/// <summary>
/// Creates instances of available extensions that extend the specified extension point and match the specified filter.
/// </summary>
/// <param name="extensionPoint">The extension point for which to create extensions.</param>
/// <param name="filter">An <see cref="ExtensionFilter"/> used to limit the result set to extensions with particular characteristics.</param>
/// <param name="justOne">Indicates whether or not to return only the first matching extension that is found.</param>
/// <returns>A set of extension instances.</returns>
/// <remarks>
/// Available extensions are those which are both enabled and licensed.
/// If <paramref name="justOne"/> is true, the first matching extension that is successfully instantiated is returned,
/// an no other extensions are instantiated.
/// </remarks>
public object[] CreateExtensions(ExtensionPoint extensionPoint, ExtensionFilter filter, bool justOne)
{
// get subset of applicable extensions
var extensions = ListExtensionsHelper(extensionPoint, filter);
// attempt to instantiate the extension classes
var createdObjects = new List <object>();
foreach (var extension in extensions)
{
if (justOne && createdObjects.Count > 0)
{
break;
}
try
{
// instantiate
var o = Activator.CreateInstance(extension.ExtensionClass.Resolve());
createdObjects.Add(o);
}
catch (Exception e)
{
// instantiation failed
// this should not be considered an exceptional circumstance
// instantiation may fail by design in some cases (e.g extension is designed only to run on a particular platform)
Platform.Log(LogLevel.Debug, e);
}
}
return(createdObjects.ToArray());
}
private List <ExtensionInfo> ListExtensionsHelper(ExtensionPoint extensionPoint, ExtensionFilter filter)
{
// ensure extension map has been constructed
BuildExtensionMapOnce();
List <ExtensionInfo> extensions;
if (_extensionMap.TryGetValue(extensionPoint.GetType(), out extensions))
{
return(CollectionUtils.Select(extensions,
extension => extension.Enabled && extension.Authorized && (filter == null || filter.Test(extension))));
}
return(new List <ExtensionInfo>());
}
/// <summary>
/// Lists all available extensions for the specified <paramref name="extensionPoint"/> that match the specified <paramref name="filter"/>.
/// </summary>
/// <param name="extensionPoint">The extension point for which to retrieve a list of extensions.</param>
/// <param name="filter">An <see cref="ExtensionFilter"/> used to limit the result set to extensions with particular characteristics.</param>
/// <returns>A list of <see cref="ExtensionInfo"/> objects describing available extensions.</returns>
/// <remarks>
/// Available extensions are those which are both enabled and licensed.
/// </remarks>
public ExtensionInfo[] ListExtensions(ExtensionPoint extensionPoint, ExtensionFilter filter)
{
return(ListExtensionsHelper(extensionPoint, filter).ToArray());
}
