code: function parseInterp(source) {
      var walker = new Walker(source);
  
      var interp = {
          type: ExprType.INTERP,
          expr: readTertiaryExpr(walker),
          filters: [],
          raw: source
      };
  
      while (walker.goUntil(124)) { // |
          var callExpr = readCall(walker, []);
          switch (callExpr.name.paths[0].value) {
              case 'html':
                  break;
              case 'raw':
                  interp.original = 1;
                  break;
              default:
                  interp.filters.push(callExpr);
          }
      }
  
      return interp;
  }
docs: 解析插值替换
  
  @param {string} source 源码
  @return {Object}