boost :: asio :: streambuf是否不可搜索？

Question

我的应用程序中需要一个整洁的可搜索流缓冲区，并且我已经将boost :: asio与异步套接字和计时器集成在一起。我还想尝试集成一个缓冲区，该缓冲区可用作具有搜索功能的流。我尝试将boost :: asio :: streambuf包装在std :: iostream中，并且tell函数返回-1，并且在搜索时遇到异常。

我用错了还是我使用了错误的缓冲对象？

BufferTest.cpp

#include <boost/asio/streambuf.hpp>
#include <iostream>

/**
 * Main when we come in
 */
int main( int argc, char *argv[] )
{
    boost::asio::streambuf streambuf;
    std::iostream stream( &streambuf );


    try
    {
        stream.exceptions ( std::iostream::failbit | std::iostream::badbit );

        stream.write( "hello", 5 );
        stream.write( "test", 4 );

        std::cout << "Step 1" << std::endl;

        char buffer[ 9 ];
        stream.read( buffer, 9 );

        std::cout << "Step 2" << std::endl;

        std::cout << "The worst: " << std::string( buffer, 9 ) << std::endl;

        std::cout << "Step 3" << std::endl;

        stream.seekg( 0 );

        std::cout << "Step 4" << std::endl;

        stream.read( buffer, 9 );
        std::cout << "The worst: " << std::string( buffer, 9 ) << std::endl;
    }
    catch( const std::exception &e )
    {
        std::cerr << "Exception: " << e.what() << std::endl;
    }
}

输出：

$ ./bin/buffer_test 
Step 1
Step 2
The worst: hellotest
Step 3
Exception: basic_ios::clear: iostream error