qt/ledset/gutil/qjson.h

#ifndef QJSON_H
#define QJSON_H

#include "cu.h"
#include "QtCore/qhashfunctions.h"
#include <QTextStream>

class JValue;
using JObj = LinkedMap<QString, JValue>;
using JArray = Vector<JValue>;

class JValue {
public:
    int data[2]{0};
    enum Type {
        Null, Bool, Int, Long, Double, Obj, Array, Str
    };
    Type type{Null};

    JValue(Type = Null) {}
    JValue(bool b) : type(Bool) {data[0] = b;}
    JValue(int n) : type(Int) {data[0] = n;}
    JValue(qint64 n) : type(Long) {*(qint64*) data = n;}
    JValue(double d) : type(Double) {*(double*) data = d;}
    JValue(const JObj &o) : type(Obj) {new (data) JObj(o);}
    JValue(const JArray &a) : type(Array) {new (data) JArray(a);}
    JValue(const QString &s) : type(Str) {*(SharedData<QString>**) data = new SharedData<QString>{s, 1};}
    JValue(const char *s) : JValue(QString::fromUtf8(s)) {}
    JValue(const JValue &other) {
        type = other.type;
        if(type==Obj) new (data) JObj(*(JObj*) other.data);
        else if(type==Array) new (data) JArray(*(JArray*) other.data);
        else {
            data[0] = other.data[0];
            data[1] = other.data[1];
            if(type==Str) (*(SharedData<QString>**) data)->cnt++;
        }
    }
    ~JValue() {
        if(type < Obj) return;
        else if(type==Obj) ((JObj*) data)->~JObj();
        else if(type==Array) ((JArray*) data)->~JArray();
        else if(type==Str) {
            auto ptr = *(SharedData<QString>**) data;
            if(ptr->cnt > 1) ptr->cnt--;
            else delete ptr;
        }
    }

    JValue &operator=(const JValue &other) {
        this->~JValue();
        new (this) JValue(other);
        return *this;
    }

    bool isNull() const {return type==Null;}
    bool isObj() const {return type==Obj;}
    bool isArray() const {return type==Array;}

    bool toBool(bool def = false) const {
        return type==Null ? def : data[0] || data[1];
    }
    int toInt(int def = 0) const {
        if(type==Bool || type==Int) return data[0];
        if(type==Long) return *(qint64*) data;
        if(type==Double) return *(double*) data;
        return def;
    }
    qint64 toLong(qint64 def = 0) const {
        if(type==Bool || type==Int) return data[0];
        if(type==Long) return *(qint64*) data;
        if(type==Double) return *(double*) data;
        return def;
    }
    double toDouble(double def = 0) const {
        if(type==Bool || type==Int) return data[0];
        if(type==Long) return *(qint64*) data;
        if(type==Double) return *(double*) data;
        return def;
    }
    QString toStr(const QString &def = "") const {
        if(type==Bool) return data[0] ? "true" : "false";
        if(type==Int) return QString::number(data[0]);
        if(type==Long) return QString::number(*(qint64*) data);
        if(type==Double) return QString::number(*(double*) data);
        if(type==Str) return (*(SharedData<QString>**) data)->data;
        return def;
    }
    JObj toObj() const {
        if(type==Obj) return *(JObj*) data;
        return JObj();
    }
    JArray toArray() const {
        if(type==Array) return *(JArray*) data;
        return JArray();
    }
    const JValue operator[](const QString &key) const {
        return type==Obj ? (*(JObj*) data)[key] : JValue();
    }
    const JValue operator[](int i) const {
        return type==Array ? (*(JArray*) data)[i] : JValue();
    }
private:
    JValue(const void *) = delete; // avoid implicit conversions from char * to bool
};

class JParser {
public:
    JParser(QTextStream &in) : in(in) {
#if(QT_VERSION_MAJOR < 6)
    in.setCodec("UTF-8");
#endif
    }

    inline JValue read() {
        skipSpace();
        return readValue();
    }
protected:
    JValue readValue();
    QString readStr();
    void skipSpace();

    QTextStream &in;
    QChar ch{0}, bk{0};
};

inline JValue JFrom(const QByteArray &json, QString *err = 0) {
    QTextStream in(json);
    try {
        return JParser(in).read();
    } catch (QString anerr) {
        if(err) *err = anerr;
    } catch (const char *anerr) {
        if(err) *err = anerr;
    } catch (...) {
        if(err) *err = "unknow error";
    }
    return JValue();
}
inline JValue JFrom(QIODevice *device, QString *err = 0) {
    QTextStream in(device);
    try {
        return JParser(in).read();
    } catch (QString anerr) {
        if(err) *err = anerr;
    } catch (const char *anerr) {
        if(err) *err = anerr;
    } catch (...) {
        if(err) *err = "unknow error";
    }
    return JValue();
}

class JOut {
public:
    JOut(QTextStream &out, QString indent = "") : out(out), indent(indent) {
#if(QT_VERSION_MAJOR < 6)
    out.setCodec("UTF-8");
#endif
    }

    void write(const JValue &obj);
    void writeStr(const QString &str);
    void writeMap(const JObj &map);
    void writeList(const JArray &objs);
protected:
    QTextStream &out;
    QString indent;
    int cnt{0};
};

inline QString JToStr(const JValue &obj, QString indent = "") {
    QString json;
    QTextStream out(&json);
    JOut(out, indent).write(obj);
    return json;
}
inline QByteArray JToBytes(const JValue &obj, QString indent = "") {
    QByteArray json;
    QTextStream out(&json);
    JOut(out, indent).write(obj);
    return json;
}
inline QTextStream::Status JWrite(const JValue &obj, QIODevice *device, QString indent = "") {
    QTextStream out(device);
    JOut(out, indent).write(obj);
    return out.status();
}

#endif // QJSON_H