/// <summary>
/// Returns the next item to be taken from the back without removing it.
/// </summary>
/// <returns>The next item to be taken from the back.</returns>
/// <exception cref="System.InvalidOperationException">No more items to be taken.</exception>
public T Peek()
{
T item;
var index = Interlocked.Add(ref _indexEnqueue, 0);
if (index < _capacity && index > 0 && _entries.TryGet(index, out item))
{
return(item);
}
throw new InvalidOperationException("Empty");
}
/// <summary>
/// Tries to retrieve the item at the specified index.
/// </summary>
/// <param name="index">The index.</param>
/// <param name="value">The value.</param>
/// <returns>
/// <c>true</c> if the item was retrieved; otherwise, <c>false</c>.
/// </returns>
/// <exception cref="ArgumentOutOfRangeException">index;index must be greater or equal to 0 and less than capacity</exception>
public bool TryGet(int index, out T value)
{
if (_entries.TryGet(index, out var found))
{
// Null resistant
found.TryGetValue(out value);
// We don't donate because we didn't remove
return(true);
}
value = default;
return(false);
}
/// <summary>
/// Tries to retrieve the item at the specified index.
/// </summary>
/// <param name="index">The index.</param>
/// <param name="value">The value.</param>
/// <returns>
/// <c>true</c> if the item was retrieved; otherwise, <c>false</c>.
/// </returns>
/// <exception cref="System.ArgumentOutOfRangeException">index;index must be greater or equal to 0 and less than capacity</exception>
public bool TryGet(int index, out T value)
{
TNeedle found;
if (_entries.TryGet(index, out found))
{
// Null resistant
found.TryGetValue(out value);
// We don't donate because we didn't remove
return true;
}
value = default(T);
return false;
}
/// <summary>
/// Tries to retrieve the item at the specified index.
/// </summary>
/// <param name="index">The index.</param>
/// <param name="value">The value.</param>
/// <returns>
/// <c>true</c> if the item was retrieved; otherwise, <c>false</c>.
/// </returns>
/// <exception cref="System.ArgumentOutOfRangeException">index;index must be greater or equal to 0 and less than capacity</exception>
public bool TryGet(int index, out T value)
{
return(_entries.TryGet(index, out value));
}
