#include <QApplication>
#include <QPlainTextEdit>
#include <QSyntaxHighlighter>

class dummyHighlighter : public QSyntaxHighlighter{
public:
    dummyHighlighter(QTextDocument *parent):
        QSyntaxHighlighter(parent)
    {

    }

    void highlightBlock(const QString &text){
        QTextCharFormat myClassFormat;
        myClassFormat.setFontWeight(QFont::Bold);
        myClassFormat.setFontCapitalization(QFont::AllUppercase);
        myClassFormat.setForeground(Qt::darkMagenta);
        QString pattern = "(input)";

        QRegExp expression(pattern);
        int index = text.indexOf(expression);
        while (index >= 0) {
            int length = expression.matchedLength();
            setFormat(index, length, myClassFormat);
            index = text.indexOf(expression, index + length);
        }
    }
};

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    QPlainTextEdit textEdit;
    dummyHighlighter highlighter(textEdit.document());

    textEdit.show();
    
    return a.exec();
}