Question

我想使用已经使用bzip2压缩的boost来解压缩文件

我尝试了以下操作，导致无法解释的错误

std::stringstream readData(const std::string path) {
        std::stringstream myStream;
        std::ifstream input(path,std::ios_base::in);

        boost::iostreams::filtering_streambuf<boost::iostreams::input>in;
        in.push(input);
        in.push(boost::iostreams::bzip2_decompressor());
        boost::iostreams::copy(in,myStream);

        return myStream;
    }

我使用c ++ 17，boost 1.58和gcc 8.0来编译上面的代码

并出现以下错误：

terminate called after throwing an instance of 'boost::exception_detail::clone_impl<boost::exception_detail::error_info_injectorstd::logic_error >'
what(): chain complete

将感谢您提供有关如何解决此问题的帮助/提示

Answer 1

设备必须是您推送到CASE..WHEN中的最后一项，在您推送设备之后，您将不能再推送其他任何东西，这就是您得到错误的原因。参见https://www.boost.org/doc/libs/1_68_0/libs/iostreams/doc/classes/filtering_streambuf.html#policy_push

您的代码应为：

SELECT
  dt.id, 
  dt.Start,
  dt.Stop, 
  @rn := CASE WHEN dt.itemId = @itm THEN @rn + 1
              ELSE 1 
         END AS Count, 
  @itm := dt.itemId AS itemId 
FROM
(
  SELECT 
    id, 
    itemId, 
    started_at AS Start, 
    stopped_at AS Stop 
  FROM events
  ORDER BY itemID, id
) AS dt
CROSS JOIN (SELECT @itm := 0, @rn := 0) AS user_init_vars

使用boost解压缩文件

1 个答案: