coffee/continuable
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Make it possible to supply the async traversal pack directly from the visitor

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This commit is contained in:
Denis Blank 2018-02-21 04:02:18 +01:00
parent 8dbd3d058a
commit 7730b85b24
1 changed files with 51 additions and 17 deletions
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68
include/continuable/detail/traverse-async.hpp
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@ -105,11 +105,56 @@ auto make_resume_traversal_callable(Frame&& frame, State&& state)
std::forward<Frame>(frame), std::forward<State>(state));
}
/// Stores the visitor and the arguments to traverse
template <typename T, typename = void>
struct has_head : std::false_type {};
template <typename T>
struct has_head<T, traits::void_t<decltype(std::declval<T>().head())>>
: std::true_type {};
template <typename Visitor, typename... Args>
class async_traversal_frame : public Visitor {
class async_traversal_frame_data : public Visitor {
std::tuple<Args...> args_;
public:
explicit async_traversal_frame_data(Visitor visitor, Args... args)
: Visitor(std::move(visitor)),
args_(std::make_tuple(std::move(args)...)) {
}
template <typename MapperArg>
explicit async_traversal_frame_data(async_traverse_in_place_tag<Visitor>,
MapperArg&& mapper_arg, Args... args)
: Visitor(std::forward<MapperArg>(mapper_arg)),
args_(std::make_tuple(std::move(args)...)) {
}
/// Returns the arguments of the frame
std::tuple<Args...>& head() noexcept {
return args_;
}
};
template <typename Visitor>
class async_traversal_frame_no_data : public Visitor {
public:
explicit async_traversal_frame_no_data(Visitor visitor)
: Visitor(std::move(visitor)) {
}
template <typename MapperArg>
explicit async_traversal_frame_no_data(async_traverse_in_place_tag<Visitor>,
MapperArg&& mapper_arg)
: Visitor(std::forward<MapperArg>(mapper_arg)) {
}
};
template <typename Visitor, typename... Args>
using data_layout_t =
std::conditional_t<has_head<Visitor>::value,
async_traversal_frame_no_data<Visitor>,
async_traversal_frame_data<Visitor, Args...>>;
/// Stores the visitor and the arguments to traverse
template <typename Visitor, typename... Args>
class async_traversal_frame : public data_layout_t<Visitor, Args...> {
#ifndef _NDEBUG
std::atomic<bool> finished_;
#endif // _NDEBUG
@ -123,8 +168,9 @@ class async_traversal_frame : public Visitor {
}
public:
explicit async_traversal_frame(Visitor visitor, Args... args)
: Visitor(std::move(visitor)), args_(std::make_tuple(std::move(args)...))
template <typename... T>
explicit async_traversal_frame(T&&... args)
: data_layout_t<Visitor, Args...>(std::forward<T>(args)...)
#ifndef _NDEBUG
,
finished_(false)
@ -135,18 +181,6 @@ public:
/// We require a virtual base
virtual ~async_traversal_frame() override = default;
template <typename MapperArg>
explicit async_traversal_frame(async_traverse_in_place_tag<Visitor>,
MapperArg&& mapper_arg, Args... args)
: Visitor(std::forward<MapperArg>(mapper_arg)),
args_(std::make_tuple(std::move(args)...)), finished_(false) {
}
/// Returns the arguments of the frame
std::tuple<Args...>& head() noexcept {
return args_;
}
/// Calls the visitor with the given element
template <typename T>
auto traverse(T&& value) -> decltype(visitor()(async_traverse_visit_tag{},
@ -184,7 +218,7 @@ public:
}
#endif // _NDEBUG
visitor()(async_traverse_complete_tag{}, std::move(args_));
visitor()(async_traverse_complete_tag{}, std::move(this->head()));
}
};