updated the code to match P3325 (#197)

* updated the code to match P3325

* it seems clang-17, clang-18 have some problem

Author: dietmarkuehl

.github/workflows/ci_tests.yml

@@ -87,13 +87,6 @@ jobs:
                   ]
                 }
               ]
-            },
-            { "versions": ["18", "17"],
-              "tests": [
-                { "cxxversions": ["c++26", "c++23"],
-                  "tests": [{"stdlibs": ["libc++"], "tests": ["Release.Default"]}]
-                }
-              ]
             }
           ],
           "msvc": [

Makefile

@@ -62,7 +62,7 @@ ifeq (${hostSystemName},Darwin)
 else ifeq (${hostSystemName},Linux)
   export LLVM_DIR=/usr/lib/llvm-20
   export PATH:=${LLVM_DIR}/bin:${PATH}
-  export CXX=clang++-20
+  # export CXX=clang++-20
 else
   export CXX=$(COMPILER)
 endif

bin/update-cmake-headers.py

@@ -23,13 +23,8 @@ def get_headers(dir):
     return result
 
 
-sections = {
-    "public": get_headers("include/beman/*"),
-    "detail": get_headers("include/beman/*/detail"),
-}
-
 file_set_re = re.compile(" *FILE_SET.*")
-section_re = re.compile(" *\${TARGET_NAME}_(?P<section>.*)_headers$")
+section_re = re.compile(" *FILE_SET *\${TARGET_NAME}_(?P<section>.*)_headers$")
 header_re = re.compile(" *\${PROJECT_SOURCE_DIR}/include/beman/.*/.*\.hpp")
 
 if len(sys.argv) != 2:
@@ -41,6 +36,10 @@ def get_headers(dir):
 
 section = ""
 section_done = False
+sections = {
+    "public": get_headers("include/beman/*"),
+    "detail": get_headers("include/beman/*/detail"),
+}
 
 with open(cmake, "r") as input:
     lines = input.readlines()
@@ -58,7 +57,7 @@ def get_headers(dir):
                 section_done = True
                 project = "${PROJECT_SOURCE_DIR}"
                 for header in sections[section]:
-                    output.write(f"         {project}/include/{header}.hpp\n")
+                    output.write(f"                {project}/include/{header}.hpp\n")
         else:
             output.write(line)
             pass

docs/dependency.txt

@@ -57,7 +57,7 @@ completion_signature set_stopped
 completion_signature set_value
 completion_signatures_for completion_signatures
 completion_signatures_of_t call_result_t
-completion_signatures_of_t empty_env
+completion_signatures_of_t env
 completion_signatures_of_t get_completion_signatures
 completion_signatures_of_t sender_in
 completion_tag set_error
@@ -98,7 +98,7 @@ default_domain queryable
 default_domain sender
 default_domain tag_of_t
 default_impls callable
-default_impls empty_env
+default_impls env
 default_impls fwd_env
 default_impls get_env
 default_impls start
@@ -107,7 +107,7 @@ default_set_error set_value
 default_set_value completion_signatures
 default_set_value set_value
 emplace_from call_result_t
-enable_sender empty_env
+enable_sender env
 enable_sender env_promise
 enable_sender is_awaitable
 enable_sender is_sender
@@ -153,7 +153,7 @@ get_domain_late get_domain
 get_domain_late get_scheduler
 get_domain_late query_with_default
 get_domain_late sender_for
-get_env empty_env
+get_env env
 get_env mandate_nothrow
 get_env queryable
 get_forward_progress_guarantee forward_progress_guarantee
@@ -201,7 +201,7 @@ let_error connect_result_t
 let_error decayed_tuple
 let_error decayed_typeof
 let_error default_impls
-let_error empty_env
+let_error env
 let_error fwd_env
 let_error get_completion_scheduler
 let_error get_domain
@@ -226,7 +226,7 @@ let_stopped connect_result_t
 let_stopped decayed_tuple
 let_stopped decayed_typeof
 let_stopped default_impls
-let_stopped empty_env
+let_stopped env
 let_stopped fwd_env
 let_stopped get_completion_scheduler
 let_stopped get_domain
@@ -251,7 +251,7 @@ let_value connect_result_t
 let_value decayed_tuple
 let_value decayed_typeof
 let_value default_impls
-let_value empty_env
+let_value env
 let_value fwd_env
 let_value get_completion_scheduler
 let_value get_domain
@@ -371,7 +371,7 @@ sender_in_of sender_in
 sender_in_of set_value
 sender_in_of value_signature
 sender_in_of value_types_of_t
-sender_of empty_env
+sender_of env
 sender_of sender_in_of
 sender_of tag_of_t
 sender_to completion_signatures_of_t
@@ -493,7 +493,7 @@ value_types_of_t variant_or_empty
 variant_or_empty empty_variant
 when_all default_domain
 when_all emplace_value
-when_all empty_env
+when_all env
 when_all env_of_t
 when_all get_domain
 when_all get_domain_early

docs/overview.md

@@ -19,7 +19,7 @@ When an asynchronous operation completes it _signals_ its completion by calling
 </details>
 <details>
 <summary>environment</summary>
-The term _enviroment_ refers to the bag of properties associated with an <code>_object_</code> by the call <code><a href=‘#get-env’>std::execution::get_env</a>(_object_)</code>. By default the environment for objects is empty (<code><a href=‘#empty-env’>std::execution::empty_env</a></code>). In particular, environments associated with <code><a href=‘#receiver’>receiver</a></code>s are used to provide access  to properties like the <a href=‘#get-stop-token’>stop token</a>, <a href=‘#get-scheduler’>scheduler</a>, or <a href=‘#get-allocator’>allocator</a> associated with the <code><a href=‘#receiver’>receiver</a></code>. The various properties associated with an object are accessed via <a href=‘#queries’>queries</a>.
+The term _enviroment_ refers to the bag of properties associated with an <code>_object_</code> by the call <code><a href=‘#get-env’>std::execution::get_env</a>(_object_)</code>. By default the environment for objects is empty (<code><a href=‘#env’>std::execution::env&lt;&gt;</a></code>). In particular, environments associated with <code><a href=‘#receiver’>receiver</a></code>s are used to provide access  to properties like the <a href=‘#get-stop-token’>stop token</a>, <a href=‘#get-scheduler’>scheduler</a>, or <a href=‘#get-allocator’>allocator</a> associated with the <code><a href=‘#receiver’>receiver</a></code>. The various properties associated with an object are accessed via <a href=‘#queries’>queries</a>.
 </details>
 
 ## Concepts
@@ -70,7 +70,7 @@ Required members for <code>_Receiver_</code>:
 - The type `receiver_concept` is an alias for `receiver_t` or a type derived thereof`.
 - Rvalues of type <code>_Receiver_</code> are movable.
 - Lvalues of type <code>_Receiver_</code> are copyable.
-- <code><a href=‘#get-env’>std::execution::get_env</a>(_receiver_)</code> returns an object. By default this operation returns <code><a href=‘empty-env’>std::execution::empty_env</a></code>.
+- <code><a href=‘#get-env’>std::execution::get_env</a>(_receiver_)</code> returns an object. By default this operation returns <code><a href=‘env’>std::execution::env&lt;&gt;</a></code>.
 
 Typical members for <code>_Receiver_</code>:
 
@@ -177,7 +177,7 @@ Senders represent asynchronous work. They may get composed from multiple senders
 
 Requirements for <code>_Sender_</code>:
 - The type <code>_Sender_::sender_concept</code> is an alias for `sender_t` or a type derived thereof or <code>_Sender_</code> is a suitable _awaitable_.
-- <code><a href='get_env'>std::execution::get_env</a>(_sender_)</code> is valid. By default this operation returns <code><a href=‘empty-env’>std::execution::empty_env</a></code>.
+- <code><a href='get_env'>std::execution::get_env</a>(_sender_)</code> is valid. By default this operation returns <code><a href=‘env’>std::execution::env&lt;&gt;</a></code>.
 - Rvalues of type <code>_Sender_</code> can be moved.
 - Lvalues of type <code>_Sender_</code> can be copied.
 
@@ -224,7 +224,7 @@ static_assert(std::execution::sender<example_sender>);
 </details>
 </details>
 <details>
-<summary><code>sender_in&lt;<i>Sender, Env</i> = std::execution::empty_env&gt;</code></summary>
+<summary><code>sender_in&lt;<i>Sender, Env</i> = std::execution::env&lt;&gt;&gt;</code></summary>
 
 The concept <code>sender_in&lt;<i>Sender, Env</i>&gt;</code> tests whether <code>_Sender_</code> is a <code><a href=‘#sender’>sender</a></code>, <code>_Env_</code> is a destructible type, and <code><a href=‘#get_completion_signatures’>std::execution::get_completion_signatures</a>(_sender_, _env_)</code> yields a specialization of <code><a href=‘#completion_signatures’>std::execution::completion_signatures</a></code>.
 </details>
@@ -236,7 +236,7 @@ The concept <code>sender_to&lt;<i>Sender, Receiver</i>&gt;</code> tests if <code
 To determine if <code>_Receiver_</code> can receive all <a href=‘#completion-signals’>completion signals</a> from <code>_Sender_</code> it checks that for each <code>_Signature_</code> in <code><a href=‘#get_completion_signals’>std::execution::get_completion_signals</a>(_sender_, std::declval&lt;<a href='#env_of_t'>std::execution::env_of_t</a>&lt;_Receiver_&gt;&gt;())</code> the test <code><a href=‘#receiver_of’>std::execution::receiver_of</a>&lt;_Receiver_, _Signature_&gt;</code> yields true. To determine if <code>_Sender_</code> can be <code><a href=‘#connect’>connect</a></code>ed to <code>_Receiver_</code> the concept checks if <code><a href=‘#connect’>connect</a>(std::declval&lt;_Sender_&gt;(), std::declval&lt;_Receiver_&gt;)</code> is a valid expression.
 </details>
 <details>
-<summary><code>sends_stopped&lt;<i>Sender, Env</i> = std::execution::empty_env&gt;</code></summary>
+<summary><code>sends_stopped&lt;<i>Sender, Env</i> = std::execution::env&lt;&gt;&gt;</code></summary>
 
 The concept <code>sends_stopped&lt;<i>Sender, Env</i>&gt;</code> determines if <code>_Sender_</code> may send a <code><a href=‘#set_stopped’>stopped</a></code> <a href=‘#completion-signals’>completion signal</a>. To do so, the concepts determines if <code><a href=‘#get_completion_signals’>std::execution::get_completion_signals</a>(_sender_, _env_)</code> contains the signatures <code><a href=‘#set_stopped’>std::execution::set_stopped_t</a>()</code>.
 </details>
@@ -407,12 +407,12 @@ struct custom_t: forwarding_query_t {
 </details>
 <details>
 <summary><code>get_env(<i>queryable</i>) -> <i>env</i></code></summary>
-**Default**: <a href='#empty_env'>`empty_env`</a>
+**Default**: <a href='#env'>`env&lt;&gt;`</a>
 <br/>
-The expression <code>get_env(<i>queryable</i>)</code> is used to get the environment <code><i>env</i></code> associated with <code><i>queryable</i></code>. To provide a non-default environment for a <code><i>queryable</i></code> a `get_env` member needs to be defined. If <code><i>queryable</i></code> doesn’t provide the <code>get_env</code> query an object of type <code><a href=‘#empty_env’>empty_env</a></code> is returned.
+The expression <code>get_env(<i>queryable</i>)</code> is used to get the environment <code><i>env</i></code> associated with <code><i>queryable</i></code>. To provide a non-default environment for a <code><i>queryable</i></code> a `get_env` member needs to be defined. If <code><i>queryable</i></code> doesn’t provide the <code>get_env</code> query an object of type <code><a href=‘#env’>env&lt;&gt;</a></code> is returned.
 The value of the expression is <ol>
    <li>the result of <code>as_const(<i>queryable</i>).get_env()</code> if this expression is valid and <code>noexcept</code>.</li>
-   <li><code>empty_env</code> otherwise.
+   <li><code>env&lt;&gt;</code> otherwise.
 </ol>
 <div>
 <details>
@@ -712,7 +712,7 @@ The expression <code>into_variant(<i>sender</i>)</code> creates a sender which t
 - `completion_signatures_t`
 - `connect_result_t`
 - `default_domain`
-- `empty_env`
+- `env&lt;T...&gt;`
 - `env_of_t`
 - `error_types_of_t`
 - `fwd_env`

examples/just_stopped.cpp

@@ -11,7 +11,7 @@ struct receiver {
 int main() {
     // ex::sync_wait(ex::just_stopped() | ex::then([]{}));
     auto then = ex::just_stopped() | ex::then([] {});
-    static_assert(std::same_as<void, decltype(ex::get_completion_signatures(then, ex::empty_env()))>);
+    static_assert(std::same_as<void, decltype(ex::get_completion_signatures(then, ex::env<>()))>);
 
     ex::connect(ex::just_stopped() | ex::then([] {}), receiver{});
 }

include/beman/execution/detail/completion_signatures_of_t.hpp

@@ -5,7 +5,7 @@
 #define INCLUDED_BEMAN_EXECUTION_DETAIL_COMPLETION_SIGNATURES_OF
 
 #include <beman/execution/detail/call_result_t.hpp>
-#include <beman/execution/detail/empty_env.hpp>
+#include <beman/execution/detail/env.hpp>
 #include <beman/execution/detail/get_completion_signatures.hpp>
 #include <beman/execution/detail/sender_in.hpp>
 
@@ -16,10 +16,10 @@ namespace beman::execution {
  * \brief Alias to access the completion signatures of a sender
  * \headerfile beman/execution/execution.hpp <beman/execution/execution.hpp>
  */
-template <typename Sender, typename Env = ::beman::execution::empty_env>
+template <typename Sender, typename Env = ::beman::execution::env<>>
     requires ::beman::execution::sender_in<Sender, Env>
 using completion_signatures_of_t =
-    ::beman::execution::detail::call_result_t< ::beman::execution::get_completion_signatures_t, Sender, Env>;
+    ::beman::execution::detail::call_result_t<::beman::execution::get_completion_signatures_t, Sender, Env>;
 } // namespace beman::execution
 
 // ----------------------------------------------------------------------------

include/beman/execution/detail/default_impls.hpp

@@ -6,7 +6,7 @@
 
 #include <beman/execution/detail/allocator_aware_move.hpp>
 #include <beman/execution/detail/callable.hpp>
-#include <beman/execution/detail/empty_env.hpp>
+#include <beman/execution/detail/env.hpp>
 #include <beman/execution/detail/forward_like.hpp>
 #include <beman/execution/detail/fwd_env.hpp>
 #include <beman/execution/detail/get_allocator.hpp>
@@ -30,7 +30,7 @@ struct default_impls {
         if constexpr (1 == sizeof...(child))
             return (::beman::execution::detail::fwd_env(::beman::execution::get_env(child)), ...);
         else
-            return ::beman::execution::empty_env{};
+            return ::beman::execution::env<>{};
     };
     static constexpr auto get_env = [](auto, auto&, const auto& receiver) noexcept -> decltype(auto) {
         return ::beman::execution::detail::fwd_env(::beman::execution::get_env(receiver));

include/beman/execution/detail/empty_env.hpp

@@ -0,0 +1,63 @@
+// include/beman/execution/detail/env.hpp                             -*-C++-*-
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+#ifndef INCLUDED_INCLUDE_BEMAN_EXECUTION_DETAIL_ENV
+#define INCLUDED_INCLUDE_BEMAN_EXECUTION_DETAIL_ENV
+
+#include <beman/execution/detail/non_assignable.hpp>
+#include <beman/execution/detail/queryable.hpp>
+#include <type_traits>
+
+// ----------------------------------------------------------------------------
+
+namespace beman::execution::detail {
+template <::beman::execution::detail::queryable>
+struct env_base;
+
+template <typename E, typename Q>
+concept has_query = requires(const E& e) { e.query(::std::declval<Q>()); };
+
+template <typename Q, typename... E>
+struct find_env;
+template <typename Q, typename E0, typename... E>
+    requires has_query<E0, Q>
+struct find_env<Q, E0, E...> {
+    using type = E0;
+};
+template <typename Q, typename E0, typename... E>
+    requires(not has_query<E0, Q>)
+struct find_env<Q, E0, E...> {
+    using type = typename find_env<Q, E...>::type;
+};
+} // namespace beman::execution::detail
+
+namespace beman::execution {
+template <::beman::execution::detail::queryable... Envs>
+struct env;
+
+template <::beman::execution::detail::queryable... Envs>
+env(Envs...) -> env<::std::unwrap_reference_t<Envs>...>;
+} // namespace beman::execution
+
+// ----------------------------------------------------------------------------
+
+template <::beman::execution::detail::queryable Env>
+struct beman::execution::detail::env_base {
+    Env env_;
+};
+
+template <::beman::execution::detail::queryable... Envs>
+struct beman::execution::env : ::beman::execution::detail::env_base<Envs>... {
+    [[no_unique_address]] ::beman::execution::detail::non_assignable na_{};
+
+    template <typename Q>
+        requires(::beman::execution::detail::has_query<Envs, Q> || ...)
+    constexpr auto query(Q q) const noexcept -> decltype(auto) {
+        using E = typename ::beman::execution::detail::find_env<Q, Envs...>::type;
+        return q(static_cast<const ::beman::execution::detail::env_base<E>&>(*this).env_);
+    }
+};
+
+// ----------------------------------------------------------------------------
+
+#endif