[C++ coroutines 5/7, v3] Standard library header.
Iain Sandoe
iain@sandoe.co.uk
Thu Jan 9 19:57:00 GMT 2020
Hi Jonathan,
thanks for the review - hopefully the attached addresses both those
and the whitespace differences we discussed off-line.
I’m attaching the header as a textfile since it’s a new one, perhaps
that will make it easier to review the whitespace stuff.
thanks
Iain
Jonathan Wakely <jwakely@redhat.com> wrote:
> On 09/01/20 12:39 +0000, Iain Sandoe wrote:
>> +#ifndef _GLIBCXX_EXPERIMENTAL_COROUTINE
>> +#define _GLIBCXX_EXPERIMENTAL_COROUTINE 1
>
> Did you mean to leave EXPERIMENTAL in this macro?
no, dropped.
>>
>> + template <typename _R, typename...> struct coroutine_traits
>
> _R isn't in our list of identifiers to avoid, but it's uncomfortably
> close to some of them. We generally try to avoid single-letter names.
> Please use something like _Ret or _Res instead.
used “_Result".
>> \+ constexpr coroutine_handle (decltype (nullptr) __h) noexcept
>
> std::nullptr_t is defined in <bits/c++config.h> so you could use that
> here.
done.
>> + {}
>
> New line after this function body please.
I’ve been through an added a newline after each body.
>> + coroutine_handle &operator= (decltype (nullptr)) noexcept
>
> Libstdc++ coding standards differ from the rest of GCC. We group the
> ptr-declarator with the type, not the name, and there's no space
> before the parens, so:
>
> coroutine_handle& operator=(nullptr_t) noexcept
Whitespace fixes applied throughout.
>> +} // namespace std_GLIBCXX_VISIBILITY(default)
>
> No need for the _GLIBCXX... part here.
indeed, that was a typo.
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====
This provides the interfaces mandated by the standard and implements
the interaction with the coroutine frame by means of inline use of
builtins expanded at compile-time. There should be a 1:1 correspondence
with the standard sections which are cross-referenced.
There is no runtime content.
At this stage we have the content in an inline namespace "__n4835" for
the current CD.
Squashed commits:
r278724 - Address review comments, GNU naming conventions
r278778 - Address review comments, update doxygen group info.
r279817 - Update copyright year.
r279845 - Address review comments, move coroutine header to std.
r280038 - Correct pathname in the edit header.
libstdc++-v3/ChangeLog:
2020-01-09 Iain Sandoe <iain@sandoe.co.uk>
* include/Makefile.am: Add coroutine to the std set.
* include/Makefile.in: Regenerated.
* include/std/coroutine: New file.
diff --git a/libstdc++-v3/include/Makefile.am b/libstdc++-v3/include/Makefile.am
index b38defcafb..ad4404793b 100644
--- a/libstdc++-v3/include/Makefile.am
+++ b/libstdc++-v3/include/Makefile.am
@@ -38,6 +38,7 @@ std_headers = \
${std_srcdir}/complex \
${std_srcdir}/concepts \
${std_srcdir}/condition_variable \
+ ${std_srcdir}/coroutine \
${std_srcdir}/deque \
${std_srcdir}/execution \
${std_srcdir}/filesystem \
diff --git a/libstdc++-v3/include/Makefile.in b/libstdc++-v3/include/Makefile.in
index ae4a493ea6..f8b5645224 100644
--- a/libstdc++-v3/include/Makefile.in
+++ b/libstdc++-v3/include/Makefile.in
@@ -382,6 +382,7 @@ std_headers = \
${std_srcdir}/complex \
${std_srcdir}/concepts \
${std_srcdir}/condition_variable \
+ ${std_srcdir}/coroutine \
${std_srcdir}/deque \
${std_srcdir}/execution \
${std_srcdir}/filesystem \
diff --git a/libstdc++-v3/include/std/coroutine b/libstdc++-v3/include/std/coroutine
new file mode 100644
index 0000000000..3c3c7d7f50
--- /dev/null
+++ b/libstdc++-v3/include/std/coroutine
@@ -0,0 +1,290 @@
+// <coroutine> -*- C++ -*-
+
+// Copyright (C) 2019-2020 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library. This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// Under Section 7 of GPL version 3, you are granted additional
+// permissions described in the GCC Runtime Library Exception, version
+// 3.1, as published by the Free Software Foundation.
+
+// You should have received a copy of the GNU General Public License and
+// a copy of the GCC Runtime Library Exception along with this program;
+// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
+// <http://www.gnu.org/licenses/>.
+
+/** @file include/coroutine
+ * This is a Standard C++ Library header.
+ */
+
+#ifndef _GLIBCXX_COROUTINE
+#define _GLIBCXX_COROUTINE 1
+
+#pragma GCC system_header
+
+// It is very likely that earlier versions would work, but they are untested.
+#if __cplusplus >= 201402L
+
+#include <bits/c++config.h>
+
+/**
+ * @defgroup coroutines Coroutines
+ *
+ * Components for supporting coroutine implementations.
+ */
+
+#if __cplusplus > 201703L && __cpp_impl_three_way_comparison >= 201907L
+# include <compare>
+# define _COROUTINES_USE_SPACESHIP 1
+#else
+# include <bits/stl_function.h> // for std::less
+# define _COROUTINES_USE_SPACESHIP 0
+#endif
+
+namespace std _GLIBCXX_VISIBILITY (default)
+{
+ _GLIBCXX_BEGIN_NAMESPACE_VERSION
+
+#if __cpp_coroutines
+ inline namespace __n4835 {
+
+ // 17.12.2 coroutine traits
+ /// [coroutine.traits]
+ /// [coroutine.traits.primary]
+ template <typename _Result, typename...>
+ struct coroutine_traits
+ {
+ using promise_type = typename _Result::promise_type;
+ };
+
+ // 17.12.3 Class template coroutine_handle
+ /// [coroutine.handle]
+ template <typename _Promise = void>
+ struct coroutine_handle;
+
+ template <> struct
+ coroutine_handle<void>
+ {
+ public:
+ // 17.12.3.1, construct/reset
+ constexpr coroutine_handle() noexcept : _M_fr_ptr(0) {}
+
+ constexpr coroutine_handle(std::nullptr_t __h) noexcept
+ : _M_fr_ptr(__h)
+ {}
+
+ coroutine_handle& operator=(std::nullptr_t) noexcept
+ {
+ _M_fr_ptr = nullptr;
+ return *this;
+ }
+
+ public:
+ // 17.12.3.2, export/import
+ constexpr void* address() const noexcept { return _M_fr_ptr; }
+
+ constexpr static coroutine_handle from_address(void* __a) noexcept
+ {
+ coroutine_handle __self;
+ __self._M_fr_ptr = __a;
+ return __self;
+ }
+
+ public:
+ // 17.12.3.3, observers
+ constexpr explicit operator bool() const noexcept
+ {
+ return bool(_M_fr_ptr);
+ }
+
+ bool done() const noexcept { return __builtin_coro_done(_M_fr_ptr); }
+
+ // 17.12.3.4, resumption
+ void operator()() const { resume(); }
+
+ void resume() const { __builtin_coro_resume(_M_fr_ptr); }
+
+ void destroy() const { __builtin_coro_destroy(_M_fr_ptr); }
+
+ protected:
+ void* _M_fr_ptr;
+ };
+
+ // 17.12.3.6 Comparison operators
+ /// [coroutine.handle.compare]
+ constexpr bool operator==(coroutine_handle<> __a,
+ coroutine_handle<> __b) noexcept
+ {
+ return __a.address() == __b.address();
+ }
+
+#if _COROUTINES_USE_SPACESHIP
+ constexpr strong_ordering
+ operator<=>(coroutine_handle<> __a, coroutine_handle<> __b) noexcept;
+#else
+ // These are to enable operation with std=c++14,17.
+ constexpr bool operator!=(coroutine_handle<> __a,
+ coroutine_handle<> __b) noexcept
+ {
+ return !(__a == __b);
+ }
+
+ constexpr bool operator<(coroutine_handle<> __a,
+ coroutine_handle<> __b) noexcept
+ {
+ return less<void*>()(__a.address(), __b.address());
+ }
+
+ constexpr bool operator>(coroutine_handle<> __a,
+ coroutine_handle<> __b) noexcept
+ {
+ return __b < __a;
+ }
+
+ constexpr bool operator<=(coroutine_handle<> __a,
+ coroutine_handle<> __b) noexcept
+ {
+ return !(__a > __b);
+ }
+
+ constexpr bool operator>=(coroutine_handle<> __a,
+ coroutine_handle<> __b) noexcept
+ {
+ return !(__a < __b);
+ }
+#endif
+
+ template <typename _Promise>
+ struct coroutine_handle : coroutine_handle<>
+ {
+ // 17.12.3.1, construct/reset
+ using coroutine_handle<>::coroutine_handle;
+
+ static coroutine_handle from_promise(_Promise& p)
+ {
+ coroutine_handle __self;
+ __self._M_fr_ptr
+ = __builtin_coro_promise((char*) &p, __alignof(_Promise), true);
+ return __self;
+ }
+
+ coroutine_handle& operator=(std::nullptr_t) noexcept
+ {
+ coroutine_handle<>::operator=(nullptr);
+ return *this;
+ }
+
+ // 17.12.3.2, export/import
+ constexpr static coroutine_handle from_address(void* __a)
+ {
+ coroutine_handle __self;
+ __self._M_fr_ptr = __a;
+ return __self;
+ }
+
+ // 17.12.3.5, promise accesss
+ _Promise& promise() const
+ {
+ void* __t
+ = __builtin_coro_promise (this->_M_fr_ptr, __alignof(_Promise), false);
+ return *static_cast<_Promise*>(__t);
+ }
+ };
+
+ /// [coroutine.noop]
+ struct noop_coroutine_promise
+ {
+ };
+
+ void __dummy_resume_destroy() __attribute__((__weak__));
+ void __dummy_resume_destroy() {}
+
+ struct __noop_coro_frame
+ {
+ void (*__r)() = __dummy_resume_destroy;
+ void (*__d)() = __dummy_resume_destroy;
+ struct noop_coroutine_promise __p;
+ } __noop_coro_fr __attribute__((__weak__));
+
+ // 17.12.4.1 Class noop_coroutine_promise
+ /// [coroutine.promise.noop]
+ template <>
+ struct coroutine_handle<noop_coroutine_promise> : public coroutine_handle<>
+ {
+ using _Promise = noop_coroutine_promise;
+
+ public:
+ // 17.12.4.2.1, observers
+ constexpr explicit operator bool() const noexcept { return true; }
+
+ constexpr bool done() const noexcept { return false; }
+
+ // 17.12.4.2.2, resumption
+ void operator()() const noexcept {}
+
+ void resume() const noexcept {}
+
+ void destroy() const noexcept {}
+
+ // 17.12.4.2.3, promise access
+ _Promise& promise() const
+ {
+ return *static_cast<_Promise*>(
+ __builtin_coro_promise(this->_M_fr_ptr, __alignof(_Promise), false));
+ }
+
+ // 17.12.4.2.4, address
+ private:
+ friend coroutine_handle<noop_coroutine_promise> noop_coroutine() noexcept;
+
+ coroutine_handle() noexcept { this->_M_fr_ptr = (void*) &__noop_coro_fr; }
+ };
+
+ using noop_coroutine_handle = coroutine_handle<noop_coroutine_promise>;
+
+ inline noop_coroutine_handle noop_coroutine() noexcept
+ {
+ return noop_coroutine_handle();
+ }
+
+ // 17.12.5 Trivial awaitables
+ /// [coroutine.trivial.awaitables]
+ struct suspend_always
+ {
+ bool await_ready() { return false; }
+
+ void await_suspend(coroutine_handle<>) {}
+
+ void await_resume() {}
+ };
+
+ struct suspend_never
+ {
+ bool await_ready() { return true; }
+
+ void await_suspend(coroutine_handle<>) {}
+
+ void await_resume() {}
+ };
+
+ } // namespace __n4835
+
+#else
+#error "the coroutine header requires -fcoroutines"
+#endif
+
+ _GLIBCXX_END_NAMESPACE_VERSION
+} // namespace std
+
+#endif // C++14 (we are allowing use from at least this)
+
+#endif // _GLIBCXX_COROUTINE
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