83 lines
2.5 KiB
C++
83 lines
2.5 KiB
C++
#ifndef SINGLETON_H
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#define SINGLETON_H
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#include "BoostLog.h"
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#include <boost/assert.hpp>
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#include <memory>
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namespace Amass {
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using GlobalInstance = std::true_type;
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using LocalInstance = std::false_type;
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struct Construct {};
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struct Reference {};
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struct Register {};
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template <typename T, typename Style = LocalInstance>
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class Singleton;
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template <typename T>
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class Singleton<T, LocalInstance> {
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public:
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template <typename Invoke = Reference, typename InstanceType = T, typename... Args>
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static std::shared_ptr<T> instance(Args &&...args) {
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// LOG(debug) << typeid(T).name() << " address: " << (size_t)&m_instance;
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static_assert(std::is_base_of_v<T, InstanceType>, "InstanceType must be child of T ...");
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if constexpr (std::is_same_v<Invoke, Construct>) {
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if (!m_instance.expired()) {
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throw std::runtime_error("an instance have constructed ...");
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}
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auto instance = std::shared_ptr<T>(new InstanceType(std::forward<Args>(args)...));
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m_instance = instance;
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return instance;
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} else if constexpr (std::is_same_v<Invoke, Reference>) {
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return m_instance.expired() ? nullptr : m_instance.lock();
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} else if constexpr (std::is_same_v<Invoke, Register>) {
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static_assert(sizeof...(args) == 1, "args must equal to 1...");
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m_instance = std::get<0>(std::forward_as_tuple(args)...);
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return std::get<0>(std::forward_as_tuple(args)...);
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} else {
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static_assert(!std::is_same_v<Invoke, GlobalInstance>, "Can not to it!");
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}
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}
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static std::weak_ptr<T> weakPointer() {
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return m_instance;
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}
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private:
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Singleton() = delete;
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~Singleton() = delete;
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Singleton(const Singleton &) = delete;
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Singleton &operator=(const Singleton &) = delete;
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private:
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inline static std::weak_ptr<T> m_instance;
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};
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template <typename T>
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class Singleton<T, GlobalInstance> {
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public:
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template <typename... Args>
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static T *instance(Args &&...args) {
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if (!m_value) {
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m_value.reset(new T(std::forward<Args>(args)...));
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}
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return m_value.get();
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}
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private:
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Singleton() = delete;
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~Singleton() = delete;
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Singleton(const Singleton &) = delete;
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Singleton &operator=(const Singleton &) = delete;
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private:
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inline static std::shared_ptr<T> m_value;
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};
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} // namespace Amass
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#endif // SINGLETON_H
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