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# highlighter.cpp Example File
richtext/syntaxhighlighter/highlighter.cpp

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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 (const 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 (const HighlightingRule &rule, highlightingRules) {
             QRegExp expression(rule.pattern);
             int index = expression.indexIn(text);
             while (index >= 0) {
                 int length = expression.matchedLength();
                 setFormat(index, length, rule.format);
                 index = expression.indexIn(text, index + length);
             }
         }
         setCurrentBlockState(0);

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

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