private bool TryBindAccumulatorExpression(MethodCallExpression node, out Expression accumulator)
{
AccumulatorType accumulatorType;
if (TryGetAccumulatorType(node.Method.Name, out accumulatorType))
{
Guid correlationId = Guid.Empty;
if (_groupMap == null || TryGetCorrelatedGroup(node.Arguments[0], out correlationId))
{
accumulator = new AccumulatorExpression(node.Type,
accumulatorType,
GetAccumulatorArgument(node));
if (_groupMap != null)
{
accumulator = new CorrelatedAccumulatorExpression(
correlationId,
(AccumulatorExpression)accumulator);
}
return(true);
}
}
accumulator = null;
return(false);
}
protected override Expression VisitNew(NewExpression node)
{
var newNode = (NewExpression)base.VisitNew(node);
if (newNode.Type.IsGenericType &&
newNode.Type.GetGenericTypeDefinition() == typeof(HashSet <>) &&
newNode.Arguments.Count == 1 &&
newNode.Arguments[0] is AccumulatorExpression &&
((AccumulatorExpression)newNode.Arguments[0]).AccumulatorType == AccumulatorType.Push)
{
Guid correlationId = Guid.Empty;
if (_groupMap == null || TryGetCorrelatedGroup(node.Arguments[0], out correlationId))
{
Expression accumulator = new AccumulatorExpression(
newNode.Type,
AccumulatorType.AddToSet,
((AccumulatorExpression)newNode.Arguments[0]).Argument);
if (_groupMap != null)
{
accumulator = new CorrelatedAccumulatorExpression(
correlationId,
(AccumulatorExpression)accumulator);
}
return(accumulator);
}
}
return(newNode);
}
protected internal override Expression VisitCorrelatedAccumulator(CorrelatedAccumulatorExpression node)
{
_accumulators.Add(node);
// there could be nested accumulators we need to get...
return(base.VisitCorrelatedAccumulator(node));
}
protected internal override Expression VisitCorrelatedAccumulator(CorrelatedAccumulatorExpression node)
{
if (node.CorrelationId == _correlationId)
{
return(Visit(node.Accumulator));
}
return(base.VisitCorrelatedAccumulator(node));
}
protected internal override Expression VisitCorrelatedAccumulator(CorrelatedAccumulatorExpression node)
{
Expression mapped;
if (_map.TryGetValue(node, out mapped))
{
return(mapped);
}
return(base.VisitCorrelatedAccumulator(node));
}
