gecko-dev/layout/style/RustCell.h
Emilio Cobos Álvarez 597c2fe947 Bug 1758223 - Use atomic ops to read / write node flags from stylo. r=nika
The flags stylo cares about reading and writing potentially at the same
time are disjoint, so there's no need for any strong memory ordering.

Differential Revision: https://phabricator.services.mozilla.com/D141829
2022-03-24 10:03:12 +00:00

46 lines
1.3 KiB
C++

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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/. */
/* an object with the same layout as a Rust std::cell::Cell<T> */
#ifndef mozilla_RustCell_h
#define mozilla_RustCell_h
namespace mozilla {
/**
* Object with the same layout as std::cell::Cell<T>.
*
* ServoBindings.toml defines a mapping so that generated bindings use a
* real std::cell::Cell<T>.
*
* Note that while the layout matches, this doesn't have the same ABI as a
* std::cell::Cell<T>, so values of this type can't be passed over FFI
* functions.
*/
template <typename T>
class RustCell {
public:
RustCell() : mValue() {}
explicit RustCell(T aValue) : mValue(aValue) {}
T Get() const { return mValue; }
void Set(T aValue) { mValue = aValue; }
// That this API doesn't mirror the API of rust's Cell because all values in
// C++ effectively act like they're wrapped in Cell<...> already, so this type
// only exists for FFI purposes.
T* AsPtr() { return &mValue; }
const T* AsPtr() const { return &mValue; }
private:
T mValue;
};
} // namespace mozilla
#endif // mozilla_RustCell_h