public override Expression Bind(ProjectionExpression projection, ProjectionBindingContext context, MethodCallExpression node, IEnumerable<Expression> arguments)
{
LambdaExpression aggregator;
if (node.Method.Name.EndsWith("Async"))
{
aggregator = CreateAsyncAggregator();
}
else
{
aggregator = CreateSyncAggregator();
}
var source = projection.Source;
var argument = arguments.FirstOrDefault();
if (argument != null && ExtensionExpressionVisitor.IsLambda(argument))
{
source = BindPredicate(projection, context, source, argument);
}
source = new TakeExpression(source, 1);
var serializer = context.SerializerRegistry.GetSerializer(typeof(int));
var accumulator = new AccumulatorExpression(typeof(int), AccumulatorType.Count, null);
var serializationAccumulator = new SerializationExpression(
accumulator,
new BsonSerializationInfo("__agg0", serializer, serializer.ValueType));
var rootAccumulator = new RootAccumulatorExpression(source, serializationAccumulator);
return new ProjectionExpression(
rootAccumulator,
serializationAccumulator,
aggregator);
}
public override Expression Bind(ProjectionExpression projection, ProjectionBindingContext context, MethodCallExpression node, IEnumerable<Expression> arguments)
{
var aggregator = CreateAggregator(node.Method.Name, projection.Projector.Type);
var source = projection.Source;
var argument = arguments.FirstOrDefault();
if (argument != null && ExtensionExpressionVisitor.IsLambda(argument))
{
source = BindPredicate(projection, context, source, argument);
}
source = new TakeExpression(source, 2);
return new ProjectionExpression(
source,
projection.Projector,
aggregator);
}
protected internal virtual Expression VisitTake(TakeExpression node)
{
return(node.Update(
Visit(node.Source),
Visit(node.Count)));
}
private void TranslateTake(TakeExpression node)
{
Translate(node.Source);
_stages.Add(new BsonDocument("$limit", (int)((ConstantExpression)node.Count).Value));
}
protected internal virtual Expression VisitTake(TakeExpression node)
{
return node.Update(
Visit(node.Source),
Visit(node.Count));
}
private BsonValue TranslateTake(TakeExpression node)
{
var arguments = new BsonArray();
var skipNode = node.Source as SkipExpression;
if (skipNode != null)
{
arguments.Add(TranslateValue(skipNode.Source));
arguments.Add(TranslateValue(skipNode.Count));
}
else
{
arguments.Add(TranslateValue(node.Source));
}
arguments.Add(TranslateValue(node.Count));
return new BsonDocument("$slice", arguments);
}
private void VisitTake(TakeExpression node)
{
Visit(node.Source);
_stages.Add(new BsonDocument("$limit", node.Count));
}
