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
38auto 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
103auto 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
110int main(int, char**) {
111 format_tests<char, execution_modus::partial>(check: test, check_exception: test_exception);
112
113#ifndef TEST_HAS_NO_WIDE_CHARACTERS
114 format_tests_char_to_wchar_t(check: test);
115 format_tests<wchar_t, execution_modus::partial>(check: test, check_exception: test_exception);
116#endif
117
118 return 0;
119}
120

source code of libcxx/test/std/utilities/format/format.functions/format_to_n.locale.pass.cpp