Bucket function return mongo $bucket operator to using in aggregates.

BucketAuto function return mongo $bucketAuto operator to using in aggregates.

CollStats function return mongo $collStats operator to using in aggregates.

CurrentOp function return mongo $currentOp operator to using in aggregates.

Group function return mongo $group operator to using in aggregates.

Lookup function return mongo $lookup operator to using in aggregates.

Merge function return mongo $merge operator to using in aggregates.

New function return new Operator.

ReplaceRoot function return mongo $replaceRoot operator to using in aggregates.

S get operators as param and return bson.M to using result as filter,stage,...

Sample function return mongo sample operator to using in aggregates.

UncorrelatedLookup function return mongo $lookup operator to using in aggregates.

Unwind function return mongo $unwind operator to using in aggregates.

BaseOperator is simple base operator that implemented Operator.

SMap is simple map that can be substitute of `bson.M` to having simpler map structure on query,aggregate,...

Operator is interface that should implement by each struct that want to be an operator.