private XmlNode GetComments(MemberInfo mi)
{
    Type declType = (mi is Type) ? ((Type)mi) : mi.DeclaringType;
    XmlDocument doc = LoadAssemblyComments(declType.Assembly);
    if (doc == null) return null;
    string xpath;

    // Handle nested classes
    string typeName = declType.FullName.Replace("+", ".");

    // Based on the member type, get the correct xpath query
    switch(mi.MemberType)
    {                    
        case MemberTypes.NestedType:
        case MemberTypes.TypeInfo:
            xpath = "//member[@name='T:" + typeName + "']";
            break;

        case MemberTypes.Constructor:
            xpath = "//member[@name='M:" + typeName + "." +
                "#ctor" + CreateParamsDescription(
                    ((ConstructorInfo)mi).GetParameters()) + "']";
            break;

        case MemberTypes.Method:
            xpath = "//member[@name='M:" + typeName + "." + 
                mi.Name + CreateParamsDescription(
                    ((MethodInfo)mi).GetParameters());
            if (mi.Name == "op_Implicit" || mi.Name == "op_Explicit")
            {
                xpath += "~{" + 
                    ((MethodInfo)mi).ReturnType.FullName + "}";
            }
            xpath += "']";
            break;

        case MemberTypes.Property:
            xpath = "//member[@name='P:" + typeName + "." + 
                mi.Name + CreateParamsDescription(
                    ((PropertyInfo)mi).GetIndexParameters()) + "']";
            break;

        case MemberTypes.Field:
            xpath = "//member[@name='F:" + typeName + "." + mi.Name + "']";
            break;

        case MemberTypes.Event:
            xpath = "//member[@name='E:" + typeName + "." + mi.Name + "']";
            break;

            // Unknown member type, nothing to do
        default: 
            return null;
    }

    // Get the node from the document
    return doc.SelectSingleNode(xpath);
}

public class LateBoundComHelper : IDisposable
{
    private Type _type;
    private object _obj;

    public LateBoundComHelper(string progId) : 
        this(Type.GetTypeFromProgID(progId, true))
    {
    }

    public LateBoundComHelper(Type t)
    {
        if (t == null) throw new ArgumentNullException("t");
        _type = t;
        _obj = Activator.CreateInstance(t);
    }

    public object Invoke(string methodName, params object [] args)
    {
        ThrowIfDisposed();
        return _type.InvokeMember(methodName, 
            BindingFlags.InvokeMethod, null, _obj, args);
    }

    public object this[string propertyName]
    {
        get
        {
            ThrowIfDisposed();
            return _type.InvokeMember(propertyName, 
                BindingFlags.GetProperty, null, _obj, null); 
        }
        set
        {
            ThrowIfDisposed();
            _type.InvokeMember(propertyName, BindingFlags.SetProperty, 
                               null, _obj, new object[]{value});
        }
    }

    private void ThrowIfDisposed()
    {
        if (_obj == null) throw new ObjectDisposedException(GetType().Name);
    }
    
    public void Dispose()
    {
        if (_obj != null)
        {
            if (_type.IsCOMObject)
            {
                while (Marshal.ReleaseComObject(_obj) > 0);
            }
            else if (_obj is IDisposable) ((IDisposable)_obj).Dispose();
            _obj = null;
        }
    }
}

public sealed class CircularBuffer : Queue
{
    private int _capacity;
    
    public CircularBuffer(int capacity) : base(capacity) 
    {
        if (capacity <= 0) 
                 throw new ArgumentOutOfRangeException("capacity");
        _capacity = capacity;
    }

    public override void Enqueue(object obj)
    {
        if (base.Count == _capacity) base.Dequeue();
        base.Enqueue(obj);
    }

    public override void TrimToSize()
    {
        throw new NotSupportedException();
    }
}