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
  23 // TODO: test_iterators.h includes <ranges>, and <ranges> includes <chrono> and <atomic>.
  24 // Lots of implementation headers under <__chrono/> and <atomic> has signed to unsigned conversion,
  25 // which will trigger the -Wsign-conversion warning.
  26 // Once those headers are fixed, enable the -Wsign-conversion for this test by removing
  27 // <TODO:Remove brackets> below
  28
  29 // Make sure we catch forced conversions to the difference_type if they happen.
  30 // ADDITIONAL_COMPILE_FLAGS<TODO:Remove brackets>(gcc-style-warnings): -Wsign-conversion
  31
  32 #include <iterator>
  33 #include <cassert>
  34 #include <cstddef>
  35 #include <type_traits>
  36
  37 #include "test_macros.h"
  38 #include "test_iterators.h"
  39
  40 template <class Distance, class It>
  41 TEST_CONSTEXPR_CXX17
  42 void check_advance(It it, Distance n, It result)
  43 {
  44     static_assert(std::is_same<decltype(std::advance(it, n)), void>::value, "");
  45     std::advance(it, n);
  46     assert(it == result);
  47 }
  48
  49 TEST_CONSTEXPR_CXX17 bool tests()
  50 {
  51     const char* s = "1234567890";
  52
  53     // Check with iterator_traits::difference_type
  54     {
  55         typedef std::iterator_traits<const char*>::difference_type Distance;
  56         check_advance<Distance>(cpp17_input_iterator<const char*>(s), 10, cpp17_input_iterator<const char*>(s+10));
  57         check_advance<Distance>(forward_iterator<const char*>(s), 10, forward_iterator<const char*>(s+10));
  58         check_advance<Distance>(bidirectional_iterator<const char*>(s+5), 5, bidirectional_iterator<const char*>(s+10));
  59         check_advance<Distance>(bidirectional_iterator<const char*>(s+5), -5, bidirectional_iterator<const char*>(s));
  60         check_advance<Distance>(random_access_iterator<const char*>(s+5), 5, random_access_iterator<const char*>(s+10));
  61         check_advance<Distance>(random_access_iterator<const char*>(s+5), -5, random_access_iterator<const char*>(s));
  62         check_advance<Distance>(s+5, 5, s+10);
  63         check_advance<Distance>(s+5, -5, s);
  64     }
  65
  66     // Also check with other distance types
  67     {
  68         typedef int Distance;
  69         check_advance<Distance>(cpp17_input_iterator<const char*>(s), 10, cpp17_input_iterator<const char*>(s+10));
  70         check_advance<Distance>(forward_iterator<const char*>(s), 10, forward_iterator<const char*>(s+10));
  71         check_advance<Distance>(bidirectional_iterator<const char*>(s), 10, bidirectional_iterator<const char*>(s+10));
  72         check_advance<Distance>(random_access_iterator<const char*>(s), 10, random_access_iterator<const char*>(s+10));
  73     }
  74
  75     // Check with unsigned distance types to catch signedness-change issues
  76     {
  77         typedef std::size_t Distance;
  78         check_advance<Distance>(cpp17_input_iterator<const char*>(s), 10u, cpp17_input_iterator<const char*>(s+10));
  79         check_advance<Distance>(forward_iterator<const char*>(s), 10u, forward_iterator<const char*>(s+10));
  80         check_advance<Distance>(bidirectional_iterator<const char*>(s), 10u, bidirectional_iterator<const char*>(s+10));
  81         check_advance<Distance>(random_access_iterator<const char*>(s), 10u, random_access_iterator<const char*>(s+10));
  82     }
  83
  84     return true;
  85 }
  86
  87 int main(int, char**)
  88 {
  89     tests();
  90 #if TEST_STD_VER >= 17
  91     static_assert(tests(), "");
  92 #endif
  93     return 0;
  94 }