1 files changed, 264 insertions, 0 deletions
diff --git a/dom/base/nsMappedAttributes.cpp b/dom/base/nsMappedAttributes.cpp
new file mode 100644
index 0000000000..43322f4d9a
--- /dev/null
+++ b/dom/base/nsMappedAttributes.cpp
@@ -0,0 +1,264 @@
+/* -*- 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/. */
+
+/*
+ * A unique per-element set of attributes that is used as an
+ * nsIStyleRule; used to implement presentational attributes.
+ */
+
+#include "nsMappedAttributes.h"
+#include "mozilla/Assertions.h"
+#include "nsHTMLStyleSheet.h"
+#include "mozilla/DeclarationBlock.h"
+#include "mozilla/HashFunctions.h"
+#include "mozilla/MappedDeclarations.h"
+#include "mozilla/MemoryReporting.h"
+
+using namespace mozilla;
+
+bool nsMappedAttributes::sShuttingDown = false;
+nsTArray<void*>* nsMappedAttributes::sCachedMappedAttributeAllocations =
+    nullptr;
+
+void nsMappedAttributes::Shutdown() {
+  sShuttingDown = true;
+  if (sCachedMappedAttributeAllocations) {
+    for (uint32_t i = 0; i < sCachedMappedAttributeAllocations->Length(); ++i) {
+      void* cachedValue = (*sCachedMappedAttributeAllocations)[i];
+      ::operator delete(cachedValue);
+    }
+  }
+
+  delete sCachedMappedAttributeAllocations;
+  sCachedMappedAttributeAllocations = nullptr;
+}
+
+nsMappedAttributes::nsMappedAttributes(nsHTMLStyleSheet* aSheet,
+                                       nsMapRuleToAttributesFunc aMapRuleFunc)
+    : mAttrCount(0),
+      mSheet(aSheet),
+      mRuleMapper(aMapRuleFunc),
+      mServoStyle(nullptr) {
+  MOZ_ASSERT(mRefCnt == 0);  // Ensure caching works as expected.
+}
+
+nsMappedAttributes::nsMappedAttributes(const nsMappedAttributes& aCopy)
+    : mAttrCount(aCopy.mAttrCount),
+      mSheet(aCopy.mSheet),
+      mRuleMapper(aCopy.mRuleMapper),
+      // This is only called by ::Clone, which is used to create independent
+      // nsMappedAttributes objects which should not share a DeclarationBlock
+      mServoStyle(nullptr) {
+  MOZ_ASSERT(mBufferSize >= aCopy.mAttrCount, "can't fit attributes");
+  MOZ_ASSERT(mRefCnt == 0);  // Ensure caching works as expected.
+
+  uint32_t i = 0;
+  for (const InternalAttr& attr : aCopy.Attrs()) {
+    new (&mBuffer[i++]) InternalAttr(attr);
+  }
+}
+
+nsMappedAttributes::~nsMappedAttributes() {
+  if (mSheet) {
+    mSheet->DropMappedAttributes(this);
+  }
+
+  for (InternalAttr& attr : Attrs()) {
+    attr.~InternalAttr();
+  }
+}
+
+nsMappedAttributes* nsMappedAttributes::Clone(bool aWillAddAttr) {
+  uint32_t extra = aWillAddAttr ? 1 : 0;
+
+  // This will call the overridden operator new
+  return new (mAttrCount + extra) nsMappedAttributes(*this);
+}
+
+void* nsMappedAttributes::operator new(size_t aSize,
+                                       uint32_t aAttrCount) noexcept(true) {
+  size_t size = aSize + aAttrCount * sizeof(InternalAttr);
+
+  if (sCachedMappedAttributeAllocations) {
+    void* cached = sCachedMappedAttributeAllocations->SafeElementAt(aAttrCount);
+    if (cached) {
+      (*sCachedMappedAttributeAllocations)[aAttrCount] = nullptr;
+      return cached;
+    }
+  }
+
+  void* newAttrs = ::operator new(size);
+
+#ifdef DEBUG
+  static_cast<nsMappedAttributes*>(newAttrs)->mBufferSize = aAttrCount;
+#endif
+  return newAttrs;
+}
+
+void nsMappedAttributes::LastRelease() {
+  if (!sShuttingDown) {
+    if (!sCachedMappedAttributeAllocations) {
+      sCachedMappedAttributeAllocations = new nsTArray<void*>();
+    }
+
+    // Ensure the cache array is at least mAttrCount + 1 long and
+    // that each item is either null or pointing to a cached item.
+    // The size of the array is capped because mapped attributes are defined
+    // statically in element implementations.
+    sCachedMappedAttributeAllocations->SetCapacity(mAttrCount + 1);
+    for (uint32_t i = sCachedMappedAttributeAllocations->Length();
+         i < (uint32_t(mAttrCount) + 1); ++i) {
+      sCachedMappedAttributeAllocations->AppendElement(nullptr);
+    }
+
+    if (!(*sCachedMappedAttributeAllocations)[mAttrCount]) {
+      void* memoryToCache = this;
+      this->~nsMappedAttributes();
+      (*sCachedMappedAttributeAllocations)[mAttrCount] = memoryToCache;
+      return;
+    }
+  }
+
+  delete this;
+}
+
+void nsMappedAttributes::SetAndSwapAttr(nsAtom* aAttrName, nsAttrValue& aValue,
+                                        bool* aValueWasSet) {
+  MOZ_ASSERT(aAttrName, "null name");
+  *aValueWasSet = false;
+  uint32_t i;
+  for (i = 0; i < mAttrCount && !mBuffer[i].mName.IsSmaller(aAttrName); ++i) {
+    if (mBuffer[i].mName.Equals(aAttrName)) {
+      mBuffer[i].mValue.SwapValueWith(aValue);
+      *aValueWasSet = true;
+      return;
+    }
+  }
+
+  MOZ_ASSERT(mBufferSize >= mAttrCount + 1, "can't fit attributes");
+
+  if (mAttrCount != i) {
+    memmove(&mBuffer[i + 1], &mBuffer[i],
+            (mAttrCount - i) * sizeof(InternalAttr));
+  }
+
+  new (&mBuffer[i].mName) nsAttrName(aAttrName);
+  new (&mBuffer[i].mValue) nsAttrValue();
+  mBuffer[i].mValue.SwapValueWith(aValue);
+  ++mAttrCount;
+}
+
+const nsAttrValue* nsMappedAttributes::GetAttr(const nsAtom* aAttrName) const {
+  MOZ_ASSERT(aAttrName, "null name");
+  for (const InternalAttr& attr : Attrs()) {
+    if (attr.mName.Equals(aAttrName)) {
+      return &attr.mValue;
+    }
+  }
+  return nullptr;
+}
+
+const nsAttrValue* nsMappedAttributes::GetAttr(
+    const nsAString& aAttrName) const {
+  for (const InternalAttr& attr : Attrs()) {
+    if (attr.mName.Atom()->Equals(aAttrName)) {
+      return &attr.mValue;
+    }
+  }
+  return nullptr;
+}
+
+bool nsMappedAttributes::Equals(const nsMappedAttributes* aOther) const {
+  if (this == aOther) {
+    return true;
+  }
+
+  if (mRuleMapper != aOther->mRuleMapper || mAttrCount != aOther->mAttrCount) {
+    return false;
+  }
+
+  uint32_t i;
+  for (i = 0; i < mAttrCount; ++i) {
+    if (!mBuffer[i].mName.Equals(aOther->mBuffer[i].mName) ||
+        !mBuffer[i].mValue.Equals(aOther->mBuffer[i].mValue)) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
+PLDHashNumber nsMappedAttributes::HashValue() const {
+  PLDHashNumber hash = HashGeneric(mRuleMapper);
+  for (const InternalAttr& attr : Attrs()) {
+    hash = AddToHash(hash, attr.mName.HashValue(), attr.mValue.HashValue());
+  }
+  return hash;
+}
+
+void nsMappedAttributes::SetStyleSheet(nsHTMLStyleSheet* aSheet) {
+  MOZ_ASSERT(!mSheet,
+             "Should either drop the sheet reference manually, "
+             "or drop the mapped attributes");
+  mSheet = aSheet;  // not ref counted
+}
+
+void nsMappedAttributes::RemoveAttrAt(uint32_t aPos, nsAttrValue& aValue) {
+  mBuffer[aPos].mValue.SwapValueWith(aValue);
+  mBuffer[aPos].~InternalAttr();
+  memmove(&mBuffer[aPos], &mBuffer[aPos + 1],
+          (mAttrCount - aPos - 1) * sizeof(InternalAttr));
+  mAttrCount--;
+}
+
+const nsAttrName* nsMappedAttributes::GetExistingAttrNameFromQName(
+    const nsAString& aName) const {
+  for (const InternalAttr& attr : Attrs()) {
+    if (attr.mName.IsAtom()) {
+      if (attr.mName.Atom()->Equals(aName)) {
+        return &attr.mName;
+      }
+    } else {
+      if (attr.mName.NodeInfo()->QualifiedNameEquals(aName)) {
+        return &attr.mName;
+      }
+    }
+  }
+
+  return nullptr;
+}
+
+int32_t nsMappedAttributes::IndexOfAttr(const nsAtom* aLocalName) const {
+  for (uint32_t i = 0; i < mAttrCount; ++i) {
+    if (mBuffer[i].mName.Equals(aLocalName)) {
+      return i;
+    }
+  }
+  return -1;
+}
+
+size_t nsMappedAttributes::SizeOfIncludingThis(
+    MallocSizeOf aMallocSizeOf) const {
+  MOZ_ASSERT(mBufferSize >= mAttrCount, "can't fit attributes");
+
+  size_t n = aMallocSizeOf(this);
+  for (const InternalAttr& attr : Attrs()) {
+    n += attr.mValue.SizeOfExcludingThis(aMallocSizeOf);
+  }
+  return n;
+}
+
+void nsMappedAttributes::LazilyResolveServoDeclaration(dom::Document* aDoc) {
+  MOZ_ASSERT(!mServoStyle,
+             "LazilyResolveServoDeclaration should not be called if "
+             "mServoStyle is already set");
+  if (mRuleMapper) {
+    MappedDeclarations declarations(
+        aDoc, Servo_DeclarationBlock_CreateEmpty().Consume());
+    (*mRuleMapper)(this, declarations);
+    mServoStyle = declarations.TakeDeclarationBlock();
+  }
+}