// private static methods
private static AstFilter CreateRegexFilter(AstFilterField field, Modifiers modifiers, string pattern)
{
var combinedPattern = "^" + modifiers.LeadingPattern + pattern + modifiers.TrailingPattern + "$";
if (combinedPattern.StartsWith("^.*"))
{
combinedPattern = combinedPattern.Substring(3);
}
if (combinedPattern.EndsWith(".*$"))
{
combinedPattern = combinedPattern.Substring(0, combinedPattern.Length - 3);
}
var options = CreateRegexOptions(modifiers);
return(AstFilter.Regex(field, combinedPattern, options));
}
public override AstNode VisitFilterField(AstFilterField node)
{
// "_elements.0.X" => { __agg0 : { $first : "$$ROOT" } } + "__agg0.X"
if (node.Path.StartsWith("_elements.0."))
{
var accumulatorExpression = AstExpression.AccumulatorExpression(AstAccumulatorOperator.First, AstExpression.Var("ROOT"));
var accumulatorFieldName = _accumulators.AddAccumulatorExpression(accumulatorExpression);
var restOfPath = node.Path.Substring("_elements.0.".Length);
var rewrittenPath = $"{accumulatorFieldName}.{restOfPath}";
return(AstFilter.Field(rewrittenPath, node.Serializer));
}
if (node.Path == "_elements" || node.Path.StartsWith("_elements."))
{
throw new UnableToRemoveReferenceToElementsException();
}
return(base.VisitFilterField(node));
}
