//===-- ModuleFileExtension.h - Module File Extensions ----------*- 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_CLANG_SERIALIZATION_MODULEFILEEXTENSION_H

#define LLVM_CLANG_SERIALIZATION_MODULEFILEEXTENSION_H

#include "llvm/ADT/IntrusiveRefCntPtr.h"

#include <memory>

#include <string>

namespace llvm {

class BitstreamCursor;

class BitstreamWriter;

class hash_code;

class raw_ostream;

}

namespace clang {

class ASTReader;

class ASTWriter;

class Sema;

namespace serialization {

  class ModuleFile;

} // end namespace serialization

/// Metadata for a module file extension.

struct ModuleFileExtensionMetadata {

  /// The name used to identify this particular extension block within

  /// the resulting module file. It should be unique to the particular

  /// extension, because this name will be used to match the name of

  /// an extension block to the appropriate reader.

  std::string BlockName;

  /// The major version of the extension data.

  unsigned MajorVersion;

  /// The minor version of the extension data.

  unsigned MinorVersion;

  /// A string containing additional user information that will be

  /// stored with the metadata.

  std::string UserInfo;

};

class ModuleFileExtensionReader;

class ModuleFileExtensionWriter;

/// An abstract superclass that describes a custom extension to the

/// module/precompiled header file format.

///

/// A module file extension can introduce additional information into

/// compiled module files (.pcm) and precompiled headers (.pch) via a

/// custom writer that can then be accessed via a custom reader when

/// the module file or precompiled header is loaded.

class ModuleFileExtension {

public:

  virtual ~ModuleFileExtension();

  /// Retrieves the metadata for this module file extension.

  virtual ModuleFileExtensionMetadata getExtensionMetadata() const = 0;

  /// Hash information about the presence of this extension into the

  /// module hash code.

  ///

  /// The module hash code is used to distinguish different variants

  /// of a module that are incompatible. If the presence, absence, or

  /// version of the module file extension should force the creation

  /// of a separate set of module files, override this method to

  /// combine that distinguishing information into the module hash

  /// code.

  ///

  /// The default implementation of this function simply returns the

  /// hash code as given, so the presence/absence of this extension

  /// does not distinguish module files.

  virtual llvm::hash_code hashExtension(llvm::hash_code c) const;

  /// Create a new module file extension writer, which will be

  /// responsible for writing the extension contents into a particular

  /// module file.

  virtual std::unique_ptr<ModuleFileExtensionWriter>

  createExtensionWriter(ASTWriter &Writer) = 0;

  /// Create a new module file extension reader, given the

  /// metadata read from the block and the cursor into the extension

  /// block.

  ///

  /// May return null to indicate that an extension block with the

  /// given metadata cannot be read.

  virtual std::unique_ptr<ModuleFileExtensionReader>

  createExtensionReader(const ModuleFileExtensionMetadata &Metadata,

                        ASTReader &Reader, serialization::ModuleFile &Mod,

                        const llvm::BitstreamCursor &Stream) = 0;

};

/// Abstract base class that writes a module file extension block into

/// a module file.

class ModuleFileExtensionWriter {

  ModuleFileExtension *Extension;

protected:

  ModuleFileExtensionWriter(ModuleFileExtension *Extension)

    : Extension(Extension) { }

public:

  virtual ~ModuleFileExtensionWriter();

  /// Retrieve the module file extension with which this writer is

  /// associated.

  ModuleFileExtension *getExtension() const { return Extension; }

  /// Write the contents of the extension block into the given bitstream.

  ///

  /// Responsible for writing the contents of the extension into the

  /// given stream. All of the contents should be written into custom

  /// records with IDs >= FIRST_EXTENSION_RECORD_ID.

  virtual void writeExtensionContents(Sema &SemaRef,

                                      llvm::BitstreamWriter &Stream) = 0;

};

/// Abstract base class that reads a module file extension block from

/// a module file.

///

/// Subclasses

class ModuleFileExtensionReader {

  ModuleFileExtension *Extension;

protected:

  ModuleFileExtensionReader(ModuleFileExtension *Extension)

    : Extension(Extension) { }

public:

  /// Retrieve the module file extension with which this reader is

  /// associated.

  ModuleFileExtension *getExtension() const { return Extension; }

  virtual ~ModuleFileExtensionReader();

};

} // end namespace clang

#endif // LLVM_CLANG_FRONTEND_MODULEFILEEXTENSION_H