#ifndef _CPPROMISE_HPP
#define _CPPROMISE_HPP
/**
* MIT License
* Copyright (c) 2018 Ted Yin <[email protected]>
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
#include <stack>
#include <vector>
#include <memory>
#include <functional>
#include <type_traits>
#if __cplusplus >= 201703L
#ifdef __has_include
# if __has_include(<any>)
# include <any>
# ifdef __cpp_lib_any
# define _CPPROMISE_STD_ANY
# endif
# endif
#endif
#endif
#ifndef _CPPROMISE_STD_ANY
#include <boost/any.hpp>
#endif
/**
* Implement type-safe Promise primitives similar to the ones specified by
* Javascript Promise/A+.
*/
namespace promise {
#ifdef _CPPROMISE_STD_ANY
using pm_any_t = std::any;
template<typename T>
constexpr auto any_cast = static_cast<T(*)(const std::any&)>(std::any_cast<T>);
using bad_any_cast = std::bad_any_cast;
#else
# warning "using boost::any"
# pragma message "using boost::any"
using pm_any_t = boost::any;
template<typename T>
constexpr auto any_cast = static_cast<T(*)(const boost::any&)>(boost::any_cast<T>);
using bad_any_cast = boost::bad_any_cast;
#endif
using callback_t = std::function<void()>;
using values_t = std::vector<pm_any_t>;
/* match lambdas */
template<typename T>
struct function_traits:
public function_traits<decltype(&T::operator())> {};
template<typename ReturnType>
struct function_traits<ReturnType()> {
using ret_type = ReturnType;
using arg_type = void;
using empty_arg = void;
};
/* match plain functions */
template<typename ReturnType, typename ArgType>
struct function_traits<ReturnType(ArgType)> {
using ret_type = ReturnType;
using arg_type = ArgType;
using non_empty_arg = void;
};
/* match function pointers */
template<typename ReturnType, typename... ArgType>
struct function_traits<ReturnType(*)(ArgType...)>:
public function_traits<ReturnType(ArgType...)> {};
/* match const member functions */
template<typename ClassType, typename ReturnType, typename... ArgType>
struct function_traits<ReturnType(ClassType::*)(ArgType...) const>:
public function_traits<ReturnType(ArgType...)> {};
/* match member functions */
template<typename ClassType, typename ReturnType, typename... ArgType>
struct function_traits<ReturnType(ClassType::*)(ArgType...)>:
public function_traits<ReturnType(ArgType...)> {};
template<typename Func, typename ReturnType>
using enable_if_return = typename std::enable_if<
std::is_same<typename function_traits<Func>::ret_type,
ReturnType>::value>;
template<typename Func, typename ReturnType>
using disable_if_return = typename std::enable_if<
!std::is_same<typename function_traits<Func>::ret_type,
ReturnType>::value>;
template<typename Func, typename ArgType>
using enable_if_arg = typename std::enable_if<
std::is_same<typename function_traits<Func>::arg_type,
ArgType>::value>;
template<typename Func, typename ArgType>
using disable_if_arg = typename std::enable_if<
!std::is_same<typename function_traits<Func>::arg_type,
ArgType>::value>;
class Promise;
//class promise_t: public std::shared_ptr<Promise> {
class promise_t {
Promise *pm;
size_t *ref_cnt;
public:
friend Promise;
template<typename PList> friend promise_t all(const PList &promise_list);
template<typename PList> friend promise_t race(const PList &promise_list);
inline promise_t();
inline ~promise_t();
template<typename Func> inline promise_t(Func callback);
void swap(promise_t &other) {
std::swap(pm, other.pm);
std::swap(ref_cnt, other.ref_cnt);
}
promise_t &operator=(const promise_t &other) {
if (this != &other)
{
promise_t tmp(other);
tmp.swap(*this);
}
return *this;
}
promise_t &operator=(promise_t &&other) {
if (this != &other)
{
promise_t tmp(std::move(other));
tmp.swap(*this);
}
return *this;
}
promise_t(const promise_t &other):
pm(other.pm),
ref_cnt(other.ref_cnt) {
++*ref_cnt;
}
promise_t(promise_t &&other):
pm(other.pm),
ref_cnt(other.ref_cnt) {
other.pm = nullptr;
}
Promise *operator->() const {
return pm;
}
template<typename T> inline void resolve(T result) const;
template<typename T> inline void reject(T reason) const;
inline void resolve() const;
inline void reject() const;
template<typename FuncFulfilled>
inline promise_t then(FuncFulfilled on_fulfilled) const;
template<typename FuncFulfilled, typename FuncRejected>
inline promise_t then(FuncFulfilled on_fulfilled,
FuncRejected on_rejected) const;
template<typename FuncRejected>
inline promise_t fail(FuncRejected on_rejected) const;
};
#define PROMISE_ERR_INVALID_STATE do {throw std::runtime_error("invalid promise state");} while (0)
#define PROMISE_ERR_MISMATCH_TYPE do {throw std::runtime_error("mismatching promise value types");} while (0)
class Promise {
template<typename PList> friend promise_t all(const PList &promise_list);
template<typename PList> friend promise_t race(const PList &promise_list);
std::vector<callback_t> fulfilled_callbacks;
std::vector<callback_t> rejected_callbacks;
#ifdef CPPROMISE_USE_STACK_FREE
std::vector<Promise *> fulfilled_pms;
std::vector<Promise *> rejected_pms;
#endif
enum class State {
Pending,
#ifdef CPPROMISE_USE_STACK_FREE
PreFulfilled,
PreRejected,
#endif
Fulfilled,
Rejected,
} state;
pm_any_t result;
pm_any_t reason;
void add_on_fulfilled(callback_t &&cb) {
fulfilled_callbacks.push_back(std::move(cb));
}
void add_on_rejected(callback_t &&cb) {
rejected_callbacks.push_back(std::move(cb));
}
template<typename Func,
typename function_traits<Func>::non_empty_arg * = nullptr>
static constexpr auto cps_transform(
Func f, const pm_any_t &result, const promise_t &npm) {
return [&result, npm, f = std::forward<Func>(f)]() mutable {
#ifndef CPPROMISE_USE_STACK_FREE
f(result)->then(
[npm] (pm_any_t result) {npm->resolve(result);},
[npm] (pm_any_t reason) {npm->reject(reason);});
#else
promise_t rpm{f(result)};
rpm->then(
[rpm, npm] (pm_any_t result) {
npm->_resolve(result);
},
[rpm, npm] (pm_any_t reason) {
npm->_reject(reason);
});
rpm->_dep_resolve(npm);
rpm->_dep_reject(npm);
#endif
};
}
template<typename Func,
typename function_traits<Func>::empty_arg * = nullptr>
static constexpr auto cps_transform(
Func f, const pm_any_t &, const promise_t &npm) {
return [npm, f = std::forward<Func>(f)]() mutable {
#ifndef CPPROMISE_USE_STACK_FREE
f()->then(
[npm] (pm_any_t result) {npm->resolve(result);},
[npm] (pm_any_t reason) {npm->reject(reason);});
#else
promise_t rpm{f()};
rpm->then(
[rpm, npm] (pm_any_t result) {
npm->_resolve(result);
},
[rpm, npm] (pm_any_t reason) {
npm->_reject(reason);
});
rpm->_dep_resolve(npm);
rpm->_dep_reject(npm);
#endif
};
}
template<typename Func,
typename enable_if_return<Func, promise_t>::type * = nullptr>
constexpr auto gen_on_fulfilled(Func on_fulfilled, const promise_t &npm) {
return cps_transform(std::forward<Func>(on_fulfilled), this->result, npm);
}
template<typename Func,
typename enable_if_return<Func, promise_t>::type * = nullptr>
constexpr auto gen_on_rejected(Func on_rejected, const promise_t &npm) {
return cps_transform(std::forward<Func>(on_rejected), this->reason, npm);
}
template<typename Func,
typename enable_if_return<Func, void>::type * = nullptr,
typename function_traits<Func>::non_empty_arg * = nullptr>
constexpr auto gen_on_fulfilled(Func on_fulfilled, const promise_t &npm) {
return [this, npm,
on_fulfilled = std::forward<Func>(on_fulfilled)]() mutable {
on_fulfilled(result);
npm->_resolve();
};
}
template<typename Func,
typename enable_if_return<Func, void>::type * = nullptr,
typename function_traits<Func>::empty_arg * = nullptr>
constexpr auto gen_on_fulfilled(Func on_fulfilled, const promise_t &npm) {
return [on_fulfilled = std::forward<Func>(on_fulfilled), npm]() mutable {
on_fulfilled();
npm->_resolve();
};
}
template<typename Func,
typename enable_if_return<Func, void>::type * = nullptr,
typename function_traits<Func>::non_empty_arg * = nullptr>
constexpr auto gen_on_rejected(Func on_rejected, const promise_t &npm) {
return [this, npm,
on_rejected = std::forward<Func>(on_rejected)]() mutable {
on_rejected(reason);
npm->_reject();
};
}
template<typename Func,
typename enable_if_return<Func, void>::type * = nullptr,
typename function_traits<Func>::empty_arg * = nullptr>
constexpr auto gen_on_rejected(Func on_rejected, const promise_t &npm) {
return [npm,
on_rejected = std::forward<Func>(on_rejected)]() mutable {
on_rejected();
npm->_reject();
};
}
template<typename Func,
typename enable_if_return<Func, pm_any_t>::type * = nullptr,
typename function_traits<Func>::non_empty_arg * = nullptr>
constexpr auto gen_on_fulfilled(Func on_fulfilled, const promise_t &npm) {
return [this, npm,
on_fulfilled = std::forward<Func>(on_fulfilled)]() mutable {
npm->_resolve(on_fulfilled(result));
};
}
template<typename Func,
typename enable_if_return<Func, pm_any_t>::type * = nullptr,
typename function_traits<Func>::empty_arg * = nullptr>
constexpr auto gen_on_fulfilled(Func on_fulfilled, const promise_t &npm) {
return [npm, on_fulfilled = std::forward<Func>(on_fulfilled)]() mutable {
npm->_resolve(on_fulfilled());
};
}
template<typename Func,
typename enable_if_return<Func, pm_any_t>::type * = nullptr,
typename function_traits<Func>::non_empty_arg * = nullptr>
constexpr auto gen_on_rejected(Func on_rejected, const promise_t &npm) {
return [this, npm, on_rejected = std::forward<Func>(on_rejected)]() mutable {
npm->_reject(on_rejected(reason));
};
}
template<typename Func,
typename enable_if_return<Func, pm_any_t>::type * = nullptr,
typename function_traits<Func>::empty_arg * = nullptr>
constexpr auto gen_on_rejected(Func on_rejected, const promise_t &npm) {
return [npm, on_rejected = std::forward<Func>(on_rejected)]() mutable {
npm->_reject(on_rejected());
};
}
#ifdef CPPROMISE_USE_STACK_FREE
void _trigger() {
std::stack<std::tuple<
std::vector<Promise *>::const_iterator,
std::vector<Promise *> *,
Promise *>> s;
auto push_frame = [&s](Promise *pm) {
if (pm->state == State::PreFulfilled)
{
pm->state = State::Fulfilled;
for (auto &cb: pm->fulfilled_callbacks) cb();
s.push(std::make_tuple(pm->fulfilled_pms.begin(),
&pm->fulfilled_pms,
pm));
}
else if (pm->state == State::PreRejected)
{
pm->state = State::Rejected;
for (auto &cb: pm->rejected_callbacks) cb();
s.push(std::make_tuple(pm->rejected_pms.begin(),
&pm->rejected_pms,
pm));
}
};
push_frame(this);
while (!s.empty())
{
auto &u = s.top();
auto &it = std::get<0>(u);
auto vec = std::get<1>(u);
auto pm = std::get<2>(u);
if (it == vec->end())
{
s.pop();
vec->clear();
pm->fulfilled_callbacks.clear();
pm->rejected_callbacks.clear();
continue;
}
push_frame(*it++);
}
}
void trigger_fulfill() {
state = State::PreFulfilled;
_trigger();
}
void trigger_reject() {
state = State::PreRejected;
_trigger();
}
void _resolve() {
if (state == State::Pending) state = State::PreFulfilled;
}
void _reject() {
if (state == State::Pending) state = State::PreRejected;
}
void _dep_resolve(const promise_t &npm) {
if (state == State::Pending)
fulfilled_pms.push_back(npm.pm);
else
npm->_trigger();
}
void _dep_reject(const promise_t &npm) {
if (state == State::Pending)
rejected_pms.push_back(npm.pm);
else
npm->_trigger();
}
void _resolve(pm_any_t _result) {
if (state == State::Pending)
{
result = _result;
state = State::PreFulfilled;
}
}
void _reject(pm_any_t _reason) {
if (state == State::Pending)
{
reason = _reason;
state = State::PreRejected;
}
}
#else
void _resolve() { resolve(); }
void _reject() { reject(); }
void _resolve(pm_any_t result) { resolve(result); }
void _reject(pm_any_t reason) { reject(reason); }
void trigger_fulfill() {
state = State::Fulfilled;
for (const auto &cb: fulfilled_callbacks) cb();
fulfilled_callbacks.clear();
}
void trigger_reject() {
state = State::Rejected;
for (const auto &cb: rejected_callbacks) cb();
rejected_callbacks.clear();
}
#endif
public:
Promise(): state(State::Pending) {}
~Promise() {}
template<typename FuncFulfilled, typename FuncRejected>
promise_t then(FuncFulfilled on_fulfilled,
FuncRejected on_rejected) {
switch (state)
{
case State::Pending:
return promise_t([this,
on_fulfilled = std::forward<FuncFulfilled>(on_fulfilled),
on_rejected = std::forward<FuncRejected>(on_rejected)
](promise_t &npm) {
add_on_fulfilled(gen_on_fulfilled(std::move(on_fulfilled), npm));
add_on_rejected(gen_on_rejected(std::move(on_rejected), npm));
#ifdef CPPROMISE_USE_STACK_FREE
_dep_resolve(npm);
_dep_reject(npm);
#endif
});
case State::Fulfilled:
return promise_t([this,
on_fulfilled = std::forward<FuncFulfilled>(on_fulfilled)
](promise_t &npm) {
gen_on_fulfilled(std::move(on_fulfilled), npm)();
});
case State::Rejected:
return promise_t([this,
on_rejected = std::forward<FuncRejected>(on_rejected)
](promise_t &npm) {
gen_on_rejected(std::move(on_rejected), npm)();
});
default: PROMISE_ERR_INVALID_STATE;
}
}
template<typename FuncFulfilled>
promise_t then(FuncFulfilled &&on_fulfilled) {
switch (state)
{
case State::Pending:
return promise_t([this,
on_fulfilled = std::forward<FuncFulfilled>(on_fulfilled)
](promise_t &npm) {
add_on_fulfilled(gen_on_fulfilled(std::move(on_fulfilled), npm));
add_on_rejected([this, npm]() {npm->_reject(reason);});
#ifdef CPPROMISE_USE_STACK_FREE
_dep_resolve(npm);
_dep_reject(npm);
#endif
});
case State::Fulfilled:
return promise_t([this,
on_fulfilled = std::forward<FuncFulfilled>(on_fulfilled)
](promise_t &npm) {
gen_on_fulfilled(std::move(on_fulfilled), npm)();
});
case State::Rejected:
return promise_t([this](promise_t &npm) {npm->_reject(reason);});
default: PROMISE_ERR_INVALID_STATE;
}
}
template<typename FuncRejected>
promise_t fail(FuncRejected &&on_rejected) {
switch (state)
{
case State::Pending:
return promise_t([this,
on_rejected = std::forward<FuncRejected>(on_rejected)
](promise_t &npm) {
callback_t ret;
add_on_rejected(gen_on_rejected(std::move(on_rejected), npm));
add_on_fulfilled([this, npm]() {npm->_resolve(result);});
#ifdef CPPROMISE_USE_STACK_FREE
_dep_resolve(npm);
_dep_reject(npm);
#endif
});
case State::Fulfilled:
return promise_t([this](promise_t &npm) {npm->_resolve(result);});
case State::Rejected:
return promise_t([this,
on_rejected = std::forward<FuncRejected>(on_rejected)
](promise_t &npm) {
gen_on_rejected(std::move(on_rejected), npm)();
});
default: PROMISE_ERR_INVALID_STATE;
}
}
void resolve() {
if (state == State::Pending) trigger_fulfill();
}
void reject() {
if (state == State::Pending) trigger_reject();
}
void resolve(pm_any_t _result) {
if (state == State::Pending)
{
result = _result;
trigger_fulfill();
}
}
void reject(pm_any_t _reason) {
if (state == State::Pending)
{
reason = _reason;
trigger_reject();
}
}
};
template<typename PList> promise_t all(const PList &promise_list) {
return promise_t([&promise_list] (promise_t &npm) {
auto size = std::make_shared<size_t>(promise_list.size());
auto results = std::make_shared<values_t>();
if (!*size) PROMISE_ERR_MISMATCH_TYPE;
results->resize(*size);
size_t idx = 0;
for (const auto &pm: promise_list) {
pm->then(
[results, size, idx, npm](pm_any_t result) {
(*results)[idx] = result;
if (!--(*size))
npm->_resolve(*results);
},
[npm](pm_any_t reason) {npm->_reject(reason);});
#ifdef CPPROMISE_USE_STACK_FREE
pm->_dep_resolve(npm);
pm->_dep_reject(npm);
#endif
idx++;
}
});
}
template<typename PList> promise_t race(const PList &promise_list) {
return promise_t([&promise_list] (promise_t &npm) {
for (const auto &pm: promise_list) {
pm->then([npm](pm_any_t result) {npm->_resolve(result);},
[npm](pm_any_t reason) {npm->_reject(reason);});
#ifdef CPPROMISE_USE_STACK_FREE
pm->_dep_resolve(npm);
pm->_dep_reject(npm);
#endif
}
});
}
template<typename Func>
inline promise_t::promise_t(Func callback):
pm(new Promise()),
ref_cnt(new size_t(1)) {
callback(*this);
}
inline promise_t::promise_t():
pm(new Promise()),
ref_cnt(new size_t(1)) {}
inline promise_t::~promise_t() {
if (pm)
{
if (--*ref_cnt) return;
delete pm;
delete ref_cnt;
}
}
template<typename T>
inline void promise_t::resolve(T result) const { (*this)->resolve(result); }
template<typename T>
inline void promise_t::reject(T reason) const { (*this)->reject(reason); }
inline void promise_t::resolve() const { (*this)->resolve(); }
inline void promise_t::reject() const { (*this)->reject(); }
template<typename T>
struct callback_types {
using arg_type = typename function_traits<T>::arg_type;
using ret_type = typename std::conditional<
std::is_same<typename function_traits<T>::ret_type, promise_t>::value,
promise_t, pm_any_t>::type;
};
template<typename Func,
typename disable_if_arg<Func, pm_any_t>::type * = nullptr,
typename enable_if_return<Func, void>::type * = nullptr,
typename function_traits<Func>::non_empty_arg * = nullptr>
constexpr auto gen_any_callback(Func f) {
using func_t = callback_types<Func>;
return [f = std::forward<Func>(f)](pm_any_t v) mutable {
try {
f(any_cast<typename func_t::arg_type>(v));
} catch (bad_any_cast &e) { PROMISE_ERR_MISMATCH_TYPE; }
};
}
template<typename Func,
typename enable_if_arg<Func, pm_any_t>::type * = nullptr,
typename enable_if_return<Func, void>::type * = nullptr,
typename function_traits<Func>::non_empty_arg * = nullptr>
constexpr auto gen_any_callback(Func f) {
return [f = std::forward<Func>(f)](pm_any_t v) mutable {f(v);};
}
template<typename Func,
typename enable_if_return<Func, void>::type * = nullptr,
typename function_traits<Func>::empty_arg * = nullptr>
constexpr auto gen_any_callback(Func f) { return std::forward<Func>(f); }
template<typename Func,
typename enable_if_arg<Func, pm_any_t>::type * = nullptr,
typename disable_if_return<Func, void>::type * = nullptr,
typename function_traits<Func>::non_empty_arg * = nullptr>
constexpr auto gen_any_callback(Func f) {
using func_t = callback_types<Func>;
return [f = std::forward<Func>(f)](pm_any_t v) mutable {
return typename func_t::ret_type(f(v));
};
}
template<typename Func,
typename disable_if_arg<Func, pm_any_t>::type * = nullptr,
typename disable_if_return<Func, void>::type * = nullptr,
typename function_traits<Func>::non_empty_arg * = nullptr>
constexpr auto gen_any_callback(Func f) {
using func_t = callback_types<Func>;
return [f = std::forward<Func>(f)](pm_any_t v) mutable {
try {
return typename func_t::ret_type(
f(any_cast<typename func_t::arg_type>(v)));
} catch (bad_any_cast &e) { PROMISE_ERR_MISMATCH_TYPE; }
};
}
template<typename Func,
typename disable_if_return<Func, void>::type * = nullptr,
typename function_traits<Func>::empty_arg * = nullptr>
constexpr auto gen_any_callback(Func f) {
using func_t = callback_types<Func>;
return [f = std::forward<Func>(f)]() mutable {
return typename func_t::ret_type(f());
};
}
template<typename FuncFulfilled>
inline promise_t promise_t::then(FuncFulfilled on_fulfilled) const {
return (*this)->then(gen_any_callback(std::forward<FuncFulfilled>(on_fulfilled)));
}
template<typename FuncFulfilled, typename FuncRejected>
inline promise_t promise_t::then(FuncFulfilled on_fulfilled,
FuncRejected on_rejected) const {
return (*this)->then(gen_any_callback(std::forward<FuncFulfilled>(on_fulfilled)),
gen_any_callback(std::forward<FuncRejected>(on_rejected)));
}
template<typename FuncRejected>
inline promise_t promise_t::fail(FuncRejected on_rejected) const {
return (*this)->fail(gen_any_callback(std::forward<FuncRejected>(on_rejected)));
}
}
#endif