正规文法转换有限自动机图像qt代码

以下是正规文法转换为有限自动机的Qt代码示例：

#include <QtWidgets>

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);

    // Define the grammar
    QStringList productions;
    productions << "S -> 0S1" << "S -> 1S0" << "S -> ε";

    // Create the automaton
    QSet<QString> states;
    QSet<QString> finalStates;
    QHash<QString, QHash<QString, QSet<QString>>> transitions;

    // Add the starting state
    QString startState = "S";
    states.insert(startState);

    // Add the production rules
    for (const QString &production : productions) {
        QStringList parts = production.split(" -> ");
        QString fromState = parts[0];
        QString toSymbols = parts[1];

        // Add the symbols to the states set
        for (const QChar &symbol : toSymbols) {
            if (symbol != QChar('ε')) {
                QString state = QString("%1_%2").arg(fromState).arg(symbol);
                states.insert(state);
            }
        }

        // Add the transitions to the hash table
        for (int i = 0; i < toSymbols.length(); i++) {
            QChar symbol = toSymbols[i];
            QString from = QString("%1_%2").arg(fromState).arg(symbol);
            QString to;
            if (i == toSymbols.length() - 1) {
                to = fromState;
            } else {
                QChar nextSymbol = toSymbols[i+1];
                to = QString("%1_%2").arg(fromState).arg(nextSymbol);
            }
            transitions[from][QString(symbol)] = QSet<QString>() << to;
        }
    }

    // Add the final states
    finalStates << startState;

    // Display the automaton
    QGraphicsScene scene;
    int x = 50, y = 50;
    QHash<QString, QGraphicsItem*> items;
    for (const QString &state : states) {
        QGraphicsEllipseItem *ellipse = new QGraphicsEllipseItem(x, y, 50, 50);
        ellipse->setPen(QPen(Qt::black));
        ellipse->setBrush(QBrush(Qt::white));
        QGraphicsTextItem *label = new QGraphicsTextItem(state, ellipse);
        label->setDefaultTextColor(Qt::black);
        label->setFont(QFont("Arial", 12));
        label->setPos(x + 10, y + 10);
        scene.addItem(ellipse);
        items[state] = ellipse;
        x += 100;
        if (x > 500) {
            x = 50;
            y += 100;
        }
    }
    for (const QString &fromState : transitions.keys()) {
        for (const QString &symbol : transitions[fromState].keys()) {
            QSet<QString> toStates = transitions[fromState][symbol];
            for (const QString &toState : toStates) {
                QGraphicsItem *fromItem = items[fromState];
                QGraphicsItem *toItem = items[toState];
                QGraphicsLineItem *line = new QGraphicsLineItem(fromItem->boundingRect().center().x(),
                                                                fromItem->boundingRect().center().y(),
                                                                toItem->boundingRect().center().x(),
                                                                toItem->boundingRect().center().y());
                line->setPen(QPen(Qt::black));
                scene.addItem(line);
            }
        }
    }
    QGraphicsView view(&scene);
    view.show();

    return app.exec();
}

这段代码实现了将正规文法 "S -> 0S1 | 1S0 | ε" 转换为有限自动机，并使用Qt图形界面库展示了自动机图像。其中，QSet和QHash是Qt中的两种容器类，用于存储状态集合和转移关系。通过循环遍历产生式，将产生式中的符号添加到状态集合中，并创建转移关系。最后，通过QGraphicsScene和QGraphicsView将自动机图像展示出来。