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highlighter.cpp Example File
^{richtext/syntaxhighlighter/highlighter.cpp}

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    ** This file is part of the documentation of the Qt Toolkit.
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    #include <QtGui>

    #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";
        foreach (QString pattern, keywordPatterns) {
            rule.pattern = QRegExp(pattern);
            rule.format = keywordFormat;
            highlightingRules.append(rule);
        }

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

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

        multiLineCommentFormat.setForeground(Qt::red);

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

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

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

    void Highlighter::highlightBlock(const QString &text)
    {
        foreach (HighlightingRule rule, highlightingRules) {
            QRegExp expression(rule.pattern);
            int index = text.indexOf(expression);
            while (index >= 0) {
                int length = expression.matchedLength();
                setFormat(index, length, rule.format);
                index = text.indexOf(expression, index + length);
            }
        }
        setCurrentBlockState(0);

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

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