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Make it possible to remap the result from promisified expressions

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This commit is contained in:
Denis Blank 2018-03-17 13:04:43 +01:00
parent b68cd1b43a
commit 7dbf22a2d2
6 changed files with 165 additions and 39 deletions
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21
examples/example-asio/example-asio.cpp
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@ -34,12 +34,30 @@
#include <string>
#include <system_error>
#if defined(CONTINUABLE_HAS_EXCEPTIONS)
#include <exception>
#endif
#include <asio.hpp>
#include <continuable/continuable.hpp>
using namespace std::chrono_literals;
inline auto error_code_remapper() {
return [](auto&& promise, asio::error_code e, auto&&... args) {
if (e) {
#if defined(CONTINUABLE_HAS_EXCEPTIONS)
promise.set_exception(std::make_exception_ptr(e));
#else
promise.set_exception(cti::error_type(e.value(), e.category()));
#endif
} else {
promise.set_value(std::forward<decltype(args)>(args)...);
}
};
}
struct functional_io_service {
asio::io_context service_;
asio::ip::udp::resolver resolver_;
@ -61,7 +79,8 @@ struct functional_io_service {
}
auto async_resolve(std::string host, std::string service) {
return cti::promisify<asio::ip::udp::resolver::iterator>::from(
return cti::promisify<asio::ip::udp::resolver::iterator>::with(
error_code_remapper(),
[&](auto&&... args) {
resolver_.async_resolve(std::forward<decltype(args)>(args)...);
},

45
include/continuable/continuable-promisify.hpp
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@ -72,18 +72,47 @@ public:
/// }
/// ```
///
/// If the error code which is passed as first parameter is set there are
/// two behaviours depending whether exceptions are enabled:
/// - If exceptions are enabled the error type is passed via
/// an exception_ptr to the failure handler.
/// - If exceptions are disabled the error type is converted to a
/// `std::error_conditon` and passed down to the error handler.
/// A given error variable is converted to the used error type.
/// If this isn't possible you need to create a custom resolver callable
/// object \see with for details.
///
/// \since 3.0.0
template <typename Callable, typename... Args>
static auto from(Callable&& callable, Args&&... args) {
return helper::template from<detail::convert::promisify_default>(
std::forward<Callable>(callable), std::forward<Args>(args)...);
return helper::template from(detail::convert::default_resolver(),
std::forward<Callable>(callable),
std::forward<Args>(args)...);
}
/// \copybrief from
///
/// This modification of \ref from additionally takes a resolver callable
/// object which is used to resolve the promise from the given result.
///
/// See an example of how to promisify boost asio's async_resolve below:
/// ```cpp
/// auto async_resolve(std::string host, std::string service) {
/// return cti::promisify<asio::ip::udp::resolver::iterator>::with(
/// [](auto&& promise, auto&& e, auto&&... args) {
/// if (e) {
/// promise.set_exception(std::forward<decltype(e)>(e));
/// } else {
/// promise.set_value(std::forward<decltype(args)>(args)...);
/// }
/// },
/// [&](auto&&... args) {
/// resolver_.async_resolve(std::forward<decltype(args)>(args)...);
/// },
/// std::move(host), std::move(service));
/// }
/// ```
///
/// \since 3.1.0
template <typename Resolver, typename Callable, typename... Args>
static auto with(Resolver&& resolver, Callable&& callable, Args&&... args) {
return helper::template from(std::forward<Resolver>(resolver),
std::forward<Callable>(callable),
std::forward<Args>(args)...);
}
};
/// \}

62
include/continuable/detail/promisify.hpp
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@ -44,46 +44,48 @@
namespace cti {
namespace detail {
namespace convert {
/// A helper class for promisifying asio and js style callback
/// taking functions into a continuable.
template <typename P>
struct promisify_default {
P promise;
template <typename E, typename... T>
void operator()(E&& error, T&&... result) {
if (error) {
#if defined(CONTINUABLE_HAS_EXCEPTIONS)
promise.set_exception(std::make_exception_ptr(std::forward<E>(error)));
#else
promise.set_exception(
std::error_condition(error.value(), error.category()));
#endif // CONTINUABLE_HAS_EXCEPTIONS
/// A resolver for promisifying asio and js style callbacks.
inline auto default_resolver() {
return [](auto&& promise, auto&& e, auto&&... args) {
static_assert(
std::is_convertible<std::decay_t<decltype(e)>, error_type>::value,
"The given error type must be convertible to the error type used! "
"Specify a custom resolver in order to apply a conversion to the "
"used error type.");
if (e) {
promise.set_exception(std::forward<decltype(e)>(e));
} else {
promise.set_value(std::forward<T>(result)...);
promise.set_value(std::forward<decltype(args)>(args)...);
}
}
};
};
}
template <typename... Result>
struct promisify_helper {
template <template <class T> class Evaluator, typename Callable,
typename... Args>
static auto from(Callable&& callable, Args&&... args) {
return make_continuable<Result...>([args = std::make_tuple(
std::forward<Callable>(callable),
std::forward<Args>(args)...)](
auto&& promise) mutable {
template <typename Resolver, typename Callable, typename... Args>
static auto from(Resolver&& resolver, Callable&& callable, Args&&... args) {
return make_continuable<Result...>([
resolver = std::forward<Resolver>(resolver),
args = traits::make_flat_tuple(std::forward<Callable>(callable),
std::forward<Args>(args)...)
](auto&& promise) mutable {
traits::unpack(
[promise = std::forward<decltype(promise)>(promise)](
auto&&... args) mutable {
Evaluator<std::decay_t<decltype(promise)>> evaluator{
std::move(promise)};
[ promise = std::forward<decltype(promise)>(promise),
&resolver ](auto&&... args) mutable {
// Call the resolver from with the promise and result
auto callback = [
resolver = std::move(resolver), promise = std::move(promise)
](auto&&... args) mutable {
resolver(std::move(promise),
std::forward<decltype(args)>(args)...);
};
// Invoke the callback taking function
util::invoke(std::forward<decltype(args)>(args)...,
std::move(evaluator));
std::move(callback));
},
std::move(args));
});

7
include/continuable/detail/traits.hpp
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@ -57,6 +57,13 @@ struct index_of_impl<T, U, Args...>
template <typename T, typename... Args>
using index_of_t = detail::index_of_impl<T, Args...>;
/// Creates a tuple in which r-values gets copied and
/// l-values keep their l-value.
template <typename... T>
auto make_flat_tuple(T&&... args) {
return std::tuple<T...>{std::forward<T>(args)...};
}
/// A tagging type for wrapping other types
template <typename... T>
struct identity {};

1
test/unit-test/CMakeLists.txt
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@ -18,6 +18,7 @@ add_executable(test-continuable-single
${CMAKE_CURRENT_LIST_DIR}/single/test-continuable-connection-noinst
${CMAKE_CURRENT_LIST_DIR}/single/test-continuable-flat-variant.cpp
${CMAKE_CURRENT_LIST_DIR}/single/test-continuable-expected.cpp
${CMAKE_CURRENT_LIST_DIR}/single/test-continuable-promisify.cpp
${CMAKE_CURRENT_LIST_DIR}/single/test-continuable-traverse.cpp
${CMAKE_CURRENT_LIST_DIR}/single/test-continuable-traverse-async.cpp)

68
test/unit-test/single/test-continuable-promisify.cpp Normal file
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@ -0,0 +1,68 @@
/*
Copyright(c) 2015 - 2018 Denis Blank <denis.blank at outlook dot com>
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 <test-continuable.hpp>
template <typename T, typename Callback>
void async_supply(T&& value, Callback&& callback) {
std::forward<Callback>(callback)(cti::error_type{}, std::forward<T>(value));
}
TEST(promisify_tests, promisify_from) {
auto c = cti::promisify<int>::from(
[&](auto&&... args) {
async_supply(std::forward<decltype(args)>(args)...);
},
36354);
EXPECT_ASYNC_RESULT(std::move(c), 36354);
}
TEST(promisify_tests, promisify_from_lvalue) {
int value = 0;
auto c = cti::promisify<int>::from(
[&](auto&&... args) {
async_supply(std::forward<decltype(args)>(args)...);
},
value);
value = 36354;
EXPECT_ASYNC_RESULT(std::move(c), 36354);
}
TEST(promisify_tests, promisify_with) {
int value = 0;
auto c = cti::promisify<int>::with(
[](auto&& promise, auto&& /*e*/, int const& value) {
EXPECT_EQ(value, 36354);
promise.set_exception(cti::error_type{});
},
[&](auto&&... args) {
async_supply(std::forward<decltype(args)>(args)...);
},
value);
value = 36354;
ASSERT_ASYNC_EXCEPTION_COMPLETION(std::move(c));
}