fmt/format.cc

/*
 String formatting library for C++

 Copyright (c) 2012, Victor Zverovich
 All rights reserved.

 Redistribution and use in source and binary forms, with or without
 modification, are permitted provided that the following conditions are met:

 1. Redistributions of source code must retain the above copyright notice, this
    list of conditions and the following disclaimer.
 2. Redistributions in binary form must reproduce the above copyright notice,
    this list of conditions and the following disclaimer in the documentation
    and/or other materials provided with the distribution.

 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
 ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

// Disable useless MSVC warnings.
#undef _CRT_SECURE_NO_WARNINGS
#define _CRT_SECURE_NO_WARNINGS
#undef _SCL_SECURE_NO_WARNINGS
#define _SCL_SECURE_NO_WARNINGS

#include "format.h"

#include <string.h>

#include <cctype>
#include <climits>
#include <cmath>
#include <cstdarg>

#ifdef _WIN32
# include <windows.h>
# undef ERROR
#endif

using fmt::ULongLong;

#if _MSC_VER
# pragma warning(push)
# pragma warning(disable: 4127) // conditional expression is constant
#endif

namespace {

#ifndef _MSC_VER

inline int SignBit(double value) {
  // When compiled in C++11 mode signbit is no longer a macro but a function
  // defined in namespace std and the macro is undefined.
#ifdef signbit
  return signbit(value);
#else
  return std::signbit(value);
#endif
}

inline int IsInf(double x) {
#ifdef isinf
  return isinf(x);
#else
  return std::isinf(x);
#endif
}

#define FMT_SNPRINTF snprintf

#else  // _MSC_VER

inline int SignBit(double value) {
  if (value < 0) return 1;
  if (value == value) return 0;
  int dec = 0, sign = 0;
  char buffer[2];  // The buffer size must be >= 2 or _ecvt_s will fail.
  _ecvt_s(buffer, sizeof(buffer), value, 0, &dec, &sign);
  return sign;
}

inline int IsInf(double x) { return !_finite(x); }

inline int FMT_SNPRINTF(char *buffer, size_t size, const char *format, ...) {
  va_list args;
  va_start(args, format);
  int result = vsnprintf_s(buffer, size, _TRUNCATE, format, args);
  va_end(args);
  return result;
}

#endif  // _MSC_VER

const char RESET_COLOR[] = "\x1b[0m";
}

template <typename T>
int fmt::internal::CharTraits<char>::FormatFloat(
    char *buffer, std::size_t size, const char *format,
    unsigned width, int precision, T value) {
  if (width == 0) {
    return precision < 0 ?
        FMT_SNPRINTF(buffer, size, format, value) :
        FMT_SNPRINTF(buffer, size, format, precision, value);
  }
  return precision < 0 ?
      FMT_SNPRINTF(buffer, size, format, width, value) :
      FMT_SNPRINTF(buffer, size, format, width, precision, value);
}

template <typename T>
int fmt::internal::CharTraits<wchar_t>::FormatFloat(
    wchar_t *buffer, std::size_t size, const wchar_t *format,
    unsigned width, int precision, T value) {
  if (width == 0) {
    return precision < 0 ?
        swprintf(buffer, size, format, value) :
        swprintf(buffer, size, format, precision, value);
  }
  return precision < 0 ?
      swprintf(buffer, size, format, width, value) :
      swprintf(buffer, size, format, width, precision, value);
}

const char fmt::internal::DIGITS[] =
    "0001020304050607080910111213141516171819"
    "2021222324252627282930313233343536373839"
    "4041424344454647484950515253545556575859"
    "6061626364656667686970717273747576777879"
    "8081828384858687888990919293949596979899";

#define FMT_POWERS_OF_10(factor) \
  factor * 10, \
  factor * 100, \
  factor * 1000, \
  factor * 10000, \
  factor * 100000, \
  factor * 1000000, \
  factor * 10000000, \
  factor * 100000000, \
  factor * 1000000000

const uint32_t fmt::internal::POWERS_OF_10_32[] = {0, FMT_POWERS_OF_10(1)};
const uint64_t fmt::internal::POWERS_OF_10_64[] = {
  0,
  FMT_POWERS_OF_10(1),
  FMT_POWERS_OF_10(ULongLong(1000000000)),
  // Multiply several constants instead of using a single long long constants
  // to avoid warnings about C++98 not supporting long long.
  ULongLong(1000000000) * ULongLong(1000000000) * 10
};

void fmt::internal::ReportUnknownType(char code, const char *type) {
  if (std::isprint(static_cast<unsigned char>(code))) {
    throw fmt::FormatError(fmt::str(
        fmt::Format("unknown format code '{}' for {}") << code << type));
  }
  throw fmt::FormatError(
      fmt::str(fmt::Format("unknown format code '\\x{:02x}' for {}")
        << static_cast<unsigned>(code) << type));
}

#ifdef _WIN32

fmt::internal::UTF8ToUTF16::UTF8ToUTF16(fmt::StringRef s) {
  int length = MultiByteToWideChar(
      CP_UTF8, MB_ERR_INVALID_CHARS, s.c_str(), -1, 0, 0);
  static const char ERROR[] = "cannot convert string from UTF-8 to UTF-16";
  if (length == 0)
    ThrowSystemError(GetLastError(), ERROR);
  buffer_.resize(length);
  length = MultiByteToWideChar(
    CP_UTF8, MB_ERR_INVALID_CHARS, s.c_str(), -1, &buffer_[0], length);
  if (length == 0)
    ThrowSystemError(GetLastError(), ERROR);
}

fmt::internal::UTF16ToUTF8::UTF16ToUTF8(fmt::WStringRef s) {
  if (int error_code = Convert(s)) {
    ThrowSystemError(GetLastError(),
        "cannot convert string from UTF-16 to UTF-8");
  }
}

int fmt::internal::UTF16ToUTF8::Convert(fmt::WStringRef s) {
  int length = WideCharToMultiByte(CP_UTF8, 0, s.c_str(), -1, 0, 0, 0, 0);
  if (length == 0)
    return GetLastError();
  buffer_.resize(length);
  length = WideCharToMultiByte(
    CP_UTF8, 0, s.c_str(), -1, &buffer_[0], length, 0, 0);
  if (length == 0)
    return GetLastError();
  return 0;
}

#endif

void fmt::internal::FormatSystemErrorMessage(
    fmt::Writer &out, int error_code, fmt::StringRef message) {
#ifndef _WIN32
  Array<char, INLINE_BUFFER_SIZE> buffer;
  buffer.resize(INLINE_BUFFER_SIZE);
  char *system_message = 0;
  for (;;) {
    errno = 0;
# ifdef _GNU_SOURCE
    system_message = strerror_r(error_code, &buffer[0], buffer.size());
# else
    strerror_r(error_code, system_message = &buffer[0], buffer.size());
# endif
    if (errno == 0)
      break;
    if (errno != ERANGE) {
      // Can't get error message, report error code instead.
      out << message << ": error code = " << error_code;
      return;
    }
    buffer.resize(buffer.size() * 2);
  }
  out << message << ": " << system_message;
#else
  class String {
   private:
    LPWSTR str_;

   public:
    String() : str_() {}
    ~String() { LocalFree(str_); }
    LPWSTR *ptr() { return &str_; }
    LPCWSTR c_str() const { return str_; }
  };
  String system_message;
  if (FormatMessageW(FORMAT_MESSAGE_ALLOCATE_BUFFER |
      FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS, 0,
      error_code, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
      reinterpret_cast<LPWSTR>(system_message.ptr()), 0, 0)) {
    UTF16ToUTF8 utf8_message;
    if (!utf8_message.Convert(system_message.c_str())) {
      out << message << ": " << c_str(utf8_message);
      return;
    }
  }
  // Can't get error message, report error code instead.
  out << message << ": error code = " << error_code;
#endif
}

// Fills the padding around the content and returns the pointer to the
// content area.
template <typename Char>
typename fmt::BasicWriter<Char>::CharPtr
  fmt::BasicWriter<Char>::FillPadding(CharPtr buffer,
    unsigned total_size, std::size_t content_size, wchar_t fill) {
  std::size_t padding = total_size - content_size;
  std::size_t left_padding = padding / 2;
  Char fill_char = static_cast<Char>(fill);
  std::fill_n(buffer, left_padding, fill_char);
  buffer += left_padding;
  CharPtr content = buffer;
  std::fill_n(buffer + content_size, padding - left_padding, fill_char);
  return content;
}

template <typename Char>
typename fmt::BasicWriter<Char>::CharPtr
  fmt::BasicWriter<Char>::PrepareFilledBuffer(
    unsigned size, const AlignSpec &spec, char sign) {
  unsigned width = spec.width();
  if (width <= size) {
    CharPtr p = GrowBuffer(size);
    *p = sign;
    return p + size - 1;
  }
  CharPtr p = GrowBuffer(width);
  CharPtr end = p + width;
  Alignment align = spec.align();
  // TODO: error if fill is not convertible to Char
  Char fill = static_cast<Char>(spec.fill());
  if (align == ALIGN_LEFT) {
    *p = sign;
    p += size;
    std::fill(p, end, fill);
  } else if (align == ALIGN_CENTER) {
    p = FillPadding(p, width, size, fill);
    *p = sign;
    p += size;
  } else {
    if (align == ALIGN_NUMERIC) {
      if (sign) {
        *p++ = sign;
        --size;
      }
    } else {
      *(end - size) = sign;
    }
    std::fill(p, end - size, fill);
    p = end;
  }
  return p - 1;
}

template <typename Char>
template <typename T>
void fmt::BasicWriter<Char>::FormatDouble(
    T value, const FormatSpec &spec, int precision) {
  // Check type.
  char type = spec.type();
  bool upper = false;
  switch (type) {
  case 0:
    type = 'g';
    break;
  case 'e': case 'f': case 'g':
    break;
  case 'F':
#ifdef _MSC_VER
    // MSVC's printf doesn't support 'F'.
    type = 'f';
#endif
    // Fall through.
  case 'E': case 'G':
    upper = true;
    break;
  default:
    internal::ReportUnknownType(type, "double");
    break;
  }

  char sign = 0;
  // Use SignBit instead of value < 0 because the latter is always
  // false for NaN.
  if (SignBit(static_cast<double>(value))) {
    sign = '-';
    value = -value;
  } else if (spec.sign_flag()) {
    sign = spec.plus_flag() ? '+' : ' ';
  }

  if (value != value) {
    // Format NaN ourselves because sprintf's output is not consistent
    // across platforms.
    std::size_t size = 4;
    const char *nan = upper ? " NAN" : " nan";
    if (!sign) {
      --size;
      ++nan;
    }
    CharPtr out = FormatString(nan, size, spec);
    if (sign)
      *out = sign;
    return;
  }

  if (IsInf(static_cast<double>(value))) {
    // Format infinity ourselves because sprintf's output is not consistent
    // across platforms.
    std::size_t size = 4;
    const char *inf = upper ? " INF" : " inf";
    if (!sign) {
      --size;
      ++inf;
    }
    CharPtr out = FormatString(inf, size, spec);
    if (sign)
      *out = sign;
    return;
  }

  std::size_t offset = buffer_.size();
  unsigned width = spec.width();
  if (sign) {
    buffer_.reserve(buffer_.size() + (std::max)(width, 1u));
    if (width > 0)
      --width;
    ++offset;
  }

  // Build format string.
  enum { MAX_FORMAT_SIZE = 10}; // longest format: %#-*.*Lg
  Char format[MAX_FORMAT_SIZE];
  Char *format_ptr = format;
  *format_ptr++ = '%';
  unsigned width_for_sprintf = width;
  if (spec.hash_flag())
    *format_ptr++ = '#';
  if (spec.align() == ALIGN_CENTER) {
    width_for_sprintf = 0;
  } else {
    if (spec.align() == ALIGN_LEFT)
      *format_ptr++ = '-';
    if (width != 0)
      *format_ptr++ = '*';
  }
  if (precision >= 0) {
    *format_ptr++ = '.';
    *format_ptr++ = '*';
  }
  if (internal::IsLongDouble<T>::VALUE)
    *format_ptr++ = 'L';
  *format_ptr++ = type;
  *format_ptr = '\0';

  // Format using snprintf.
  Char fill = static_cast<Char>(spec.fill());
  for (;;) {
    std::size_t size = buffer_.capacity() - offset;
#if _MSC_VER
    // MSVC's vsnprintf_s doesn't work with zero size, so reserve
    // space for at least one extra character to make the size non-zero.
    // Note that the buffer's capacity will increase by more than 1.
    if (size == 0) {
      buffer_.reserve(offset + 1);
      size = buffer_.capacity() - offset;
    }
#endif
    Char *start = &buffer_[offset];
    int n = internal::CharTraits<Char>::FormatFloat(
        start, size, format, width_for_sprintf, precision, value);
    if (n >= 0 && offset + n < buffer_.capacity()) {
      if (sign) {
        if ((spec.align() != ALIGN_RIGHT && spec.align() != ALIGN_DEFAULT) ||
            *start != ' ') {
          *(start - 1) = sign;
          sign = 0;
        } else {
          *(start - 1) = fill;
        }
        ++n;
      }
      if (spec.align() == ALIGN_CENTER &&
          spec.width() > static_cast<unsigned>(n)) {
        unsigned width = spec.width();
        CharPtr p = GrowBuffer(width);
        std::copy(p, p + n, p + (width - n) / 2);
        FillPadding(p, spec.width(), n, fill);
        return;
      }
      if (spec.fill() != ' ' || sign) {
        while (*start == ' ')
          *start++ = fill;
        if (sign)
          *(start - 1) = sign;
      }
      GrowBuffer(n);
      return;
    }
    // If n is negative we ask to increase the capacity by at least 1,
    // but as std::vector, the buffer grows exponentially.
    buffer_.reserve(n >= 0 ? offset + n + 1 : buffer_.capacity() + 1);
  }
}

// Throws Exception(message) if format contains '}', otherwise throws
// FormatError reporting unmatched '{'. The idea is that unmatched '{'
// should override other errors.
template <typename Char>
void fmt::BasicWriter<Char>::FormatParser::ReportError(
    const Char *s, StringRef message) const {
  for (int num_open_braces = num_open_braces_; *s; ++s) {
    if (*s == '{') {
      ++num_open_braces;
    } else if (*s == '}') {
      if (--num_open_braces == 0)
        throw fmt::FormatError(message);
    }
  }
  throw fmt::FormatError("unmatched '{' in format");
}

// Parses an unsigned integer advancing s to the end of the parsed input.
// This function assumes that the first character of s is a digit.
template <typename Char>
unsigned fmt::BasicWriter<Char>::FormatParser::ParseUInt(const Char *&s) const {
  assert('0' <= *s && *s <= '9');
  unsigned value = 0;
  do {
    unsigned new_value = value * 10 + (*s++ - '0');
    if (new_value < value)  // Check if value wrapped around.
      ReportError(s, "number is too big in format");
    value = new_value;
  } while ('0' <= *s && *s <= '9');
  return value;
}

template <typename Char>
inline const typename fmt::BasicWriter<Char>::ArgInfo
    &fmt::BasicWriter<Char>::FormatParser::ParseArgIndex(const Char *&s) {
  unsigned arg_index = 0;
  if (*s < '0' || *s > '9') {
    if (*s != '}' && *s != ':')
      ReportError(s, "invalid argument index in format string");
    if (next_arg_index_ < 0) {
      ReportError(s,
          "cannot switch from manual to automatic argument indexing");
    }
    arg_index = next_arg_index_++;
  } else {
    if (next_arg_index_ > 0) {
      ReportError(s,
          "cannot switch from automatic to manual argument indexing");
    }
    next_arg_index_ = -1;
    arg_index = ParseUInt(s);
  }
  if (arg_index >= num_args_)
    ReportError(s, "argument index is out of range in format");
  return args_[arg_index];
}

template <typename Char>
void fmt::BasicWriter<Char>::FormatParser::CheckSign(
    const Char *&s, const ArgInfo &arg) {
  char sign = static_cast<char>(*s);
  if (arg.type > LAST_NUMERIC_TYPE) {
    ReportError(s,
        fmt::Format("format specifier '{}' requires numeric argument") << sign);
  }
  if (arg.type == UINT || arg.type == ULONG || arg.type == ULONG_LONG) {
    ReportError(s,
        fmt::Format("format specifier '{}' requires signed argument") << sign);
  }
  ++s;
}

template <typename Char>
void fmt::BasicWriter<Char>::FormatParser::Format(
    BasicWriter<Char> &writer, BasicStringRef<Char> format,
    std::size_t num_args, const ArgInfo *args) {
  const Char *start = format.c_str();
  num_args_ = num_args;
  args_ = args;
  next_arg_index_ = 0;
  const Char *s = start;
  while (*s) {
    Char c = *s++;
    if (c != '{' && c != '}') continue;
    if (*s == c) {
      writer.buffer_.append(start, s);
      start = ++s;
      continue;
    }
    if (c == '}')
      throw FormatError("unmatched '}' in format");
    num_open_braces_= 1;
    writer.buffer_.append(start, s - 1);

    const ArgInfo &arg = ParseArgIndex(s);

    FormatSpec spec;
    int precision = -1;
    if (*s == ':') {
      ++s;

      // Parse fill and alignment.
      if (Char c = *s) {
        const Char *p = s + 1;
        spec.align_ = ALIGN_DEFAULT;
        do {
          switch (*p) {
          case '<':
            spec.align_ = ALIGN_LEFT;
            break;
          case '>':
            spec.align_ = ALIGN_RIGHT;
            break;
          case '=':
            spec.align_ = ALIGN_NUMERIC;
            break;
          case '^':
            spec.align_ = ALIGN_CENTER;
            break;
          }
          if (spec.align_ != ALIGN_DEFAULT) {
            if (p != s) {
              if (c == '}') break;
              if (c == '{')
                ReportError(s, "invalid fill character '{'");
              s += 2;
              spec.fill_ = c;
            } else ++s;
            if (spec.align_ == ALIGN_NUMERIC && arg.type > LAST_NUMERIC_TYPE)
              ReportError(s, "format specifier '=' requires numeric argument");
            break;
          }
        } while (--p >= s);
      }

      // Parse sign.
      switch (*s) {
      case '+':
        CheckSign(s, arg);
        spec.flags_ |= SIGN_FLAG | PLUS_FLAG;
        break;
      case '-':
        CheckSign(s, arg);
        break;
      case ' ':
        CheckSign(s, arg);
        spec.flags_ |= SIGN_FLAG;
        break;
      }

      if (*s == '#') {
        if (arg.type > LAST_NUMERIC_TYPE)
          ReportError(s, "format specifier '#' requires numeric argument");
        spec.flags_ |= HASH_FLAG;
        ++s;
      }

      // Parse width and zero flag.
      if ('0' <= *s && *s <= '9') {
        if (*s == '0') {
          if (arg.type > LAST_NUMERIC_TYPE)
            ReportError(s, "format specifier '0' requires numeric argument");
          spec.align_ = ALIGN_NUMERIC;
          spec.fill_ = '0';
        }
        // Zero may be parsed again as a part of the width, but it is simpler
        // and more efficient than checking if the next char is a digit.
        unsigned value = ParseUInt(s);
        if (value > INT_MAX)
          ReportError(s, "number is too big in format");
        spec.width_ = value;
      }

      // Parse precision.
      if (*s == '.') {
        ++s;
        precision = 0;
        if ('0' <= *s && *s <= '9') {
          unsigned value = ParseUInt(s);
          if (value > INT_MAX)
            ReportError(s, "number is too big in format");
          precision = value;
        } else if (*s == '{') {
          ++s;
          ++num_open_braces_;
          const ArgInfo &precision_arg = ParseArgIndex(s);
          ULongLong value = 0;
          switch (precision_arg.type) {
          case INT:
            if (precision_arg.int_value < 0)
              ReportError(s, "negative precision in format");
            value = precision_arg.int_value;
            break;
          case UINT:
            value = precision_arg.uint_value;
            break;
          case LONG:
            if (precision_arg.long_value < 0)
              ReportError(s, "negative precision in format");
            value = precision_arg.long_value;
            break;
          case ULONG:
            value = precision_arg.ulong_value;
            break;
          case LONG_LONG:
            if (precision_arg.long_long_value < 0)
              ReportError(s, "negative precision in format");
            value = precision_arg.long_long_value;
            break;
          case ULONG_LONG:
            value = precision_arg.ulong_long_value;
            break;
          default:
            ReportError(s, "precision is not integer");
          }
          if (value > INT_MAX)
            ReportError(s, "number is too big in format");
          precision = static_cast<int>(value);
          if (*s++ != '}')
            throw FormatError("unmatched '{' in format");
          --num_open_braces_;
        } else {
          ReportError(s, "missing precision in format");
        }
        if (arg.type != DOUBLE && arg.type != LONG_DOUBLE) {
          ReportError(s,
              "precision specifier requires floating-point argument");
        }
      }

      // Parse type.
      if (*s != '}' && *s)
        spec.type_ = static_cast<char>(*s++);
    }

    if (*s++ != '}')
      throw FormatError("unmatched '{' in format");
    start = s;

    // Format argument.
    switch (arg.type) {
    case INT:
      writer.FormatInt(arg.int_value, spec);
      break;
    case UINT:
      writer.FormatInt(arg.uint_value, spec);
      break;
    case LONG:
      writer.FormatInt(arg.long_value, spec);
      break;
    case ULONG:
      writer.FormatInt(arg.ulong_value, spec);
      break;
    case LONG_LONG:
      writer.FormatInt(arg.long_long_value, spec);
      break;
    case ULONG_LONG:
      writer.FormatInt(arg.ulong_long_value, spec);
      break;
    case DOUBLE:
      writer.FormatDouble(arg.double_value, spec, precision);
      break;
    case LONG_DOUBLE:
      writer.FormatDouble(arg.long_double_value, spec, precision);
      break;
    case CHAR: {
      if (spec.type_ && spec.type_ != 'c')
        internal::ReportUnknownType(spec.type_, "char");
      typedef typename BasicWriter<Char>::CharPtr CharPtr;
      CharPtr out = CharPtr();
      if (spec.width_ > 1) {
        Char fill = static_cast<Char>(spec.fill());
        out = writer.GrowBuffer(spec.width_);
        if (spec.align_ == ALIGN_RIGHT) {
          std::fill_n(out, spec.width_ - 1, fill);
          out += spec.width_ - 1;
        } else if (spec.align_ == ALIGN_CENTER) {
          out = writer.FillPadding(out, spec.width_, 1, fill);
        } else {
          std::fill_n(out + 1, spec.width_ - 1, fill);
        }
      } else {
        out = writer.GrowBuffer(1);
      }
      *out = static_cast<Char>(arg.int_value);
      break;
    }
    case STRING: {
      if (spec.type_ && spec.type_ != 's')
        internal::ReportUnknownType(spec.type_, "string");
      const Char *str = arg.string.value;
      std::size_t size = arg.string.size;
      if (size == 0) {
        if (!str)
          throw FormatError("string pointer is null");
        if (*str)
          size = std::char_traits<Char>::length(str);
      }
      writer.FormatString(str, size, spec);
      break;
    }
    case POINTER:
      if (spec.type_ && spec.type_ != 'p')
        internal::ReportUnknownType(spec.type_, "pointer");
      spec.flags_= HASH_FLAG;
      spec.type_ = 'x';
      writer.FormatInt(reinterpret_cast<uintptr_t>(arg.pointer_value), spec);
      break;
    case CUSTOM:
      if (spec.type_)
        internal::ReportUnknownType(spec.type_, "object");
      arg.custom.format(writer, arg.custom.value, spec);
      break;
    default:
      assert(false);
      break;
    }
  }
  writer.buffer_.append(start, s);
}

void fmt::SystemErrorSink::operator()(const fmt::Writer &w) const {
  Writer message;
  internal::FormatSystemErrorMessage(message, error_code_, w.c_str());
  throw SystemError(message.c_str(), error_code_);
}

void fmt::ANSITerminalSink::operator()(
    const fmt::BasicWriter<char> &w) const {
  char escape[] = "\x1b[30m";
  escape[3] = '0' + static_cast<char>(color_);
  std::fputs(escape, file_);
  std::fwrite(w.data(), 1, w.size(), file_);
  std::fputs(RESET_COLOR, file_);
}

// Explicit instantiations for char.

template void fmt::BasicWriter<char>::FormatDouble<double>(
    double value, const FormatSpec &spec, int precision);

template void fmt::BasicWriter<char>::FormatDouble<long double>(
    long double value, const FormatSpec &spec, int precision);

template fmt::BasicWriter<char>::CharPtr
  fmt::BasicWriter<char>::FillPadding(CharPtr buffer,
    unsigned total_size, std::size_t content_size, wchar_t fill);

template fmt::BasicWriter<char>::CharPtr
  fmt::BasicWriter<char>::PrepareFilledBuffer(
    unsigned size, const AlignSpec &spec, char sign);

template void fmt::BasicWriter<char>::FormatParser::ReportError(
    const char *s, StringRef message) const;

template unsigned fmt::BasicWriter<char>::FormatParser::ParseUInt(
    const char *&s) const;

template const fmt::BasicWriter<char>::ArgInfo
    &fmt::BasicWriter<char>::FormatParser::ParseArgIndex(const char *&s);

template void fmt::BasicWriter<char>::FormatParser::CheckSign(
    const char *&s, const ArgInfo &arg);

template void fmt::BasicWriter<char>::FormatParser::Format(
  BasicWriter<char> &writer, BasicStringRef<char> format,
  std::size_t num_args, const ArgInfo *args);

// Explicit instantiations for wchar_t.

template void fmt::BasicWriter<wchar_t>::FormatDouble<double>(
    double value, const FormatSpec &spec, int precision);

template void fmt::BasicWriter<wchar_t>::FormatDouble<long double>(
    long double value, const FormatSpec &spec, int precision);

template fmt::BasicWriter<wchar_t>::CharPtr
  fmt::BasicWriter<wchar_t>::FillPadding(CharPtr buffer,
      unsigned total_size, std::size_t content_size, wchar_t fill);

template fmt::BasicWriter<wchar_t>::CharPtr
  fmt::BasicWriter<wchar_t>::PrepareFilledBuffer(
    unsigned size, const AlignSpec &spec, char sign);

template void fmt::BasicWriter<wchar_t>::FormatParser::ReportError(
    const wchar_t *s, StringRef message) const;

template unsigned fmt::BasicWriter<wchar_t>::FormatParser::ParseUInt(
    const wchar_t *&s) const;

template const fmt::BasicWriter<wchar_t>::ArgInfo
    &fmt::BasicWriter<wchar_t>::FormatParser::ParseArgIndex(const wchar_t *&s);

template void fmt::BasicWriter<wchar_t>::FormatParser::CheckSign(
    const wchar_t *&s, const ArgInfo &arg);

template void fmt::BasicWriter<wchar_t>::FormatParser::Format(
        BasicWriter<wchar_t> &writer, BasicStringRef<wchar_t> format,
        std::size_t num_args, const ArgInfo *args);

#if _MSC_VER
# pragma warning(pop)
#endif