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Diffstat (limited to 'layout/style/ServoUtils.h')
| -rw-r--r-- | layout/style/ServoUtils.h | 82 |
1 files changed, 82 insertions, 0 deletions
diff --git a/layout/style/ServoUtils.h b/layout/style/ServoUtils.h new file mode 100644 index 000000000..b116b9c4f --- /dev/null +++ b/layout/style/ServoUtils.h @@ -0,0 +1,82 @@ +/* -*- 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/. */ + +/* some utilities for stylo */ + +#ifndef mozilla_ServoUtils_h +#define mozilla_ServoUtils_h + +#include "mozilla/TypeTraits.h" + +#ifdef MOZ_STYLO +# define MOZ_DECL_STYLO_CHECK_METHODS \ + bool IsGecko() const { return !IsServo(); } \ + bool IsServo() const { return mType == StyleBackendType::Servo; } +#else +# define MOZ_DECL_STYLO_CHECK_METHODS \ + bool IsGecko() const { return true; } \ + bool IsServo() const { return false; } +#endif + +/** + * Macro used in a base class of |geckotype_| and |servotype_|. + * The class should define |StyleBackendType mType;| itself. + */ +#define MOZ_DECL_STYLO_METHODS(geckotype_, servotype_) \ + MOZ_DECL_STYLO_CHECK_METHODS \ + inline geckotype_* AsGecko(); \ + inline servotype_* AsServo(); \ + inline const geckotype_* AsGecko() const; \ + inline const servotype_* AsServo() const; + +/** + * Macro used in inline header of class |type_| with its Gecko and Servo + * subclasses named |geckotype_| and |servotype_| correspondingly for + * implementing the inline methods defined by MOZ_DECL_STYLO_METHODS. + */ +#define MOZ_DEFINE_STYLO_METHODS(type_, geckotype_, servotype_) \ + geckotype_* type_::AsGecko() { \ + MOZ_ASSERT(IsGecko()); \ + return static_cast<geckotype_*>(this); \ + } \ + servotype_* type_::AsServo() { \ + MOZ_ASSERT(IsServo()); \ + return static_cast<servotype_*>(this); \ + } \ + const geckotype_* type_::AsGecko() const { \ + MOZ_ASSERT(IsGecko()); \ + return static_cast<const geckotype_*>(this); \ + } \ + const servotype_* type_::AsServo() const { \ + MOZ_ASSERT(IsServo()); \ + return static_cast<const servotype_*>(this); \ + } + +#define MOZ_STYLO_THIS_TYPE mozilla::RemovePointer<decltype(this)>::Type +#define MOZ_STYLO_GECKO_TYPE mozilla::RemovePointer<decltype(AsGecko())>::Type +#define MOZ_STYLO_SERVO_TYPE mozilla::RemovePointer<decltype(AsServo())>::Type + +/** + * Macro used to forward a method call to the concrete method defined by + * the Servo or Gecko implementation. The class of the method using it + * should use MOZ_DECL_STYLO_METHODS to define basic stylo methods. + */ +#define MOZ_STYLO_FORWARD_CONCRETE(method_, geckoargs_, servoargs_) \ + static_assert(!mozilla::IsSame<decltype(&MOZ_STYLO_THIS_TYPE::method_), \ + decltype(&MOZ_STYLO_GECKO_TYPE::method_)> \ + ::value, "Gecko subclass should define its own " #method_); \ + static_assert(!mozilla::IsSame<decltype(&MOZ_STYLO_THIS_TYPE::method_), \ + decltype(&MOZ_STYLO_SERVO_TYPE::method_)> \ + ::value, "Servo subclass should define its own " #method_); \ + if (IsServo()) { \ + return AsServo()->method_ servoargs_; \ + } \ + return AsGecko()->method_ geckoargs_; + +#define MOZ_STYLO_FORWARD(method_, args_) \ + MOZ_STYLO_FORWARD_CONCRETE(method_, args_, args_) + +#endif // mozilla_ServoUtils_h |