comparison win32-mingw/include/kj/async-prelude.h @ 50:37d53a7e8262

Headers for KJ/Capnp Win32

+// Copyright (c) 2013-2014 Sandstorm Development Group, Inc. and contributors
+// Licensed under the MIT License:
+//
+// 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.
+
+// This file contains a bunch of internal declarations that must appear before async.h can start.
+// We don't define these directly in async.h because it makes the file hard to read.
+
+#ifndef KJ_ASYNC_PRELUDE_H_
+#define KJ_ASYNC_PRELUDE_H_
+
+#if defined(__GNUC__) && !KJ_HEADER_WARNINGS
+#pragma GCC system_header
+#endif
+
+#include "exception.h"
+#include "tuple.h"
+
+namespace kj {
+
+class EventLoop;
+template <typename T>
+class Promise;
+class WaitScope;
+
+template <typename T>
+Promise<Array<T>> joinPromises(Array<Promise<T>>&& promises);
+Promise<void> joinPromises(Array<Promise<void>>&& promises);
+
+namespace _ {  // private
+
+template <typename T> struct JoinPromises_ { typedef T Type; };
+template <typename T> struct JoinPromises_<Promise<T>> { typedef T Type; };
+
+template <typename T>
+using JoinPromises = typename JoinPromises_<T>::Type;
+// If T is Promise<U>, resolves to U, otherwise resolves to T.
+//
+// TODO(cleanup):  Rename to avoid confusion with joinPromises() call which is completely
+//   unrelated.
+
+class PropagateException {
+  // A functor which accepts a kj::Exception as a parameter and returns a broken promise of
+  // arbitrary type which simply propagates the exception.
+public:
+  class Bottom {
+  public:
+    Bottom(Exception&& exception): exception(kj::mv(exception)) {}
+
+    Exception asException() { return kj::mv(exception); }
+
+  private:
+    Exception exception;
+  };
+
+  Bottom operator()(Exception&& e) {
+    return Bottom(kj::mv(e));
+  }
+  Bottom operator()(const  Exception& e) {
+    return Bottom(kj::cp(e));
+  }
+};
+
+template <typename Func, typename T>
+struct ReturnType_ { typedef decltype(instance<Func>()(instance<T>())) Type; };
+template <typename Func>
+struct ReturnType_<Func, void> { typedef decltype(instance<Func>()()) Type; };
+
+template <typename Func, typename T>
+using ReturnType = typename ReturnType_<Func, T>::Type;
+// The return type of functor Func given a parameter of type T, with the special exception that if
+// T is void, this is the return type of Func called with no arguments.
+
+template <typename T> struct SplitTuplePromise_ { typedef Promise<T> Type; };
+template <typename... T>
+struct SplitTuplePromise_<kj::_::Tuple<T...>> {
+  typedef kj::Tuple<Promise<JoinPromises<T>>...> Type;
+};
+
+template <typename T>
+using SplitTuplePromise = typename SplitTuplePromise_<T>::Type;
+// T -> Promise<T>
+// Tuple<T> -> Tuple<Promise<T>>
+
+struct Void {};
+// Application code should NOT refer to this!  See `kj::READY_NOW` instead.
+
+template <typename T> struct FixVoid_ { typedef T Type; };
+template <> struct FixVoid_<void> { typedef Void Type; };
+template <typename T> using FixVoid = typename FixVoid_<T>::Type;
+// FixVoid<T> is just T unless T is void in which case it is _::Void (an empty struct).
+
+template <typename T> struct UnfixVoid_ { typedef T Type; };
+template <> struct UnfixVoid_<Void> { typedef void Type; };
+template <typename T> using UnfixVoid = typename UnfixVoid_<T>::Type;
+// UnfixVoid is the opposite of FixVoid.
+
+template <typename In, typename Out>
+struct MaybeVoidCaller {
+  // Calls the function converting a Void input to an empty parameter list and a void return
+  // value to a Void output.
+
+  template <typename Func>
+  static inline Out apply(Func& func, In&& in) {
+    return func(kj::mv(in));
+  }
+};
+template <typename In, typename Out>
+struct MaybeVoidCaller<In&, Out> {
+  template <typename Func>
+  static inline Out apply(Func& func, In& in) {
+    return func(in);
+  }
+};
+template <typename Out>
+struct MaybeVoidCaller<Void, Out> {
+  template <typename Func>
+  static inline Out apply(Func& func, Void&& in) {
+    return func();
+  }
+};
+template <typename In>
+struct MaybeVoidCaller<In, Void> {
+  template <typename Func>
+  static inline Void apply(Func& func, In&& in) {
+    func(kj::mv(in));
+    return Void();
+  }
+};
+template <typename In>
+struct MaybeVoidCaller<In&, Void> {
+  template <typename Func>
+  static inline Void apply(Func& func, In& in) {
+    func(in);
+    return Void();
+  }
+};
+template <>
+struct MaybeVoidCaller<Void, Void> {
+  template <typename Func>
+  static inline Void apply(Func& func, Void&& in) {
+    func();
+    return Void();
+  }
+};
+
+template <typename T>
+inline T&& returnMaybeVoid(T&& t) {
+  return kj::fwd<T>(t);
+}
+inline void returnMaybeVoid(Void&& v) {}
+
+class ExceptionOrValue;
+class PromiseNode;
+class ChainPromiseNode;
+template <typename T>
+class ForkHub;
+
+class TaskSetImpl;
+
+class Event;
+
+class PromiseBase {
+public:
+  kj::String trace();
+  // Dump debug info about this promise.
+
+private:
+  Own<PromiseNode> node;
+
+  PromiseBase() = default;
+  PromiseBase(Own<PromiseNode>&& node): node(kj::mv(node)) {}
+
+  friend class kj::EventLoop;
+  friend class ChainPromiseNode;
+  template <typename>
+  friend class kj::Promise;
+  friend class TaskSetImpl;
+  template <typename U>
+  friend Promise<Array<U>> kj::joinPromises(Array<Promise<U>>&& promises);
+  friend Promise<void> kj::joinPromises(Array<Promise<void>>&& promises);
+};
+
+void detach(kj::Promise<void>&& promise);
+void waitImpl(Own<_::PromiseNode>&& node, _::ExceptionOrValue& result, WaitScope& waitScope);
+Promise<void> yield();
+Own<PromiseNode> neverDone();
+
+class NeverDone {
+public:
+  template <typename T>
+  operator Promise<T>() const {
+    return Promise<T>(false, neverDone());
+  }
+
+  KJ_NORETURN(void wait(WaitScope& waitScope) const);
+};
+
+}  // namespace _ (private)
+}  // namespace kj
+
+#endif  // KJ_ASYNC_PRELUDE_H_