[libcxx-commits] [libcxx] [libc++] P2502R2: `std::generator` (PR #92213)

[Mark de Wever via libcxx-commits]

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@@ -0,0 +1,593 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP_GENERATOR
+#define _LIBCPP_GENERATOR
+
+/*
+
+namespace std {
+  // [coro.generator.class], class template generator
+  template<class Ref, class V = void, class Allocator = void>
+    class generator;
+
+  namespace pmr {
+    template<class R, class V = void>
+      using generator = std::generator<R, V, polymorphic_allocator<>>;
+  }
+}
+
+*/
+
+#include <__algorithm/max.h>
+#include <__assert>
+#include <__concepts/common_reference_with.h>
+#include <__concepts/constructible.h>
+#include <__concepts/convertible_to.h>
+#include <__concepts/same_as.h>
+#include <__config>
+#include <__coroutine/coroutine_handle.h>
+#include <__coroutine/coroutine_traits.h>
+#include <__coroutine/noop_coroutine_handle.h>
+#include <__coroutine/trivial_awaitables.h>
+#include <__exception/exception_ptr.h>
+#include <__iterator/default_sentinel.h>
+#include <__memory/addressof.h>
+#include <__memory/allocator_arg_t.h>
+#include <__memory/allocator_traits.h>
+#include <__memory/construct_at.h>
+#include <__memory_resource/polymorphic_allocator.h>
+#include <__ranges/access.h>
+#include <__ranges/concepts.h>
+#include <__ranges/elements_of.h>
+#include <__ranges/view_interface.h>
+#include <__type_traits/add_pointer.h>
+#include <__type_traits/common_reference.h>
+#include <__type_traits/conditional.h>
+#include <__type_traits/is_nothrow_constructible.h>
+#include <__type_traits/is_object.h>
+#include <__type_traits/is_pointer.h>
+#include <__type_traits/is_reference.h>
+#include <__type_traits/is_void.h>
+#include <__type_traits/remove_cvref.h>
+#include <__type_traits/remove_reference.h>
+#include <__utility/exchange.h>
+#include <__utility/move.h>
+#include <__utility/swap.h>
+#include <cstdint>
+#include <new>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+#if _LIBCPP_STD_VER >= 23
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _Ref, class _Val>
+using __gen_val = conditional_t<is_void_v<_Val>, remove_cvref_t<_Ref>, _Val>;
+
+template <class _Ref, class _Val>
+using __gen_ref = conditional_t<is_void_v<_Val>, _Ref&&, _Ref>;
+
+template <class _Ref, class _Val>
+using __gen_yielded =
+    conditional_t<is_reference_v<__gen_ref<_Ref, _Val>>, __gen_ref<_Ref, _Val>, const __gen_ref<_Ref, _Val>&>;
+
+template <class, class, class>
+class generator;
+
+template <class _Yielded>
+class __gen_promise_base {
+private:
+  template <class, class, class>
+  friend class generator;
+
+  template <class, class>
+  friend class __gen_iter;
+
+  // Each promise object stores either a `__root_data` when associated with a root generator, or a `__recursive_data`
+  // when associated with a generator that is yielded recursively.
+  struct __root_data {
+    // The client code has access only to the iterator of the root generator. Thus, the root generator must store the
+    // yielded values of recursively-yielded generators, which will then be returned when the client code dereferences
+    // the iterator.
+    add_pointer_t<_Yielded> __value_ptr;
+    // The client code has access only to the iterator of the root generator. Thus, the root generator needs to identify
+    // which generator is currently active. This active generator will then be resumed when the client code increments
+    // the iterator.
+    std::coroutine_handle<__gen_promise_base> __active;
+  };
+
+  struct __recursive_data {
+    std::exception_ptr __exception;
----------------
mordante wrote:

Types are not susceptible to ADL so they don't need to be qualified.

https://github.com/llvm/llvm-project/pull/92213