ceph/src/seastar/fmt/test/custom-formatter-test.cc

   1 // Formatting library for C++ - custom argument formatter tests
   2 //
   3 // Copyright (c) 2012 - present, Victor Zverovich
   4 // All rights reserved.
   5 //
   6 // For the license information refer to format.h.
   7
   8 #include "fmt/format.h"
   9 #include "gtest-extra.h"
  10
  11 // MSVC 2013 is known to be broken.
  12 #if !FMT_MSC_VER || FMT_MSC_VER > 1800
  13
  14 // A custom argument formatter that doesn't print `-` for floating-point values
  15 // rounded to 0.
  16 class custom_arg_formatter :
  17     public fmt::arg_formatter<fmt::back_insert_range<fmt::internal::buffer>> {
  18  public:
  19   typedef fmt::back_insert_range<fmt::internal::buffer> range;
  20   typedef fmt::arg_formatter<range> base;
  21
  22   custom_arg_formatter(
  23       fmt::format_context &ctx, fmt::format_specs *s = FMT_NULL)
  24   : base(ctx, s) {}
  25
  26   using base::operator();
  27
  28   iterator operator()(double value) {
  29     // Comparing a float to 0.0 is safe.
  30     if (round(value * pow(10, spec()->precision)) == 0.0)
  31       value = 0;
  32     return base::operator()(value);
  33   }
  34 };
  35
  36 std::string custom_vformat(fmt::string_view format_str, fmt::format_args args) {
  37   fmt::memory_buffer buffer;
  38   // Pass custom argument formatter as a template arg to vwrite.
  39   fmt::vformat_to<custom_arg_formatter>(buffer, format_str, args);
  40   return std::string(buffer.data(), buffer.size());
  41 }
  42
  43 template <typename... Args>
  44 std::string custom_format(const char *format_str, const Args & ... args) {
  45   auto va = fmt::make_format_args(args...);
  46   return custom_vformat(format_str, va);
  47 }
  48
  49 TEST(CustomFormatterTest, Format) {
  50   EXPECT_EQ("0.00", custom_format("{:.2f}", -.00001));
  51 }
  52 #endif