src/compile/literal.js
function(literal) {
      var val = literal.value;
      var ret = val;

      if (literal.isEval && (val.indexOf('#') !== -1 ||
            val.indexOf("$") !== -1)) {
        ret = this.evalStr(val);
      }

      return ret;
    }
function(literal) {
      var val = literal.value;
      var ret = val;

      if (literal.isEval && (val.indexOf('#') !== -1 ||
            val.indexOf("$") !== -1)) {
        ret = this.evalStr(val);
      }

      return ret;
    }
对字符串求值，对已双引号字符串，需要做变量替换