Livt.Collections

src/list/ListIterator.lvt

namespace Livt.Collections.List

using Livt.Lang

/**
 * A caller-owned cursor over an existing typed list; list storage is not copied.
 * The list must remain unchanged during traversal. Separate cursors have
 * independent positions but do not provide synchronization for list mutation.
 */
component ListIterator<T> : IResettableIterator<T>
{
	// Borrowed list reference and cursor position; the iterator owns no elements.
	source: IList<T>
	position: int

	/**
	 * Binds the borrowed list and positions the cursor before its first value.
	 */
	new(source: IList<T>)
	{
		this.source = source
		this.position = 0
	}

	/**
	 * Rewinds the cursor without changing the source list.
	 */
	override fn Reset()
	{
		this.position = 0
	}

	/**
	 * Returns true when the current source size contains another value.
	 */
	override fn HasNext() bool
	{
		return this.position < this.source.GetSize()
	}

	/**
	 * Returns the current value and advances; callers must check HasNext first.
	 */
	override fn Next() T
	{
		assert this.position < this.source.GetSize(), "List iterator is exhausted"
		var value = this.source.Get(this.position)
		this.position++
		return value
	}
}