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