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);
}
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;
}
public CorrelatedAccumulatorExpression Update(AccumulatorExpression accumulator)
{
if (accumulator != _accumulator)
{
return(new CorrelatedAccumulatorExpression(_correlationId, accumulator));
}
return(this);
}
public CorrelatedAccumulatorExpression Update(AccumulatorExpression accumulator)
{
if (accumulator != _accumulator)
{
return new CorrelatedAccumulatorExpression(_correlationId, accumulator);
}
return this;
}
public override Expression Bind(Expressions.ProjectionExpression projection, ProjectionBindingContext context, System.Linq.Expressions.MethodCallExpression node, IEnumerable<System.Linq.Expressions.Expression> arguments)
{
var aggregatorName = "Single";
var returnType = node.Method.ReturnType;
if (node.Method.Name.EndsWith("Async"))
{
aggregatorName += "Async";
returnType = returnType.GetGenericArguments()[0];
}
var aggregator = CreateAggregator(aggregatorName, returnType);
var source = projection.Source;
var argument = arguments.FirstOrDefault();
if (argument != null && ExtensionExpressionVisitor.IsLambda(argument))
{
var lambda = ExtensionExpressionVisitor.GetLambda(argument);
var binder = new AccumulatorBinder(context.GroupMap, context.SerializerRegistry);
binder.RegisterParameterReplacement(lambda.Parameters[0], projection.Projector);
argument = binder.Bind(lambda.Body);
}
else
{
argument = projection.Projector;
var select = source as SelectExpression;
if (select != null)
{
source = select.Source;
}
}
var serializer = context.SerializerRegistry.GetSerializer(returnType);
var accumulator = new AccumulatorExpression(returnType, AccumulatorType, argument);
var serializationAccumulator = new SerializationExpression(
accumulator,
new BsonSerializationInfo("__agg0", serializer, serializer.ValueType));
var rootAccumulator = new RootAccumulatorExpression(source, serializationAccumulator);
return new ProjectionExpression(
rootAccumulator,
serializationAccumulator,
aggregator);
}
protected internal override Expression VisitPipeline(PipelineExpression node)
{
Guid correlationId;
if (TryGetCorrelatedGroup(node.Source, out correlationId))
{
AccumulatorType accumulatorType;
Expression argument;
if (TryGetAccumulatorTypeAndArgument(node, out accumulatorType, out argument))
{
var accumulator = new AccumulatorExpression(
node.Type,
"__agg" + _count++,
_bindingContext.GetSerializer(node.Type, argument),
accumulatorType,
argument);
return new CorrelatedExpression(
correlationId,
accumulator);
}
}
return node;
}
protected internal virtual Expression VisitAccumulator(AccumulatorExpression node)
{
return(node.Update(Visit(node.Argument)));
}
public CorrelatedAccumulatorExpression(Guid correlationId, AccumulatorExpression accumulator)
{
_correlationId = correlationId;
_accumulator = Ensure.IsNotNull(accumulator, "accumulator");
}
protected internal virtual Expression VisitAccumulator(AccumulatorExpression node)
{
return node.Update(Visit(node.Argument));
}
private BsonValue TranslateAccumulator(AccumulatorExpression node)
{
switch (node.AccumulatorType)
{
case AccumulatorType.AddToSet:
return new BsonDocument("$addToSet", TranslateValue(node.Argument));
case AccumulatorType.Average:
return new BsonDocument("$avg", TranslateValue(node.Argument));
case AccumulatorType.First:
return new BsonDocument("$first", TranslateValue(node.Argument));
case AccumulatorType.Last:
return new BsonDocument("$last", TranslateValue(node.Argument));
case AccumulatorType.Max:
return new BsonDocument("$max", TranslateValue(node.Argument));
case AccumulatorType.Min:
return new BsonDocument("$min", TranslateValue(node.Argument));
case AccumulatorType.Push:
return new BsonDocument("$push", TranslateValue(node.Argument));
case AccumulatorType.StandardDeviationPopulation:
return new BsonDocument("$stdDevPop", TranslateValue(node.Argument));
case AccumulatorType.StandardDeviationSample:
return new BsonDocument("$stdDevSamp", TranslateValue(node.Argument));
case AccumulatorType.Sum:
return new BsonDocument("$sum", TranslateValue(node.Argument));
}
// we should never ever get here.
var message = string.Format("Unrecognized aggregation type in the expression tree {0}.",
node.ToString());
throw new MongoInternalException(message);
}
public CorrelatedAccumulatorExpression(Guid correlationId, AccumulatorExpression accumulator)
{
_correlationId = correlationId;
_accumulator = Ensure.IsNotNull(accumulator, "accumulator");
}
// private methods
private bool CompareAccumulator(AccumulatorExpression a, AccumulatorExpression b)
{
return(a.AccumulatorType == b.AccumulatorType &&
Compare(a.Argument, b.Argument));
}
protected internal override Expression VisitAccumulator(AccumulatorExpression node)
{
return node;
}
private Expression VisitCorrelatedGroup(CorrelatedExpression node)
{
var groupExpression = (GroupByExpression)node.Expression;
if (_accumulatorLookup != null && _accumulatorLookup.Contains(node.CorrelationId))
{
var source = Visit(groupExpression.Source);
var accumulators = new List<AccumulatorExpression>();
var fieldExpressions = new List<FieldExpression>();
var comparer = new ExpressionComparer();
foreach (var correlatedAccumulator in _accumulatorLookup[node.CorrelationId])
{
var index = accumulators.FindIndex(x => comparer.Compare((Expression)x, correlatedAccumulator.Expression));
FieldExpression fieldExpression;
if (index == -1)
{
var accumulator = (AccumulatorExpression)correlatedAccumulator.Expression;
// TODO: might not need to do any renames...
accumulator = new AccumulatorExpression(
accumulator.Type,
"__agg" + accumulators.Count,
accumulator.Serializer,
accumulator.AccumulatorType,
accumulator.Argument);
accumulators.Add(accumulator);
fieldExpression = new FieldExpression(accumulator.FieldName, accumulator.Serializer);
fieldExpressions.Add(fieldExpression);
}
else
{
fieldExpression = fieldExpressions[index];
}
_accumulatorReplacementMap[correlatedAccumulator] = fieldExpression;
}
groupExpression = new GroupByExpression(
groupExpression.Type,
source,
groupExpression.KeySelector,
accumulators.AsReadOnly());
}
return Visit(groupExpression);
}
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;
}
