gecko-dev/layout/style/ServoCSSRuleList.cpp

/* -*- 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/. */

/* representation of CSSRuleList for stylo */

#include "mozilla/ServoCSSRuleList.h"

#include "mozilla/dom/CSSCounterStyleRule.h"
#include "mozilla/dom/CSSFontFaceRule.h"
#include "mozilla/dom/CSSFontFeatureValuesRule.h" 
#include "mozilla/dom/CSSImportRule.h"
#include "mozilla/dom/CSSKeyframesRule.h"
#include "mozilla/dom/CSSMediaRule.h"
#include "mozilla/dom/CSSMozDocumentRule.h"
#include "mozilla/dom/CSSNamespaceRule.h"
#include "mozilla/dom/CSSPageRule.h"
#include "mozilla/dom/CSSStyleRule.h"
#include "mozilla/dom/CSSSupportsRule.h"
#include "mozilla/IntegerRange.h"
#include "mozilla/ServoBindings.h"
#include "mozilla/StyleSheet.h"

using namespace mozilla::dom;

namespace mozilla {

ServoCSSRuleList::ServoCSSRuleList(already_AddRefed<ServoCssRules> aRawRules,
                                   StyleSheet* aSheet,
                                   css::GroupRule* aParentRule)
  : mStyleSheet(aSheet)
  , mParentRule(aParentRule)
  , mRawRules(aRawRules)
{
  Servo_CssRules_ListTypes(mRawRules, &mRules);
}

// QueryInterface implementation for ServoCSSRuleList
NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(ServoCSSRuleList)
NS_INTERFACE_MAP_END_INHERITING(dom::CSSRuleList)

NS_IMPL_ADDREF_INHERITED(ServoCSSRuleList, dom::CSSRuleList)
NS_IMPL_RELEASE_INHERITED(ServoCSSRuleList, dom::CSSRuleList)

NS_IMPL_CYCLE_COLLECTION_CLASS(ServoCSSRuleList)

NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(ServoCSSRuleList)
  tmp->DropAllRules();
NS_IMPL_CYCLE_COLLECTION_UNLINK_END_INHERITED(dom::CSSRuleList)
NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_INHERITED(ServoCSSRuleList,
                                                  dom::CSSRuleList)
  tmp->EnumerateInstantiatedRules([&](css::Rule* aRule) {
    if (!aRule->IsCCLeaf()) {
      NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(cb, "mRules[i]");
      cb.NoteXPCOMChild(aRule);
    }
  });
NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END

css::Rule*
ServoCSSRuleList::GetRule(uint32_t aIndex)
{
  uintptr_t rule = mRules[aIndex];
  if (rule <= kMaxRuleType) {
    RefPtr<css::Rule> ruleObj = nullptr;
    switch (rule) {
#define CASE_RULE(const_, name_)                                            \
      case CSSRule_Binding::const_##_RULE: {                                \
        uint32_t line = 0, column = 0;                                      \
        RefPtr<RawServo##name_##Rule> rule =                                \
          Servo_CssRules_Get##name_##RuleAt(                                \
              mRawRules, aIndex, &line, &column                             \
          ).Consume();                                                      \
        MOZ_ASSERT(rule);                                                   \
        ruleObj = new CSS##name_##Rule(rule.forget(), mStyleSheet,          \
                                       mParentRule, line, column);          \
        break;                                                              \
      }
      CASE_RULE(STYLE, Style)
      CASE_RULE(KEYFRAMES, Keyframes)
      CASE_RULE(MEDIA, Media)
      CASE_RULE(NAMESPACE, Namespace)
      CASE_RULE(PAGE, Page)
      CASE_RULE(SUPPORTS, Supports)
      CASE_RULE(DOCUMENT, MozDocument)
      CASE_RULE(IMPORT, Import)
      CASE_RULE(FONT_FEATURE_VALUES, FontFeatureValues)
      CASE_RULE(FONT_FACE, FontFace)
      CASE_RULE(COUNTER_STYLE, CounterStyle)
#undef CASE_RULE
      case CSSRule_Binding::KEYFRAME_RULE:
        MOZ_ASSERT_UNREACHABLE("keyframe rule cannot be here");
        return nullptr;
      default:
        NS_WARNING("stylo: not implemented yet");
        return nullptr;
    }
    rule = CastToUint(ruleObj.forget().take());
    mRules[aIndex] = rule;
  }
  return CastToPtr(rule);
}

css::Rule*
ServoCSSRuleList::IndexedGetter(uint32_t aIndex, bool& aFound)
{
  if (aIndex >= mRules.Length()) {
    aFound = false;
    return nullptr;
  }
  aFound = true;
  return GetRule(aIndex);
}

template<typename Func>
void
ServoCSSRuleList::EnumerateInstantiatedRules(Func aCallback)
{
  for (uintptr_t rule : mRules) {
    if (rule > kMaxRuleType) {
      aCallback(CastToPtr(rule));
    }
  }
}

static void
DropRule(already_AddRefed<css::Rule> aRule)
{
  RefPtr<css::Rule> rule = aRule;
  rule->DropReferences();
}

void
ServoCSSRuleList::DropAllRules()
{
  mStyleSheet = nullptr;
  mParentRule = nullptr;
  EnumerateInstantiatedRules([](css::Rule* rule) {
    DropRule(already_AddRefed<css::Rule>(rule));
  });
  mRules.Clear();
  mRawRules = nullptr;
}

void
ServoCSSRuleList::DropSheetReference()
{
  // If mStyleSheet is not set on this rule list, then it is not set on any of
  // its instantiated rules either.  To avoid O(N^2) beavhior in the depth of
  // group rule nesting, which can happen if we are unlinked starting from the
  // deepest nested group rule, skip recursing into the rule list if we know we
  // don't need to.
  if (!mStyleSheet) {
    return;
  }
  mStyleSheet = nullptr;
  EnumerateInstantiatedRules([](css::Rule* rule) {
    rule->DropSheetReference();
  });
}

void
ServoCSSRuleList::DropParentRuleReference()
{
  mParentRule = nullptr;
  EnumerateInstantiatedRules([](css::Rule* rule) {
    rule->DropParentRuleReference();
  });
}

nsresult
ServoCSSRuleList::InsertRule(const nsAString& aRule, uint32_t aIndex)
{
  MOZ_ASSERT(mStyleSheet, "Caller must ensure that "
             "the list is not unlinked from stylesheet");
  NS_ConvertUTF16toUTF8 rule(aRule);
  bool nested = !!mParentRule;
  css::Loader* loader = nullptr;
  if (nsIDocument* doc = mStyleSheet->GetAssociatedDocument()) {
    loader = doc->CSSLoader();
  }
  uint16_t type;
  nsresult rv = Servo_CssRules_InsertRule(mRawRules, mStyleSheet->RawContents(),
                                          &rule, aIndex, nested,
                                          loader, mStyleSheet, &type);
  if (NS_FAILED(rv)) {
    return rv;
  }
  mRules.InsertElementAt(aIndex, type);
  return rv;
}

nsresult
ServoCSSRuleList::DeleteRule(uint32_t aIndex)
{
  nsresult rv = Servo_CssRules_DeleteRule(mRawRules, aIndex);
  if (!NS_FAILED(rv)) {
    uintptr_t rule = mRules[aIndex];
    if (rule > kMaxRuleType) {
      DropRule(already_AddRefed<css::Rule>(CastToPtr(rule)));
    }
    mRules.RemoveElementAt(aIndex);
  }
  return rv;
}

uint16_t
ServoCSSRuleList::GetDOMCSSRuleType(uint32_t aIndex) const
{
  uintptr_t rule = mRules[aIndex];
  if (rule <= kMaxRuleType) {
    return rule;
  }
  return CastToPtr(rule)->Type();
}

ServoCSSRuleList::~ServoCSSRuleList()
{
  MOZ_ASSERT(!mStyleSheet, "Backpointer should have been cleared");
  MOZ_ASSERT(!mParentRule, "Backpointer should have been cleared");
  DropAllRules();
}

} // namespace mozilla