//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
// UNSUPPORTED: c++03, c++11, c++14, c++17
// UNSUPPORTED: no-localization
// UNSUPPORTED: GCC-ALWAYS_INLINE-FIXME
// XFAIL: availability-fp_to_chars-missing
// <format>
// template<class Out, class... Args>
// format_to_n_result<Out> format_to_n(Out out, iter_difference_t<Out> n,
// const locale& loc, format-string<Args...> fmt,
// const Args&... args);
// template<class Out, class... Args>
// format_to_n_result<Out> format_to_n(Out out, iter_difference_t<Out> n,
// const locale& loc, wformat-string<Args...> fmt,
// const Args&... args);
#include <format>
#include <algorithm>
#include <cassert>
#include <list>
#include <locale>
#include <vector>
#include "test_macros.h"
#include "format_tests.h"
#include "string_literal.h"
#include "test_format_string.h"
auto test =
[]<class CharT, class... Args>(
std::basic_string_view<CharT> expected, test_format_string<CharT, Args...> fmt, Args&&... args) constexpr {
{
std::list<CharT> out;
std::format_to_n_result result =
std::format_to_n(std::back_inserter(out), 0, std::locale(), fmt, std::forward<Args>(args)...);
// To avoid signedness warnings make sure formatted_size uses the same type
// as result.size.
using diff_type = decltype(result.size);
diff_type formatted_size = std::formatted_size(std::locale(), fmt, std::forward<Args>(args)...);
assert(result.size == formatted_size);
assert(out.empty());
}
{
std::vector<CharT> out;
std::format_to_n_result result =
std::format_to_n(std::back_inserter(out), 5, std::locale(), fmt, std::forward<Args>(args)...);
using diff_type = decltype(result.size);
diff_type formatted_size = std::formatted_size(std::locale(), fmt, std::forward<Args>(args)...);
diff_type size = std::min<diff_type>(5, formatted_size);
assert(result.size == formatted_size);
assert(std::equal(out.begin(), out.end(), expected.begin(), expected.begin() + size));
}
{
std::basic_string<CharT> out;
std::format_to_n_result result =
std::format_to_n(std::back_inserter(out), 1000, std::locale(), fmt, std::forward<Args>(args)...);
using diff_type = decltype(result.size);
diff_type formatted_size = std::formatted_size(std::locale(), fmt, std::forward<Args>(args)...);
diff_type size = std::min<diff_type>(1000, formatted_size);
assert(result.size == formatted_size);
assert(out == expected.substr(0, size));
}
{
// Test the returned iterator.
std::basic_string<CharT> out(10, CharT(' '));
std::format_to_n_result result =
std::format_to_n(out.begin(), 10, std::locale(), fmt, std::forward<Args>(args)...);
using diff_type = decltype(result.size);
diff_type formatted_size = std::formatted_size(std::locale(), fmt, std::forward<Args>(args)...);
diff_type size = std::min<diff_type>(10, formatted_size);
assert(result.size == formatted_size);
assert(result.out == out.begin() + size);
assert(out.substr(0, size) == expected.substr(0, size));
}
{
static_assert(std::is_signed_v<std::iter_difference_t<CharT*>>,
"If the difference type isn't negative the test will fail "
"due to using a large positive value.");
CharT buffer[1] = {CharT(0)};
std::format_to_n_result result = std::format_to_n(buffer, -1, std::locale(), fmt, std::forward<Args>(args)...);
using diff_type = decltype(result.size);
diff_type formatted_size = std::formatted_size(std::locale(), fmt, std::forward<Args>(args)...);
assert(result.size == formatted_size);
assert(result.out == buffer);
assert(buffer[0] == CharT(0));
}
};
auto test_exception = []<class CharT, class... Args>(std::string_view, std::basic_string_view<CharT>, Args&&...) {
// After P2216 most exceptions thrown by std::format_to_n become ill-formed.
// Therefore this tests does nothing.
// A basic ill-formed test is done in format_to_n.locale.verify.cpp
// The exceptions are tested by other functions that don't use the basic-format-string as fmt argument.
};
int main(int, char**) {
format_tests<char, execution_modus::partial>(test, test_exception);
#ifndef TEST_HAS_NO_WIDE_CHARACTERS
format_tests_char_to_wchar_t(test);
format_tests<wchar_t, execution_modus::partial>(test, test_exception);
#endif
return 0;
}