/// <summary>
/// Производит выборку поддеревьев узла, указанного <paramref name="hnd"/>.
/// <para>Порядок обхода — breadth-first.</para>
/// </summary>
/// <typeparam name="T">Тип узла дерева.</typeparam>
/// <param name="hnd">
/// Узел.
/// </param>
/// <param name="predicate">Предикат выборки поддерева.</param>
/// <param name="childrenSelector">Селектор дочерных узлов.</param>
/// <returns>Объект <see cref="IEnumerable{T}"/>.</returns>
public static IEnumerable <T> Subtrees <T>(this SingleTreeNodeUtilitiesHandle <T> hnd, Func <T, bool> predicate, Func <T, IEnumerable <T> > childrenSelector)
{
predicate.EnsureNotNull(nameof(predicate));
childrenSelector.EnsureNotNull(nameof(childrenSelector));
//
if (predicate(arg: hnd.Source))
{
yield return(hnd.Source);
}
else
{
var traversal = new Queue <T>(collection: hnd.Source.Sequence());
for (; traversal.Count > 0;)
{
var current = traversal.Dequeue();
foreach (var child in childrenSelector(arg: current).EmptyIfNull())
{
if (predicate(child))
{
yield return(child);
}
else
{
traversal.Enqueue(child);
}
}
}
}
}
public static IEnumerable <T> Ancestors <T>(this SingleTreeNodeUtilitiesHandle <T> hnd, Func <T, T> parentSelector)
{
parentSelector.EnsureNotNull(nameof(parentSelector));
//
var parent = parentSelector(hnd.Source);
for (; parent != null;)
{
yield return(parent);
parent = parentSelector(parent);
}
}
public static TResult Transform <TSource, TResult>(this SingleTreeNodeUtilitiesHandle <TSource> hnd, Func <TSource, IEnumerable <TSource> > childrenSelector, Func <TSource, IEnumerable <TResult>, TResult> transform)
{
childrenSelector.EnsureNotNull(nameof(childrenSelector));
transform.EnsureNotNull(nameof(transform));
//
var root = new P_TreeNodeTransformState <TSource, TResult>(hnd.Source);
var traversalStack = new Stack <P_TreeNodeTransformState <TSource, TResult> >(root.Sequence());
for (; traversalStack.Count > 0;)
{
var currentTraversalEntry = traversalStack.Peek();
//
var initialSizeOfTraversalStack = traversalStack.Count;
if (currentTraversalEntry.SourceChildren == null)
{
currentTraversalEntry.SourceChildren =
childrenSelector(currentTraversalEntry.Source)
.EmptyIfNull()
.ToArray();
for (var i = currentTraversalEntry.SourceChildren.Length - 1; i > -1; i--)
{
traversalStack
.Push(
new P_TreeNodeTransformState <TSource, TResult>(
currentTraversalEntry,
currentTraversalEntry.SourceChildren[i]));
}
}
//
if (initialSizeOfTraversalStack == traversalStack.Count)
{
traversalStack.Pop();
if (!ReferenceEquals(currentTraversalEntry, root))
{
currentTraversalEntry
.Parent
.TransformedSourceChildren
.Add(transform(currentTraversalEntry.Source, currentTraversalEntry.TransformedSourceChildren));
}
}
}
return(transform(root.Source, root.TransformedSourceChildren));
}
public static IEnumerable <T> Descendants <T>(this SingleTreeNodeUtilitiesHandle <T> hnd, Func <T, IEnumerable <T> > childrenSelector)
{
childrenSelector.EnsureNotNull(nameof(childrenSelector));
//
var traversalBuffer = new Queue <T>();
foreach (var child in childrenSelector(arg: hnd.Source).EmptyIfNull())
{
traversalBuffer.Enqueue(child);
}
for (; traversalBuffer.Count > 0;)
{
var current = traversalBuffer.Dequeue();
foreach (var child in childrenSelector(current).EmptyIfNull())
{
traversalBuffer.Enqueue(child);
}
yield return(current);
}
}
public static IEnumerable <T> SelfAndDescendants <T>(this SingleTreeNodeUtilitiesHandle <T> hnd, Func <T, IEnumerable <T> > childrenSelector) => Enumerable.Concat(first: hnd.Source.Sequence(), second: Descendants(hnd: hnd, childrenSelector: childrenSelector));
public static IEnumerable <T> SelfAndAncestors <T>(this SingleTreeNodeUtilitiesHandle <T> hnd, Func <T, T> parentSelector) => Enumerable.Concat(first: hnd.Source.Sequence(), second: Ancestors(hnd: hnd, parentSelector: parentSelector));
