OwnedRustBuffer.h - mozsearch

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */

/* vim:set ts=2 sw=2 sts=2 et cindent: */

/* This Source Code Form is subject to the terms of the Mozilla Public

 * License, v. 2.0. If a copy of the MPL was not distributed with this

 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef mozilla_OwnedRustBuffer_h

#define mozilla_OwnedRustBuffer_h

#include "mozilla/ErrorResult.h"

#include "mozilla/ResultVariant.h"

#include "mozilla/dom/TypedArray.h"

#include "mozilla/dom/UniFFIRust.h"

namespace mozilla::uniffi {

// RustBuffer that's owned by the JS code and handles the memory management

class OwnedRustBuffer final {

 private:

  RustBuffer mBuf;

  void FreeData();

 public:

  // The default constructor creates an invalid OwnedRustBuffer

  OwnedRustBuffer() : mBuf{0} {};

  // Constructor for creating an OwnedRustBuffer from a raw RustBuffer struct

  // that was returned by Rust (therefore we now own the RustBuffer).

  explicit OwnedRustBuffer(const RustBuffer& aBuf);

  // Manual implementation of move constructor and assignment operator.

  OwnedRustBuffer(OwnedRustBuffer&& aOther);

  OwnedRustBuffer& operator=(OwnedRustBuffer&& aOther);

  // Delete copy & move constructor as this type is non-copyable.

  OwnedRustBuffer(const OwnedRustBuffer&) = delete;

  OwnedRustBuffer& operator=(const OwnedRustBuffer&) = delete;

  // Destructor that frees the RustBuffer if it is still valid

  ~OwnedRustBuffer();

  // Constructor for creating an OwnedRustBuffer from an ArrayBuffer. Will set

  // aError to failed and construct an invalid OwnedRustBuffer if the

  // conversion failed.

  static Result<OwnedRustBuffer, nsCString> FromArrayBuffer(

      const mozilla::dom::ArrayBuffer& aArrayBuffer);

  // Moves the buffer out of this `OwnedArrayBuffer` into a raw `RustBuffer`

  // struct.  The raw struct must be passed into a Rust function, transfering

  // ownership to Rust.  After this call the buffer will no longer be valid.

  RustBuffer IntoRustBuffer();

  // Moves the buffer out of this `OwnedArrayBuffer` into a JS ArrayBuffer.

  // This transfers ownership into the JS engine.  After this call the buffer

  // will no longer be valid.

  JSObject* IntoArrayBuffer(JSContext* cx);

  // Is this RustBuffer pointing to valid data?

  bool IsValid() const { return mBuf.data != nullptr; }

 private:

  // Helper function used by IntoArrayBuffer.

  static void ArrayBufferFreeFunc(void* contents, void* userData);

};

}  // namespace mozilla::uniffi

#endif  // mozilla_OwnedRustBuffer_h