From 26a029d407be480d791972afb5975cf62c9360a6 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Fri, 19 Apr 2024 02:47:55 +0200 Subject: Adding upstream version 124.0.1. Signed-off-by: Daniel Baumann --- mfbt/MoveOnlyFunction.h | 47 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 47 insertions(+) create mode 100644 mfbt/MoveOnlyFunction.h (limited to 'mfbt/MoveOnlyFunction.h') diff --git a/mfbt/MoveOnlyFunction.h b/mfbt/MoveOnlyFunction.h new file mode 100644 index 0000000000..d6ade3fd49 --- /dev/null +++ b/mfbt/MoveOnlyFunction.h @@ -0,0 +1,47 @@ +/* -*- 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/. */ + +#ifndef mozilla_MoveOnlyFunction_h +#define mozilla_MoveOnlyFunction_h + +// Use stl-like empty propagation to avoid issues with wrapping closures which +// implicitly coerce to bool. +#define FU2_WITH_LIMITED_EMPTY_PROPAGATION + +#include "function2/function2.hpp" + +namespace mozilla { + +/// A type like `std::function`, but with support for move-only callable +/// objects. +/// +/// A similar type is proposed to be added to the standard library as +/// `std::move_only_function` in C++23. +/// +/// Unlike `std::function`, the function signature may be given const or +/// reference qualifiers which will be applied to `operator()`. This can be used +/// to declare const qualified or move-only functions. +/// +/// The implementation this definition depends on (function2) also has support +/// for callables with overload sets, however support for this was not exposed +/// to align better with the proposed `std::move_only_function`, which does not +/// support overload sets. +/// +/// A custom typedef over `fu2::function_base` is used to control the size and +/// alignment of the inline storage to store 2 aligned pointers, and ensure the +/// type is compatible with `nsTArray`. +template +using MoveOnlyFunction = fu2::function_base< + /* IsOwning */ true, + /* IsCopyable */ false, + /* Capacity */ fu2::capacity_fixed<2 * sizeof(void*), alignof(void*)>, + /* IsThrowing */ false, + /* HasStrongExceptionGuarantee */ false, + /* Signature */ Signature>; + +} // namespace mozilla + +#endif // mozilla_MoveOnlyFunction_h -- cgit v1.2.3