//---------------------------------------------------------------------------------------
// MoveNext will invoke the entire query sub-tree, accumulating results into a hash-
// table, upon the first call. Then for the first call and all subsequent calls, we will
// just enumerate the key-set from the hash-table, retrieving groupings of key-elements.
//
internal override bool MoveNext(ref IGrouping <TGroupKey, TElement> currentElement, ref TOrderKey currentKey)
{
Debug.Assert(_source != null);
// Lazy-init the mutable state. This also means we haven't yet built our lookup of
// groupings, so we can go ahead and do that too.
Mutables mutables = _mutables;
if (mutables == null)
{
mutables = _mutables = new Mutables();
// Build the hash lookup and start enumerating the lookup at the beginning.
mutables._hashLookup = BuildHashLookup();
Debug.Assert(mutables._hashLookup != null);
mutables._hashLookupIndex = -1;
}
// Now, with a hash lookup in hand, we just enumerate the keys. So long
// as the key-value lookup has elements, we have elements.
if (++mutables._hashLookupIndex < mutables._hashLookup.Count)
{
currentElement = new GroupByGrouping <TGroupKey, TElement>(
mutables._hashLookup[mutables._hashLookupIndex]);
return(true);
}
return(false);
}
internal override bool MoveNext(ref IGrouping <TGroupKey, TElement> currentElement, ref TOrderKey currentKey)
{
Mutables <TSource, TGroupKey, TElement, TOrderKey> mutables = this.m_mutables;
if (mutables == null)
{
mutables = this.m_mutables = new Mutables <TSource, TGroupKey, TElement, TOrderKey>();
mutables.m_hashLookup = this.BuildHashLookup();
mutables.m_hashLookupIndex = -1;
}
if (++mutables.m_hashLookupIndex < mutables.m_hashLookup.Count)
{
currentElement = new GroupByGrouping <TGroupKey, TElement>(mutables.m_hashLookup[mutables.m_hashLookupIndex]);
return(true);
}
return(false);
}