/// <summary>
/// Initializes an <see cref="Enumerator"/> structure.
/// </summary>
/// <param name="root">The root of the set to be enumerated.</param>
/// <param name="builder">The builder, if applicable.</param>
/// <param name="startIndex">The index of the first element to enumerate.</param>
/// <param name="count">The number of elements in this collection.</param>
/// <param name="reversed"><c>true</c> if the list should be enumerated in reverse order.</param>
internal Enumerator(Node root, Builder builder = null, int startIndex = -1, int count = -1, bool reversed = false)
{
Requires.NotNull(root, nameof(root));
Requires.Range(startIndex >= -1, nameof(startIndex));
Requires.Range(count >= -1, nameof(count));
Requires.Argument(reversed || count == -1 || (startIndex == -1 ? 0 : startIndex) + count <= root.Count);
Requires.Argument(!reversed || count == -1 || (startIndex == -1 ? root.Count - 1 : startIndex) - count + 1 >= 0);
_root = root;
_builder = builder;
_current = null;
_currentNodeEnumeratingByIndex = null;
_startIndex = startIndex >= 0 ? startIndex : (reversed ? root.Count - 1 : 0);
_currentIndex = _startIndex;
_count = count == -1 ? root.Count : count;
_remainingCount = _count;
_reversed = reversed;
_enumeratingBuilderVersion = builder != null ? builder.Version : -1;
_stackSlot0 = default;
_stackSlot1 = default;
_stackSlot2 = default;
_stackSlot3 = default;
_stackSlot4 = default;
_stackSlot5 = default;
_stackSlot6 = default;
_stackSlot7 = default;
_stackSlot8 = default;
_stackSlot9 = default;
_stackSlot10 = default;
_stackSlot11 = default;
_stackSlot12 = default;
_stackSlot13 = default;
_stackSlot14 = default;
_stackSlot15 = default;
_stackSlot16 = default;
_stackSlot17 = default;
_stackSlot18 = default;
_stackSlot19 = default;
_stackSlot20 = default;
_stackSlot21 = default;
_stackSlot22 = default;
_stackSlot23 = default;
_stackSlot24 = default;
_stackSlot25 = default;
_stackSlot26 = default;
_stackSlot27 = default;
_stackSlot28 = default;
_stackSlot29 = default;
_stackSlot30 = default;
_stackSlot31 = default;
_stackSlot32 = default;
_stackSlot33 = default;
_stackSlot34 = default;
_stackSlot35 = default;
_stackSlot36 = default;
_stackSlot37 = default;
_stackSlot38 = default;
_stackSlot39 = default;
_stackSlot40 = default;
_stackSlot41 = default;
_stackSlot42 = default;
_stackSlot43 = default;
_stackSlot44 = default;
_stackSlot45 = default;
_stackSlot46 = default;
_stackTopIndex = -1;
if (_count > 0)
{
this.ResetStack();
}
}