libcxx/test/std/utilities/format/format.functions/format_to.pass.cpp

   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
  33 auto 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
  62 auto 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
  69 int main(int, char**) {
  70   format_tests<char, execution_modus::partial>(test, test_exception);
  71
  72 #ifndef TEST_HAS_NO_WIDE_CHARACTERS
  73   format_tests_char_to_wchar_t(test);
  74   format_tests<wchar_t, execution_modus::partial>(test, test_exception);
  75 #endif
  76
  77   return 0;
  78 }