/// <summary>
/// Creates a group join include used to describe an Include operation that should
/// be performed as part of a GroupJoin.
/// </summary>
/// <param name="navigationPath"> The included navigation path. </param>
/// <param name="querySourceRequiresTracking"> true if this query source requires tracking. </param>
/// <param name="existingGroupJoinInclude"> A possibly null existing group join include. </param>
/// <param name="relatedEntitiesLoaders"> The related entities loaders. </param>
/// <returns>
/// A new group join include.
/// </returns>
public virtual object CreateGroupJoinInclude(
IReadOnlyList <INavigation> navigationPath,
bool querySourceRequiresTracking,
object existingGroupJoinInclude,
object relatedEntitiesLoaders)
{
var previousGroupJoinInclude
= new GroupJoinInclude(
navigationPath,
(IReadOnlyList <Func <QueryContext, IRelatedEntitiesLoader> >)relatedEntitiesLoaders,
querySourceRequiresTracking);
var groupJoinInclude = existingGroupJoinInclude as GroupJoinInclude;
if (groupJoinInclude != null)
{
groupJoinInclude.SetPrevious(previousGroupJoinInclude);
return(null);
}
return(previousGroupJoinInclude);
}
// ReSharper disable once InconsistentNaming
private static IEnumerable <TResult> _GroupJoin <TOuter, TInner, TKey, TResult>(
RelationalQueryContext queryContext,
IEnumerable <ValueBuffer> source,
IShaper <TOuter> outerShaper,
IShaper <TInner> innerShaper,
Func <TInner, TKey> innerKeySelector,
Func <TOuter, IEnumerable <TInner>, TResult> resultSelector,
GroupJoinInclude outerGroupJoinInclude,
GroupJoinInclude innerGroupJoinInclude)
{
var outerGroupJoinIncludeContext = outerGroupJoinInclude?.CreateIncludeContext(queryContext);
var innerGroupJoinIncludeContext = innerGroupJoinInclude?.CreateIncludeContext(queryContext);
try
{
using (var sourceEnumerator = source.GetEnumerator())
{
var comparer = EqualityComparer <TKey> .Default;
var hasNext = sourceEnumerator.MoveNext();
var nextOuter = default(TOuter);
while (hasNext)
{
var outer
= Equals(nextOuter, default(TOuter))
? outerShaper.Shape(queryContext, sourceEnumerator.Current)
: nextOuter;
nextOuter = default(TOuter);
outerGroupJoinIncludeContext?.Include(outer);
var inner = innerShaper.Shape(queryContext, sourceEnumerator.Current);
var inners = new List <TInner>();
if (inner == null)
{
yield return(resultSelector(outer, inners));
hasNext = sourceEnumerator.MoveNext();
}
else
{
var currentGroupKey = innerKeySelector(inner);
innerGroupJoinIncludeContext?.Include(inner);
inners.Add(inner);
while (true)
{
hasNext = sourceEnumerator.MoveNext();
if (!hasNext)
{
break;
}
nextOuter = outerShaper.Shape(queryContext, sourceEnumerator.Current);
if (!Equals(outer, nextOuter))
{
break;
}
nextOuter = default(TOuter);
inner = innerShaper.Shape(queryContext, sourceEnumerator.Current);
if (inner == null)
{
break;
}
var innerKey = innerKeySelector(inner);
if (!comparer.Equals(currentGroupKey, innerKey))
{
break;
}
innerGroupJoinIncludeContext?.Include(inner);
inners.Add(inner);
}
yield return(resultSelector(outer, inners));
}
}
}
}
finally
{
innerGroupJoinIncludeContext?.Dispose();
outerGroupJoinIncludeContext?.Dispose();
}
}