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);
     QStringList keywordPatterns;
     keywordPatterns << "\\bchar\\b" << "\\bclass\\b" << "\\bconst\\b"
                     << "\\bdouble\\b" << "\\benum\\b" << "\\bexplicit\\b"
                     << "\\bfriend\\b" << "\\binline\\b" << "\\bint\\b"
                     << "\\blong\\b" << "\\bnamespace\\b" << "\\boperator\\b"
                     << "\\bprivate\\b" << "\\bprotected\\b" << "\\bpublic\\b"
                     << "\\bshort\\b" << "\\bsignals\\b" << "\\bsigned\\b"
                     << "\\bslots\\b" << "\\bstatic\\b" << "\\bstruct\\b"
                     << "\\btemplate\\b" << "\\btypedef\\b" << "\\btypename\\b"
                     << "\\bunion\\b" << "\\bunsigned\\b" << "\\bvirtual\\b"
                     << "\\bvoid\\b" << "\\bvolatile\\b" << "\\bbool\\b";
     foreach (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("\\bQ[A-Za-z]+\\b");
     rule.format = classFormat;
     highlightingRules.append(rule);

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

     multiLineCommentFormat.setForeground(Qt::red);

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

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

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

 void Highlighter::highlightBlock(const QString &text)
 {
     foreach (const HighlightingRule &rule, 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);
     }
 }