libcxx/test/support/test_basic_format_arg.h

   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 #include <concepts>
  10 #include <format>
  11 #include <utility>
  12
  13 #include "test_macros.h"
  14
  15 /// Returns whether the basic_format_arg contains a type T with the expected value.
  16 template <class Context, class T>
  17 bool test_basic_format_arg(std::basic_format_arg<Context> arg, T expected) {
  18   auto visitor = [expected](auto a) {
  19     if constexpr (std::same_as<decltype(a), T>)
  20       return a == expected;
  21     else
  22       return false;
  23   };
  24 #if TEST_STD_VER >= 26 && defined(TEST_HAS_EXPLICIT_THIS_PARAMETER)
  25   return arg.visit(std::move(visitor));
  26 #else
  27   return std::visit_format_arg(std::move(visitor), arg);
  28 #endif
  29 }