特定のデータ形式と変換用に C でカスタム入力ストリームを作成する方法

<code class="cpp">class CompressedStreamBuf : public std::streambuf {
public:
    // Constructor takes the original stream buffer and the compression parameters
    CompressedStreamBuf(std::streambuf* original, CompressionAlgorithm algorithm)
        : m_original(original), m_algorithm(algorithm) {}

    // Underflow implementation decompresses data into the buffer
    std::streambuf::int_type underflow() {
        // Decompress data from original stream into the buffer
        m_algorithm.decompress(m_original, m_buffer, m_buffer_size);

        // If no more data, return EOF
        if (std::streamsize read = m_original->gcount()) {
            return traits_type::to_int_type(*pptr());
        } else {
            return traits_type::eof();
        }
    }

private:
    std::streambuf* m_original;
    CompressionAlgorithm m_algorithm;
    char* m_buffer;
    std::streamsize m_buffer_size;
};</code>

<code class="cpp">std::ifstream compressed_file("file.cmp");
CompressedStreamBuf compressed_streambuf(compressed_file, CompressionAlgorithm::GZIP);
std::istream compressed_stream(&compressed_streambuf);</code>