[libcxx-commits] [libcxx] [libc++] Mostly Implement P1885R12: `<text_encoding>` (PR #141312)

[A. Jiang via libcxx-commits]

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@@ -0,0 +1,143 @@
+// -*- 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_TEXT_ENCODING
+#define _LIBCPP_TEXT_ENCODING
+
+/* text_encoding synopsis
+namespace std {
+
+struct text_encoding;
+
+// [text.encoding.hash], hash support
+template<class T> struct hash;
+template<> struct hash<text_encoding>;
+
+struct text_encoding
+{
+    static constexpr size_t max_name_length = 63;
+
+    // [text.encoding.id], enumeration text_encoding::id
+    enum class id : int_least32_t {
+      see below
+    };
+    using enum id;
+
+    constexpr text_encoding() = default;
+    constexpr explicit text_encoding(string_view enc) noexcept;
+    constexpr text_encoding(id i) noexcept;
+
+    constexpr id mib() const noexcept;
+    constexpr const char* name() const noexcept;
+
+    // [text.encoding.aliases], class text_encoding::aliases_view
+    // struct aliases_view;
+    constexpr aliases_view aliases() const noexcept;
+
+    friend constexpr bool operator==(const text_encoding& a,
+                                     const text_encoding& b) noexcept;
+    friend constexpr bool operator==(const text_encoding& encoding, id i) noexcept;
+
+    static consteval text_encoding literal() noexcept;
+    static text_encoding environment();
+    template<id i> static bool environment_is();
+
+  private:
+    id mib_ = id::unknown;                                              // exposition only
+    char name_[max_name_length + 1] = {0};                              // exposition only
+    static constexpr bool comp-name(string_view a, string_view b);      // exposition only
+};
+}
+
+*/
+
+#if __cplusplus < 201103L && defined(_LIBCPP_USE_FROZEN_CXX03_HEADERS)
+#  include <__cxx03/__config>
+#else
+#  include <__config>
+
+#  if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#    pragma GCC system_header
+#  endif
+
+#  if _LIBCPP_STD_VER >= 26
+
+#    include <__functional/hash.h>
+#    include <__ranges/enable_borrowed_range.h>
+#    include <__ranges/view_interface.h>
+#    include <__text_encoding/te_impl.h>
+#    include <string_view>
+#    include <version>
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frederick-vs-ja wrote:

I think we should unconditionally include `<version>`. Was the unconditional inclusion problematic?

https://github.com/llvm/llvm-project/pull/141312