libcxx/test/std/containers/views/views.span/span.iterators/rend.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 // UNSUPPORTED: c++03, c++11, c++14, c++17
   9
  10 // <span>
  11
  12 // constexpr       reverse_iterator  rend() const noexcept;
  13 // constexpr const_reverse_iterator crend() const noexcept;
  14
  15 #include <span>
  16 #include <cassert>
  17 #include <string>
  18
  19 #include "test_macros.h"
  20
  21 template <class Span>
  22 constexpr bool testConstexprSpan(Span s)
  23 {
  24     bool ret = true;
  25     typename Span::reverse_iterator e = s.rend();
  26     if (s.empty())
  27     {
  28         ret = ret &&  (e == s.rbegin());
  29     }
  30     else
  31     {
  32         ret = ret &&  (e != s.rbegin());
  33     }
  34
  35     ret = ret &&  (static_cast<std::size_t>(e - s.rbegin()) == s.size());
  36     return ret;
  37 }
  38
  39 template <class Span>
  40 void testRuntimeSpan(Span s)
  41 {
  42     typename Span::reverse_iterator e = s.rend();
  43     if (s.empty())
  44     {
  45         assert(e == s.rbegin());
  46     }
  47     else
  48     {
  49         assert(e != s.rbegin());
  50     }
  51
  52     assert(static_cast<std::size_t>(e - s.rbegin()) == s.size());
  53 }
  54
  55
  56 struct A{};
  57 bool operator==(A, A) {return true;}
  58
  59 constexpr int iArr1[] = { 0,  1,  2,  3,  4,  5,  6,  7,  8,  9};
  60           int iArr2[] = {10, 11, 12, 13, 14, 15, 16, 17, 18, 19};
  61
  62
  63 int main(int, char**)
  64 {
  65     static_assert(testConstexprSpan(std::span<int>()),            "");
  66     static_assert(testConstexprSpan(std::span<long>()),           "");
  67     static_assert(testConstexprSpan(std::span<double>()),         "");
  68     static_assert(testConstexprSpan(std::span<A>()),              "");
  69     static_assert(testConstexprSpan(std::span<std::string>()),    "");
  70
  71     static_assert(testConstexprSpan(std::span<int, 0>()),         "");
  72     static_assert(testConstexprSpan(std::span<long, 0>()),        "");
  73     static_assert(testConstexprSpan(std::span<double, 0>()),      "");
  74     static_assert(testConstexprSpan(std::span<A, 0>()),           "");
  75     static_assert(testConstexprSpan(std::span<std::string, 0>()), "");
  76
  77     static_assert(testConstexprSpan(std::span<const int>(iArr1, 1)),    "");
  78     static_assert(testConstexprSpan(std::span<const int>(iArr1, 2)),    "");
  79     static_assert(testConstexprSpan(std::span<const int>(iArr1, 3)),    "");
  80     static_assert(testConstexprSpan(std::span<const int>(iArr1, 4)),    "");
  81     static_assert(testConstexprSpan(std::span<const int>(iArr1, 5)),    "");
  82
  83
  84     testRuntimeSpan(std::span<int>        ());
  85     testRuntimeSpan(std::span<long>       ());
  86     testRuntimeSpan(std::span<double>     ());
  87     testRuntimeSpan(std::span<A>          ());
  88     testRuntimeSpan(std::span<std::string>());
  89
  90     testRuntimeSpan(std::span<int, 0>        ());
  91     testRuntimeSpan(std::span<long, 0>       ());
  92     testRuntimeSpan(std::span<double, 0>     ());
  93     testRuntimeSpan(std::span<A, 0>          ());
  94     testRuntimeSpan(std::span<std::string, 0>());
  95
  96     testRuntimeSpan(std::span<int>(iArr2, 1));
  97     testRuntimeSpan(std::span<int>(iArr2, 2));
  98     testRuntimeSpan(std::span<int>(iArr2, 3));
  99     testRuntimeSpan(std::span<int>(iArr2, 4));
 100     testRuntimeSpan(std::span<int>(iArr2, 5));
 101
 102     std::string s;
 103     testRuntimeSpan(std::span<std::string>(&s, (std::size_t) 0));
 104     testRuntimeSpan(std::span<std::string>(&s, 1));
 105
 106   return 0;
 107 }