中序遍历迭代器

MidIterator.js

var MidIterator = function(root) {
  this.stack = [root];
  this.__pushLeft(root);
};
MidIterator.prototype.__pushLeft = function(node) {
  if (!node) return;
  var left = node.left;
  while (left) {
    this.stack.push(left);
    left = left.left;
  }
};
MidIterator.prototype.next = function() {
  var stack = this.stack;
  if (stack.length === 0) {
    return {
      finished: true
    }
  }
  var top = stack.pop();
  if (top.right) {
    stack.push(top.right);
    this.__pushLeft(top.right);
  }
  return {
    value: top.value,
    finished: false
  };
};

var iter = new MidIterator(root);
for (var it = iter.next(); !it.finished; it = iter.next()) {
  console.log(it.value);
}