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/*
* Copyright (c) 2021, kleines Filmröllchen <filmroellchen@serenityos.org>.
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/Error.h>
#include <AK/NonnullOwnPtr.h>
#include <AK/OwnPtr.h>
#include <AK/Span.h>
#include <AK/TypedTransfer.h>
#include <LibCore/Stream.h>
namespace Core::Stream {
class MemoryStream final : public SeekableStream {
public:
static ErrorOr<NonnullOwnPtr<MemoryStream>> construct(Bytes bytes)
{
return adopt_nonnull_own_or_enomem<MemoryStream>(new (nothrow) MemoryStream(bytes));
}
virtual bool is_eof() const override { return m_offset >= m_bytes.size(); }
virtual bool is_open() const override { return true; }
// FIXME: It doesn't make sense to close an memory stream. Therefore, we don't do anything here. Is that fine?
virtual void close() override { }
// FIXME: It doesn't make sense to truncate a memory stream. Therefore, we don't do anything here. Is that fine?
virtual ErrorOr<void> truncate(off_t) override { return Error::from_errno(ENOTSUP); }
virtual ErrorOr<Bytes> read(Bytes bytes) override
{
auto to_read = min(remaining(), bytes.size());
if (to_read == 0)
return Bytes {};
m_bytes.slice(m_offset, to_read).copy_to(bytes);
m_offset += to_read;
return bytes.trim(to_read);
}
virtual ErrorOr<off_t> seek(i64 offset, SeekMode seek_mode = SeekMode::SetPosition) override
{
switch (seek_mode) {
case SeekMode::SetPosition:
if (offset >= static_cast<i64>(m_bytes.size()))
return Error::from_string_literal("Offset past the end of the stream memory"sv);
m_offset = offset;
break;
case SeekMode::FromCurrentPosition:
if (offset + static_cast<i64>(m_offset) >= static_cast<i64>(m_bytes.size()))
return Error::from_string_literal("Offset past the end of the stream memory"sv);
m_offset += offset;
break;
case SeekMode::FromEndPosition:
if (offset >= static_cast<i64>(m_bytes.size()))
return Error::from_string_literal("Offset past the start of the stream memory"sv);
m_offset = m_bytes.size() - offset;
break;
}
return static_cast<off_t>(m_offset);
}
virtual ErrorOr<size_t> write(ReadonlyBytes bytes) override
{
// FIXME: Can this not error?
auto const nwritten = bytes.copy_trimmed_to(m_bytes.slice(m_offset));
m_offset += nwritten;
return nwritten;
}
virtual bool write_or_error(ReadonlyBytes bytes) override
{
if (remaining() < bytes.size())
return false;
MUST(write(bytes));
return true;
}
Bytes bytes() { return m_bytes; }
ReadonlyBytes bytes() const { return m_bytes; }
size_t offset() const { return m_offset; }
size_t remaining() const { return m_bytes.size() - m_offset; }
protected:
explicit MemoryStream(Bytes bytes)
: m_bytes(bytes)
{
}
private:
Bytes m_bytes;
size_t m_offset { 0 };
};
}
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