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// This source code is released into the public domain.
export module nihil.core:capture_stream;
import nihil.std;
namespace nihil {
// Capture output written to a stream and redirect it to an internal string
// buffer. Call .str() to get the data written. Call .release() to stop
// capturing (or simply delete the capture_stream object).
export template<typename Char, typename Traits>
struct capture_stream {
capture_stream(std::basic_ostream<Char, Traits> &stream)
: m_stream(&stream)
{
m_old_streambuf = m_stream->rdbuf();
m_stream->rdbuf(m_buffer.rdbuf());
}
~capture_stream()
{
if (m_old_streambuf == nullptr)
return;
m_stream->rdbuf(m_old_streambuf);
}
/*
* Release this capture, returning the stream to its previous state.
*/
auto release(this capture_stream &self) -> void
{
if (self.m_old_streambuf == nullptr)
throw std::logic_error(
"release() called on empty capture_stream");
self.m_stream->rdbuf(self.m_old_streambuf);
self.m_old_streambuf = nullptr;
}
/*
* Get the data which has been written to the stream.
*/
[[nodiscard]] auto str(this capture_stream const &self)
-> std::basic_string_view<Char, Traits>
{
return self.m_buffer.view();
}
private:
std::basic_ostringstream<Char, Traits> m_buffer;
std::basic_ostream<Char, Traits> *m_stream;
std::streambuf *m_old_streambuf;
};
} // namespace nihil
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