let AST = {
  // Public API used to evaluate derived attributes regarding AST nodes
  helpers: {
    // a mustache is definitely a helper if:
    // * it is an eligible helper, and
    // * it has at least one parameter or hash segment
    helperExpression: function(node) {
      return (
        node.type === 'SubExpression' ||
        ((node.type === 'MustacheStatement' ||
          node.type === 'BlockStatement') &&
          !!((node.params && node.params.length) || node.hash))
      );
    },

    scopedId: function(path) {
      return /^\.|this\b/.test(path.original);
    },

    // an ID is simple if it only has one part, and that part is not
    // `..` or `this`.
    simpleId: function(path) {
      return (
        path.parts.length === 1 && !AST.helpers.scopedId(path) && !path.depth
      );
    }
  }
};

// Must be exported as an object rather than the root of the module as the jison lexer
// must modify the object to operate properly.
export default AST;