Walk trees.

TreeWalker.hx

import js.html.Element;

interface TreeWalker<T, Cls> {
  function attr(target:T, name:String):String;
  function hasClass(target:T, cls:Cls):Bool;
  function parent(target:T):Null<T>;
  function prev(target:T):Null<T>;
  function next(target:T):Null<T>;
  function firstChild(target:T):Null<T>;
}

class DomWalker implements TreeWalker<Element, String> {
  
  public function hasClass(target:Element, cls:String):Bool
    return target.classList.contains(cls);

  public function attr(target:Element, name:String):String 
    return target.getAttribute(name);
    
  public function parent(target:Element):Null<Element>
    return target.parentElement;
  
  public function prev(target:Element):Null<Element> 
    return target.previousElementSibling;
    
  public function next(target:Element):Null<Element>
    return target.nextElementSibling;
    
  public function firstChild(target:Element):Null<Element>
    return target.nextElementSibling;
}

class WalkUp<T, Cls> {
  var cur:T;
  var walker:TreeWalker<T, Cls>;
  
  public inline function new(cur, walker) {
    this.walker = walker;
    this.cur = walker.parent(cur);
  }
  
  public inline function hasNext()
    return cur != null;
    
  public inline function next() {
    var ret = cur;
    cur = walker.parent(cur);
    return ret;
  }
}

class WalkPrev<T, Cls> {
  var cur:T;
  var walker:TreeWalker<T, Cls>;
  
  public inline function new(cur, walker) {
    this.walker = walker;
    this.cur = walker.parent(cur);
  }
  
  public inline function hasNext()
    return cur != null;
    
  public inline function next() {
    var ret = cur;
    cur = walker.prev(cur);
    return ret;
  }
}