File indexing completed on 2024-05-26 04:26:22

 /* This file is part of the KDE project
  * SPDX-FileCopyrightText: 2009 Jan Hambrecht <jaham@gmx.net>
  *
  * SPDX-License-Identifier: LGPL-2.0-or-later
  */
 
 #include "SvgCssHelper.h"
 #include <FlakeDebug.h>
 #include <QPair>
 
 /// Token types used for tokenizing complex selectors
 enum CssTokenType {
     SelectorToken,  ///< a selector token
     CombinatorToken ///< a combinator token
 };
 
 /// A token used for tokenizing complex selectors
 typedef QPair<CssTokenType, QString> CssToken;
 
 /// Selector base class, merely an interface
 class CssSelectorBase
 {
 public:
     virtual ~CssSelectorBase() {}
     /// Matches the given element
     virtual bool match(const QDomElement &) = 0;
     /// Returns string representation of selector
     virtual QString toString() const { return QString(); }
     /**
      * Returns priority of selector
      * see http://www.w3.org/TR/1998/REC-CSS2-19980512/cascade.html#specificity
      */
     virtual int priority() { return 0; }
 };
 
 /// Universal selector, matching anything
 class UniversalSelector : public CssSelectorBase
 {
 public:
     bool match(const QDomElement &) override
     {
         // matches always
         return true;
     }
     QString toString() const override
     {
         return "*";
     }
 };
 
 /// Type selector, matching the type of an element
 class TypeSelector : public CssSelectorBase
 {
 public:
     TypeSelector(const QString &type)
     : m_type(type)
     {
     }
     bool match(const QDomElement &e) override
     {
         return e.tagName() == m_type;
     }
     QString toString() const override
     {
         return m_type;
     }
     int priority() override
     {
         return 1;
     }
 
 private:
     QString m_type;
 };
 
 /// Id selector, matching the id attribute
 class IdSelector : public CssSelectorBase
 {
 public:
     IdSelector(const QString &id)
     : m_id(id)
     {
         if (id.startsWith('#'))
             m_id = id.mid(1);
     }
     bool match(const QDomElement &e) override
     {
         return e.attribute("id") == m_id;
     }
     QString toString() const override
     {
         return '#'+m_id;
     }
     int priority() override
     {
         return 100;
     }
 private:
     QString m_id;
 };
 
 /// Attribute selector, matching existence or content of attributes
 class AttributeSelector : public CssSelectorBase
 {
 public:
     AttributeSelector(const QString &attribute)
     : m_type(Unknown)
     {
         QString pattern = attribute;
         if (pattern.startsWith('['))
             pattern.remove(0,1);
         if (pattern.endsWith(']'))
             pattern.remove(pattern.length()-1,1);
         int equalPos = pattern.indexOf('=');
         if (equalPos == -1) {
             m_type = Exists;
             m_attribute = pattern;
         } else if (equalPos > 0){
             if (pattern[equalPos-1] == '~') {
                 m_attribute = pattern.left(equalPos-1);
                 m_type = InList;
             } else if(pattern[equalPos-1] == '|') {
                 m_attribute = pattern.left(equalPos-1) + '-';
                 m_type = StartsWith;
             } else {
                 m_attribute = pattern.left(equalPos);
                 m_type = Equals;
             }
             m_value = pattern.mid(equalPos+1);
             if (m_value.startsWith(QLatin1Char('"')))
                 m_value.remove(0,1);
             if (m_value.endsWith(QLatin1Char('"')))
                 m_value.chop(1);
         }
     }
 
     bool match(const QDomElement &e) override
     {
         switch(m_type) {
             case Exists:
                 return e.hasAttribute(m_attribute);
                 break;
             case Equals:
                 return e.attribute(m_attribute) == m_value;
                 break;
             case InList:
                 {
 #if (QT_VERSION >= QT_VERSION_CHECK(5, 14, 0))
                     QStringList tokens = e.attribute(m_attribute).split(' ', Qt::SkipEmptyParts);
 #else
                     QStringList tokens = e.attribute(m_attribute).split(' ', QString::SkipEmptyParts);
 #endif
                     return tokens.contains(m_value);
                 }
                 break;
             case StartsWith:
                 return e.attribute(m_attribute).startsWith(m_value);
                 break;
             default:
                 return false;
         }
     }
     QString toString() const override
     {
         QString str('[');
         str += m_attribute;
         if (m_type == Equals) {
             str += '=';
         } else if (m_type == InList) {
             str += "~=";
         } else if (m_type == StartsWith) {
             str += "|=";
         }
         str += m_value;
         str += ']';
         return str;
     }
     int priority() override
     {
         return 10;
     }
 
 private:
     enum MatchType {
         Unknown,   ///< unknown    -> error state
         Exists,    ///< [att]      -> attribute exists
         Equals,    ///< [att=val]  -> attribute value matches exactly val
         InList,    ///< [att~=val] -> attribute is whitespace separated list where one is val
         StartsWith ///< [att|=val] -> attribute starts with val-
     };
     QString m_attribute;
     QString m_value;
     MatchType m_type;
 };
 
 /// Pseudo-class selector
 class PseudoClassSelector : public CssSelectorBase
 {
 public:
     PseudoClassSelector(const QString &pseudoClass)
     : m_pseudoClass(pseudoClass)
     {
     }
 
     bool match(const QDomElement &e) override
     {
         if (m_pseudoClass == ":first-child") {
             QDomNode parent = e.parentNode();
             if (parent.isNull()) {
                 return false;
             }
             QDomNode firstChild = parent.firstChild();
             while(!firstChild.isElement() || firstChild.isNull()) {
                 firstChild = firstChild.nextSibling();
             }
             return firstChild == e;
         } else {
             return false;
         }
     }
     QString toString() const override
     {
         return m_pseudoClass;
     }
     int priority() override
     {
         return 10;
     }
 
 private:
     QString m_pseudoClass;
 };
 
 /// A simple selector, i.e. a type/universal selector followed by attribute, id or pseudo-class selectors
 class CssSimpleSelector : public CssSelectorBase
 {
 public:
     CssSimpleSelector(const QString &token)
     : m_token(token)
     {
         compile();
     }
     ~CssSimpleSelector() override
     {
         qDeleteAll(m_selectors);
     }
 
     bool match(const QDomElement &e) override
     {
         Q_FOREACH (CssSelectorBase *s, m_selectors) {
             if (!s->match(e))
                 return false;
         }
 
         return true;
     }
 
     QString toString() const override
     {
         QString str;
         Q_FOREACH (CssSelectorBase *s, m_selectors) {
             str += s->toString();
         }
         return str;
     }
     int priority() override
     {
         int p = 0;
         Q_FOREACH (CssSelectorBase *s, m_selectors) {
             p += s->priority();
         }
         return p;
     }
 
 private:
     void compile()
     {
         if (m_token == "*") {
             m_selectors.append(new UniversalSelector());
             return;
         }
 
         enum {
             Start,
             Finish,
             Bad,
             InType,
             InId,
             InAttribute,
             InClassAttribute,
             InPseudoClass
         } state;
 
         // add terminator to string
         QString expr = m_token + QChar();
         int i = 0;
         state = Start;
 
         QString token;
         QString sep("#[:.");
         // split into base selectors
         while((state != Finish) && (state != Bad) && (i < expr.length())) {
             QChar ch = expr[i];
             switch(state) {
                 case Start:
                     token += ch;
                     if (ch == '#')
                         state = InId;
                     else if (ch == '[')
                         state = InAttribute;
                     else if (ch == ':')
                         state = InPseudoClass;
                     else if (ch == '.')
                         state = InClassAttribute;
                     else if (ch != '*')
                         state = InType;
                     break;
                 case InAttribute:
                     if (ch.isNull()) {
                         // reset state and token string
                         state = Finish;
                         token.clear();
                         continue;
                     } else {
                         token += ch;
                         if (ch == ']') {
                             m_selectors.append(new AttributeSelector(token));
                             state = Start;
                             token.clear();
                         }
                     }
                     break;
                 case InType:
                 case InId:
                 case InClassAttribute:
                 case InPseudoClass:
                     // are we at the start of the next selector or even finished?
                     if (sep.contains(ch) || ch.isNull()) {
                         if (state == InType)
                             m_selectors.append(new TypeSelector(token));
                         else if (state == InId)
                             m_selectors.append(new IdSelector(token));
                         else if ( state == InClassAttribute)
                             m_selectors.append(new AttributeSelector("[class~="+token.mid(1)+']'));
                         else if (state == InPseudoClass) {
                             m_selectors.append(new PseudoClassSelector(token));
                         }
                         // reset state and token string
                         state = ch.isNull() ? Finish : Start;
                         token.clear();
                         continue;
                     } else {
                         // append character to current token
                         if (!ch.isNull())
                             token += ch;
                     }
                     break;
                 default:
                     break;
             }
             i++;
         }
     }
 
     QList<CssSelectorBase*> m_selectors;
     QString m_token;
 };
 
 /// Complex selector, i.e. a combination of simple selectors
 class CssComplexSelector : public CssSelectorBase
 {
 public:
     CssComplexSelector(const QList<CssToken> &tokens)
     {
         compile(tokens);
     }
     ~CssComplexSelector() override
     {
         qDeleteAll(m_selectors);
     }
     QString toString() const override
     {
         QString str;
         int selectorCount = m_selectors.count();
         if (selectorCount) {
             for(int i = 0; i < selectorCount-1; ++i) {
                 str += m_selectors[i]->toString() +
                        m_combinators[i];
             }
             str += m_selectors.last()->toString();
         }
         return str;
     }
 
     bool match(const QDomElement &e) override
     {
         int selectorCount = m_selectors.count();
         int combinatorCount = m_combinators.length();
         // check count of selectors and combinators
         if (selectorCount-combinatorCount != 1)
             return false;
 
         QDomElement currentElement = e;
 
         // match in reverse order
         for(int i = 0; i < selectorCount; ++i) {
             CssSelectorBase * curr = m_selectors[selectorCount-1-i];
             if (!curr->match(currentElement)) {
                 return false;
             }
             // last selector and still there -> rule matched completely
             if(i == selectorCount-1)
                 return true;
 
             CssSelectorBase * next = m_selectors[selectorCount-1-i-1];
             QChar combinator = m_combinators[combinatorCount-1-i];
             if (combinator == ' ') {
                 bool matched = false;
                 // descendant combinator
                 QDomNode parent = currentElement.parentNode();
                 while(!parent.isNull()) {
                     currentElement = parent.toElement();
                     if (next->match(currentElement)) {
                         matched = true;
                         break;
                     }
                     parent = currentElement.parentNode();
                 }
                 if(!matched)
                     return false;
             } else if (combinator == '>') {
                 // child selector
                 QDomNode parent = currentElement.parentNode();
                 if (parent.isNull())
                     return false;
                 QDomElement parentElement = parent.toElement();
                 if (next->match(parentElement)) {
                     currentElement = parentElement;
                 } else {
                     return false;
                 }
             } else if (combinator == '+') {
                 QDomNode neighbor = currentElement.previousSibling();
                 while(!neighbor.isNull() && !neighbor.isElement())
                     neighbor = neighbor.previousSibling();
                 if (neighbor.isNull() || !neighbor.isElement())
                     return false;
                 QDomElement neighborElement = neighbor.toElement();
                 if (next->match(neighborElement)) {
                     currentElement = neighborElement;
                 } else {
                     return false;
                 }
             } else {
                 return false;
             }
         }
         return true;
     }
     int priority() override
     {
         int p = 0;
         Q_FOREACH (CssSelectorBase *s, m_selectors) {
             p += s->priority();
         }
         return p;
     }
 
 private:
     void compile(const QList<CssToken> &tokens)
     {
         Q_FOREACH (const CssToken &token, tokens) {
             if(token.first == SelectorToken) {
                 m_selectors.append(new CssSimpleSelector(token.second));
             } else {
                 m_combinators += token.second;
             }
         }
     }
 
     QString m_combinators;
     QList<CssSelectorBase*> m_selectors;
 };
 
 /// A group of selectors (comma separated in css style sheet)
 typedef QList<CssSelectorBase*> SelectorGroup;
 /// A css rule consisting of group of selectors corresponding to a style
 typedef QPair<SelectorGroup, QString> CssRule;
 
 class SvgCssHelper::Private
 {
 public:
     ~Private()
     {
         Q_FOREACH (const CssRule &rule, cssRules) {
             qDeleteAll(rule.first);
         }
     }
 
     SelectorGroup parsePattern(const QString &pattern)
     {
         SelectorGroup group;
 
 #if (QT_VERSION >= QT_VERSION_CHECK(5, 14, 0))
         QStringList selectors = pattern.split(',', Qt::SkipEmptyParts);
 #else
         QStringList selectors = pattern.split(',', QString::SkipEmptyParts);
 #endif
         for (int i = 0; i < selectors.count(); ++i ) {
             CssSelectorBase * selector = compileSelector(selectors[i].simplified());
             if (selector)
                 group.append(selector);
         }
         return group;
     }
 
     QList<CssToken> tokenize(const QString &selector)
     {
         // add terminator to string
         QString expr = selector + QChar();
         enum {
             Finish,
             Bad,
             InCombinator,
             InSelector
         } state;
 
         QChar combinator;
         int selectorStart = 0;
 
         QList<CssToken> tokenList;
 
         QChar ch = expr[0];
         if (ch.isSpace() || ch == '>' || ch == '+') {
             debugFlake << "selector starting with combinator is not allowed:" << selector;
             return tokenList;
         } else {
             state = InSelector;
             selectorStart = 0;
         }
         int i = 1;
 
         // split into simple selectors and combinators
         while((state != Finish) && (state != Bad) && (i < expr.length())) {
             QChar ch = expr[i];
             switch(state) {
                 case InCombinator:
                     // consume as long as there a combinator characters
                     if( ch == '>' || ch == '+') {
                         if( ! combinator.isSpace() ) {
                             // two non whitespace combinators in sequence are not allowed
                             state = Bad;
                         } else {
                             // switch combinator
                             combinator = ch;
                         }
                     } else if (!ch.isSpace()) {
                         tokenList.append(CssToken(CombinatorToken, combinator));
                         state = InSelector;
                         selectorStart = i;
                         combinator = QChar();
                     }
                     break;
                 case InSelector:
                     // consume as long as there a non combinator characters
                     if (ch.isSpace() || ch == '>' || ch == '+') {
                         state = InCombinator;
                         combinator = ch;
                     } else if (ch.isNull()) {
                         state = Finish;
                     }
                     if (state != InSelector) {
                         QString simpleSelector = selector.mid(selectorStart, i-selectorStart);
                         tokenList.append(CssToken(SelectorToken, simpleSelector));
                     }
                     break;
                 default:
                     break;
             }
             i++;
         }
 
         return tokenList;
     }
 
     CssSelectorBase * compileSelector(const QString &selector)
     {
         QList<CssToken> tokenList = tokenize(selector);
         if (tokenList.isEmpty())
             return 0;
 
         if (tokenList.count() == 1) {
             // simple selector
             return new CssSimpleSelector(tokenList.first().second);
         } else if (tokenList.count() > 2) {
             // complex selector
             return new CssComplexSelector(tokenList);
         }
         return 0;
     }
 
     QMap<QString, QString> cssStyles;
     QList<CssRule> cssRules;
 };
 
 SvgCssHelper::SvgCssHelper()
 : d(new Private())
 {
 }
 
 SvgCssHelper::~SvgCssHelper()
 {
     delete d;
 }
 
 void SvgCssHelper::parseStylesheet(const QDomElement &e)
 {
     QString data;
 
     if (e.hasChildNodes()) {
         QDomNode c = e.firstChild();
         if (c.isCDATASection()) {
             QDomCDATASection cdata = c.toCDATASection();
             data = cdata.data().simplified();
         } else if (c.isText()) {
             QDomText text = c.toText();
             data = text.data().simplified();
         }
     }
     if (data.isEmpty())
         return;
 
     // remove comments
     QRegExp commentExp("\\/\\*.*\\*\\/");
     commentExp.setMinimal(true); // do not match greedy
     data.remove(commentExp);
 
 #if (QT_VERSION >= QT_VERSION_CHECK(5, 14, 0))
     QStringList defs = data.split('}', Qt::SkipEmptyParts);
 #else
     QStringList defs = data.split('}', QString::SkipEmptyParts);
 #endif
     for (int i = 0; i < defs.count(); ++i) {
         QStringList def = defs[i].split('{');
         if( def.count() != 2 )
             continue;
         QString pattern = def[0].simplified();
         if (pattern.isEmpty())
             break;
         QString style = def[1].simplified();
         if (style.isEmpty())
             break;
 #if (QT_VERSION >= QT_VERSION_CHECK(5, 14, 0))
         QStringList selectors = pattern.split(',', Qt::SkipEmptyParts);
 #else
         QStringList selectors = pattern.split(',', QString::SkipEmptyParts);
 #endif
         for (int i = 0; i < selectors.count(); ++i ) {
             QString selector = selectors[i].simplified();
             d->cssStyles[selector] = style;
         }
         SelectorGroup group = d->parsePattern(pattern);
         d->cssRules.append(CssRule(group, style));
     }
 }
 
 QStringList SvgCssHelper::matchStyles(const QDomElement &element) const
 {
     QMap<int, QString> prioritizedRules;
     // match rules to element
     Q_FOREACH (const CssRule &rule, d->cssRules) {
         Q_FOREACH (CssSelectorBase *s, rule.first) {
             bool matched = s->match(element);
             if (matched)
                 prioritizedRules[s->priority()] = rule.second;
         }
     }
 
     // css style attribute has the priority of 100
     QString styleAttribute = element.attribute("style").simplified();
     if (!styleAttribute.isEmpty())
         prioritizedRules[100] = styleAttribute;
 
     QStringList cssStyles;
     // add matching styles in correct order to style list
     QMapIterator<int, QString> it(prioritizedRules);
     while (it.hasNext()) {
         it.next();
         cssStyles.append(it.value());
     }
 
     return cssStyles;
 }