CSS Parser: Implement selector parsing [1/3]

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 "config.h"
+#include "core/css/parser/CSSSelectorParser.h"
+
+#include "core/css/CSSSelectorList.h"
+#include "core/css/StyleSheetContents.h"
+#include "platform/RuntimeEnabledFeatures.h"
+
+namespace blink {
+
+void CSSSelectorParser::parseSelector(CSSParserTokenRange tokenRange, const CSSParserContext& context, CSSSelectorList& output)
+{
+    CSSSelectorParser parser(tokenRange, context);
+    parser.m_tokenRange.consumeWhitespaceAndComments();
+    CSSSelectorList result;
+    parser.consumeComplexSelectorList(result);
+    if (parser.m_tokenRange.atEnd())
+        output.adopt(result);
+    ASSERT(!(output.isValid() && parser.m_failedParsing));
+}
+
+CSSSelectorParser::CSSSelectorParser(CSSParserTokenRange tokenRange, const CSSParserContext& context)
+: m_tokenRange(tokenRange)
+, m_context(context)
+, m_defaultNamespace(starAtom)
+, m_styleSheet(nullptr)
+, m_failedParsing(false)
+{
+}
+
+void CSSSelectorParser::consumeComplexSelectorList(CSSSelectorList& output)
+{
+    Vector<OwnPtr<CSSParserSelector>> selectorList;
+    OwnPtr<CSSParserSelector> selector = consumeComplexSelector();
+    if (!selector)
+        return;
+    selectorList.append(selector.release());
+    while (!m_tokenRange.atEnd() && m_tokenRange.peek().type() == CommaToken) {
+        m_tokenRange.consumeIncludingWhitespaceAndComments();
+        selector = consumeComplexSelector();
+        if (!selector)
+            return;
+        selectorList.append(selector.release());
+    }
+
+    if (!m_failedParsing)
+        output.adoptSelectorVector(selectorList);
+}
+
+PassOwnPtr<CSSParserSelector> CSSSelectorParser::consumeComplexSelector()
+{
+    OwnPtr<CSSParserSelector> selector = consumeCompoundSelector();
+    if (!selector)
+        return nullptr;
+    while (CSSSelector::Relation combinator = consumeCombinator()) {
+        OwnPtr<CSSParserSelector> nextSelector = consumeCompoundSelector();
+        if (!nextSelector)
+            return combinator == CSSSelector::Descendant ? selector.release() : nullptr;
+        CSSParserSelector* end = nextSelector.get();
+        while (end->tagHistory())
+            end = end->tagHistory();
+        end->setRelation(combinator);
+        if (selector->isContentPseudoElement())
+            end->setRelationIsAffectedByPseudoContent();
+        end->setTagHistory(selector.release());
+
+        selector = nextSelector.release();
+    }
+
+    return selector.release();
+}
+
+PassOwnPtr<CSSParserSelector> CSSSelectorParser::consumeCompoundSelector()
+{
+    OwnPtr<CSSParserSelector> selector;
+
+    AtomicString namespacePrefix;
+    AtomicString elementName;
+    bool hasNamespace;
+    if (!consumeName(elementName, namespacePrefix, hasNamespace)) {
+        selector = consumeSimpleSelector();
+        if (!selector)
+            return nullptr;
+    }
+    if (m_context.isHTMLDocument())
+        elementName = elementName.lower();
+
+    while (OwnPtr<CSSParserSelector> nextSelector = consumeSimpleSelector()) {
+        if (selector)
+            selector = rewriteSpecifiers(selector.release(), nextSelector.release());
+        else
+            selector = nextSelector.release();
+    }
+
+    if (!selector) {
+        if (hasNamespace)
+            return CSSParserSelector::create(determineNameInNamespace(namespacePrefix, elementName));
+        return CSSParserSelector::create(QualifiedName(nullAtom, elementName, m_defaultNamespace));
+    }
+    if (elementName.isNull())
+        rewriteSpecifiersWithNamespaceIfNeeded(selector.get());
+    else
+        rewriteSpecifiersWithElementName(namespacePrefix, elementName, selector.get());
+    return selector.release();
+}
+
+PassOwnPtr<CSSParserSelector> CSSSelectorParser::consumeSimpleSelector()
+{
+    const CSSParserToken& token = m_tokenRange.peek();
+    OwnPtr<CSSParserSelector> selector;
+    if (token.type() == HashToken)
+        selector = consumeId();
+    else if (token.type() == DelimiterToken && token.delimiter() == '.')
+        selector = consumeClass();
+    else if (token.type() == LeftBracketToken)
+        selector = consumeAttribute();
+    else if (token.type() == ColonToken)
+        selector = consumePseudo();
+    else
+        return nullptr;
+    if (!selector)
+        m_failedParsing = true;
+    return selector.release();
+}
+
+bool CSSSelectorParser::consumeName(AtomicString& name, AtomicString& namespacePrefix, bool& hasNamespace)
+{
+    name = nullAtom;
+    namespacePrefix = nullAtom;
+    hasNamespace = false;
+
+    const CSSParserToken& firstToken = m_tokenRange.peek();
+    if (firstToken.type() == IdentToken) {
+        name = AtomicString(firstToken.value());
+        m_tokenRange.consumeIncludingComments();
+    } else if (firstToken.type() == DelimiterToken && firstToken.delimiter() == '*') {
+        name = starAtom;
+        m_tokenRange.consumeIncludingComments();
+    } else if (firstToken.type() == DelimiterToken && firstToken.delimiter() == '|') {
+        // No namespace
+    } else {
+        return false;
+    }
+
+    if (m_tokenRange.peek().type() != DelimiterToken || m_tokenRange.peek().delimiter() != '|')
+        return true;
+    m_tokenRange.consumeIncludingComments();
+
+    hasNamespace = true;
+    namespacePrefix = name;
+    const CSSParserToken& nameToken = m_tokenRange.consumeIncludingComments();
+    if (nameToken.type() == IdentToken) {
+        name = AtomicString(nameToken.value());
+    } else if (nameToken.type() == DelimiterToken && nameToken.delimiter() == '*') {
+        name = starAtom;
+    } else {
+        name = nullAtom;
+        namespacePrefix = nullAtom;
+        return false;
+    }
+
+    return true;
+}
+
+PassOwnPtr<CSSParserSelector> CSSSelectorParser::consumeId()
+{
+    ASSERT(m_tokenRange.peek().type() == HashToken);
+    if (m_tokenRange.peek().hashTokenType() != HashTokenId)
+        return nullptr;
+    OwnPtr<CSSParserSelector> selector = CSSParserSelector::create();
+    selector->setMatch(CSSSelector::Id);
+    const String& value = m_tokenRange.consumeIncludingComments().value();
+    if (isQuirksModeBehavior(m_context.mode()))
+        selector->setValue(AtomicString(value.lower()));
+    else
+        selector->setValue(AtomicString(value));
+    return selector.release();
+}
+
+PassOwnPtr<CSSParserSelector> CSSSelectorParser::consumeClass()
+{
+    ASSERT(m_tokenRange.peek().type() == DelimiterToken);
+    ASSERT(m_tokenRange.peek().delimiter() == '.');
+    m_tokenRange.consumeIncludingComments();
+    if (m_tokenRange.peek().type() != IdentToken)
+        return nullptr;
+    OwnPtr<CSSParserSelector> selector = CSSParserSelector::create();
+    selector->setMatch(CSSSelector::Class);
+    const String& value = m_tokenRange.consumeIncludingComments().value();
+    if (isQuirksModeBehavior(m_context.mode()))
+        selector->setValue(AtomicString(value.lower()));
+    else
+        selector->setValue(AtomicString(value));
+    return selector.release();
+}
+
+PassOwnPtr<CSSParserSelector> CSSSelectorParser::consumeAttribute()
+{
+    // FIXME: Implement attribute parsing
+    return nullptr;
+}
+
+PassOwnPtr<CSSParserSelector> CSSSelectorParser::consumePseudo()
+{
+    // FIXME: Implement pseudo-element and pseudo-class parsing
+    return nullptr;
+}
+
+CSSSelector::Relation CSSSelectorParser::consumeCombinator()
+{
+    CSSSelector::Relation fallbackResult = CSSSelector::SubSelector;
+    while (m_tokenRange.peek().type() == WhitespaceToken || m_tokenRange.peek().type() == CommentToken) {
+        if (m_tokenRange.consume().type() == WhitespaceToken)
+            fallbackResult = CSSSelector::Descendant;
+    }
+
+    if (m_tokenRange.peek().type() != DelimiterToken)
+        return fallbackResult;
+
+    UChar delimiter = m_tokenRange.peek().delimiter();
+
+    if (delimiter == '+' || delimiter == '~' || delimiter == '>') {
+        m_tokenRange.consumeIncludingWhitespaceAndComments();
+        if (delimiter == '+')
+            return CSSSelector::DirectAdjacent;
+        if (delimiter == '~')
+            return CSSSelector::IndirectAdjacent;
+        return CSSSelector::Child;
+    }
+
+    // Match /deep/
+    if (delimiter != '/')
+        return fallbackResult;
+    m_tokenRange.consumeIncludingComments();
+    const CSSParserToken& ident = m_tokenRange.consumeIncludingComments();
+    if (ident.type() != IdentToken || !equalIgnoringCase(ident.value(), "deep"))
+        m_failedParsing = true;
+    const CSSParserToken& slash = m_tokenRange.consumeIncludingWhitespaceAndComments();
+    if (slash.type() != DelimiterToken || slash.delimiter() != '/')
+        m_failedParsing = true;
+    return CSSSelector::ShadowDeep;
+}
+
+QualifiedName CSSSelectorParser::determineNameInNamespace(const AtomicString& prefix, const AtomicString& localName)
+{
+    if (!m_styleSheet)
+        return QualifiedName(prefix, localName, m_defaultNamespace);
+    return QualifiedName(prefix, localName, m_styleSheet->determineNamespace(prefix));
+}
+
+void CSSSelectorParser::rewriteSpecifiersWithNamespaceIfNeeded(CSSParserSelector* specifiers)
+{
+    if (m_defaultNamespace != starAtom || specifiers->crossesTreeScopes())
+        rewriteSpecifiersWithElementName(nullAtom, starAtom, specifiers, /*tagIsForNamespaceRule*/true);
+}
+
+void CSSSelectorParser::rewriteSpecifiersWithElementName(const AtomicString& namespacePrefix, const AtomicString& elementName, CSSParserSelector* specifiers, bool tagIsForNamespaceRule)
+{
+    AtomicString determinedNamespace = namespacePrefix != nullAtom && m_styleSheet ? m_styleSheet->determineNamespace(namespacePrefix) : m_defaultNamespace;
+    QualifiedName tag(namespacePrefix, elementName, determinedNamespace);
+
+    if (specifiers->crossesTreeScopes())
+        return rewriteSpecifiersWithElementNameForCustomPseudoElement(tag, elementName, specifiers, tagIsForNamespaceRule);
+
+    if (specifiers->isContentPseudoElement())
+        return rewriteSpecifiersWithElementNameForContentPseudoElement(tag, elementName, specifiers, tagIsForNamespaceRule);
+
+    // *:host never matches, so we can't discard the * otherwise we can't tell the
+    // difference between *:host and just :host.
+    if (tag == anyQName() && !specifiers->hasHostPseudoSelector())
+        return;
+    if (specifiers->pseudoType() != CSSSelector::PseudoCue)
+        specifiers->prependTagSelector(tag, tagIsForNamespaceRule);
+}
+
+void CSSSelectorParser::rewriteSpecifiersWithElementNameForCustomPseudoElement(const QualifiedName& tag, const AtomicString& elementName, CSSParserSelector* specifiers, bool tagIsForNamespaceRule)
+{
+    CSSParserSelector* lastShadowPseudo = specifiers;
+    CSSParserSelector* history = specifiers;
+    while (history->tagHistory()) {
+        history = history->tagHistory();
+        if (history->crossesTreeScopes() || history->hasShadowPseudo())
+            lastShadowPseudo = history;
+    }
+
+    if (lastShadowPseudo->tagHistory()) {
+        if (tag != anyQName())
+            lastShadowPseudo->tagHistory()->prependTagSelector(tag, tagIsForNamespaceRule);
+        return;
+    }
+
+    // For shadow-ID pseudo-elements to be correctly matched, the ShadowPseudo combinator has to be used.
+    // We therefore create a new Selector with that combinator here in any case, even if matching any (host) element in any namespace (i.e. '*').
+    OwnPtr<CSSParserSelector> elementNameSelector = adoptPtr(new CSSParserSelector(tag));
+    lastShadowPseudo->setTagHistory(elementNameSelector.release());
+    lastShadowPseudo->setRelation(CSSSelector::ShadowPseudo);
+}
+
+void CSSSelectorParser::rewriteSpecifiersWithElementNameForContentPseudoElement(const QualifiedName& tag, const AtomicString& elementName, CSSParserSelector* specifiers, bool tagIsForNamespaceRule)
+{
+    CSSParserSelector* last = specifiers;
+    CSSParserSelector* history = specifiers;
+    while (history->tagHistory()) {
+        history = history->tagHistory();
+        if (history->isContentPseudoElement() || history->relationIsAffectedByPseudoContent())
+            last = history;
+    }
+
+    if (last->tagHistory()) {
+        if (tag != anyQName())
+            last->tagHistory()->prependTagSelector(tag, tagIsForNamespaceRule);
+        return;
+    }
+
+    // For shadow-ID pseudo-elements to be correctly matched, the ShadowPseudo combinator has to be used.
+    // We therefore create a new Selector with that combinator here in any case, even if matching any (host) element in any namespace (i.e. '*').
+    OwnPtr<CSSParserSelector> elementNameSelector = adoptPtr(new CSSParserSelector(tag));
+    last->setTagHistory(elementNameSelector.release());
+}
+
+PassOwnPtr<CSSParserSelector> CSSSelectorParser::rewriteSpecifiers(PassOwnPtr<CSSParserSelector> specifiers, PassOwnPtr<CSSParserSelector> newSpecifier)
+{
+    if (newSpecifier->crossesTreeScopes()) {
+        // Unknown pseudo element always goes at the top of selector chain.
+        newSpecifier->appendTagHistory(CSSSelector::ShadowPseudo, specifiers);
+        return newSpecifier;
+    }
+    if (newSpecifier->isContentPseudoElement()) {
+        newSpecifier->appendTagHistory(CSSSelector::SubSelector, specifiers);
+        return newSpecifier;
+    }
+    if (specifiers->crossesTreeScopes()) {
+        // Specifiers for unknown pseudo element go right behind it in the chain.
+        specifiers->insertTagHistory(CSSSelector::SubSelector, newSpecifier, CSSSelector::ShadowPseudo);
+        return specifiers;
+    }
+    if (specifiers->isContentPseudoElement()) {
+        specifiers->insertTagHistory(CSSSelector::SubSelector, newSpecifier, CSSSelector::SubSelector);
+        return specifiers;
+    }
+    specifiers->appendTagHistory(CSSSelector::SubSelector, newSpecifier);
+    return specifiers;
+}
+
+} // namespace blink