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Valentin Platzgummer
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#pragma once
#include "call_once.h"
#include <QScopedPointer>
#include <QtGlobal>
template <class T> class GenericSingelton {
private:
typedef T *(*CreateInstanceFunction)();
public:
static T *instance(CreateInstanceFunction create);
private:
static void init();
GenericSingelton();
~GenericSingelton();
Q_DISABLE_COPY(GenericSingelton)
static QBasicAtomicPointer<void> create;
static QBasicAtomicInt flag;
static QBasicAtomicPointer<void> tptr;
bool inited;
};
template <class T>
T *GenericSingelton<T>::instance(CreateInstanceFunction create) {
GenericSingelton::create.store(reinterpret_cast<void *>(create));
qCallOnce(init, flag);
return (T *)tptr.load();
}
template <class T> void GenericSingelton<T>::init() {
static GenericSingelton singleton;
if (singleton.inited) {
CreateInstanceFunction createFunction =
(CreateInstanceFunction)GenericSingelton::create.load();
tptr.store(createFunction());
}
}
template <class T> GenericSingelton<T>::GenericSingelton() { inited = true; }
template <class T> GenericSingelton<T>::~GenericSingelton() {
T *createdTptr = (T *)tptr.fetchAndStoreOrdered(nullptr);
if (createdTptr) {
delete createdTptr;
}
create.store(nullptr);
}
template <class T>
QBasicAtomicPointer<void>
GenericSingelton<T>::create = Q_BASIC_ATOMIC_INITIALIZER(nullptr);
template <class T>
QBasicAtomicInt GenericSingelton<T>::flag =
Q_BASIC_ATOMIC_INITIALIZER(CallOnce::CO_Request);
template <class T>
QBasicAtomicPointer<void>
GenericSingelton<T>::tptr = Q_BASIC_ATOMIC_INITIALIZER(nullptr);