format.cc

/*
 Formatting library for C++

 Copyright (c) 2012 - 2014, 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 <cerrno>
#include <climits>
#include <cmath>
#include <cstdarg>

#ifdef _WIN32
# define WIN32_LEAN_AND_MEAN
# ifdef __MINGW32__
#  include <cstring>
# endif
# include <windows.h>
# undef ERROR
#endif

using fmt::LongLong;
using fmt::ULongLong;
using fmt::internal::Arg;

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

namespace {

#ifndef _MSC_VER

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

// Portable version of isinf.
inline int isinfinity(double x) {
#ifdef isinf
  return isinf(x);
#else
  return std::isinf(x);
#endif
}

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

#define FMT_SNPRINTF snprintf

#else  // _MSC_VER

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

inline int safe_printf(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;
}
#define FMT_SNPRINTF safe_printf

#endif  // _MSC_VER

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

typedef void (*FormatFunc)(fmt::Writer &, int , fmt::StringRef);

void report_error(FormatFunc func,
    int error_code, fmt::StringRef message) FMT_NOEXCEPT(true) {
  try {
    fmt::Writer full_message;
    func(full_message, error_code, message); // TODO: make sure this doesn't throw
    std::fwrite(full_message.c_str(), full_message.size(), 1, stderr);
    std::fputc('\n', stderr);
  } catch (...) {}
}

const Arg DUMMY_ARG = {Arg::INT, 0};

// IsZeroInt::visit(arg) returns true iff arg is a zero integer.
class IsZeroInt : public fmt::internal::ArgVisitor<IsZeroInt, bool> {
 public:
  template <typename T>
  bool visit_any_int(T value) { return value == 0; }
};

// 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>
int parse_nonnegative_int(
    const Char *&s, const char *&error) FMT_NOEXCEPT(true) {
  assert('0' <= *s && *s <= '9');
  unsigned value = 0;
  do {
    unsigned new_value = value * 10 + (*s++ - '0');
    // Check if value wrapped around.
    value = new_value >= value ? new_value : UINT_MAX;
  } while ('0' <= *s && *s <= '9');
  if (value > INT_MAX) {
    if (!error)
      error = "number is too big in format";
    return 0;
  }
  return value;
}

template <typename Char>
const Char *find_closing_brace(const Char *s, int num_open_braces = 1) {
  for (int n = num_open_braces; *s; ++s) {
    if (*s == '{') {
      ++n;
    } else if (*s == '}') {
      if (--n == 0)
        return s;
    }
  }
  throw fmt::FormatError("unmatched '{' in format");
}

// Checks if an argument is a valid printf width specifier and sets
// left alignment if it is negative.
class WidthHandler : public fmt::internal::ArgVisitor<WidthHandler, unsigned> {
 private:
  fmt::FormatSpec &spec_;

 public:
  explicit WidthHandler(fmt::FormatSpec &spec) : spec_(spec) {}

  unsigned visit_unhandled_arg() {
    throw fmt::FormatError("width is not integer");
  }

  template <typename T>
  unsigned visit_any_int(T value) {
    typedef typename fmt::internal::IntTraits<T>::MainType UnsignedType;
    UnsignedType width = value;
    if (fmt::internal::is_negative(value)) {
      spec_.align_ = fmt::ALIGN_LEFT;
      width = 0 - width;
    }
    if (width > INT_MAX)
      throw fmt::FormatError("number is too big in format");
    return static_cast<unsigned>(width);
  }
};

class PrecisionHandler :
    public fmt::internal::ArgVisitor<PrecisionHandler, int> {
 public:
  unsigned visit_unhandled_arg() {
    throw fmt::FormatError("precision is not integer");
  }

  template <typename T>
  int visit_any_int(T value) {
    if (value < INT_MIN || value > INT_MAX)
      throw fmt::FormatError("number is too big in format");
    return static_cast<int>(value);
  }
};

// Converts an integer argument to type T.
template <typename T>
class ArgConverter : public fmt::internal::ArgVisitor<ArgConverter<T>, void> {
 private:
  fmt::internal::Arg &arg_;
  wchar_t type_;

 public:
  ArgConverter(fmt::internal::Arg &arg, wchar_t type)
    : arg_(arg), type_(type) {}

  template <typename U>
  void visit_any_int(U value) {
    bool is_signed = type_ == 'd' || type_ == 'i';
    using fmt::internal::Arg;
    if (sizeof(T) <= sizeof(int)) {
      if (is_signed) {
        arg_.type = Arg::INT;
        arg_.int_value = static_cast<T>(value);
      } else {
        arg_.type = Arg::UINT;
        arg_.uint_value =
            static_cast<typename fmt::internal::MakeUnsigned<T>::Type>(value);
      }
    } else {
      if (is_signed) {
        arg_.type = Arg::LONG_LONG;
        arg_.long_long_value =
            static_cast<typename fmt::internal::MakeUnsigned<U>::Type>(value);
      } else {
        arg_.type = Arg::ULONG_LONG;
        arg_.ulong_long_value =
            static_cast<typename fmt::internal::MakeUnsigned<U>::Type>(value);
      }
    }
  }
};

// This function template is used to prevent compile errors when handling
// incompatible string arguments, e.g. handling a wide string in a narrow
// string formatter.
template <typename Char>
Arg::StringValue<Char> ignore_incompatible_str(Arg::StringValue<wchar_t>);

template <>
inline Arg::StringValue<char> ignore_incompatible_str(
    Arg::StringValue<wchar_t>) { return Arg::StringValue<char>(); }

template <>
inline Arg::StringValue<wchar_t> ignore_incompatible_str(
    Arg::StringValue<wchar_t> s) { return s; }
}  // namespace

int fmt::internal::signbit_noinline(double value) { return getsign(value); }

void fmt::SystemError::init(
    int error_code, StringRef format_str, const ArgList &args) {
  error_code_ = error_code;
  Writer w;
  internal::format_system_error(w, error_code, format(format_str, args));
  std::runtime_error &base = *this;
  base = std::runtime_error(w.str());
}

template <typename T>
int fmt::internal::CharTraits<char>::format_float(
    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>::format_float(
    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::report_unknown_type(char code, const char *type) {
  if (std::isprint(static_cast<unsigned char>(code))) {
    throw fmt::FormatError(
        fmt::format("unknown format code '{}' for {}", code, type));
  }
  throw fmt::FormatError(
      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)
    throw WindowsError(GetLastError(), ERROR);
  buffer_.resize(length);
  length = MultiByteToWideChar(
    CP_UTF8, MB_ERR_INVALID_CHARS, s.c_str(), -1, &buffer_[0], length);
  if (length == 0)
    throw WindowsError(GetLastError(), ERROR);
}

fmt::internal::UTF16ToUTF8::UTF16ToUTF8(fmt::WStringRef s) {
  if (int error_code = convert(s)) {
    throw WindowsError(error_code,
        "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;
}

void fmt::WindowsError::init(
    int error_code, StringRef format_str, const ArgList &args) {
  error_code_ = error_code;
  Writer w;
  internal::format_windows_error(w, error_code, format(format_str, args));
  std::runtime_error &base = *this;
  base = std::runtime_error(w.str());
}

#endif

int fmt::internal::safe_strerror(
    int error_code, char *&buffer, std::size_t buffer_size) FMT_NOEXCEPT(true) {
  assert(buffer != 0 && buffer_size != 0);
  int result = 0;
#ifdef _GNU_SOURCE
  char *message = strerror_r(error_code, buffer, buffer_size);
  // If the buffer is full then the message is probably truncated.
  if (message == buffer && strlen(buffer) == buffer_size - 1)
    result = ERANGE;
  buffer = message;
#elif __MINGW32__
  errno = 0;
  (void)buffer_size;
  buffer = strerror(error_code);
  result = errno;
#elif _WIN32
  result = strerror_s(buffer, buffer_size, error_code);
  // If the buffer is full then the message is probably truncated.
  if (result == 0 && std::strlen(buffer) == buffer_size - 1)
    result = ERANGE;
#else
  result = strerror_r(error_code, buffer, buffer_size);
  if (result == -1)
    result = errno;  // glibc versions before 2.13 return result in errno.
#endif
  return result;
}

void fmt::internal::format_system_error(
    fmt::Writer &out, int error_code, fmt::StringRef message) {
  Array<char, INLINE_BUFFER_SIZE> buffer;
  buffer.resize(INLINE_BUFFER_SIZE);
  char *system_message = 0;
  for (;;) {
    system_message = &buffer[0];
    int result = safe_strerror(error_code, system_message, buffer.size());
    if (result == 0)
      break;
    if (result != 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;
}

#ifdef _WIN32
void fmt::internal::format_windows_error(
    fmt::Writer &out, int error_code, fmt::StringRef message) {
  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 << ": " << utf8_message;
      return;
    }
  }
  // Can't get error message, report error code instead.
  out << message << ": error code = " << error_code;
}
#endif

// An argument formatter.
template <typename Char>
class fmt::internal::ArgFormatter :
    public fmt::internal::ArgVisitor<fmt::internal::ArgFormatter<Char>, void> {
 private:
  fmt::BasicFormatter<Char> &formatter_;
  fmt::BasicWriter<Char> &writer_;
  fmt::FormatSpec &spec_;
  const Char *format_;

 public:
  ArgFormatter(
      fmt::BasicFormatter<Char> &f,fmt::FormatSpec &s, const Char *fmt)
  : formatter_(f), writer_(f.writer()), spec_(s), format_(fmt) {}

  template <typename T>
  void visit_any_int(T value) { writer_.write_int(value, spec_); }

  template <typename T>
  void visit_any_double(T value) { writer_.write_double(value, spec_); }

  void visit_char(int value) {
    if (spec_.type_ && spec_.type_ != 'c') {
      spec_.flags_ |= CHAR_FLAG;
      writer_.write_int(value, spec_);
      return;
    }
    if (spec_.align_ == ALIGN_NUMERIC || spec_.flags_ != 0)
      throw FormatError("invalid format specifier for char");
    typedef typename fmt::BasicWriter<Char>::CharPtr CharPtr;
    CharPtr out = CharPtr();
    if (spec_.width_ > 1) {
      Char fill = static_cast<Char>(spec_.fill());
      out = writer_.grow_buffer(spec_.width_);
      if (spec_.align_ == fmt::ALIGN_RIGHT) {
        std::fill_n(out, spec_.width_ - 1, fill);
        out += spec_.width_ - 1;
      } else if (spec_.align_ == fmt::ALIGN_CENTER) {
        out = writer_.fill_padding(out, spec_.width_, 1, fill);
      } else {
        std::fill_n(out + 1, spec_.width_ - 1, fill);
      }
    } else {
      out = writer_.grow_buffer(1);
    }
    *out = static_cast<Char>(value);
  }

  void visit_string(Arg::StringValue<char> value) {
    writer_.write_str(value, spec_);
  }
  void visit_wstring(Arg::StringValue<wchar_t> value) {
    writer_.write_str(ignore_incompatible_str<Char>(value), spec_);
  }

  void visit_pointer(const void *value) {
    if (spec_.type_ && spec_.type_ != 'p')
      fmt::internal::report_unknown_type(spec_.type_, "pointer");
    spec_.flags_ = fmt::HASH_FLAG;
    spec_.type_ = 'x';
    writer_.write_int(reinterpret_cast<uintptr_t>(value), spec_);
  }

  void visit_custom(Arg::CustomValue c) {
    c.format(&formatter_, c.value, format_);
  }
};

template <typename Char>
void fmt::internal::FormatErrorReporter<Char>::operator()(
        const Char *s, fmt::StringRef message) const {
  if (find_closing_brace(s, num_open_braces))
    throw fmt::FormatError(message);
}

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

  char sign = 0;
  // Use getsign instead of value < 0 because the latter is always
  // false for NaN.
  if (getsign(static_cast<double>(value))) {
    sign = '-';
    value = -value;
  } else if (spec.flag(SIGN_FLAG)) {
    sign = spec.flag(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 = write_str(nan, size, spec);
    if (sign)
      *out = sign;
    return;
  }

  if (isinfinity(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 = write_str(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.flag(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 (spec.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>::format_float(
        start, size, format, width_for_sprintf, spec.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 = grow_buffer(width);
        std::copy(p, p + n, p + (width - n) / 2);
        fill_padding(p, spec.width(), n, fill);
        return;
      }
      if (spec.fill() != ' ' || sign) {
        while (*start == ' ')
          *start++ = fill;
        if (sign)
          *(start - 1) = sign;
      }
      grow_buffer(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);
  }
}

template <typename Char>
template <typename StrChar>
void fmt::BasicWriter<Char>::write_str(
    const Arg::StringValue<StrChar> &str, const FormatSpec &spec) {
  // Check if StrChar is convertible to Char.
  internal::CharTraits<Char>::convert(StrChar());
  if (spec.type_ && spec.type_ != 's')
    internal::report_unknown_type(spec.type_, "string");
  const StrChar *s = str.value;
  std::size_t size = str.size;
  if (size == 0) {
    if (!s)
      throw FormatError("string pointer is null");
    if (*s)
      size = std::char_traits<StrChar>::length(s);
  }
  write_str(s, size, spec);
}

template <typename Char>
inline const Arg
    &fmt::BasicFormatter<Char>::parse_arg_index(const Char *&s) {
  unsigned arg_index = 0;
  if (*s < '0' || *s > '9') {
    if (*s != '}' && *s != ':')
      report_error_(s, "invalid argument index in format string");
    const Arg &arg = next_arg();
    if (error_)
      report_error_(s, error_);
    return arg;
  }
  if (next_arg_index_ > 0) {
    report_error_(s,
        "cannot switch from automatic to manual argument indexing");
  }
  next_arg_index_ = -1;
  arg_index = parse_nonnegative_int(s, error_);
  if (error_)
    report_error_(s, error_); // TODO: don't use report_error_
  if (arg_index >= args_.size())
    report_error_(s, "argument index is out of range in format");
  return args_[arg_index];
}

template <typename Char>
void fmt::BasicFormatter<Char>::check_sign(
    const Char *&s, const Arg &arg) {
  char sign = static_cast<char>(*s);
  if (arg.type > Arg::LAST_NUMERIC_TYPE) {
    report_error_(s, fmt::format(
      "format specifier '{}' requires numeric argument", sign).c_str());
  }
  if (arg.type == Arg::UINT || arg.type == Arg::ULONG_LONG) {
    report_error_(s, fmt::format(
      "format specifier '{}' requires signed argument", sign).c_str());
  }
  ++s;
}

const Arg &fmt::internal::FormatterBase::next_arg() {
  if (next_arg_index_ < 0) {
    if (!error_)
      error_ = "cannot switch from manual to automatic argument indexing";
    return DUMMY_ARG;
  }
  unsigned arg_index = next_arg_index_++;
  if (arg_index < args_.size())
    return args_[arg_index];
  if (!error_)
    error_ = "argument index is out of range in format";
  return DUMMY_ARG;
}

const Arg &fmt::internal::FormatterBase::handle_arg_index(unsigned arg_index) {
  if (arg_index != UINT_MAX) {
    if (next_arg_index_ <= 0) {
      next_arg_index_ = -1;
      --arg_index;
    } else if (!error_) {
      error_ = "cannot switch from automatic to manual argument indexing";
    }
    if (arg_index < args_.size())
      return args_[arg_index];
    if (!error_)
      error_ = "argument index is out of range in format";
    return DUMMY_ARG;
  }
  return next_arg();
}

template <typename Char>
void fmt::internal::PrintfFormatter<Char>::parse_flags(
    FormatSpec &spec, const Char *&s) {
  for (;;) {
    switch (*s++) {
      case '-':
        spec.align_ = ALIGN_LEFT;
        break;
      case '+':
        spec.flags_ |= SIGN_FLAG | PLUS_FLAG;
        break;
      case '0':
        spec.fill_ = '0';
        break;
      case ' ':
        spec.flags_ |= SIGN_FLAG;
        break;
      case '#':
        spec.flags_ |= HASH_FLAG;
        break;
      default:
        --s;
        return;
    }
  }
}

template <typename Char>
unsigned fmt::internal::PrintfFormatter<Char>::parse_header(
  const Char *&s, FormatSpec &spec) {
  unsigned arg_index = UINT_MAX;
  Char c = *s;
  if (c >= '0' && c <= '9') {
    // Parse an argument index (if followed by '$') or a width possibly
    // preceded with '0' flag(s).
    unsigned value = parse_nonnegative_int(s, error_);
    if (*s == '$') {  // value is an argument index
      ++s;
      arg_index = value;
    } else {
      if (c == '0')
        spec.fill_ = '0';
      if (value != 0) {
        // Nonzero value means that we parsed width and don't need to
        // parse it or flags again, so return now.
        spec.width_ = value;
        return arg_index;
      }
    }
  }
  parse_flags(spec, s);
  // Parse width.
  if (*s >= '0' && *s <= '9') {
    spec.width_ = parse_nonnegative_int(s, error_);
  } else if (*s == '*') {
    ++s;
    spec.width_ = WidthHandler(spec).visit(handle_arg_index(UINT_MAX));
  }
  return arg_index;
}

template <typename Char>
void fmt::internal::PrintfFormatter<Char>::format(
    BasicWriter<Char> &writer, BasicStringRef<Char> format,
    const ArgList &args) {
  const Char *start = format.c_str();
  args_ = args;
  next_arg_index_ = 0;
  const Char *s = start;
  while (*s) {
    Char c = *s++;
    if (c != '%') continue;
    if (*s == c) {
      write(writer, start, s);
      start = ++s;
      continue;
    }
    write(writer, start, s - 1);

    FormatSpec spec;
    spec.align_ = ALIGN_RIGHT;

    // Reporting errors is delayed till the format specification is
    // completely parsed. This is done to avoid potentially confusing
    // error messages for incomplete format strings. For example, in
    //   sprintf("%2$", 42);
    // the format specification is incomplete. In a naive approach we
    // would parse 2 as an argument index and report an error that the
    // index is out of range which would be rather confusing if the
    // use meant "%2d$" rather than "%2$d". If we delay an error, the
    // user will get an error that the format string is invalid which
    // is OK for both cases.

    // Parse argument index, flags and width.
    unsigned arg_index = parse_header(s, spec);

    // Parse precision.
    if (*s == '.') {
      ++s;
      if ('0' <= *s && *s <= '9') {
        spec.precision_ = parse_nonnegative_int(s, error_);
      } else if (*s == '*') {
        ++s;
        spec.precision_ = PrecisionHandler().visit(handle_arg_index(UINT_MAX));
      }
    }

    Arg arg = handle_arg_index(arg_index);
    if (spec.flag(HASH_FLAG) && IsZeroInt().visit(arg))
      spec.flags_ &= ~HASH_FLAG;
    if (spec.fill_ == '0') {
      if (arg.type <= Arg::LAST_NUMERIC_TYPE)
        spec.align_ = ALIGN_NUMERIC;
      else
        spec.fill_ = ' ';  // Ignore '0' flag for non-numeric types.
    }

    // Parse length and convert the argument to the required type.
    switch (*s++) {
    case 'h':
      if (*s == 'h')
        ArgConverter<signed char>(arg, *++s).visit(arg);
      else
        ArgConverter<short>(arg, *s).visit(arg);
      break;
    case 'l':
      if (*s == 'l')
        ArgConverter<fmt::LongLong>(arg, *++s).visit(arg);
      else
        ArgConverter<long>(arg, *s).visit(arg);
      break;
    case 'j':
      ArgConverter<intmax_t>(arg, *s).visit(arg);
      break;
    case 'z':
      ArgConverter<size_t>(arg, *s).visit(arg);
      break;
    case 't':
      ArgConverter<ptrdiff_t>(arg, *s).visit(arg);
      break;
    case 'L':
      // TODO: handle length
      break;
    default:
      --s;
    }

    // Parse type.
    if (!*s)
      throw FormatError("invalid format string");
    if (error_)
      throw FormatError(error_);
    spec.type_ = static_cast<char>(*s++);
    if (arg.type <= Arg::LAST_INTEGER_TYPE &&
        (spec.type_ == 'i' || spec.type_ == 'u')) {
        spec.type_ = 'd';
    }

    start = s;

    // Format argument.
    switch (arg.type) {
    case Arg::INT:
      writer.write_int(arg.int_value, spec);
      break;
    case Arg::UINT:
      writer.write_int(arg.uint_value, spec);
      break;
    case Arg::LONG_LONG:
      writer.write_int(arg.long_long_value, spec);
      break;
    case Arg::ULONG_LONG:
      writer.write_int(arg.ulong_long_value, spec);
      break;
    case Arg::CHAR: {
      if (spec.type_ && spec.type_ != 'c')
        writer.write_int(arg.int_value, spec);
      typedef typename BasicWriter<Char>::CharPtr CharPtr;
      CharPtr out = CharPtr();
      if (spec.width_ > 1) {
        Char fill = ' ';
        out = writer.grow_buffer(spec.width_);
        if (spec.align_ != ALIGN_LEFT) {
          std::fill_n(out, spec.width_ - 1, fill);
          out += spec.width_ - 1;
        } else {
          std::fill_n(out + 1, spec.width_ - 1, fill);
        }
      } else {
        out = writer.grow_buffer(1);
      }
      *out = static_cast<Char>(arg.int_value);
      break;
    }
    case Arg::DOUBLE:
      writer.write_double(arg.double_value, spec);
      break;
    case Arg::LONG_DOUBLE:
      writer.write_double(arg.long_double_value, spec);
      break;
    case Arg::STRING:
      writer.write_str(arg.string, spec);
      break;
    case Arg::WSTRING:
      writer.write_str(ignore_incompatible_str<Char>(arg.wstring), spec);
      break;
    case Arg::POINTER:
      if (spec.type_ && spec.type_ != 'p')
        internal::report_unknown_type(spec.type_, "pointer");
      spec.flags_= HASH_FLAG;
      spec.type_ = 'x';
      writer.write_int(reinterpret_cast<uintptr_t>(arg.pointer_value), spec);
      break;
    case Arg::CUSTOM:
      if (spec.type_)
        internal::report_unknown_type(spec.type_, "object");
      arg.custom.format(&writer, arg.custom.value, "s");
      break;
    default:
      assert(false);
      break;
    }
  }
  write(writer, start, s);
}

template <typename Char>
const Char *fmt::BasicFormatter<Char>::format(
    const Char *format_str, const Arg &arg) {
  const Char *s = format_str;
  const char *error = 0;
  FormatSpec spec;
  if (*s == ':') {
    if (arg.type == Arg::CUSTOM) {
      arg.custom.format(this, arg.custom.value, s);
      return find_closing_brace(s) + 1;
    }
    ++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 == '{')
              report_error_(s, "invalid fill character '{'");
            s += 2;
            spec.fill_ = c;
          } else ++s;
          if (spec.align_ == ALIGN_NUMERIC && arg.type > Arg::LAST_NUMERIC_TYPE)
            report_error_(s, "format specifier '=' requires numeric argument");
          break;
        }
      } while (--p >= s);
    }

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

    if (*s == '#') {
      if (arg.type > Arg::LAST_NUMERIC_TYPE)
        report_error_(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 > Arg::LAST_NUMERIC_TYPE)
          report_error_(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.
      spec.width_ = parse_nonnegative_int(s, error);
      if (error)
        report_error_(s, error);
    }

    // Parse precision.
    if (*s == '.') {
      ++s;
      spec.precision_ = 0;
      if ('0' <= *s && *s <= '9') {
        spec.precision_ = parse_nonnegative_int(s, error);
        if (error)
          report_error_(s, error);
      } else if (*s == '{') {
        ++s;
        ++report_error_.num_open_braces;
        const Arg &precision_arg = parse_arg_index(s);
        ULongLong value = 0;
        switch (precision_arg.type) {
          case Arg::INT:
            if (precision_arg.int_value < 0)
              report_error_(s, "negative precision in format");
            value = precision_arg.int_value;
            break;
          case Arg::UINT:
            value = precision_arg.uint_value;
            break;
          case Arg::LONG_LONG:
            if (precision_arg.long_long_value < 0)
              report_error_(s, "negative precision in format");
            value = precision_arg.long_long_value;
            break;
          case Arg::ULONG_LONG:
            value = precision_arg.ulong_long_value;
            break;
          default:
            report_error_(s, "precision is not integer");
        }
        if (value > INT_MAX)
          report_error_(s, "number is too big in format");
        spec.precision_ = static_cast<int>(value);
        if (*s++ != '}')
          throw FormatError("unmatched '{' in format");
        --report_error_.num_open_braces;
      } else {
        report_error_(s, "missing precision in format");
      }
      if (arg.type != Arg::DOUBLE && arg.type != Arg::LONG_DOUBLE) {
        report_error_(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.
  internal::ArgFormatter<Char>(*this, spec, s - 1).visit(arg);
  return s;
}

template <typename Char>
void fmt::BasicFormatter<Char>::format(
    BasicStringRef<Char> format_str, const ArgList &args) {
  const Char *s = start_ = format_str.c_str();
  args_ = args;
  next_arg_index_ = 0;
  while (*s) {
    Char c = *s++;
    if (c != '{' && c != '}') continue;
    if (*s == c) {
      write(writer_, start_, s);
      start_ = ++s;
      continue;
    }
    if (c == '}')
      throw FormatError("unmatched '}' in format");
    report_error_.num_open_braces = 1;
    write(writer_, start_, s - 1);
    Arg arg = parse_arg_index(s);
    s = format(s, arg);
  }
  write(writer_, start_, s);
}

void fmt::report_system_error(
    int error_code, fmt::StringRef message) FMT_NOEXCEPT(true) {
  // FIXME: format_system_error may throw
  report_error(internal::format_system_error, error_code, message);
}

#ifdef _WIN32
void fmt::report_windows_error(
    int error_code, fmt::StringRef message) FMT_NOEXCEPT(true) {
  // FIXME: format_windows_error may throw
  report_error(internal::format_windows_error, error_code, message);
}
#endif

void fmt::print(StringRef format, const ArgList &args) {
  Writer w;
  w.write(format, args);
  std::fwrite(w.data(), 1, w.size(), stdout);
}

void fmt::print(std::FILE *f, StringRef format, const ArgList &args) {
  Writer w;
  w.write(format, args);
  std::fwrite(w.data(), 1, w.size(), f);
}

void fmt::print(std::ostream &os, StringRef format, const ArgList &args) {
  Writer w;
  w.write(format, args);
  os.write(w.data(), w.size());
}

void fmt::print_colored(Color c, StringRef format, const ArgList &args) {
  char escape[] = "\x1b[30m";
  escape[3] = '0' + static_cast<char>(c);
  std::fputs(escape, stdout);
  print(format, args);
  std::fputs(RESET_COLOR, stdout);
}

void fmt::printf(StringRef format, const ArgList &args) {
  Writer w;
  printf(w, format, args);
  std::fwrite(w.data(), 1, w.size(), stdout);
}

// Explicit instantiations for char.

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

template void fmt::BasicFormatter<char>::format(
  BasicStringRef<char> format, const ArgList &args);

template void fmt::internal::PrintfFormatter<char>::format(
  BasicWriter<char> &writer, BasicStringRef<char> format, const ArgList &args);

// Explicit instantiations for wchar_t.

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

template void fmt::BasicFormatter<wchar_t>::format(
    BasicStringRef<wchar_t> format, const ArgList &args);

template void fmt::internal::PrintfFormatter<wchar_t>::format(
    BasicWriter<wchar_t> &writer, BasicStringRef<wchar_t> format,
    const ArgList &args);

#if _MSC_VER
# pragma warning(pop)
#endif