils
{
///
/// Plugins that live on both the server and UI are going to have references to assemblies from both sides.
/// But looks for Parts on one side, it will throw an exception when it seems Types from the other side that it doesn't have a reference to.
/// For example, a plugin provides a Resolver. When MEF runs in the UI, it will throw an exception when it sees the resolver because there won't be a reference to the base class.
/// This method will catch those exceptions while retining the list of Types that MEF is able to resolve.
///
/// The catalogs.
/// CompositionContainer.
/// catalogs
public static CompositionContainer GetSafeCompositionContainer(IEnumerable catalogs)
{
if (catalogs == null)
{
throw new ArgumentNullException("catalogs");
}
var newList = new List();
// Go through each Catalog
foreach (var catalog in catalogs)
{
try
{
// Try to have MEF find Parts
catalog.Parts.ToArray();
// If it succeeds we can use the entire catalog
newList.Add(catalog);
}
catch (ReflectionTypeLoadException ex)
{
// If it fails we can still get a list of the Types it was able to resolve and create TypeCatalogs
var typeCatalogs = ex.Types.Where(t => t != null).Select(t => new TypeCatalog(t));
newList.AddRange(typeCatalogs);
}
}
return new CompositionContainer(new AggregateCatalog(newList));
}
///
/// Gets a list of types within an assembly
/// This will handle situations that would normally throw an exception - such as a type within the assembly that depends on some other non-existant reference
///
/// The assembly.
/// IEnumerable{Type}.
/// assembly
public static IEnumerable GetTypes(Assembly assembly)
{
if (assembly == null)
{
throw new ArgumentNullException("assembly");
}
try
{
return assembly.GetTypes();
}
catch (ReflectionTypeLoadException ex)
{
// If it fails we can still get a list of the Types it was able to resolve
return ex.Types.Where(t => t != null);
}
}
}
}