ladybird/AK/Buffered.h
Lenny Maiorani 2844f7c333 Everywhere: Switch from EnableIf to requires
C++20 provides the `requires` clause which simplifies the ability to
limit overload resolution. Prefer it over `EnableIf`

With all uses of `EnableIf` being removed, also remove the
implementation so future devs are not tempted.
2022-03-17 22:15:42 -07:00

198 lines
5.3 KiB
C++

/*
* Copyright (c) 2020, the SerenityOS developers.
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/Noncopyable.h>
#include <AK/Span.h>
#include <AK/StdLibExtras.h>
#include <AK/Stream.h>
#include <AK/Types.h>
#include <AK/kmalloc.h>
namespace AK {
// FIXME: Implement Buffered<T> for DuplexStream.
template<typename StreamType, size_t Size = 4096>
class Buffered;
template<typename StreamType, size_t Size>
requires(IsBaseOf<InputStream, StreamType>) class Buffered<StreamType, Size> final : public InputStream {
AK_MAKE_NONCOPYABLE(Buffered);
public:
template<typename... Parameters>
explicit Buffered(Parameters&&... parameters)
: m_stream(forward<Parameters>(parameters)...)
{
}
Buffered(Buffered&& other)
: m_stream(move(other.m_stream))
{
other.buffer().copy_to(buffer());
m_buffered = exchange(other.m_buffered, 0);
}
bool has_recoverable_error() const override { return m_stream.has_recoverable_error(); }
bool has_fatal_error() const override { return m_stream.has_fatal_error(); }
bool has_any_error() const override { return m_stream.has_any_error(); }
bool handle_recoverable_error() override { return m_stream.handle_recoverable_error(); }
bool handle_fatal_error() override { return m_stream.handle_fatal_error(); }
bool handle_any_error() override { return m_stream.handle_any_error(); }
void set_recoverable_error() const override { return m_stream.set_recoverable_error(); }
void set_fatal_error() const override { return m_stream.set_fatal_error(); }
size_t read(Bytes bytes) override
{
if (has_any_error())
return 0;
auto nread = buffer().trim(m_buffered).copy_trimmed_to(bytes);
m_buffered -= nread;
if (m_buffered > 0)
buffer().slice(nread, m_buffered).copy_to(buffer());
if (nread < bytes.size()) {
nread += m_stream.read(bytes.slice(nread));
m_buffered = m_stream.read(buffer());
}
return nread;
}
bool read_or_error(Bytes bytes) override
{
if (read(bytes) < bytes.size()) {
set_fatal_error();
return false;
}
return true;
}
bool unreliable_eof() const override { return m_buffered == 0 && m_stream.unreliable_eof(); }
bool eof() const
{
if (m_buffered > 0)
return false;
m_buffered = m_stream.read(buffer());
return m_buffered == 0;
}
bool discard_or_error(size_t count) override
{
size_t ndiscarded = 0;
while (ndiscarded < count) {
u8 dummy[Size];
if (!read_or_error({ dummy, min(Size, count - ndiscarded) }))
return false;
ndiscarded += min(Size, count - ndiscarded);
}
return true;
}
size_t buffered() const { return m_buffered; }
// Reading from the stream returned here will most definitely brick the buffering behavior of Buffered.
StreamType& underlying_stream() { return m_stream; }
private:
Bytes buffer() const { return { m_buffer, Size }; }
mutable StreamType m_stream;
mutable u8 m_buffer[Size];
mutable size_t m_buffered { 0 };
};
template<typename StreamType, size_t Size>
requires(IsBaseOf<OutputStream, StreamType>) class Buffered<StreamType, Size> : public OutputStream {
AK_MAKE_NONCOPYABLE(Buffered);
public:
template<typename... Parameters>
explicit Buffered(Parameters&&... parameters)
: m_stream(forward<Parameters>(parameters)...)
{
}
Buffered(Buffered&& other)
: m_stream(move(other.m_stream))
{
other.buffer().copy_to(buffer());
m_buffered = exchange(other.m_buffered, 0);
}
~Buffered()
{
if (m_buffered > 0)
flush();
}
bool has_recoverable_error() const override { return m_stream.has_recoverable_error(); }
bool has_fatal_error() const override { return m_stream.has_fatal_error(); }
bool has_any_error() const override { return m_stream.has_any_error(); }
bool handle_recoverable_error() override { return m_stream.handle_recoverable_error(); }
bool handle_fatal_error() override { return m_stream.handle_fatal_error(); }
bool handle_any_error() override { return m_stream.handle_any_error(); }
void set_recoverable_error() const override { return m_stream.set_recoverable_error(); }
void set_fatal_error() const override { return m_stream.set_fatal_error(); }
size_t write(ReadonlyBytes bytes) override
{
if (has_any_error())
return 0;
auto nwritten = bytes.copy_trimmed_to(buffer().slice(m_buffered));
m_buffered += nwritten;
if (m_buffered == Size) {
flush();
if (bytes.size() - nwritten >= Size)
nwritten += m_stream.write(bytes.slice(nwritten));
nwritten += write(bytes.slice(nwritten));
}
return nwritten;
}
bool write_or_error(ReadonlyBytes bytes) override
{
write(bytes);
return true;
}
void flush()
{
m_stream.write_or_error({ m_buffer, m_buffered });
m_buffered = 0;
}
private:
Bytes buffer() { return { m_buffer, Size }; }
StreamType m_stream;
u8 m_buffer[Size];
size_t m_buffered { 0 };
};
}
using AK::Buffered;