/// <summary>
/// Evaluates filter expression agains message context
/// </summary>
/// <param name="messageContext">Key value pair store with message context</param>
/// <returns>Evaluation result task</returns>
public async Task <IComparable> EvaluateAsync(IReadOnlyDictionary <string, object> messageContext)
{
// When no actual filter was created as expression we think that evaluation passed successfully, because there were nothing to compare to
if (Operation == 0 && (LeftExpression == null || RightExpression == null))
{
return(true);
}
var left = LeftExpression.EvaluateAsync(messageContext);
var right = RightExpression.EvaluateAsync(messageContext);
await Task.WhenAll(left, right);
if (object.ReferenceEquals(left.Result, NullEvaluationResult.Value))
{
return(false);
}
//actual operation between left and right
switch (Operation)
{
case FilterOperator.And:
{
return((bool)left.Result && (bool)right.Result);
}
case FilterOperator.Or:
{
return((bool)left.Result || (bool)right.Result);
}
case FilterOperator.EqualTo:
{
return(left.Result.Equals(right.Result));
}
case FilterOperator.NotEqualTo:
{
return(!left.Result.Equals(right.Result));
}
case FilterOperator.GreaterThan:
{
return(left.Result.CompareTo(right.Result) == 1);
}
case FilterOperator.GreaterThanOrEqualTo:
{
return(left.Result.CompareTo(right.Result) >= 0);
}
case FilterOperator.LessThanOrEqualTo:
{
return(left.Result.CompareTo(right.Result) <= 0);
}
case FilterOperator.LessThan:
{
return(left.Result.CompareTo(right.Result) == -1);
}
}
return(false);
}