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 // UNSUPPORTED: c++03, c++11, c++14, c++17 10 // UNSUPPORTED: no-localization 11 // UNSUPPORTED: GCC-ALWAYS_INLINE-FIXME 12 13 // XFAIL: availability-fp_to_chars-missing 14 15 // <format> 16 17 // template<class Out, class... Args> 18 // format_to_n_result<Out> format_to_n(Out out, iter_difference_t<Out> n, 19 // const locale& loc, format-string<Args...> fmt, 20 // const Args&... args); 21 // template<class Out, class... Args> 22 // format_to_n_result<Out> format_to_n(Out out, iter_difference_t<Out> n, 23 // const locale& loc, wformat-string<Args...> fmt, 24 // const Args&... args); 25 26 #include <format> 27 #include <algorithm> 28 #include <cassert> 29 #include <list> 30 #include <locale> 31 #include <vector> 32 33 #include "test_macros.h" 34 #include "format_tests.h" 35 #include "string_literal.h" 36 #include "test_format_string.h" 37 38 auto test = 39 []<class CharT, class... Args>( 40 std::basic_string_view<CharT> expected, test_format_string<CharT, Args...> fmt, Args&&... args) constexpr { 41 { 42 std::list<CharT> out; 43 std::format_to_n_result result = 44 std::format_to_n(std::back_inserter(out), 0, std::locale(), fmt, std::forward<Args>(args)...); 45 // To avoid signedness warnings make sure formatted_size uses the same type 46 // as result.size. 47 using diff_type = decltype(result.size); 48 diff_type formatted_size = std::formatted_size(std::locale(), fmt, std::forward<Args>(args)...); 49 50 assert(result.size == formatted_size); 51 assert(out.empty()); 52 } 53 { 54 std::vector<CharT> out; 55 std::format_to_n_result result = 56 std::format_to_n(std::back_inserter(out), 5, std::locale(), fmt, std::forward<Args>(args)...); 57 using diff_type = decltype(result.size); 58 diff_type formatted_size = std::formatted_size(std::locale(), fmt, std::forward<Args>(args)...); 59 diff_type size = std::min<diff_type>(5, formatted_size); 60 61 assert(result.size == formatted_size); 62 assert(std::equal(out.begin(), out.end(), expected.begin(), expected.begin() + size)); 63 } 64 { 65 std::basic_string<CharT> out; 66 std::format_to_n_result result = 67 std::format_to_n(std::back_inserter(out), 1000, std::locale(), fmt, std::forward<Args>(args)...); 68 using diff_type = decltype(result.size); 69 diff_type formatted_size = std::formatted_size(std::locale(), fmt, std::forward<Args>(args)...); 70 diff_type size = std::min<diff_type>(1000, formatted_size); 71 72 assert(result.size == formatted_size); 73 assert(out == expected.substr(0, size)); 74 } 75 { 76 // Test the returned iterator. 77 std::basic_string<CharT> out(10, CharT(' ')); 78 std::format_to_n_result result = 79 std::format_to_n(out.begin(), 10, std::locale(), fmt, std::forward<Args>(args)...); 80 using diff_type = decltype(result.size); 81 diff_type formatted_size = std::formatted_size(std::locale(), fmt, std::forward<Args>(args)...); 82 diff_type size = std::min<diff_type>(10, formatted_size); 83 84 assert(result.size == formatted_size); 85 assert(result.out == out.begin() + size); 86 assert(out.substr(0, size) == expected.substr(0, size)); 87 } 88 { 89 static_assert(std::is_signed_v<std::iter_difference_t<CharT*>>, 90 "If the difference type isn't negative the test will fail " 91 "due to using a large positive value."); 92 CharT buffer[1] = {CharT(0)}; 93 std::format_to_n_result result = std::format_to_n(buffer, -1, std::locale(), fmt, std::forward<Args>(args)...); 94 using diff_type = decltype(result.size); 95 diff_type formatted_size = std::formatted_size(std::locale(), fmt, std::forward<Args>(args)...); 96 97 assert(result.size == formatted_size); 98 assert(result.out == buffer); 99 assert(buffer[0] == CharT(0)); 100 } 101 }; 102 103 auto test_exception = []<class CharT, class... Args>(std::string_view, std::basic_string_view<CharT>, Args&&...) { 104 // After P2216 most exceptions thrown by std::format_to_n become ill-formed. 105 // Therefore this tests does nothing. 106 // A basic ill-formed test is done in format_to_n.locale.verify.cpp 107 // The exceptions are tested by other functions that don't use the basic-format-string as fmt argument. 108 }; 109 110 int main(int, char**) { 111 format_tests<char, execution_modus::partial>(test, test_exception); 112 113 #ifndef TEST_HAS_NO_WIDE_CHARACTERS 114 format_tests_char_to_wchar_t(test); 115 format_tests<wchar_t, execution_modus::partial>(test, test_exception); 116 #endif 117 118 return 0; 119 } 120