Qt QRegularExpression正则类的使用小结

#include <QRegularExpression>
#include <QDebug>

QString text = "Video Resolution: 1920x1080 @ 60Hz";
QRegularExpression re("(\\d{4})x(\\d{4})");

QRegularExpressionMatch match = re.match(text);
if (match.hasMatch()) {
    QString width = match.captured(1);  // "1920"
    QString height = match.captured(2); // "1080"
}

QString data = "<video>4K</video><audio>AAC</audio>";

// 贪婪匹配（默认）：会匹配到最后一个 </xxx>
QRegularExpression greedyRe("<video>.*</video>");
// 非贪婪匹配：只匹配到第一个结束标签
QRegularExpression lazyRe("<video>.*?</video>");

QRegularExpression re(
    "^(?<type>\\w+)://"
    "(?<ip>\\d+\\.\\d+\\.\\d+\\.\\d+):"
    "(?<port>\\d+)$"
);

QRegularExpressionMatch match = re.match("rtsp://192.168.1.100:554");
if (match.hasMatch()) {
    qDebug() << "Type:" << match.captured("type"); // rtsp
    qDebug() << "IP:"   << match.captured("ip");   // 192.168.1.100
    qDebug() << "Port:" << match.captured("port"); // 554
}

QString logData = "Pkt:123 Size:1500\nPkt:124 Size:1450";
QRegularExpression re("Pkt:(\\d+) Size:(\\d+)");

QRegularExpressionMatchIterator it = re.globalMatch(logData);
while (it.hasNext()) {
    QRegularExpressionMatch match = it.next();
    qDebug() << "Packet" << match.captured(1) 
             << "Size" << match.captured(2);
}

// ❌ 错误示范：每次调用都会重新编译正则
void badParse(QString data) {
    QRegularExpression re("pattern"); // 开销大
    ...
}

// ✅ 正确做法：使用静态变量或成员变量
void goodParse(QString data) {
    static const QRegularExpression re("pattern"); // 只编译一次
    ...
}

QRegularExpression re("pattern");
re.setPatternOptions(QRegularExpression::DotMatchesEverythingOption |
                    QRegularExpression::DontCaptureOption); // 不捕获提高效率

QLineEdit *ipInput = new QLineEdit(this);
QRegularExpression ipRegex(
    "^((25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\\.){3}"
    "(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)$"
);
QValidator *validator = new QRegularExpressionValidator(ipRegex, this);
ipInput->setValidator(validator);