创造一个ostream [英] creating an ostream

问题描述

我出于教育原因尝试创建一个c ++ ostream。我的测试将创建一个ostream，其行为像一个流，除了而不是写入一个文件，它将写入一个deque或向量容器。

I am trying to create a c++ ostream for educational reasons. My test will be creating an ostream that acts like a ofstream would except instead of writing to a file it would write to a deque or vector container.

推荐答案

正如你所说的，我会告诉你我将如何做这样的事情。否则， stringstream 是真的要走。

听起来你想创建一个streambuf实现，然后写入向量/ deque。这样的东西（复制从我的另一个答案，定向/ dev / null stream ）：

Sounds like you want to create a streambuf implementation that then writes to a vector / deque. Something like this (copying from another answer of me that targeted a /dev/null stream):

template<typename Ch, typename Traits = std::char_traits<Ch>,
         typename Sequence = std::vector<Ch> >
struct basic_seqbuf : std::basic_streambuf<Ch, Traits> {
     typedef std::basic_streambuf<Ch, Traits> base_type;
     typedef typename base_type::int_type int_type;
     typedef typename base_type::traits_type traits_type;

     virtual int_type overflow(int_type ch) {
         if(traits_type::eq_int_type(ch, traits_type::eof()))
             return traits_type::eof();
         c.push_back(traits_type::to_char_type(ch));
         return ch;
     }

    Sequence const& get_sequence() const {
        return c;
    }
protected:
    Sequence c;
};

// convenient typedefs
typedef basic_seqbuf<char> seqbuf;
typedef basic_seqbuf<wchar_t> wseqbuf;

您可以这样使用：

seqbuf s;
std::ostream os(&s);
os << "hello, i'm " << 22 << " years old" << std::endl;
std::vector<char> v = s.get_sequence();

如果你想要一个deque作为序列，你可以这样做：

If you want to have a deque as sequence, you can do so:

typedef basic_seqbuf< char, char_traits<char>, std::deque<char> > dseq_buf;

或类似的东西...我没有测试过。但也许这也是一件好事 - 所以如果它仍然包含错误，你可以尝试修复它们。

Or something similar... Well i haven't tested it. But maybe that's also a good thing - so if it contains still bugs, you can try fixing them.

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