gecko-dev/layout/style/PostTraversalTask.h

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/* -*- 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_PostTraversalTask_h
#define mozilla_PostTraversalTask_h
#include "nscore.h"
/* a task to be performed immediately after a Servo traversal */
namespace mozilla {
namespace dom {
class FontFace;
class FontFaceSet;
} // namespace dom
} // namespace mozilla
class gfxUserFontEntry;
namespace mozilla {
/**
* A PostTraversalTask is a task to be performed immediately after a Servo
* traversal. There are just a few tasks we need to perform, so we use this
* class rather than Runnables, to avoid virtual calls and some allocations.
*
* A PostTraversalTask is only safe to run immediately after the Servo
* traversal, since it can hold raw pointers to DOM objects.
*/
class PostTraversalTask {
public:
static PostTraversalTask ResolveFontFaceLoadedPromise(
dom::FontFace* aFontFace) {
auto task = PostTraversalTask(Type::ResolveFontFaceLoadedPromise);
task.mTarget = aFontFace;
return task;
}
static PostTraversalTask RejectFontFaceLoadedPromise(dom::FontFace* aFontFace,
nsresult aResult) {
auto task = PostTraversalTask(Type::ResolveFontFaceLoadedPromise);
task.mTarget = aFontFace;
task.mResult = aResult;
return task;
}
static PostTraversalTask DispatchLoadingEventAndReplaceReadyPromise(
dom::FontFaceSet* aFontFaceSet) {
auto task =
PostTraversalTask(Type::DispatchLoadingEventAndReplaceReadyPromise);
task.mTarget = aFontFaceSet;
return task;
}
static PostTraversalTask DispatchFontFaceSetCheckLoadingFinishedAfterDelay(
dom::FontFaceSet* aFontFaceSet) {
auto task = PostTraversalTask(
Type::DispatchFontFaceSetCheckLoadingFinishedAfterDelay);
task.mTarget = aFontFaceSet;
return task;
}
static PostTraversalTask LoadFontEntry(gfxUserFontEntry* aFontEntry) {
auto task = PostTraversalTask(Type::LoadFontEntry);
task.mTarget = aFontEntry;
return task;
}
void Run();
private:
// For any new raw pointer type that we need to store in a PostTraversalTask,
// please add an assertion that class' destructor that we are not in a Servo
// traversal, to protect against the possibility of having dangling pointers.
enum class Type {
// mTarget (FontFace*)
ResolveFontFaceLoadedPromise,
// mTarget (FontFace*)
// mResult
RejectFontFaceLoadedPromise,
// mTarget (FontFaceSet*)
DispatchLoadingEventAndReplaceReadyPromise,
// mTarget (FontFaceSet*)
DispatchFontFaceSetCheckLoadingFinishedAfterDelay,
// mTarget (gfxUserFontEntry*)
LoadFontEntry,
};
explicit PostTraversalTask(Type aType)
: mType(aType), mTarget(nullptr), mResult(NS_OK) {}
Type mType;
void* mTarget;
nsresult mResult;
};
} // namespace mozilla
#endif // mozilla_PostTraversalTask_h