src/fmt-c.cc

// Formatting library for C++ - the C API
//
// Copyright (c) 2012 - present, Victor Zverovich and {fmt} contributors
// All rights reserved.
//
// For the license information refer to format.h.

#include "fmt/fmt-c.h"

#include <fmt/core.h>

constexpr size_t max_c_format_args = 16;

static int convert_c_format_args(
    fmt::basic_format_arg<fmt::format_context>* format_args,
    const fmt_arg* args, size_t num_args) {
  if (num_args > max_c_format_args) return fmt_error_invalid_arg;

  for (size_t i = 0; i < num_args; ++i) {
    switch (args[i].type) {
    case fmt_int:    format_args[i] = args[i].value.int_value; break;
    case fmt_uint:   format_args[i] = args[i].value.uint_value; break;
    case fmt_bool:   format_args[i] = args[i].value.bool_value; break;
    case fmt_char:   format_args[i] = args[i].value.char_value; break;
    case fmt_float:  format_args[i] = args[i].value.float_value; break;
    case fmt_double: format_args[i] = args[i].value.double_value; break;
    case fmt_long_double:
      format_args[i] = args[i].value.long_double_value;
      break;
    case fmt_cstring: format_args[i] = args[i].value.cstring; break;
    case fmt_pointer: format_args[i] = args[i].value.pointer; break;
    default:          return fmt_error_invalid_arg;
    }
  }
  return 0;
}

extern "C" int fmt_vformat(char* buffer, size_t size, const char* fmt,
                           const fmt_arg* args, size_t num_args) {
  fmt::basic_format_arg<fmt::format_context> format_args[max_c_format_args];
  int error = convert_c_format_args(format_args, args, num_args);
  if (error != 0) return error;

  FMT_TRY {
    auto result = fmt::vformat_to_n(
        buffer, size, fmt,
        fmt::format_args(format_args, static_cast<int>(num_args)));
    return static_cast<int>(result.size);
  }
  FMT_CATCH(...) {}
  return fmt_error;
}

extern "C" int fmt_vprint(FILE* stream, const char* fmt, const fmt_arg* args,
                          size_t num_args) {
  fmt::basic_format_arg<fmt::format_context> format_args[max_c_format_args];
  int error = convert_c_format_args(format_args, args, num_args);
  if (error != 0) return error;

  FMT_TRY {
    fmt::vprint(stream, fmt,
                fmt::format_args(format_args, static_cast<int>(num_args)));
    return 0;
  }
  FMT_CATCH(...) {}
  return fmt_error;
}