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/* SPDX-License-Identifier: LGPL-2.1-or-later */
/*
* Copyright (C) 2019, Google Inc.
*
* signal.h - Signal & slot implementation
*/
#ifndef __LIBCAMERA_SIGNAL_H__
#define __LIBCAMERA_SIGNAL_H__
#include <list>
#include <tuple>
#include <type_traits>
#include <vector>
#include <libcamera/object.h>
namespace libcamera {
template<typename... Args>
class Signal;
class SignalBase;
class SlotBase
{
public:
SlotBase(void *obj, Object *object)
: obj_(obj), object_(object) {}
virtual ~SlotBase() {}
template<typename T, typename std::enable_if<!std::is_same<Object, T>::value>::type * = nullptr>
bool match(T *obj) { return obj == obj_; }
bool match(Object *object) { return object == object_; }
void disconnect(SignalBase *signal);
void activatePack(void *pack);
virtual void invokePack(void *pack) = 0;
protected:
void *obj_;
Object *object_;
};
template<typename... Args>
class SlotArgs : public SlotBase
{
private:
#ifndef __DOXYGEN__
/*
* This is a cheap partial implementation of std::integer_sequence<>
* from C++14.
*/
template<int...>
struct sequence {
};
template<int N, int... S>
struct generator : generator<N-1, N-1, S...> {
};
template<int... S>
struct generator<0, S...> {
typedef sequence<S...> type;
};
#endif
using PackType = std::tuple<typename std::remove_reference<Args>::type...>;
template<int... S>
void invokePack(void *pack, sequence<S...>)
{
PackType *args = static_cast<PackType *>(pack);
invoke(std::get<S>(*args)...);
delete args;
}
public:
SlotArgs(void *obj, Object *object)
: SlotBase(obj, object) {}
void invokePack(void *pack) override
{
invokePack(pack, typename generator<sizeof...(Args)>::type());
}
virtual void activate(Args... args) = 0;
virtual void invoke(Args... args) = 0;
};
template<typename T, typename... Args>
class SlotMember : public SlotArgs<Args...>
{
public:
using PackType = std::tuple<typename std::remove_reference<Args>::type...>;
SlotMember(T *obj, Object *object, void (T::*func)(Args...))
: SlotArgs<Args...>(obj, object), func_(func) {}
void activate(Args... args)
{
if (this->object_)
SlotBase::activatePack(new PackType{ args... });
else
(static_cast<T *>(this->obj_)->*func_)(args...);
}
void invoke(Args... args)
{
(static_cast<T *>(this->obj_)->*func_)(args...);
}
private:
friend class Signal<Args...>;
void (T::*func_)(Args...);
};
template<typename... Args>
class SlotStatic : public SlotArgs<Args...>
{
public:
SlotStatic(void (*func)(Args...))
: SlotArgs<Args...>(nullptr, nullptr), func_(func) {}
void activate(Args... args) { (*func_)(args...); }
void invoke(Args... args) {}
private:
friend class Signal<Args...>;
void (*func_)(Args...);
};
class SignalBase
{
public:
template<typename T>
void disconnect(T *obj)
{
for (auto iter = slots_.begin(); iter != slots_.end(); ) {
SlotBase *slot = *iter;
if (slot->match(obj)) {
iter = slots_.erase(iter);
delete slot;
} else {
++iter;
}
}
}
protected:
friend class Object;
std::list<SlotBase *> slots_;
};
template<typename... Args>
class Signal : public SignalBase
{
public:
Signal() {}
~Signal()
{
for (SlotBase *slot : slots_) {
slot->disconnect(this);
delete slot;
}
}
#ifndef __DOXYGEN__
template<typename T, typename std::enable_if<std::is_base_of<Object, T>::value>::type * = nullptr>
void connect(T *obj, void (T::*func)(Args...))
{
Object *object = static_cast<Object *>(obj);
object->connect(this);
slots_.push_back(new SlotMember<T, Args...>(obj, object, func));
}
template<typename T, typename std::enable_if<!std::is_base_of<Object, T>::value>::type * = nullptr>
#else
template<typename T>
#endif
void connect(T *obj, void (T::*func)(Args...))
{
slots_.push_back(new SlotMember<T, Args...>(obj, nullptr, func));
}
void connect(void (*func)(Args...))
{
slots_.push_back(new SlotStatic<Args...>(func));
}
void disconnect()
{
for (SlotBase *slot : slots_)
delete slot;
slots_.clear();
}
template<typename T>
void disconnect(T *obj)
{
SignalBase::disconnect(obj);
}
template<typename T>
void disconnect(T *obj, void (T::*func)(Args...))
{
for (auto iter = slots_.begin(); iter != slots_.end(); ) {
SlotArgs<Args...> *slot = static_cast<SlotArgs<Args...> *>(*iter);
/*
* If the object matches the slot, the slot is
* guaranteed to be a member slot, so we can safely
* cast it to SlotMember<T, Args...> and access its
* func_ member.
*/
if (slot->match(obj) &&
static_cast<SlotMember<T, Args...> *>(slot)->func_ == func) {
iter = slots_.erase(iter);
delete slot;
} else {
++iter;
}
}
}
void disconnect(void (*func)(Args...))
{
for (auto iter = slots_.begin(); iter != slots_.end(); ) {
SlotArgs<Args...> *slot = *iter;
if (slot->match(nullptr) &&
static_cast<SlotStatic<Args...> *>(slot)->func_ == func) {
iter = slots_.erase(iter);
delete slot;
} else {
++iter;
}
}
}
void emit(Args... args)
{
/*
* Make a copy of the slots list as the slot could call the
* disconnect operation, invalidating the iterator.
*/
std::vector<SlotBase *> slots{ slots_.begin(), slots_.end() };
for (SlotBase *slot : slots)
static_cast<SlotArgs<Args...> *>(slot)->activate(args...);
}
};
} /* namespace libcamera */
#endif /* __LIBCAMERA_SIGNAL_H__ */
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