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: GCC-ALWAYS_INLINE-FIXME
11
12// XFAIL: availability-fp_to_chars-missing
13
14// <format>
15
16// template<class Out, class... Args>
17// Out format_to(Out out, format-string<Args...> fmt, const Args&... args);
18// template<class Out, class... Args>
19// Out format_to(Out out, wformat-string<Args...> fmt, const Args&... args);
20
21#include <format>
22#include <algorithm>
23#include <cassert>
24#include <iterator>
25#include <list>
26#include <vector>
27
28#include "test_macros.h"
29#include "format_tests.h"
30#include "string_literal.h"
31#include "test_format_string.h"
32#include "test_iterators.h"
33
34auto test =
35 []<class CharT, class... Args>(
36 std::basic_string_view<CharT> expected, test_format_string<CharT, Args...> fmt, Args&&... args) constexpr {
37 {
38 std::basic_string<CharT> out(expected.size(), CharT(' '));
39 auto it = std::format_to(out.begin(), fmt, std::forward<Args>(args)...);
40 assert(it == out.end());
41 assert(out == expected);
42 }
43 {
44 std::list<CharT> out;
45 std::format_to(std::back_inserter(out), fmt, std::forward<Args>(args)...);
46 assert(std::equal(out.begin(), out.end(), expected.begin(), expected.end()));
47 }
48 {
49 std::vector<CharT> out;
50 std::format_to(std::back_inserter(out), fmt, std::forward<Args>(args)...);
51 assert(std::equal(out.begin(), out.end(), expected.begin(), expected.end()));
52 }
53 {
54 assert(expected.size() < 4096 && "Update the size of the buffer.");
55 CharT out[4096];
56 cpp20_output_iterator<CharT*> it = std::format_to(cpp20_output_iterator{out}, fmt, std::forward<Args>(args)...);
57 assert(std::distance(out, base(it)) == int(expected.size()));
58 // Convert to std::string since output contains '\0' for boolean tests.
59 assert(std::basic_string<CharT>(out, base(it)) == expected);
60 }
61 };
62
63auto test_exception = []<class CharT, class... Args>(std::string_view, std::basic_string_view<CharT>, Args&&...) {
64 // After P2216 most exceptions thrown by std::format become ill-formed.
65 // Therefore this tests does nothing.
66 // A basic ill-formed test is done in format.verify.cpp
67 // The exceptions are tested by other functions that don't use the basic-format-string as fmt argument.
68};
69
70int main(int, char**) {
71 format_tests<char, execution_modus::partial>(check: test, check_exception: test_exception);
72
73#ifndef TEST_HAS_NO_WIDE_CHARACTERS
74 format_tests_char_to_wchar_t(check: test);
75 format_tests<wchar_t, execution_modus::partial>(check: test, check_exception: test_exception);
76#endif
77
78 return 0;
79}
80

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