libcxx/test/std/algorithms/alg.modifying.operations/alg.copy/copy_backward.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 // <algorithm>
  10
  11 // template<BidirectionalIterator InIter, BidirectionalIterator OutIter>
  12 //   requires OutputIterator<OutIter, InIter::reference>
  13 //   constexpr OutIter   // constexpr after C++17
  14 //   copy_backward(InIter first, InIter last, OutIter result);
  15
  16 #include <algorithm>
  17 #include <cassert>
  18
  19 #include "test_macros.h"
  20 #include "test_iterators.h"
  21 #include "user_defined_integral.h"
  22
  23 class PaddedBase {
  24 public:
  25   TEST_CONSTEXPR PaddedBase(std::int16_t a, std::int8_t b) : a_(a), b_(b) {}
  26
  27   std::int16_t a_;
  28   std::int8_t b_;
  29 };
  30
  31 class Derived : public PaddedBase {
  32 public:
  33   TEST_CONSTEXPR Derived(std::int16_t a, std::int8_t b, std::int8_t c) : PaddedBase(a, b), c_(c) {}
  34
  35   std::int8_t c_;
  36 };
  37
  38 template <class InIter, class OutIter>
  39 TEST_CONSTEXPR_CXX20 void
  40 test_copy_backward()
  41 {
  42   {
  43     const unsigned N = 1000;
  44     int ia[N] = {};
  45     for (unsigned i = 0; i < N; ++i)
  46         ia[i] = i;
  47     int ib[N] = {0};
  48
  49     OutIter r = std::copy_backward(InIter(ia), InIter(ia+N), OutIter(ib+N));
  50     assert(base(r) == ib);
  51     for (unsigned i = 0; i < N; ++i)
  52         assert(ia[i] == ib[i]);
  53   }
  54 }
  55
  56 TEST_CONSTEXPR_CXX20 bool
  57 test()
  58 {
  59     test_copy_backward<bidirectional_iterator<const int*>, bidirectional_iterator<int*> >();
  60     test_copy_backward<bidirectional_iterator<const int*>, random_access_iterator<int*> >();
  61     test_copy_backward<bidirectional_iterator<const int*>, int*>();
  62
  63     test_copy_backward<random_access_iterator<const int*>, bidirectional_iterator<int*> >();
  64     test_copy_backward<random_access_iterator<const int*>, random_access_iterator<int*> >();
  65     test_copy_backward<random_access_iterator<const int*>, int*>();
  66
  67     test_copy_backward<const int*, bidirectional_iterator<int*> >();
  68     test_copy_backward<const int*, random_access_iterator<int*> >();
  69     test_copy_backward<const int*, int*>();
  70
  71 #if TEST_STD_VER > 17
  72     test_copy_backward<contiguous_iterator<const int*>, bidirectional_iterator<int*>>();
  73     test_copy_backward<contiguous_iterator<const int*>, random_access_iterator<int*>>();
  74     test_copy_backward<contiguous_iterator<const int*>, int*>();
  75
  76     test_copy_backward<bidirectional_iterator<const int*>, contiguous_iterator<int*>>();
  77     test_copy_backward<random_access_iterator<const int*>, contiguous_iterator<int*>>();
  78     test_copy_backward<contiguous_iterator<const int*>, contiguous_iterator<int*>>();
  79     test_copy_backward<const int*, contiguous_iterator<int*>>();
  80 #endif
  81
  82   { // Make sure that padding bits aren't copied
  83     Derived src(1, 2, 3);
  84     Derived dst(4, 5, 6);
  85     std::copy_backward(
  86         static_cast<PaddedBase*>(&src), static_cast<PaddedBase*>(&src) + 1, static_cast<PaddedBase*>(&dst) + 1);
  87     assert(dst.a_ == 1);
  88     assert(dst.b_ == 2);
  89     assert(dst.c_ == 6);
  90   }
  91
  92   { // Make sure that overlapping ranges can be copied
  93     int a[] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
  94     std::copy_backward(a, a + 7, a + 10);
  95     int expected[] = {1, 2, 3, 1, 2, 3, 4, 5, 6, 7};
  96     assert(std::equal(a, a + 10, expected));
  97   }
  98
  99     return true;
 100 }
 101
 102 int main(int, char**)
 103 {
 104     test();
 105
 106 #if TEST_STD_VER > 17
 107     static_assert(test());
 108 #endif
 109
 110   return 0;
 111 }