added get_stop_token

docs/TODO.json

@@ -6,6 +6,7 @@
     "execution.queryable.general]": { "code":true, "test":true, "doc":false, "comment":"nothing testable" },
     "execution.forwarding_query": { "code":true, "test":true, "doc":false },
     "execution.get_allocator": { "code":true, "test":true, "doc":false },
+    "execution.get_stop_token": { "code":true, "test":true, "doc":false },
     "execution.queryable.concepts": { "code":true, "test":true, "doc":false },
     "execution.receivers": { "code":true, "test":true, "doc":true, "comment":"empty" },
     "execution.senders": { "code":true, "test":true, "doc":true, "comment":"empty" },

docs/TODO.md

@@ -51,7 +51,7 @@
 | [[execution.queries](https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2024/p2300r10.html#execution.queries)] | ✅ | ✅ | ✅ | empty |
 | [[execution.forwarding_query](https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2024/p2300r10.html#execution.forwarding_query)] | ✅ | ✅ | 🔴 |  |
 | [[execution.get_allocator](https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2024/p2300r10.html#execution.get_allocator)] | ✅ | ✅ | 🔴 |  |
-| [[execution.get_stop_token](https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2024/p2300r10.html#execution.get_stop_token)] | 🔴 | 🔴 | 🔴 |  |
+| [[execution.get_stop_token](https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2024/p2300r10.html#execution.get_stop_token)] | ✅ | ✅ | 🔴 |  |
 | [[execution.environment.get_env](https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2024/p2300r10.html#execution.environment.get_env)] | 🔴 | 🔴 | 🔴 |  |
 | [[execution.get_domain](https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2024/p2300r10.html#execution.get_domain)] | 🔴 | 🔴 | 🔴 |  |
 | [[execution.get_scheduler](https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2024/p2300r10.html#execution.get_scheduler)] | 🔴 | 🔴 | 🔴 |  |

docs/questions.md

@@ -14,4 +14,4 @@ likely observable.
     The "Mandates" should be "Precondition".
 - [exec.fwd.env] states "Mandates: ... is a core constant expression if
     `q` is a core constant expression": I don't know how to possibly
-    implement that.
+    implement that.

include/Beman/Execution26/detail/get_stop_token.hpp

@@ -0,0 +1,45 @@
+// include/Beman/Execution26/detail/get_stop_token.hpp                -*-C++-*-
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+#ifndef INCLUDED_BEMAN_EXECUTION26_DETAIL_GET_STOP_TOKEN
+#define INCLUDED_BEMAN_EXECUTION26_DETAIL_GET_STOP_TOKEN
+
+#include <Beman/Execution26/detail/forwarding_query.hpp>
+#include <Beman/Execution26/detail/never_stop_token.hpp>
+#include <Beman/Execution26/detail/stoppable_token.hpp>
+#include <utility>
+
+// ----------------------------------------------------------------------------
+
+namespace Beman::Execution26
+{
+    struct get_stop_token_t
+    {
+        template <typename Object>
+            requires requires(Object&& object, get_stop_token_t const& tag)
+            {
+                { ::std::as_const(object).query(tag) } noexcept -> ::Beman::Execution26::stoppable_token;
+            }
+        auto operator()(Object&& object) const noexcept
+        {
+            return ::std::as_const(object).query(*this);
+        }
+
+        template <typename Object>
+        auto operator()(Object&&) const noexcept -> ::Beman::Execution26::never_stop_token
+        {
+            return {};
+        }
+
+        constexpr auto query(::Beman::Execution26::forwarding_query_t const&) const noexcept -> bool
+        {
+            return true;
+        }
+    };
+
+    inline constexpr get_stop_token_t get_stop_token{};
+}
+
+// ----------------------------------------------------------------------------
+
+#endif

include/Beman/Execution26/execution.hpp

@@ -8,6 +8,8 @@
 
 #include <Beman/Execution26/detail/queryable.hpp>
 #include <Beman/Execution26/detail/forwarding_query.hpp>
+#include <Beman/Execution26/detail/get_allocator.hpp>
+#include <Beman/Execution26/detail/get_stop_token.hpp>
 #include <Beman/Execution26/detail/get_env.hpp>
 
 #include <Beman/Execution26/detail/completion_signature.hpp>

include/Beman/Execution26/stop_token.hpp

@@ -11,6 +11,7 @@
 #include <Beman/Execution26/detail/stop_callback_for_t.hpp>
 #include <Beman/Execution26/detail/stop_source.hpp>
 #include <Beman/Execution26/detail/stoppable_source.hpp>
+#include <Beman/Execution26/detail/stoppable_token.hpp>
 #include <Beman/Execution26/detail/unstoppable_token.hpp>
 
 // ----------------------------------------------------------------------------

src/Beman/Execution26/tests/CMakeLists.txt

@@ -2,6 +2,7 @@
 # SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
 list(APPEND execution_tests
+    exec-get-stop-token.pass
     exec-get-allocator.pass
     exec-fwd-env.pass
     exec-opstate.pass

src/Beman/Execution26/tests/exec-get-allocator.pass.cpp

@@ -1,7 +1,6 @@
-// src/Beman/Execution26/tests/exec.get.allocator.pass.cpp            -*-C++-*-
+// src/Beman/Execution26/tests/exec-get-allocator.pass.cpp            -*-C++-*-
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
-#include <Beman/Execution26/detail/get_allocator.hpp>
 #include <Beman/Execution26/execution.hpp>
 #include <test/execution.hpp>
 #include <concepts>

src/Beman/Execution26/tests/exec-get-stop-token.pass.cpp

@@ -0,0 +1,63 @@
+// src/Beman/Execution26/tests/exec-get-stop-token.pass.cpp           -*-C++-*-
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+#include <Beman/Execution26/execution.hpp>
+#include <Beman/Execution26/stop_token.hpp>
+#include <test/execution.hpp>
+#include <concepts>
+
+// ----------------------------------------------------------------------------
+
+namespace
+{
+    struct non_stop_token {};
+    struct stop_token
+    {
+        template <typename CB>
+        struct callback_type {};
+        auto stop_requested() const noexcept -> bool { return {}; }
+        auto stop_possible() const noexcept -> bool { return {}; }
+        auto operator== (stop_token const&) const noexcept -> bool = default;
+    };
+
+    struct no_get_stop_token {};
+
+    struct non_const_get_stop_token
+    {
+        auto query(test_std::get_stop_token_t const&) noexcept -> stop_token { return {}; }
+    };
+    template <bool Noexcept>
+    struct has_get_stop_token
+    {
+        auto query(test_std::get_stop_token_t const&) const noexcept(Noexcept) -> stop_token { return {}; }
+    };
+
+    struct inconsistent_get_stop_token
+    {
+        auto query(test_std::get_stop_token_t const&) const noexcept -> stop_token { return {}; }
+        auto query(test_std::get_stop_token_t const&) noexcept -> non_stop_token { return {}; }
+    };
+
+
+    template <typename Result, typename Object>
+    auto test_get_stop_token(Object&& object)
+    {
+        static_assert(requires { test_std::get_stop_token(object); });
+        static_assert(std::same_as<Result, decltype(test_std::get_stop_token(object))>);
+    }
+}
+
+auto main() -> int
+{
+    static_assert(std::same_as<test_std::get_stop_token_t const,
+                               decltype(test_std::get_stop_token)>);
+    static_assert(test_std::forwarding_query(test_std::get_stop_token));
+
+    test_get_stop_token<test_std::never_stop_token>(no_get_stop_token());
+    test_get_stop_token<stop_token>(has_get_stop_token<true>());
+    test_get_stop_token<test_std::never_stop_token>(has_get_stop_token<false>());
+    test_get_stop_token<test_std::never_stop_token>(non_const_get_stop_token());
+    test_get_stop_token<stop_token>(inconsistent_get_stop_token());
+
+    static_assert(test_std::stoppable_token<stop_token>);
+}