export default class Walker {
  constructor(order) {
    this.order = order;
    this.stack = [];
  }

  visit(node, callback) {
    if (!node) {
      return;
    }

    this.stack.push(node);

    if (this.order === 'post') {
      this.children(node, callback);
      callback(node, this);
    } else {
      callback(node, this);
      this.children(node, callback);
    }

    this.stack.pop();
  }

  children(node, callback) {
    switch (node.type) {
      case 'Block':
      case 'Template':
        return visitors.Program(this, node, callback);

      case 'ElementNode':
        return visitors.ElementNode(this, node, callback);

      case 'BlockStatement':
        return visitors.BlockStatement(this, node, callback);

      default:
        return;
    }
  }

}
const visitors = {
  Program(walker, node, callback) {
    for (let i = 0; i < node.body.length; i++) {
      walker.visit(node.body[i], callback);
    }
  },

  Template(walker, node, callback) {
    for (let i = 0; i < node.body.length; i++) {
      walker.visit(node.body[i], callback);
    }
  },

  Block(walker, node, callback) {
    for (let i = 0; i < node.body.length; i++) {
      walker.visit(node.body[i], callback);
    }
  },

  ElementNode(walker, node, callback) {
    for (let i = 0; i < node.children.length; i++) {
      walker.visit(node.children[i], callback);
    }
  },

  BlockStatement(walker, node, callback) {
    walker.visit(node.program, callback);
    walker.visit(node.inverse || null, callback);
  }

};
//# sourceMappingURL=data:application/json;charset=utf-8;base64,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