private void InitializePriorityQueue(IList <IEnumerable <T> > inputList)
{
foreach (var list in inputList)
{
ComparableSortedSequenceEnumerator <T> enumerator = new ComparableSortedSequenceEnumerator <T>(list, this.keyComparer);
bool enumeratorIsNotEmpty = this.PrepareEnumerator(enumerator);
if (enumeratorIsNotEmpty == false)
{
// Since enumerator does not have any items that fit the filter, discard the enumerator.
enumerator.Dispose();
continue;
}
this.InsertToPriortyQueueIfNecessary(enumerator);
}
}
private bool InsertToPriortyQueueIfNecessary(ComparableSortedSequenceEnumerator <T> enumerator)
{
Diagnostics.Assert(enumerator != null, ClassName, "Input enumerator must not be null.");
while (true)
{
bool wasPushed = this.priorityQueue.TryPush(enumerator);
if (wasPushed)
{
return(true);
}
var isNotEmpty = enumerator.MoveNext();
if (isNotEmpty == false)
{
enumerator.Dispose();
return(false);
}
}
}
/// <summary>
/// Prepares the enumerator to be added to the priority queue.
/// Preparation includes moving the enumerator until the current key obides filters.
/// </summary>
/// <param name="enumerator">The enumerator.</param>
/// <returns>Boolean that indicates that the enumerator is now empty.</returns>
private bool PrepareEnumerator(ComparableSortedSequenceEnumerator <T> enumerator)
{
while (true)
{
bool itemExists = enumerator.MoveNext();
if (itemExists == false)
{
return(false);
}
if (this.useFirstKey)
{
int firstKeyComparison = this.keyComparer.Compare(this.firstKey, enumerator.Current);
// If firstKey for the filter is greater than the current, continue moving the enumerator.
if (firstKeyComparison > 0)
{
continue;
}
}
if (this.useLastKey)
{
int lastKeyComparison = this.keyComparer.Compare(this.lastKey, enumerator.Current);
// If lastKey for the filter is less than the current, indicate that the enumerator is practically empty
if (lastKeyComparison < 0)
{
return(false);
}
}
// If current item does not fit the filter, go to next.
if (this.keyFilter != null && this.keyFilter.Invoke(enumerator.Current) == false)
{
continue;
}
return(true);
}
}
public int CompareTo(ComparableSortedSequenceEnumerator <T> other)
{
return(this.keyComparer.Compare(this.Current, other.Current));
}
