libcxx/test/std/iterators/iterator.primitives/iterator.operations/advance.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 // <iterator>
  10
  11 //   All of these became constexpr in C++17
  12 //
  13 // template <InputIterator Iter, class Distance>
  14 //   constexpr void advance(Iter& i, Distance n);
  15 //
  16 // template <BidirectionalIterator Iter, class Distance>
  17 //   constexpr void advance(Iter& i, Distance n);
  18 //
  19 // template <RandomAccessIterator Iter, class Distance>
  20 //   constexpr void advance(Iter& i, Distance n);
  21
  22 // Make sure we catch forced conversions to the difference_type if they happen.
  23 // ADDITIONAL_COMPILER_FLAGS: -Wsign-conversion
  24
  25 #include <iterator>
  26 #include <cassert>
  27 #include <cstddef>
  28 #include <type_traits>
  29
  30 #include "test_macros.h"
  31 #include "test_iterators.h"
  32
  33 template <class Distance, class It>
  34 TEST_CONSTEXPR_CXX17
  35 void check_advance(It it, Distance n, It result)
  36 {
  37     static_assert(std::is_same<decltype(std::advance(it, n)), void>::value, "");
  38     std::advance(it, n);
  39     assert(it == result);
  40 }
  41
  42 TEST_CONSTEXPR_CXX17 bool tests()
  43 {
  44     const char* s = "1234567890";
  45     typedef std::iterator_traits<const char*>::difference_type Distance;
  46     check_advance<Distance>(input_iterator<const char*>(s), 10, input_iterator<const char*>(s+10));
  47     check_advance<Distance>(forward_iterator<const char*>(s), 10, forward_iterator<const char*>(s+10));
  48     check_advance<Distance>(bidirectional_iterator<const char*>(s+5), 5, bidirectional_iterator<const char*>(s+10));
  49     check_advance<Distance>(bidirectional_iterator<const char*>(s+5), -5, bidirectional_iterator<const char*>(s));
  50     check_advance<Distance>(random_access_iterator<const char*>(s+5), 5, random_access_iterator<const char*>(s+10));
  51     check_advance<Distance>(random_access_iterator<const char*>(s+5), -5, random_access_iterator<const char*>(s));
  52     check_advance<Distance>(s+5, 5, s+10);
  53     check_advance<Distance>(s+5, -5, s);
  54
  55     // Also check with other distance types
  56     check_advance<std::size_t>(input_iterator<const char*>(s), 10u, input_iterator<const char*>(s+10));
  57     check_advance<std::size_t>(forward_iterator<const char*>(s), 10u, forward_iterator<const char*>(s+10));
  58     check_advance<std::size_t>(bidirectional_iterator<const char*>(s), 10u, bidirectional_iterator<const char*>(s+10));
  59     check_advance<std::size_t>(random_access_iterator<const char*>(s), 10u, random_access_iterator<const char*>(s+10));
  60
  61     return true;
  62 }
  63
  64 int main(int, char**)
  65 {
  66     tests();
  67 #if TEST_STD_VER >= 17
  68     static_assert(tests(), "");
  69 #endif
  70     return 0;
  71 }