/// <summary>
/// Deferred execution of iterator
/// </summary>
private void EnsureReady()
{
// only execute when requested
if (this.isReady || this.isCompleted)
{
return;
}
this.isReady = true;
// store the current item or null if complete
int next = this.index + 1;
SequenceBuffer <T> sBuffer = this.Buffer as SequenceBuffer <T>;
if (sBuffer != null)
{
// avoid using SequenceBuffer<T>.Count as will need to enumerate entire sequence
if (sBuffer.TryAdvance(next))
{
this.current = this.Buffer[next];
}
else
{
this.isCompleted = true;
this.current = default(T);
}
}
else
{
if (next < this.Buffer.Count)
{
this.current = this.Buffer[next];
}
else
{
this.isCompleted = true;
this.current = default(T);
}
}
}