[libcxx-commits] [libcxx] 45d048c - [libc++] Add C++20 contiguous_iterator_tag.
Eric Fiselier via libcxx-commits
libcxx-commits at lists.llvm.org
Sat Nov 16 17:15:11 PST 2019
Author: Eric Fiselier
Date: 2019-11-16T20:14:44-05:00
New Revision: 45d048c20440989df2b4e1be1f9343225e7741ab
URL: https://github.com/llvm/llvm-project/commit/45d048c20440989df2b4e1be1f9343225e7741ab
DIFF: https://github.com/llvm/llvm-project/commit/45d048c20440989df2b4e1be1f9343225e7741ab.diff
LOG: [libc++] Add C++20 contiguous_iterator_tag.
This work is part of an ongoing effort to allow libc++ to
optimize user provided contiguous iterators.
Added:
libcxx/test/std/iterators/iterator.primitives/std.iterator.tags/contiguous_iterator_tag.pass.cpp
Modified:
libcxx/include/iterator
libcxx/test/std/iterators/iterator.primitives/iterator.traits/pointer.pass.cpp
Removed:
################################################################################
diff --git a/libcxx/include/iterator b/libcxx/include/iterator
index c5c0f669ee83..6a9a08241b64 100644
--- a/libcxx/include/iterator
+++ b/libcxx/include/iterator
@@ -440,6 +440,11 @@ struct _LIBCPP_TEMPLATE_VIS output_iterator_tag {};
struct _LIBCPP_TEMPLATE_VIS forward_iterator_tag : public input_iterator_tag {};
struct _LIBCPP_TEMPLATE_VIS bidirectional_iterator_tag : public forward_iterator_tag {};
struct _LIBCPP_TEMPLATE_VIS random_access_iterator_tag : public bidirectional_iterator_tag {};
+#if _LIBCPP_STD_VER > 17
+// TODO(EricWF) contiguous_iterator_tag is provided as an extension prior to
+// C++20 to allow optimizations for users providing wrapped iterator types.
+struct _LIBCPP_TEMPLATE_VIS contiguous_iterator_tag: public random_access_iterator_tag { };
+#endif
template <class _Tp>
struct __has_iterator_typedefs
@@ -510,6 +515,9 @@ struct _LIBCPP_TEMPLATE_VIS iterator_traits<_Tp*>
typedef _Tp* pointer;
typedef _Tp& reference;
typedef random_access_iterator_tag iterator_category;
+#if _LIBCPP_STD_VER > 17
+ typedef contiguous_iterator_tag iterator_concept;
+#endif
};
template <class _Tp, class _Up, bool = __has_iterator_category<iterator_traits<_Tp> >::value>
@@ -532,6 +540,11 @@ struct __is_bidirectional_iterator : public __has_iterator_category_convertible_
template <class _Tp>
struct __is_random_access_iterator : public __has_iterator_category_convertible_to<_Tp, random_access_iterator_tag> {};
+#if _LIBCPP_STD_VER > 17
+template <class _Tp>
+struct __is_contiguous_iterator : public __has_iterator_category_convertible_to<_Tp, contiguous_iterator_tag> {};
+#endif
+
template <class _Tp>
struct __is_exactly_input_iterator
: public integral_constant<bool,
diff --git a/libcxx/test/std/iterators/iterator.primitives/iterator.traits/pointer.pass.cpp b/libcxx/test/std/iterators/iterator.primitives/iterator.traits/pointer.pass.cpp
index 79deed7b7ba7..4cf214a8be87 100644
--- a/libcxx/test/std/iterators/iterator.primitives/iterator.traits/pointer.pass.cpp
+++ b/libcxx/test/std/iterators/iterator.primitives/iterator.traits/pointer.pass.cpp
@@ -16,6 +16,7 @@
// typedef T* pointer;
// typedef T& reference;
// typedef random_access_iterator_tag iterator_category;
+// typedef contiguous_iterator_tag iterator_category; // C++20
// };
#include <iterator>
@@ -33,6 +34,8 @@ int main(int, char**)
static_assert((std::is_same<It::pointer, A*>::value), "");
static_assert((std::is_same<It::reference, A&>::value), "");
static_assert((std::is_same<It::iterator_category, std::random_access_iterator_tag>::value), "");
-
+#if TEST_STD_VER > 17
+ ASSERT_SAME_TYPE(It::iterator_concept, std::contiguous_iterator_tag);
+#endif
return 0;
}
diff --git a/libcxx/test/std/iterators/iterator.primitives/std.iterator.tags/contiguous_iterator_tag.pass.cpp b/libcxx/test/std/iterators/iterator.primitives/std.iterator.tags/contiguous_iterator_tag.pass.cpp
new file mode 100644
index 000000000000..7527668c7a59
--- /dev/null
+++ b/libcxx/test/std/iterators/iterator.primitives/std.iterator.tags/contiguous_iterator_tag.pass.cpp
@@ -0,0 +1,31 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// <iterator>
+
+// struct contiguous_iterator_tag : public random_access_iterator_tag {};
+
+// UNSUPPORTED: c++98, c++03, c++11, c++14, c++17
+
+
+#include <iterator>
+#include <type_traits>
+
+#include "test_macros.h"
+
+int main(int, char**)
+{
+ std::contiguous_iterator_tag tag;
+ ((void)tag); // Prevent unused warning
+ static_assert((std::is_base_of<std::random_access_iterator_tag,
+ std::contiguous_iterator_tag>::value), "");
+ static_assert((!std::is_base_of<std::output_iterator_tag,
+ std::contiguous_iterator_tag>::value), "");
+
+ return 0;
+}
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