A thread-safe Media Query Parser

Source/core/css/parser/MediaQueryParser.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/MediaQueryParser.h"
+
+#include "MediaTypeNames.h"
+#include "core/css/parser/CSSPropertyParser.h"
+#include "core/css/parser/MediaQueryTokenizer.h"
+
+namespace WebCore {
+
+PassRefPtrWillBeRawPtr<MediaQuerySet> MediaQueryParser::parse(const String& queryString)
+{
+    return MediaQueryParser(queryString).parseImpl();
+}
+
+const MediaQueryParser::State MediaQueryParser::ReadRestrictor = &MediaQueryParser::readRestrictor;
+const MediaQueryParser::State MediaQueryParser::ReadMediaType = &MediaQueryParser::readMediaType;
+const MediaQueryParser::State MediaQueryParser::ReadAnd = &MediaQueryParser::readAnd;
+const MediaQueryParser::State MediaQueryParser::ReadFeatureStart = &MediaQueryParser::readFeatureStart;
+const MediaQueryParser::State MediaQueryParser::ReadFeature = &MediaQueryParser::readFeature;
+const MediaQueryParser::State MediaQueryParser::ReadFeatureColon = &MediaQueryParser::readFeatureColon;
+const MediaQueryParser::State MediaQueryParser::ReadFeatureValue = &MediaQueryParser::readFeatureValue;
+const MediaQueryParser::State MediaQueryParser::ReadFeatureEnd = &MediaQueryParser::readFeatureEnd;
+const MediaQueryParser::State MediaQueryParser::SkipUntilComma = &MediaQueryParser::skipUntilComma;
+const MediaQueryParser::State MediaQueryParser::SkipUntilParenthesis = &MediaQueryParser::skipUntilParenthesis;
+const MediaQueryParser::State MediaQueryParser::Done = &MediaQueryParser::done;
+
+// FIXME: Replace the MediaQueryTokenizer with a generic CSSTokenizer, once there is one,
+// or better yet, replace the MediaQueryParser with a generic thread-safe CSS parser.
+MediaQueryParser::MediaQueryParser(const String& queryString)
+    : m_state(&MediaQueryParser::readRestrictor)
+    , m_querySet(MediaQuerySet::create())
+{
+    MediaQueryTokenizer::tokenize(queryString, m_tokens);
+}
+
+void MediaQueryParser::setStateAndRestrict(State state, MediaQuery::Restrictor restrictor)
+{
+    m_mediaQueryData.setRestrictor(restrictor);
+    m_state = state;
+}
+
+// State machine member functions start here
+void MediaQueryParser::readRestrictor(MediaQueryTokenType type, TokenIterator& token)
+{
+    readMediaType(type, token);
+}
+
+void MediaQueryParser::readMediaType(MediaQueryTokenType type, TokenIterator& token)
+{
+    if (type == LeftParenthesisToken) {
+        m_state = ReadFeature;
+    } else if (type == IdentToken) {
+        if (m_state == ReadRestrictor && equalIgnoringCase(token->value(), "not")) {
+            setStateAndRestrict(ReadMediaType, MediaQuery::Not);
+        } else if (m_state == ReadRestrictor && equalIgnoringCase(token->value(), "only")) {
+            setStateAndRestrict(ReadMediaType, MediaQuery::Only);
+        } else {
+            m_mediaQueryData.setMediaType(token->value());
+            m_state = ReadAnd;
+        }
+    } else if (type == EOFToken && (!m_querySet->queryVector().size() || m_state != ReadRestrictor)) {
+        m_state = Done;
+    } else {
+        if (type == CommaToken)
+            --token;
+        m_state = SkipUntilComma;
+    }
+}
+
+void MediaQueryParser::readAnd(MediaQueryTokenType type, TokenIterator& token)
+{
+    if (type == IdentToken && equalIgnoringCase(token->value(), "and")) {
+        m_state = ReadFeatureStart;
+    } else if (type == CommaToken) {
+        m_querySet->addMediaQuery(m_mediaQueryData.takeMediaQuery());
+        m_state = ReadRestrictor;
+    } else if (type == EOFToken) {
+        m_state = Done;
+    } else {
+        m_state = SkipUntilComma;
+    }
+}
+
+void MediaQueryParser::readFeatureStart(MediaQueryTokenType type, TokenIterator& token)
+{
+    if (type == LeftParenthesisToken)
+        m_state = ReadFeature;
+    else
+        m_state = SkipUntilComma;
+}
+
+void MediaQueryParser::readFeature(MediaQueryTokenType type, TokenIterator& token)
+{
+    if (type == IdentToken) {
+        m_mediaQueryData.setMediaFeature(token->value());
+        m_state = ReadFeatureColon;
+    } else {
+        m_state = SkipUntilComma;
+    }
+}
+
+void MediaQueryParser::readFeatureColon(MediaQueryTokenType type, TokenIterator& token)
+{
+    if (type == ColonToken) {
+        m_state = ReadFeatureValue;
+    } else if (type == RightParenthesisToken || type == EOFToken) {
+        --token;
+        m_state = ReadFeatureEnd;
+    } else {
+        m_state = SkipUntilParenthesis;
+    }
+}
+
+void MediaQueryParser::readFeatureValue(MediaQueryTokenType type, TokenIterator& token)
+{
+    if (type == DimensionToken && token->unitType() == CSSPrimitiveValue::CSS_UNKNOWN) {
+        m_state = SkipUntilComma;
+    } else {
+        m_mediaQueryData.addParserValue(type, *token);
+        m_state = ReadFeatureEnd;
+    }
+}
+
+void MediaQueryParser::readFeatureEnd(MediaQueryTokenType type, TokenIterator& token)
+{
+    if (type == RightParenthesisToken || type == EOFToken) {
+        if (m_mediaQueryData.addExpression())
+            m_state = ReadAnd;
+        else
+            m_state = SkipUntilComma;
+    } else if (type == DelimiterToken && token->delimiter() == '/') {
+        m_mediaQueryData.addParserValue(type, *token);
+        m_state = ReadFeatureValue;
+    } else {
+        m_state = SkipUntilParenthesis;
+    }
+}
+
+void MediaQueryParser::skipUntilComma(MediaQueryTokenType type, TokenIterator& token)
+{
+    if (type == CommaToken || type == EOFToken) {
+        m_state = ReadRestrictor;
+        m_mediaQueryData.clear();
+        m_querySet->addMediaQuery(MediaQuery::createNotAll());
+    }
+}
+
+void MediaQueryParser::skipUntilParenthesis(MediaQueryTokenType type, TokenIterator& token)
+{
+    if (type == RightParenthesisToken)
+        m_state = SkipUntilComma;
+}
+
+void MediaQueryParser::done(MediaQueryTokenType type, TokenIterator& token) { }
+
+void MediaQueryParser::processToken(TokenIterator& token)
+{
+    MediaQueryTokenType type = token->type();
+
+    // Call the function that handles current state
+    if (type != WhitespaceToken)
+        ((this)->*(m_state))(type, token);
+}
+
+// The state machine loop
+PassRefPtrWillBeRawPtr<MediaQuerySet> MediaQueryParser::parseImpl()
+{
+    for (Vector<MediaQueryToken>::iterator token = m_tokens.begin(); token != m_tokens.end(); ++token)
+        processToken(token);
+
+    if (m_state != ReadAnd && m_state != ReadRestrictor && m_state != Done)
+        m_querySet->addMediaQuery(MediaQuery::createNotAll());
+    else if (m_mediaQueryData.currentMediaQueryChanged())
+        m_querySet->addMediaQuery(m_mediaQueryData.takeMediaQuery());
+
+    return m_querySet;
+}
+
+MediaQueryData::MediaQueryData()
+    : m_restrictor(MediaQuery::None)
+    , m_mediaType(MediaTypeNames::all)
+    , m_expressions(adoptPtr(new ExpressionHeapVector))
+    , m_mediaTypeSet(false)
+{
+}
+
+void MediaQueryData::clear()
+{
+    m_restrictor = MediaQuery::None;
+    m_mediaType = MediaTypeNames::all;
+    m_mediaTypeSet = false;
+    m_mediaFeature = String();
+    m_valueList.clear();
+    m_expressions = adoptPtr(new ExpressionHeapVector);
+}
+
+PassOwnPtr<MediaQuery> MediaQueryData::takeMediaQuery()
+{
+    OwnPtr<MediaQuery> mediaQuery = adoptPtr(new MediaQuery(m_restrictor, m_mediaType, m_expressions.release()));
+    clear();
+    return mediaQuery.release();
+}
+
+bool MediaQueryData::addExpression()
+{
+    OwnPtr<MediaQueryExp> expression = MediaQueryExp::create(m_mediaFeature, &m_valueList);
+    bool isValid = !!expression;
+    m_expressions->append(expression.release());
+    m_valueList.clear();
+    return isValid;
+}
+
+void MediaQueryData::addParserValue(MediaQueryTokenType type, MediaQueryToken& token)
+{
+    CSSParserValue value;
+    if (type == NumberToken || type == PercentageToken || type == DimensionToken) {
+        value.setFromNumber(token.numericValue(), token.unitType());
+        value.isInt = (token.numericValueType() == IntegerValueType);
+    } else if (type == DelimiterToken) {
+        value.unit = CSSParserValue::Operator;
+        value.iValue = token.delimiter();
+    } else {
+        CSSParserFunction* function = new CSSParserFunction;
+        function->name.init(token.value());
+        value.setFromFunction(function);
+        CSSParserString tokenValue;
+        tokenValue.init(token.value());
+        value.id = cssValueKeywordID(tokenValue);
+    }
+    m_valueList.addValue(value);
+}
+
+void MediaQueryData::setMediaType(const String& mediaType)
+{
+    m_mediaType = mediaType;
+    m_mediaTypeSet = true;
+}
+
+} // namespace WebCore