libcxx/test/std/ranges/range.factories/range.istream.view/range.concept.compile.pass.cpp

   1 //===----------------------------------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 // UNSUPPORTED: no-localization
  10 // UNSUPPORTED: c++03, c++11, c++14, c++17
  11
  12 // concept checking istream_view
  13
  14 #include <istream>
  15 #include <ranges>
  16
  17 #include "test_macros.h"
  18
  19 template <class Val, class CharT, class Traits = std::char_traits<CharT>>
  20 concept HasIstreamView = requires { typename std::ranges::basic_istream_view<Val, CharT, Traits>; };
  21
  22 static_assert(HasIstreamView<int, char>);
  23
  24 #ifndef TEST_HAS_NO_WIDE_CHARACTERS
  25 static_assert(HasIstreamView<int, wchar_t>);
  26 #endif
  27
  28 // Unmovable Val
  29 struct Unmovable {
  30   Unmovable()            = default;
  31   Unmovable(Unmovable&&) = delete;
  32   template <class CharT>
  33   friend std::basic_istream<CharT>& operator>>(std::basic_istream<CharT>& x, const Unmovable&) {
  34     return x;
  35   }
  36 };
  37 static_assert(!HasIstreamView<Unmovable, char>);
  38
  39 #ifndef TEST_HAS_NO_WIDE_CHARACTERS
  40 static_assert(!HasIstreamView<Unmovable, wchar_t>);
  41 #endif
  42
  43 // !default_initializable<Val>
  44 struct NoDefaultCtor {
  45   NoDefaultCtor(int) {}
  46   friend std::istream& operator>>(std::istream& x, const NoDefaultCtor&) { return x; }
  47 };
  48 static_assert(!HasIstreamView<NoDefaultCtor, char>);
  49 #ifndef TEST_HAS_NO_WIDE_CHARACTERS
  50 static_assert(!HasIstreamView<NoDefaultCtor, wchar_t>);
  51 #endif
  52
  53 // !stream-extractable<Val, CharT, Traits>
  54 struct Foo {};
  55 static_assert(!HasIstreamView<Foo, char>);
  56 #ifndef TEST_HAS_NO_WIDE_CHARACTERS
  57 static_assert(!HasIstreamView<Foo, wchar_t>);
  58 #endif
  59
  60 template <class T>
  61 concept OnlyInputRange = std::ranges::input_range<T> && !std::ranges::forward_range<T>;
  62
  63 static_assert(OnlyInputRange<std::ranges::istream_view<int>>);
  64 static_assert(OnlyInputRange<std::ranges::istream_view<long>>);
  65 static_assert(OnlyInputRange<std::ranges::istream_view<double>>);
  66 static_assert(OnlyInputRange<std::ranges::istream_view<char>>);
  67
  68 #ifndef TEST_HAS_NO_WIDE_CHARACTERS
  69 static_assert(OnlyInputRange<std::ranges::wistream_view<int>>);
  70 static_assert(OnlyInputRange<std::ranges::wistream_view<long>>);
  71 static_assert(OnlyInputRange<std::ranges::wistream_view<double>>);
  72 static_assert(OnlyInputRange<std::ranges::wistream_view<wchar_t>>);
  73 #endif