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#pragma once
#include <cru/common/Bitmask.h>
#include <cru/common/SelfResolvable.h>
#include <cstddef>
#include <functional>
#include <type_traits>
#include <utility>
#include <vector>
namespace cru {
class Event2Base {
public:
virtual ~Event2Base() = default;
virtual void RevokeHandler(int token_value) = 0;
};
template <typename TArgument, typename TResult>
class EventContext {
public:
EventContext() : argument_(), result_() {}
explicit EventContext(TArgument argument)
: argument_(std::move(argument)), result_() {}
EventContext(TArgument argument, TResult result)
: argument_(std::move(argument)), result_(std::move(result)) {}
TArgument& GetArgument() { return argument_; }
const TArgument& GetArgument() const { return argument_; }
TResult& GetResult() { return result_; }
const TResult& GetResult() const { return result_; }
void SetResult(const TResult& result) { result_ = result; }
void SetResult(TResult&& result) { result_ = std::move(result); }
TResult TakeResult() { return std::move(result_); }
bool GetStopHandling() const { return stop_handling_; }
void SetStopHandling(bool stop = true) { stop_handling_ = stop; }
private:
TArgument argument_;
TResult result_;
bool stop_handling_ = false;
};
template <typename TArgument, typename TResult>
class Event2;
template <typename T>
constexpr bool is_event2_v = false;
template <typename TArgument, typename TResult>
constexpr bool is_event2_v<Event2<TArgument, TResult>> = true;
class EventHandlerToken {
public:
EventHandlerToken(ObjectResolver<Event2Base> event_resolver, int token_value)
: event_resolver_(std::move(event_resolver)), token_value_(token_value) {}
ObjectResolver<Event2Base> GetEventResolver() const {
return event_resolver_;
}
int GetTokenValue() const { return token_value_; }
inline void RevokeHandler() const;
private:
ObjectResolver<Event2Base> event_resolver_;
int token_value_;
};
namespace details {
struct Event2BehaviorFlagTag {};
} // namespace details
using Event2BehaviorFlag = Bitmask<details::Event2BehaviorFlagTag>;
struct Event2BehaviorFlags {
/**
* @brief Make a copy of handler list before invoking handlers. So the event
* object or its owner can be destroyed during running handlers.
*/
static constexpr Event2BehaviorFlag CopyHandlers =
Event2BehaviorFlag::FromOffset(1);
};
template <typename TArgument = std::nullptr_t,
typename TResult = std::nullptr_t>
class Event2 : public Event2Base,
public SelfResolvable<Event2<TArgument, TResult>> {
public:
using HandlerToken = EventHandlerToken;
using Context = EventContext<TArgument, TResult>;
using Handler = std::function<void(Context*)>;
using SpyOnlyHandler = std::function<void()>;
template <typename TFunc>
static std::enable_if_t<std::invocable<TFunc>, Handler> WrapAsHandler(
TFunc&& handler) {
return Handler([h = std::forward<TFunc>(handler)](Context*) { h(); });
}
template <typename TFunc>
static std::enable_if_t<std::invocable<TFunc, Context*>, Handler>
WrapAsHandler(TFunc&& handler) {
return Handler(std::forward<TFunc>(handler));
}
private:
struct HandlerData {
int token_value;
Handler handler;
};
public:
explicit Event2(Event2BehaviorFlag flags = {}) : flags_(flags) {}
Event2(const Event2&) = delete;
Event2(Event2&&) = delete;
Event2& operator=(const Event2&) = delete;
Event2& operator=(Event2&&) = delete;
~Event2() override = default;
public:
template <typename TFunc>
HandlerToken AddHandler(TFunc&& handler) {
auto token = this->current_token_value_++;
auto real_handler = WrapAsHandler(std::forward<TFunc>(handler));
HandlerData handler_data{token, std::move(real_handler)};
this->handlers_.push_back(std::move(handler_data));
return HandlerToken(this->CreateResolver(), token);
}
void RevokeHandler(int token_value) override {
auto iter = this->handlers_.cbegin();
auto end = this->handlers_.cend();
for (; iter != end; ++iter) {
if (iter->token_value == token_value) {
this->handlers_.erase(iter);
break;
}
}
}
void RevokeHandler(const HandlerToken& token) {
return RevokeHandler(token.GetTokenValue());
}
TResult Raise() {
Context context;
RunInContext(&context);
return context.TakeResult();
}
TResult Raise(TArgument argument) {
Context context(std::move(argument));
RunInContext(&context);
return context.TakeResult();
}
TResult Raise(TArgument argument, TResult result) {
Context context(std::move(argument), std::move(result));
RunInContext(&context);
return context.TakeResult();
}
private:
void RunInContext(Context* context) {
if (this->flags_ & Event2BehaviorFlags::CopyHandlers) {
std::vector<Handler> handlers_copy;
for (const auto& handler : this->handlers_) {
handlers_copy.push_back(handler.handler);
}
for (const auto& handler : handlers_copy) {
if (context->GetStopHandling()) {
break;
}
handler(context);
}
} else {
for (const auto& handler : this->handlers_) {
if (context->GetStopHandling()) {
break;
}
handler.handler(context);
}
}
}
private:
int current_token_value_ = 1;
std::vector<HandlerData> handlers_;
Event2BehaviorFlag flags_;
};
inline void EventHandlerToken::RevokeHandler() const {
auto event = this->event_resolver_.Resolve();
if (event) {
event->RevokeHandler(this->token_value_);
}
}
} // namespace cru
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