mpd/src/io/BufferedOutputStream.cxx
2023-05-21 21:35:11 +02:00

114 lines
2.4 KiB
C++

// SPDX-License-Identifier: BSD-2-Clause
// author: Max Kellermann <max.kellermann@gmail.com>
#include "BufferedOutputStream.hxx"
#include "OutputStream.hxx"
#include "util/SpanCast.hxx"
#include <fmt/format.h>
#include <cstdarg>
#include <string.h>
#ifdef _UNICODE
#include "system/Error.hxx"
#include <stringapiset.h>
#endif
bool
BufferedOutputStream::AppendToBuffer(std::span<const std::byte> src) noexcept
{
auto w = buffer.Write();
if (w.size() < src.size())
return false;
std::copy(src.begin(), src.end(), w.begin());
buffer.Append(src.size());
return true;
}
void
BufferedOutputStream::Write(std::span<const std::byte> src)
{
/* try to append to the current buffer */
if (AppendToBuffer(src))
return;
/* not enough room in the buffer - flush it */
Flush();
/* see if there's now enough room */
if (AppendToBuffer(src))
return;
/* too large for the buffer: direct write */
os.Write(src);
}
void
BufferedOutputStream::VFmt(fmt::string_view format_str, fmt::format_args args)
{
/* TODO format into this object's buffer instead of allocating
a new one */
fmt::memory_buffer b;
#if FMT_VERSION >= 80000
fmt::vformat_to(std::back_inserter(b), format_str, args);
#else
fmt::vformat_to(b, format_str, args);
#endif
return Write(std::as_bytes(std::span{b.data(), b.size()}));
}
#ifdef _UNICODE
void
BufferedOutputStream::WriteWideToUTF8(std::wstring_view src)
{
if (src.empty())
return;
auto r = buffer.Write();
if (r.empty()) {
Flush();
r = buffer.Write();
}
int length = WideCharToMultiByte(CP_UTF8, 0, src.data(), src.size(),
(char *)r.data(), r.size(),
nullptr, nullptr);
if (length <= 0) {
const auto error = GetLastError();
if (error != ERROR_INSUFFICIENT_BUFFER)
throw MakeLastError(error, "UTF-8 conversion failed");
/* how much buffer do we need? */
length = WideCharToMultiByte(CP_UTF8, 0, src.data(), src.size(),
nullptr, 0, nullptr, nullptr);
if (length <= 0)
throw MakeLastError(error, "UTF-8 conversion failed");
/* grow the buffer and try again */
length = WideCharToMultiByte(CP_UTF8, 0, src.data(), src.size(),
(char *)buffer.Write(length), length,
nullptr, nullptr);
if (length <= 0)
throw MakeLastError(error, "UTF-8 conversion failed");
}
buffer.Append(length);
}
#endif
void
BufferedOutputStream::Flush()
{
auto r = buffer.Read();
if (r.empty())
return;
os.Write(r);
buffer.Consume(r.size());
}