1// Copyright 2024 The Go Authors. All rights reserved.
 2// Use of this source code is governed by a BSD-style
 3// license that can be found in the LICENSE file.
 4
 5//go:build go1.23
 6
 7package html
 8
 9import "iter"
10
11// Ancestors returns an iterator over the ancestors of n, starting with n.Parent.
12//
13// Mutating a Node or its parents while iterating may have unexpected results.
14func (n *Node) Ancestors() iter.Seq[*Node] {
15	_ = n.Parent // eager nil check
16
17	return func(yield func(*Node) bool) {
18		for p := n.Parent; p != nil && yield(p); p = p.Parent {
19		}
20	}
21}
22
23// ChildNodes returns an iterator over the immediate children of n,
24// starting with n.FirstChild.
25//
26// Mutating a Node or its children while iterating may have unexpected results.
27func (n *Node) ChildNodes() iter.Seq[*Node] {
28	_ = n.FirstChild // eager nil check
29
30	return func(yield func(*Node) bool) {
31		for c := n.FirstChild; c != nil && yield(c); c = c.NextSibling {
32		}
33	}
34
35}
36
37// Descendants returns an iterator over all nodes recursively beneath
38// n, excluding n itself. Nodes are visited in depth-first preorder.
39//
40// Mutating a Node or its descendants while iterating may have unexpected results.
41func (n *Node) Descendants() iter.Seq[*Node] {
42	_ = n.FirstChild // eager nil check
43
44	return func(yield func(*Node) bool) {
45		n.descendants(yield)
46	}
47}
48
49func (n *Node) descendants(yield func(*Node) bool) bool {
50	for c := range n.ChildNodes() {
51		if !yield(c) || !c.descendants(yield) {
52			return false
53		}
54	}
55	return true
56}