highlighter.cpp Example File

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 #include "highlighter.h"

 Highlighter::Highlighter(QTextDocument *parent)
     : QSyntaxHighlighter(parent)
 {
     HighlightingRule rule;

     keywordFormat.setForeground(Qt::darkBlue);
     keywordFormat.setFontWeight(QFont::Bold);
     const QString keywordPatterns[] = {
         QStringLiteral("\\bchar\\b"), QStringLiteral("\\bclass\\b"), QStringLiteral("\\bconst\\b"),
         QStringLiteral("\\bdouble\\b"), QStringLiteral("\\benum\\b"), QStringLiteral("\\bexplicit\\b"),
         QStringLiteral("\\bfriend\\b"), QStringLiteral("\\binline\\b"), QStringLiteral("\\bint\\b"),
         QStringLiteral("\\blong\\b"), QStringLiteral("\\bnamespace\\b"), QStringLiteral("\\boperator\\b"),
         QStringLiteral("\\bprivate\\b"), QStringLiteral("\\bprotected\\b"), QStringLiteral("\\bpublic\\b"),
         QStringLiteral("\\bshort\\b"), QStringLiteral("\\bsignals\\b"), QStringLiteral("\\bsigned\\b"),
         QStringLiteral("\\bslots\\b"), QStringLiteral("\\bstatic\\b"), QStringLiteral("\\bstruct\\b"),
         QStringLiteral("\\btemplate\\b"), QStringLiteral("\\btypedef\\b"), QStringLiteral("\\btypename\\b"),
         QStringLiteral("\\bunion\\b"), QStringLiteral("\\bunsigned\\b"), QStringLiteral("\\bvirtual\\b"),
         QStringLiteral("\\bvoid\\b"), QStringLiteral("\\bvolatile\\b"), QStringLiteral("\\bbool\\b")
     };
     for (const QString &pattern : keywordPatterns) {
         rule.pattern = QRegularExpression(pattern);
         rule.format = keywordFormat;
         highlightingRules.append(rule);
     }

     classFormat.setFontWeight(QFont::Bold);
     classFormat.setForeground(Qt::darkMagenta);
     rule.pattern = QRegularExpression(QStringLiteral("\\bQ[A-Za-z]+\\b"));
     rule.format = classFormat;
     highlightingRules.append(rule);

     singleLineCommentFormat.setForeground(Qt::red);
     rule.pattern = QRegularExpression(QStringLiteral("//[^\n]*"));
     rule.format = singleLineCommentFormat;
     highlightingRules.append(rule);

     multiLineCommentFormat.setForeground(Qt::red);

     quotationFormat.setForeground(Qt::darkGreen);
     rule.pattern = QRegularExpression(QStringLiteral("\".*\""));
     rule.format = quotationFormat;
     highlightingRules.append(rule);

     functionFormat.setFontItalic(true);
     functionFormat.setForeground(Qt::blue);
     rule.pattern = QRegularExpression(QStringLiteral("\\b[A-Za-z0-9_]+(?=\\()"));
     rule.format = functionFormat;
     highlightingRules.append(rule);

     commentStartExpression = QRegularExpression(QStringLiteral("/\\*"));
     commentEndExpression = QRegularExpression(QStringLiteral("\\*/"));
 }

 void Highlighter::highlightBlock(const QString &text)
 {
     for (const HighlightingRule &rule : qAsConst(highlightingRules)) {
         QRegularExpressionMatchIterator matchIterator = rule.pattern.globalMatch(text);
         while (matchIterator.hasNext()) {
             QRegularExpressionMatch match = matchIterator.next();
             setFormat(match.capturedStart(), match.capturedLength(), rule.format);
         }
     }
     setCurrentBlockState(0);

     int startIndex = 0;
     if (previousBlockState() != 1)
         startIndex = text.indexOf(commentStartExpression);

     while (startIndex >= 0) {
         QRegularExpressionMatch match = commentEndExpression.match(text, startIndex);
         int endIndex = match.capturedStart();
         int commentLength = 0;
         if (endIndex == -1) {
             setCurrentBlockState(1);
             commentLength = text.length() - startIndex;
         } else {
             commentLength = endIndex - startIndex
                             + match.capturedLength();
         }
         setFormat(startIndex, commentLength, multiLineCommentFormat);
         startIndex = text.indexOf(commentStartExpression, startIndex + commentLength);
     }
 }