/// <summary>
/// Visits a MongoSelectExpression.
/// </summary>
/// <param name="node">The expression to visit.</param>
/// <returns>The modified expression, if it or any subexpression was modified; otherwise, returns the original expression.</returns>
protected virtual Expression VisitSelect(MongoSelectExpression node)
{
throw new NotImplementedException();
}
/// <summary>
/// Initializes an instance of the MongoProjectionExpression class.
/// </summary>
/// <param name="source">The select expression that is the source of the data</param>
/// <param name="projector">The expression that does the projection.</param>
public MongoProjectionExpression(MongoSelectExpression source, Expression projector)
: base(MongoExpressionType.Projection, typeof(IEnumerable<>).MakeGenericType(projector.Type))
{
_source = source;
_projector = projector;
}