prev.pass.cpp (2316B)
1 //===----------------------------------------------------------------------===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is dual licensed under the MIT and the University of Illinois Open 6 // Source Licenses. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 10 // <iterator> 11 12 // template <BidirectionalIterator Iter> 13 // Iter prev(Iter x, Iter::difference_type n = 1); 14 15 #include <iterator> 16 #include <cassert> 17 18 #include "test_iterators.h" 19 20 template <class It> 21 void 22 test(It i, typename std::iterator_traits<It>::difference_type n, It x) 23 { 24 assert(std::prev(i, n) == x); 25 26 It (*prev)(It, typename std::iterator_traits<It>::difference_type) = std::prev; 27 assert(prev(i, n) == x); 28 } 29 30 template <class It> 31 void 32 test(It i, It x) 33 { 34 assert(std::prev(i) == x); 35 } 36 37 #if TEST_STD_VER > 14 38 template <class It> 39 constexpr bool 40 constexpr_test(It i, typename std::iterator_traits<It>::difference_type n, It x) 41 { 42 return std::prev(i, n) == x; 43 } 44 45 template <class It> 46 constexpr bool 47 constexpr_test(It i, It x) 48 { 49 return std::prev(i) == x; 50 } 51 #endif 52 53 int main() 54 { 55 { 56 const char* s = "1234567890"; 57 test(bidirectional_iterator<const char*>(s+10), 10, bidirectional_iterator<const char*>(s)); 58 test(random_access_iterator<const char*>(s+10), 10, random_access_iterator<const char*>(s)); 59 test(s+10, 10, s); 60 61 test(bidirectional_iterator<const char*>(s+1), bidirectional_iterator<const char*>(s)); 62 test(random_access_iterator<const char*>(s+1), random_access_iterator<const char*>(s)); 63 test(s+1, s); 64 } 65 #if TEST_STD_VER > 14 66 { 67 constexpr const char* s = "1234567890"; 68 static_assert( constexpr_test(bidirectional_iterator<const char*>(s+10), 10, bidirectional_iterator<const char*>(s)), "" ); 69 static_assert( constexpr_test(random_access_iterator<const char*>(s+10), 10, random_access_iterator<const char*>(s)), "" ); 70 static_assert( constexpr_test(s+10, 10, s), "" ); 71 72 static_assert( constexpr_test(bidirectional_iterator<const char*>(s+1), bidirectional_iterator<const char*>(s)), "" ); 73 static_assert( constexpr_test(random_access_iterator<const char*>(s+1), random_access_iterator<const char*>(s)), "" ); 74 static_assert( constexpr_test(s+1, s), "" ); 75 } 76 #endif 77 78 }