1//===----------------------------------------------------------------------===//
2// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
3// See https://llvm.org/LICENSE.txt for license information.
4// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
5//
6//===----------------------------------------------------------------------===//
7
8// UNSUPPORTED: c++03, c++11, c++14, c++17
9// UNSUPPORTED: GCC-ALWAYS_INLINE-FIXME
10
11// XFAIL: availability-fp_to_chars-missing
12
13// <format>
14
15// template<class Out, class... Args>
16// Out format_to(Out out, format-string<Args...> fmt, const Args&... args);
17// template<class Out, class... Args>
18// Out format_to(Out out, wformat-string<Args...> fmt, const Args&... args);
19
20#include <format>
21#include <algorithm>
22#include <cassert>
23#include <iterator>
24#include <list>
25#include <vector>
26
27#include "test_macros.h"
28#include "format_tests.h"
29#include "string_literal.h"
30#include "test_format_string.h"
31#include "test_iterators.h"
32
33auto test =
34 []<class CharT, class... Args>(
35 std::basic_string_view<CharT> expected, test_format_string<CharT, Args...> fmt, Args&&... args) constexpr {
36 {
37 std::basic_string<CharT> out(expected.size(), CharT(' '));
38 auto it = std::format_to(out.begin(), fmt, std::forward<Args>(args)...);
39 assert(it == out.end());
40 assert(out == expected);
41 }
42 {
43 std::list<CharT> out;
44 std::format_to(std::back_inserter(out), fmt, std::forward<Args>(args)...);
45 assert(std::equal(out.begin(), out.end(), expected.begin(), expected.end()));
46 }
47 {
48 std::vector<CharT> out;
49 std::format_to(std::back_inserter(out), fmt, std::forward<Args>(args)...);
50 assert(std::equal(out.begin(), out.end(), expected.begin(), expected.end()));
51 }
52 {
53 assert(expected.size() < 4096 && "Update the size of the buffer.");
54 CharT out[4096];
55 cpp20_output_iterator<CharT*> it = std::format_to(cpp20_output_iterator{out}, fmt, std::forward<Args>(args)...);
56 assert(std::distance(out, base(it)) == int(expected.size()));
57 // Convert to std::string since output contains '\0' for boolean tests.
58 assert(std::basic_string<CharT>(out, base(it)) == expected);
59 }
60 };
61
62auto test_exception = []<class CharT, class... Args>(std::string_view, std::basic_string_view<CharT>, Args&&...) {
63 // After P2216 most exceptions thrown by std::format become ill-formed.
64 // Therefore this tests does nothing.
65 // A basic ill-formed test is done in format.verify.cpp
66 // The exceptions are tested by other functions that don't use the basic-format-string as fmt argument.
67};
68
69int main(int, char**) {
70 format_tests<char, execution_modus::partial>(check: test, check_exception: test_exception);
71
72#ifndef TEST_HAS_NO_WIDE_CHARACTERS
73 format_tests_char_to_wchar_t(check: test);
74 format_tests<wchar_t, execution_modus::partial>(check: test, check_exception: test_exception);
75#endif
76
77 return 0;
78}
79

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