/// <summary>
/// Iterates over the descendant elements for the specified markdown <see cref="Block" /> element and filters by the type {T}.
/// </summary>
/// <typeparam name="T">Type to use for filtering the descendants</typeparam>
/// <param name="block">The markdown object.</param>
/// <returns>
/// An iteration over the descendant elements
/// </returns>
public static IEnumerable <T> Descendants <T>(this ContainerBlock block) where T : Block
{
// Fast-path an empty container to avoid allocating a Stack
if (block.Count == 0)
{
yield break;
}
Stack <Block> stack = new Stack <Block>();
int childrenCount = block.Count;
while (childrenCount-- > 0)
{
stack.Push(block[childrenCount]);
}
while (stack.Count > 0)
{
var subBlock = stack.Pop();
if (subBlock is T subBlockT)
{
yield return(subBlockT);
}
if (subBlock is ContainerBlock subBlockContainer)
{
childrenCount = subBlockContainer.Count;
while (childrenCount-- > 0)
{
stack.Push(subBlockContainer[childrenCount]);
}
}
}
}
internal Enumerator(ContainerBlock block)
{
this.block = block;
index = 0;
current = null;
}