来自file_descriptor_source(boost :: iostreams)或文件的istream

Question

我需要为我的程序输入执行类似的操作:

stream input;
if (decompressed)
    input.open(filepath);
else {
    file_descriptor=_popen("decompressor "+filepath,"r");
    input.open(file_descriptor);
}
input.read(...)
...

我可以看到一个解决方案 - 在两种情况下都使用_popen,如果它已经解压缩,只需将文件复制到stdout,但这似乎不是很优雅.

有趣的是,与C相比有多难 - 我想标准库错过了它.现在我迷失在神秘的boost :: iostreams文档中.如果有人知道如何,示例代码会很棒.

Answer 1

这就是你所追求的:

#include <cstdio>
#include <string>
#include <iostream>
#include <boost/iostreams/device/file_descriptor.hpp>
#include <boost/iostreams/stream.hpp>

namespace io = boost::iostreams;

int main()
{
    bool flag = false;

    FILE* handle = 0; 
    if (flag)
    {
        handle = _popen("dir", "r");
    }
    else
    {
        handle = fopen ("main.cpp", "r");
    }

    io::stream_buffer<io::file_descriptor_source> fpstream (fileno(handle));
    std::istream in (&fpstream);

    std::string line;
    while (in)
    {
        std::getline (in, line);
        std::cout << line << std::endl;
    }

    return 0;
}