1 files changed, 103 insertions, 0 deletions
diff --git a/layout/xul/tree/nsTreeStyleCache.cpp b/layout/xul/tree/nsTreeStyleCache.cpp
new file mode 100644
index 0000000000..d5823ac38e
--- /dev/null
+++ b/layout/xul/tree/nsTreeStyleCache.cpp
@@ -0,0 +1,103 @@
+/* -*- 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/. */
+
+#include "nsTreeStyleCache.h"
+#include "mozilla/ComputedStyleInlines.h"
+#include "mozilla/dom/Element.h"
+#include "mozilla/ServoStyleSet.h"
+#include "nsPresContextInlines.h"
+
+using namespace mozilla;
+
+nsTreeStyleCache::Transition::Transition(DFAState aState, nsAtom* aSymbol)
+    : mState(aState), mInputSymbol(aSymbol) {}
+
+bool nsTreeStyleCache::Transition::operator==(const Transition& aOther) const {
+  return aOther.mState == mState && aOther.mInputSymbol == mInputSymbol;
+}
+
+uint32_t nsTreeStyleCache::Transition::Hash() const {
+  // Make a 32-bit integer that combines the low-order 16 bits of the state and
+  // the input symbol.
+  uint32_t hb = mState << 16;
+  uint32_t lb = (NS_PTR_TO_UINT32(mInputSymbol.get()) << 16) >> 16;
+  return hb + lb;
+}
+
+// The ComputedStyle cache impl
+ComputedStyle* nsTreeStyleCache::GetComputedStyle(
+    nsPresContext* aPresContext, nsIContent* aContent, ComputedStyle* aStyle,
+    nsCSSAnonBoxPseudoStaticAtom* aPseudoElement, const AtomArray& aInputWord) {
+  MOZ_ASSERT(nsCSSAnonBoxes::IsTreePseudoElement(aPseudoElement));
+
+  uint32_t count = aInputWord.Length();
+
+  // Go ahead and init the transition table.
+  if (!mTransitionTable) {
+    // Automatic miss. Build the table
+    mTransitionTable = MakeUnique<TransitionTable>();
+  }
+
+  // The first transition is always made off the supplied pseudo-element.
+  Transition transition(0, aPseudoElement);
+  DFAState currState = mTransitionTable->Get(transition);
+
+  if (!currState) {
+    // We had a miss. Make a new state and add it to our hash.
+    currState = mNextState;
+    mNextState++;
+    mTransitionTable->InsertOrUpdate(transition, currState);
+  }
+
+  for (uint32_t i = 0; i < count; i++) {
+    Transition transition(currState, aInputWord[i]);
+    currState = mTransitionTable->Get(transition);
+
+    if (!currState) {
+      // We had a miss. Make a new state and add it to our hash.
+      currState = mNextState;
+      mNextState++;
+      mTransitionTable->InsertOrUpdate(transition, currState);
+    }
+  }
+
+  // We're in a final state.
+  // Look up our ComputedStyle for this state.
+  ComputedStyle* result = nullptr;
+  if (mCache) {
+    result = mCache->GetWeak(currState);
+  }
+  if (!result) {
+    // We missed the cache. Resolve this pseudo-style.
+    RefPtr<ComputedStyle> newResult =
+        aPresContext->StyleSet()->ResolveXULTreePseudoStyle(
+            aContent->AsElement(), aPseudoElement, aStyle, aInputWord);
+
+    // Normally we rely on nsIFrame::Init / RestyleManager to call this, but
+    // these are weird and don't use a frame, yet ::-moz-tree-twisty definitely
+    // pokes at list-style-image.
+    newResult->StartImageLoads(*aPresContext->Document());
+
+    // Even though xul-tree pseudos are defined in nsCSSAnonBoxList, nothing has
+    // ever treated them as an anon box, and they don't ever get boxes anyway.
+    //
+    // This is really weird, and probably nothing really relies on the result of
+    // these assert, but it's here just to avoid changing them accidentally.
+    MOZ_ASSERT(newResult->GetPseudoType() == PseudoStyleType::XULTree);
+    MOZ_ASSERT(!newResult->IsAnonBox());
+    MOZ_ASSERT(!newResult->IsPseudoElement());
+
+    // Put the ComputedStyle in our table, transferring the owning reference to
+    // the table.
+    if (!mCache) {
+      mCache = MakeUnique<ComputedStyleCache>();
+    }
+    result = newResult.get();
+    mCache->InsertOrUpdate(currState, std::move(newResult));
+  }
+
+  return result;
+}