public void Traverse(IVisitor visitor)
{
if (visitor == null)
{
throw new ArgumentNullException("visitor");
}
visitor.PerformBefore(this);
if (m_selectItems == null)
{
throw new InvalidOperationException(
"Fully-constructed query expression must have select items.");
}
m_selectItems.Traverse(visitor);
visitor.PerformOnFrom(this);
if (m_from != null)
{
m_from.Traverse(visitor);
}
visitor.PerformOnWhere(this);
if (m_where != null)
{
m_where.Traverse(visitor);
}
visitor.PerformOnGroupBy(this);
if (m_groupBy != null)
{
m_groupBy.Traverse(visitor);
}
visitor.PerformOnOrderBy(this);
if (m_orderBy != null)
{
m_orderBy.Traverse(visitor);
}
visitor.PerformAfter(this);
if (m_next != null)
{
m_next.Traverse(visitor);
}
}
