26 lines
442 B
C++
26 lines
442 B
C++
#include <functional>
|
|
#include <memory>
|
|
|
|
template <typename T>
|
|
class Lazy {
|
|
public:
|
|
explicit Lazy(std::function<T*()> init) : init_(init) {}
|
|
|
|
T* get() {
|
|
if (!ptr_) {
|
|
ptr_.reset(init_());
|
|
}
|
|
return ptr_.get();
|
|
}
|
|
|
|
typename std::add_lvalue_reference<T>::type operator*() const {
|
|
return *ptr_;
|
|
}
|
|
|
|
T* operator->() const { return ptr_.get(); }
|
|
|
|
private:
|
|
std::function<T*()> init_;
|
|
std::unique_ptr<T> ptr_;
|
|
};
|