libcxx/test/std/ranges/range.factories/range.iota.view/empty.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: c++03, c++11, c++14, c++17
  10
  11 // constexpr bool empty() const;
  12
  13 #include <cassert>
  14 #include <concepts>
  15 #include <ranges>
  16 #include <utility>
  17 #include <vector>
  18
  19 #include "types.h"
  20
  21 template <typename R>
  22 concept HasEmpty = requires(const R r) {
  23   std::ranges::empty(r);
  24   { r.empty() } -> std::same_as<bool>;
  25 };
  26
  27 constexpr void test_empty_iota_sfinae() {
  28   std::vector<int> ev;
  29
  30   auto iv = std::views::iota(std::ranges::begin(ev), std::ranges::end(ev));
  31
  32   static_assert(HasEmpty<decltype(iv)>);
  33   static_assert(HasEmpty<decltype(std::as_const(iv))>);
  34 }
  35
  36 constexpr void test_nonempty_iota_sfinae() {
  37   // Default ctr
  38   {
  39     std::ranges::iota_view<Int42<DefaultTo42>> iv;
  40
  41     static_assert(HasEmpty<decltype(iv)>);
  42   }
  43   // Value pass
  44   {
  45     std::ranges::iota_view<SomeInt> iv(SomeInt(94));
  46
  47     static_assert(HasEmpty<decltype(iv)>);
  48   }
  49
  50   {
  51     std::vector<char> v;
  52     auto it = std::back_inserter(v);
  53     auto iv = std::views::iota(it);
  54
  55     static_assert(HasEmpty<decltype(iv)>);
  56   }
  57   {
  58     std::vector<char> v{'b', 'a', 'b', 'a', 'z', 'm', 't'};
  59     auto it = std::back_inserter(v);
  60     auto iv = std::views::iota(it);
  61
  62     static_assert(HasEmpty<decltype(iv)>);
  63   }
  64 }
  65
  66 constexpr void test_empty_iota() {
  67   std::vector<int> ev;
  68
  69   auto iv = std::views::iota(std::ranges::begin(ev), std::ranges::end(ev));
  70
  71   assert(iv.empty());
  72   assert(std::as_const(iv).empty());
  73 }
  74
  75 constexpr void test_nonempty_iota() {
  76   // Default ctr
  77   {
  78     std::ranges::iota_view<Int42<DefaultTo42>> iv;
  79
  80     assert(!iv.empty());
  81   }
  82   // Value pass
  83   {
  84     std::ranges::iota_view<SomeInt> iv(SomeInt(94));
  85
  86     assert(!iv.empty());
  87   }
  88
  89   {
  90     std::vector<char> v;
  91     auto it = std::back_inserter(v);
  92     auto iv = std::views::iota(it);
  93
  94     assert(!iv.empty());
  95   }
  96   {
  97     std::vector<char> v{'b', 'a', 'b', 'a', 'z', 'm', 't'};
  98     auto it = std::back_inserter(v);
  99     auto iv = std::views::iota(it);
 100
 101     assert(!iv.empty());
 102   }
 103 }
 104
 105 constexpr bool test() {
 106   test_empty_iota();
 107   test_nonempty_iota();
 108
 109   return true;
 110 }
 111
 112 int main(int, char**) {
 113   test();
 114   static_assert(test());
 115
 116   return 0;
 117 }