//===- DXContainer.h - DXContainer file implementation ----------*- 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
//
//===----------------------------------------------------------------------===//
//
// This file declares the DXContainerFile class, which implements the ObjectFile
// interface for DXContainer files.
//
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_OBJECT_DXCONTAINER_H
#define LLVM_OBJECT_DXCONTAINER_H

#include "llvm/ADT/Optional.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/BinaryFormat/DXContainer.h"
#include "llvm/Support/Error.h"
#include "llvm/Support/MemoryBufferRef.h"

namespace llvm {
namespace object {
class DXContainer {
public:
  using DXILData = std::pair<dxbc::ProgramHeader, const char *>;

private:
  DXContainer(MemoryBufferRef O);

  MemoryBufferRef Data;
  dxbc::Header Header;
  SmallVector<uint32_t, 4> PartOffsets;
  Optional<DXILData> DXIL;

  Error parseHeader();
  Error parsePartOffsets();
  Error parseDXILHeader(uint32_t Offset);
  friend class PartIterator;

public:
  // The PartIterator is a wrapper around the iterator for the PartOffsets
  // member of the DXContainer. It contains a refernce to the container, and the
  // current iterator value, as well as storage for a parsed part header.
  class PartIterator {
    const DXContainer &Container;
    SmallVectorImpl<uint32_t>::const_iterator OffsetIt;
    struct PartData {
      dxbc::PartHeader Part;
      uint32_t Offset;
      StringRef Data;
    } IteratorState;

    friend class DXContainer;

    PartIterator(const DXContainer &C,
                 SmallVectorImpl<uint32_t>::const_iterator It)
        : Container(C), OffsetIt(It) {
      if (OffsetIt == Container.PartOffsets.end())
        updateIteratorImpl(Container.PartOffsets.back());
      else
        updateIterator();
    }

    // Updates the iterator's state data. This results in copying the part
    // header into the iterator and handling any required byte swapping. This is
    // called when incrementing or decrementing the iterator.
    void updateIterator() {
      if (OffsetIt != Container.PartOffsets.end())
        updateIteratorImpl(*OffsetIt);
    }

    // Implementation for updating the iterator state based on a specified
    // offest.
    void updateIteratorImpl(const uint32_t Offset);

  public:
    PartIterator &operator++() {
      if (OffsetIt == Container.PartOffsets.end())
        return *this;
      ++OffsetIt;
      updateIterator();
      return *this;
    }

    PartIterator operator++(int) {
      PartIterator Tmp = *this;
      ++(*this);
      return Tmp;
    }

    bool operator==(const PartIterator &RHS) const {
      return OffsetIt == RHS.OffsetIt;
    }

    bool operator!=(const PartIterator &RHS) const {
      return OffsetIt != RHS.OffsetIt;
    }

    const PartData &operator*() { return IteratorState; }
    const PartData *operator->() { return &IteratorState; }
  };

  PartIterator begin() const {
    return PartIterator(*this, PartOffsets.begin());
  }

  PartIterator end() const { return PartIterator(*this, PartOffsets.end()); }

  StringRef getData() const { return Data.getBuffer(); }
  static Expected<DXContainer> create(MemoryBufferRef Object);

  const dxbc::Header &getHeader() const { return Header; }

  Optional<DXILData> getDXIL() const { return DXIL; }
};

} // namespace object
} // namespace llvm

#endif // LLVM_OBJECT_DXCONTAINER_H