using System;

using System.Collections;

using System.Collections.Generic;

namespace ModuleManager.Collections

{

public struct ArrayEnumerator<T> : IEnumerator<T>

{

private readonly T[] array;

private readonly int startIndex;

private readonly int length;

private int index;

public ArrayEnumerator(params T[] array) : this(array, 0) { }

public ArrayEnumerator(T[] array, int startIndex) : this(array, startIndex, (array?.Length ?? -1) - startIndex) { }

public ArrayEnumerator(T[] array, int startIndex, int length)

{

this.array = array ?? throw new ArgumentNullException(nameof(array));

if (startIndex < 0)

throw new ArgumentException($"must be non-negative (got {startIndex})", nameof(startIndex));

if (startIndex > array.Length)

throw new ArgumentException(

$"must be less than or equal to array length (array length {array.Length}, startIndex {startIndex})",

nameof(startIndex)

);

if (length < 0)

throw new ArgumentException($"must be non-negative (got {length})", nameof(length));

if (startIndex + length > array.Length)

throw new ArgumentException(

$"must fit within the string (array length {array.Length}, startIndex {startIndex}, length {length})",

nameof(length)

);

this.startIndex = startIndex;

this.length = length;

index = startIndex - 1;

}

public T Current => array[index];

object IEnumerator.Current => Current;

public void Dispose() { }

public bool MoveNext()

{

index++;

return index < startIndex + length;

}

public void Reset()

{

index = startIndex - 1;

}

}

}