llvm/llvm/include/llvm/Support/BinaryItemStream.h

//===- BinaryItemStream.h ---------------------------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_SUPPORT_BINARYITEMSTREAM_H
#define LLVM_SUPPORT_BINARYITEMSTREAM_H

#include "llvm/ADT/ArrayRef.h"
#include "llvm/Support/BinaryStream.h"
#include "llvm/Support/BinaryStreamError.h"
#include "llvm/Support/Error.h"
#include <cstddef>
#include <cstdint>

namespace llvm {

template <typename T> struct BinaryItemTraits { … };

/// BinaryItemStream represents a sequence of objects stored in some kind of
/// external container but for which it is useful to view as a stream of
/// contiguous bytes.  An example of this might be if you have a collection of
/// records and you serialize each one into a buffer, and store these serialized
/// records in a container.  The pointers themselves are not laid out
/// contiguously in memory, but we may wish to read from or write to these
/// records as if they were.
template <typename T, typename Traits = BinaryItemTraits<T>>
class BinaryItemStream : public BinaryStream {
public:
  explicit BinaryItemStream(llvm::endianness Endian) : … { … }

  llvm::endianness getEndian() const override { … }

  Error readBytes(uint64_t Offset, uint64_t Size,
                  ArrayRef<uint8_t> &Buffer) override { … }

  Error readLongestContiguousChunk(uint64_t Offset,
                                   ArrayRef<uint8_t> &Buffer) override { … }

  void setItems(ArrayRef<T> ItemArray) { … }

  uint64_t getLength() override { … }

private:
  void computeItemOffsets() { … }

  Expected<uint32_t> translateOffsetIndex(uint64_t Offset) { … }

  llvm::endianness Endian;
  ArrayRef<T> Items;

  // Sorted vector of offsets to accelerate lookup.
  std::vector<uint64_t> ItemEndOffsets;
};

} // end namespace llvm

#endif // LLVM_SUPPORT_BINARYITEMSTREAM_H