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

   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
  34 auto 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
  63 auto 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
  70 int main(int, char**) {
  71   format_tests<char, execution_modus::partial>(test, test_exception);
  72
  73 #ifndef TEST_HAS_NO_WIDE_CHARACTERS
  74   format_tests_char_to_wchar_t(test);
  75   format_tests<wchar_t, execution_modus::partial>(test, test_exception);
  76 #endif
  77
  78   return 0;
  79 }