code: function init() {
      if (tokens) {
        return;
      }
      if (fromString) {
        tokens = cbml.parse(contentString);
      }
      else {
        tokens = cbml.parse(fs.readFileSync(filename));
      }
      /*<debug>
      console.log(JSON.stringify(tokens, null, '  '));
      //</debug>*/
    }
docs: 编译 jdists 文件，初始化语法树