Add support for new CSS ::slotted() pseudo element

third_party/WebKit/Source/core/css/SelectorChecker.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 2004-2005 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2006, 2007 Nicholas Shanks (webkit@nickshanks.com)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Alexey Proskuryakov <ap@webkit.org>
  * Copyright (C) 2007, 2008 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (c) 2011, Code Aurora Forum. All rights reserved.
  * Copyright (C) Research In Motion Limited 2011. All rights reserved.
@@ skipping 29 matching lines @@
 #include "core/dom/shadow/ComposedTreeTraversal.h"
 #include "core/dom/shadow/InsertionPoint.h"
 #include "core/dom/shadow/ShadowRoot.h"
 #include "core/editing/FrameSelection.h"
 #include "core/frame/LocalFrame.h"
 #include "core/html/HTMLDocument.h"
 #include "core/html/HTMLFrameElementBase.h"
 #include "core/html/HTMLInputElement.h"
 #include "core/html/HTMLOptionElement.h"
 #include "core/html/HTMLSelectElement.h"
+#include "core/html/HTMLSlotElement.h"
 #include "core/html/parser/HTMLParserIdioms.h"
 #include "core/html/track/vtt/VTTElement.h"
 #include "core/inspector/InspectorInstrumentation.h"
 #include "core/layout/LayoutObject.h"
 #include "core/layout/LayoutScrollbar.h"
 #include "core/page/FocusController.h"
 #include "core/page/Page.h"
 #include "core/style/ComputedStyle.h"
 #include "platform/scroll/ScrollableArea.h"
 #include "platform/scroll/ScrollbarTheme.h"
@@ skipping 46 matching lines @@
     // - If context.scope is a shadow root, we should walk up to its shadow host.
     // - If context.scope is some element in some shadow tree and querySelector initialized the context,
     //   e.g. shadowRoot.querySelector(':host *'),
     //   (a) context.element has the same treescope as context.scope, need to walk up to its shadow host.
     //   (b) Otherwise, should not walk up from a shadow root to a shadow host.
     if (context.scope && (context.scope == context.element->containingShadowRoot() || context.scope->treeScope() == context.element->treeScope()))
         return context.element->parentOrShadowHostElement();
     return context.element->parentElement();
 }
 
+static const HTMLSlotElement* findSlotElementInScope(const SelectorChecker::SelectorCheckingContext& context)
+{
+    if (!context.scope)
+        return nullptr;
+
+    const HTMLSlotElement* slot = context.element->assignedSlot();
+    while (slot) {
+        if (slot->treeScope() == context.scope->treeScope())
+            return slot;
+        slot = slot->assignedSlot();
+    }
+    return nullptr;
+}
+
 static bool scopeContainsLastMatchedElement(const SelectorChecker::SelectorCheckingContext& context)
 {
     // If this context isn't scoped, skip checking.
     if (!context.scope)
         return true;
 
     if (context.scope->treeScope() == context.element->treeScope())
         return true;
 
     // Because Blink treats a shadow host's TreeScope as a separate one from its descendent shadow roots,
@@ skipping 319 matching lines @@
             for (nextContext.element = parentOrV0ShadowHostElement(*context.element); nextContext.element; nextContext.element = parentOrV0ShadowHostElement(*nextContext.element)) {
                 Match match = matchSelector(nextContext, result);
                 if (match == SelectorMatches || match == SelectorFailsCompletely)
                     return match;
                 if (nextSelectorExceedsScope(nextContext))
                     return SelectorFailsCompletely;
             }
             return SelectorFailsCompletely;
         }
 
+    case CSSSelector::ShadowSlot:
+        {
+            const HTMLSlotElement* slot = findSlotElementInScope(context);
+            if (!slot)
+                return SelectorFailsCompletely;
+
+            nextContext.element = const_cast<HTMLSlotElement*>(slot);
+            return matchSelector(nextContext, result);
+        }
+
     case CSSSelector::SubSelector:
         ASSERT_NOT_REACHED();
     }
 
     ASSERT_NOT_REACHED();
     return SelectorFailsCompletely;
 }
 
 SelectorChecker::Match SelectorChecker::matchForShadowDistributed(const SelectorCheckingContext& context, const Element& element, MatchResult& result) const
 {
@@ skipping 559 matching lines @@
                     return true;
             }
             return false;
         }
     case CSSSelector::PseudoWebKitCustomElement:
         {
             if (ShadowRoot* root = element.containingShadowRoot())
                 return root->type() == ShadowRootType::UserAgent && element.shadowPseudoId() == selector.value();
             return false;
         }
+    case CSSSelector::PseudoSlotted:
+        {
+            SelectorCheckingContext subContext(context);
+            subContext.isSubSelector = true;
+            subContext.scope = nullptr;
+            subContext.treatShadowHostAsNormalScope = false;
+
+            // ::slotted() only allows one compound selector.
+            ASSERT(selector.selectorList()->first());
+            ASSERT(!CSSSelectorList::next(*selector.selectorList()->first()));
+            subContext.selector = selector.selectorList()->first();
+            return match(subContext);
+        }
     case CSSSelector::PseudoContent:
         return element.isInShadowTree() && element.isInsertionPoint();
     case CSSSelector::PseudoShadow:
         return element.isInShadowTree() && context.previousElement;
     default:
         break;
     }
 
     if (!context.inRightmostCompound && m_mode == ResolvingStyle)
         return false;
@@ skipping 154 matching lines @@
 }
 
 bool SelectorChecker::matchesFocusPseudoClass(const Element& element)
 {
     if (InspectorInstrumentation::forcePseudoState(const_cast<Element*>(&element), CSSSelector::PseudoFocus))
         return true;
     return element.focused() && isFrameFocused(element);
 }
 
 }