protected override Expression VisitLambda <T>(Expression <T> node)
{
if (_parameter != null)
{
throw new NotSupportedException("Only one lambda expression is allowed in a subdocument path.");
}
_parameter = node.Parameters[0];
// Simplify the body before processing. This makes any external variable references constants, and also
// reduces any expressions that can be simplified.
var body = LambdaSimplifyingExpressionVisitor.Simplify(node.Body);
body = Visit(body);
if (!_parameterEncountered)
{
throw new NotSupportedException("The first statement in a subdocument path must be a reference to the lambda parameter.");
}
return(node.Update(body, node.Parameters));
}
