lib/ometa/ometa/base.js
function _lookahead(expr) {
      var state = this.bt.current_state(),
          ans = expr.call(this);
      this.bt.restore(state);
      return ans
    }
function _lookahead(expr) {
      var state = this.bt.current_state(),
          ans = expr.call(this);
      this.bt.restore(state);
      return ans
    }
function _lookahead ( expr ) { var state = this . bt . current_state ( ) , ans = expr . call ( this ) ; this . bt . restore ( state ) ; return ans }
positive lookahead &rule
positive lookahead &rule