/// <summary>
/// GROUP BY: Apply groupBy expression and aggregate results in DocumentGroup
/// </summary>
private IEnumerable <DocumentGroup> GroupBy(IEnumerable <BsonDocument> source, GroupBy groupBy)
{
using (var enumerator = source.GetEnumerator())
{
var done = new Done {
Running = enumerator.MoveNext()
};
while (done.Running)
{
var key = groupBy.Expression.ExecuteScalar(enumerator.Current);
groupBy.Select.Parameters["key"] = key;
var group = YieldDocuments(key, enumerator, groupBy, done);
yield return(new DocumentGroup(key, enumerator.Current, group, _lookup));
}
}
}
/// <summary>
/// YieldDocuments will run over all key-ordered source and returns groups of source
/// </summary>
private IEnumerable <BsonDocument> YieldDocuments(BsonValue key, IEnumerator <BsonDocument> enumerator, GroupBy groupBy, Done done)
{
yield return(enumerator.Current);
while (done.Running = enumerator.MoveNext())
{
var current = groupBy.Expression.ExecuteScalar(enumerator.Current);
if (key == current)
{
// yield return document in same key (group)
yield return(enumerator.Current);
}
else
{
groupBy.Select.Parameters["key"] = current;
// stop current sequence
yield break;
}
}
}
/// <summary>
/// Split values in many IEnumerable. Each enumerable contains values to be insert in a single container
/// </summary>
private IEnumerable <IEnumerable <KeyValuePair <BsonValue, PageAddress> > > SliptValues(IEnumerable <KeyValuePair <BsonValue, PageAddress> > source, Done done)
{
using (var enumerator = source.GetEnumerator())
{
if (enumerator.MoveNext())
{
done.Count = 1;
while (done.Running)
{
yield return(this.YieldValues(enumerator, done));
}
}
}
}
/// <summary>
/// Loop in values enumerator to return N values for a single container
/// </summary>
private IEnumerable <KeyValuePair <BsonValue, PageAddress> > YieldValues(IEnumerator <KeyValuePair <BsonValue, PageAddress> > source, Done done)
{
var size = SortContainer.GetKeyLength(source.Current.Key) + PageAddress.SIZE;
yield return(source.Current);
while (source.MoveNext())
{
var length = SortContainer.GetKeyLength(source.Current.Key) + PageAddress.SIZE;
done.Count++;
if (size + length > _containerSize)
{
yield break;
}
size += length;
yield return(source.Current);
}
done.Running = false;
}
/// <summary>
/// Loop in values enumerator to return N values for a single container
/// </summary>
private IEnumerable <KeyValuePair <BsonValue, PageAddress> > YieldValues(IEnumerator <KeyValuePair <BsonValue, PageAddress> > source, Done done)
{
var size = IndexNode.GetKeyLength(source.Current.Key, false) + PageAddress.SIZE;
if (size > MAX_INDEX_KEY_LENGTH)
{
throw new LiteException(0, $"Current value are larger than {MAX_INDEX_KEY_LENGTH} bytes and can't be sorted.");
}
yield return(source.Current);
while (source.MoveNext())
{
var length = IndexNode.GetKeyLength(source.Current.Key, false) + PageAddress.SIZE;
done.Count++;
if (size + length > _containerSize)
{
yield break;
}
size += length;
yield return(source.Current);
}
done.Running = false;
}