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/*
* Copyright (c) 2021, kleines Filmröllchen <filmroellchen@serenityos.org>.
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/OwnPtr.h>
#include <AK/Stream.h>
#include <AK/Vector.h>
namespace AK {
/// A stream class that allows for reading/writing on a preallocated memory area
/// using a single read/write head.
class FixedMemoryStream final : public SeekableStream {
public:
static ErrorOr<NonnullOwnPtr<FixedMemoryStream>> construct(Bytes bytes);
static ErrorOr<NonnullOwnPtr<FixedMemoryStream>> construct(ReadonlyBytes bytes);
virtual bool is_eof() const override;
virtual bool is_open() const override;
virtual void close() override;
virtual ErrorOr<void> truncate(size_t) override;
virtual ErrorOr<Bytes> read(Bytes bytes) override;
virtual ErrorOr<size_t> seek(i64 offset, SeekMode seek_mode = SeekMode::SetPosition) override;
virtual ErrorOr<size_t> write(ReadonlyBytes bytes) override;
virtual ErrorOr<void> write_entire_buffer(ReadonlyBytes bytes) override;
Bytes bytes();
ReadonlyBytes bytes() const;
size_t offset() const;
size_t remaining() const;
private:
explicit FixedMemoryStream(Bytes bytes);
explicit FixedMemoryStream(ReadonlyBytes bytes);
Bytes m_bytes;
size_t m_offset { 0 };
bool m_writing_enabled { true };
};
/// A stream class that allows for writing to an automatically allocating memory area
/// and reading back the written data afterwards.
class AllocatingMemoryStream final : public Stream {
public:
virtual ErrorOr<Bytes> read(Bytes) override;
virtual ErrorOr<size_t> write(ReadonlyBytes) override;
virtual ErrorOr<void> discard(size_t) override;
virtual bool is_eof() const override;
virtual bool is_open() const override;
virtual void close() override;
size_t used_buffer_size() const;
ErrorOr<Optional<size_t>> offset_of(ReadonlyBytes needle) const;
private:
// Note: We set the inline buffer capacity to zero to make moving chunks as efficient as possible.
using Chunk = AK::Detail::ByteBuffer<0>;
static constexpr size_t chunk_size = 4096;
ErrorOr<ReadonlyBytes> next_read_range();
ErrorOr<Bytes> next_write_range();
void cleanup_unused_chunks();
Vector<Chunk> m_chunks;
size_t m_read_offset = 0;
size_t m_write_offset = 0;
};
}
#if USING_AK_GLOBALLY
using AK::AllocatingMemoryStream;
using AK::FixedMemoryStream;
#endif
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