Implement CSS parser part for ::slotted pseudo element

third_party/WebKit/Source/core/css/parser/CSSSelectorParser.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/css/parser/CSSSelectorParser.h"
 
 #include "core/css/CSSSelectorList.h"
 #include "core/css/StyleSheetContents.h"
 #include "core/frame/UseCounter.h"
 #include "platform/RuntimeEnabledFeatures.h"
 
 namespace blink {
 
 static void recordSelectorStats(const CSSParserContext& context, const CSSSelectorList& selectorList)
 {
     if (!context.useCounter())
         return;
 
     for (const CSSSelector* selector = selectorList.first(); selector; selector = CSSSelectorList::next(*selector)) {
         for (const CSSSelector* current = selector; current ; current = current->tagHistory()) {
             UseCounter::Feature feature = UseCounter::NumberOfFeatures;
             switch (current->pseudoType()) {
             case CSSSelector::PseudoUnresolved:
                 feature = UseCounter::CSSSelectorPseudoUnresolved;
                 break;
+            case CSSSelector::PseudoSlotted:
+                feature = UseCounter::CSSSelectorPseudoSlotted;
+                break;
             case CSSSelector::PseudoContent:
                 feature = UseCounter::CSSSelectorPseudoContent;
                 break;
             case CSSSelector::PseudoHost:
                 feature = UseCounter::CSSSelectorPseudoHost;
                 break;
             case CSSSelector::PseudoHostContext:
                 feature = UseCounter::CSSSelectorPseudoHostContext;
                 break;
             case CSSSelector::PseudoFullScreenAncestor:
@@ skipping 428 matching lines @@
         {
             OwnPtr<CSSParserSelector> innerSelector = consumeCompoundSelector(block);
             block.consumeWhitespace();
             if (!innerSelector || !innerSelector->isSimple() || !block.atEnd())
                 return nullptr;
             Vector<OwnPtr<CSSParserSelector>> selectorVector;
             selectorVector.append(innerSelector.release());
             selector->adoptSelectorVector(selectorVector);
             return selector.release();
         }
+    case CSSSelector::PseudoSlotted:
+        {
+            DisallowPseudoElementsScope scope(this);
+
+            OwnPtr<CSSParserSelector> innerSelector = consumeCompoundSelector(block);
+            block.consumeWhitespace();
+            if (!innerSelector || !block.atEnd() || !RuntimeEnabledFeatures::shadowDOMV1Enabled())
+                return nullptr;
+            Vector<OwnPtr<CSSParserSelector>> selectorVector;
+            selectorVector.append(innerSelector.release());
+            selector->adoptSelectorVector(selectorVector);
+            return selector.release();
+        }
     case CSSSelector::PseudoLang:
         {
             // FIXME: CSS Selectors Level 4 allows :lang(*-foo)
             const CSSParserToken& ident = block.consumeIncludingWhitespace();
             if (ident.type() != IdentToken || !block.atEnd())
                 return nullptr;
             selector->setArgument(ident.value());
             return selector.release();
         }
     case CSSSelector::PseudoNthChild:
@@ skipping 173 matching lines @@
 
 const AtomicString& CSSSelectorParser::determineNamespace(const AtomicString& prefix)
 {
     if (!m_styleSheet)
         return defaultNamespace();
     return m_styleSheet->determineNamespace(prefix);
 }
 
 void CSSSelectorParser::prependTypeSelectorIfNeeded(const AtomicString& namespacePrefix, const AtomicString& elementName, CSSParserSelector* compoundSelector)
 {
-    if (elementName.isNull() && defaultNamespace() == starAtom && !compoundSelector->needsImplicitShadowCrossingCombinatorForMatching())
+    if (elementName.isNull() && defaultNamespace() == starAtom && !compoundSelector->needsImplicitShadowCrossingCombinatorForMatching() && compoundSelector->pseudoType() != CSSSelector::PseudoSlotted)
         return;
 
     AtomicString determinedElementName = elementName.isNull() ? starAtom : elementName;
     AtomicString namespaceURI = determineNamespace(namespacePrefix);
     if (namespaceURI.isNull()) {
         m_failedParsing = true;
         return;
     }
     QualifiedName tag = QualifiedName(namespacePrefix, determinedElementName, namespaceURI);
 
     // *:host/*:host-context never matches, so we can't discard the *,
     // otherwise we can't tell the difference between *:host and just :host.
     //
     // Also, selectors where we use a ShadowPseudo combinator between the
     // element and the pseudo element for matching (custom pseudo elements,
     // ::cue, ::shadow), we need a universal selector to set the combinator
     // (relation) on in the cases where there are no simple selectors preceding
     // the pseudo element.
-    if (tag != anyQName() || compoundSelector->isHostPseudoSelector() || compoundSelector->needsImplicitShadowCrossingCombinatorForMatching())
+    if (tag != anyQName() || compoundSelector->isHostPseudoSelector() || compoundSelector->needsImplicitShadowCrossingCombinatorForMatching() || compoundSelector->pseudoType() == CSSSelector::PseudoSlotted)
         compoundSelector->prependTagSelector(tag, elementName.isNull());
 }
 
 PassOwnPtr<CSSParserSelector> CSSSelectorParser::addSimpleSelectorToCompound(PassOwnPtr<CSSParserSelector> compoundSelector, PassOwnPtr<CSSParserSelector> simpleSelector)
 {
     compoundSelector->appendTagHistory(CSSSelector::SubSelector, simpleSelector);
     return compoundSelector;
 }
 
 PassOwnPtr<CSSParserSelector> CSSSelectorParser::splitCompoundAtImplicitShadowCrossingCombinator(PassOwnPtr<CSSParserSelector> compoundSelector)
 {
     // The tagHistory is a linked list that stores combinator separated compound selectors
     // from right-to-left. Yet, within a single compound selector, stores the simple selectors
     // from left-to-right.
     //
     // ".a.b > div#id" is stored in a tagHistory as [div, #id, .a, .b], each element in the
     // list stored with an associated relation (combinator or SubSelector).
     //
     // ::cue, ::shadow, and custom pseudo elements have an implicit ShadowPseudo combinator
     // to their left, which really makes for a new compound selector, yet it's consumed by
     // the selector parser as a single compound selector.
     //
     // Example: input#x::-webkit-clear-button -> [ ::-webkit-clear-button, input, #x ]
-
+    //
+    // Likewise, ::slotted() pseudo element has an implicit ShadowSlot combinator to its left
+    // for finding matching slot element in other TreeScope.
+    //
+    // Example: slot[name=foo]::slotted(div) -> [ ::slotted(div), slot, [name=foo] ]
     CSSParserSelector* splitAfter = compoundSelector.get();
 
-    while (splitAfter->tagHistory() && !splitAfter->tagHistory()->needsImplicitShadowCrossingCombinatorForMatching())
+    while (splitAfter->tagHistory() && !splitAfter->tagHistory()->needsImplicitShadowCrossingCombinatorForMatching() && splitAfter->tagHistory()->pseudoType() != CSSSelector::PseudoSlotted)

[rune, 2016/01/19 09:16:09]

You may move the PseudoSlotted into
needsImplicitShadowCrossingCombinatorForMatching() (and possibly drop "Crossing"
from the name, which might yield a better common name).

[kochi, 2016/01/19 11:09:12]

Done.

         splitAfter = splitAfter->tagHistory();
 
     if (!splitAfter || !splitAfter->tagHistory())
         return compoundSelector;
 
     OwnPtr<CSSParserSelector> secondCompound = splitAfter->releaseTagHistory();
-    secondCompound->appendTagHistory(CSSSelector::ShadowPseudo, compoundSelector);
+    secondCompound->appendTagHistory(secondCompound->pseudoType() == CSSSelector::PseudoSlotted ? CSSSelector::ShadowSlot : CSSSelector::ShadowPseudo, compoundSelector);
     return secondCompound.release();
 }
 
 } // namespace blink