gecko-dev/layout/style/Rule.cpp
Emilio Cobos Álvarez 039592f4d8 Bug 1682003 - Avoid UTF-8 -> UTF-16 conversion during CSSOM serialization. r=heycam
This lifts a bunch of string conversions higher up the stack, but allows
us to make the servo code use utf-8 unconditionally, and seemed faster
in my benchmarking (see comment 0).

It should also make a bunch of attribute setters faster too (like
setting .cssText), now that we use UTF8String for them (we couldn't
because we couldn't specify different string types for the getter and
setters).

Differential Revision: https://phabricator.services.mozilla.com/D99590
2020-12-17 14:04:35 +00:00

114 lines
3.7 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/. */
/* base class for all rule types in a CSS style sheet */
#include "Rule.h"
#include "mozilla/css/GroupRule.h"
#include "mozilla/dom/CSSImportRule.h"
#include "mozilla/dom/DocumentOrShadowRoot.h"
#include "nsCCUncollectableMarker.h"
#include "mozilla/dom/Document.h"
#include "mozilla/HoldDropJSObjects.h"
#include "nsWrapperCacheInlines.h"
using namespace mozilla;
using namespace mozilla::dom;
namespace mozilla {
namespace css {
NS_IMPL_CYCLE_COLLECTING_ADDREF(Rule)
NS_IMPL_CYCLE_COLLECTING_RELEASE(Rule)
NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(Rule)
NS_WRAPPERCACHE_INTERFACE_MAP_ENTRY
NS_INTERFACE_MAP_ENTRY(nsISupports)
NS_INTERFACE_MAP_END
NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE_0(Rule)
bool Rule::IsCCLeaf() const { return !PreservingWrapper(); }
bool Rule::IsKnownLive() const {
if (HasKnownLiveWrapper()) {
return true;
}
StyleSheet* sheet = GetStyleSheet();
if (!sheet) {
return false;
}
Document* doc = sheet->GetKeptAliveByDocument();
return doc &&
nsCCUncollectableMarker::InGeneration(doc->GetMarkedCCGeneration());
}
void Rule::UnlinkDeclarationWrapper(nsWrapperCache& aDecl) {
// We have to be a bit careful here. We have two separate nsWrapperCache
// instances, aDecl and this, that both correspond to the same CC participant:
// this. If we just used ReleaseWrapper() on one of them, that would
// unpreserve that one wrapper, then trace us with a tracer that clears JS
// things, and we would clear the wrapper on the cache that has not
// unpreserved the wrapper yet. That would violate the invariant that the
// cache keeps caching the wrapper until the wrapper dies.
//
// So we reimplement a modified version of nsWrapperCache::ReleaseWrapper here
// that unpreserves both wrappers before doing any clearing.
bool needDrop = PreservingWrapper() || aDecl.PreservingWrapper();
SetPreservingWrapper(false);
aDecl.SetPreservingWrapper(false);
if (needDrop) {
DropJSObjects(this);
}
}
NS_IMPL_CYCLE_COLLECTION_CAN_SKIP_BEGIN(Rule)
return tmp->IsCCLeaf() || tmp->IsKnownLive();
NS_IMPL_CYCLE_COLLECTION_CAN_SKIP_END
NS_IMPL_CYCLE_COLLECTION_CAN_SKIP_IN_CC_BEGIN(Rule)
// Please see documentation for nsCycleCollectionParticipant::CanSkip* for why
// we need to check HasNothingToTrace here but not in the other two CanSkip
// methods.
return tmp->IsCCLeaf() || (tmp->IsKnownLive() && tmp->HasNothingToTrace(tmp));
NS_IMPL_CYCLE_COLLECTION_CAN_SKIP_IN_CC_END
NS_IMPL_CYCLE_COLLECTION_CAN_SKIP_THIS_BEGIN(Rule)
return tmp->IsCCLeaf() || tmp->IsKnownLive();
NS_IMPL_CYCLE_COLLECTION_CAN_SKIP_THIS_END
/* virtual */
void Rule::DropSheetReference() { mSheet = nullptr; }
void Rule::SetCssText(const nsACString& aCssText) {
// We used to throw for some rule types, but not all. Specifically, we did
// not throw for StyleRule. Let's just always not throw.
}
Rule* Rule::GetParentRule() const { return mParentRule; }
bool Rule::IsReadOnly() const {
MOZ_ASSERT(!mSheet || !mParentRule ||
mSheet->IsReadOnly() == mParentRule->IsReadOnly(),
"a parent rule should be read only iff the owning sheet is "
"read only");
return mSheet && mSheet->IsReadOnly();
}
bool Rule::IsIncompleteImportRule() const {
if (Type() != CSSRule_Binding::IMPORT_RULE) {
return false;
}
auto* sheet = static_cast<const dom::CSSImportRule*>(this)->GetStyleSheet();
return !sheet || !sheet->IsComplete();
}
} // namespace css
} // namespace mozilla