chrono.h

Go to the documentation of this file.

// Formatting library for C++ - chrono support
//
// Copyright (c) 2012 - present, Victor Zverovich
// All rights reserved.
//
// For the license information refer to format.h.

#ifndef FMT_CHRONO_H_
#define FMT_CHRONO_H_

#include "format.h"
#include "locale.h"

#include <chrono>
#include <ctime>
#include <locale>
#include <sstream>

FMT_BEGIN_NAMESPACE

namespace internal{

enum class numeric_system {
  standard,
  // Alternative numeric system, e.g. 十二 instead of 12 in ja_JP locale.
  alternative
};

// Parses a put_time-like format string and invokes handler actions.
template <typename Char, typename Handler>
FMT_CONSTEXPR const Char *parse_chrono_format(
    const Char *begin, const Char *end, Handler &&handler) {
  auto ptr = begin;
  while (ptr != end) {
    auto c = *ptr;
    if (c == '}') break;
    if (c != '%') {
      ++ptr;
      continue;
    }
    if (begin != ptr)
      handler.on_text(begin, ptr);
    ++ptr; // consume '%'
    if (ptr == end)
      throw format_error("invalid format");
    c = *ptr++;
    switch (c) {
    case '%':
      handler.on_text(ptr - 1, ptr);
      break;
    case 'n': {
      const char newline[] = "\n";
      handler.on_text(newline, newline + 1);
      break;
    }
    case 't': {
      const char tab[] = "\t";
      handler.on_text(tab, tab + 1);
      break;
    }
    // Day of the week:
    case 'a':
      handler.on_abbr_weekday();
      break;
    case 'A':
      handler.on_full_weekday();
      break;
    case 'w':
      handler.on_dec0_weekday(numeric_system::standard);
      break;
    case 'u':
      handler.on_dec1_weekday(numeric_system::standard);
      break;
    // Month:
    case 'b':
      handler.on_abbr_month();
      break;
    case 'B':
      handler.on_full_month();
      break;
    // Hour, minute, second:
    case 'H':
      handler.on_24_hour(numeric_system::standard);
      break;
    case 'I':
      handler.on_12_hour(numeric_system::standard);
      break;
    case 'M':
      handler.on_minute(numeric_system::standard);
      break;
    case 'S':
      handler.on_second(numeric_system::standard);
      break;
    // Other:
    case 'c':
      handler.on_datetime(numeric_system::standard);
      break;
    case 'x':
      handler.on_loc_date(numeric_system::standard);
      break;
    case 'X':
      handler.on_loc_time(numeric_system::standard);
      break;
    case 'D':
      handler.on_us_date();
      break;
    case 'F':
      handler.on_iso_date();
      break;
    case 'r':
      handler.on_12_hour_time();
      break;
    case 'R':
      handler.on_24_hour_time();
      break;
    case 'T':
      handler.on_iso_time();
      break;
    case 'p':
      handler.on_am_pm();
      break;
    case 'z':
      handler.on_utc_offset();
      break;
    case 'Z':
      handler.on_tz_name();
      break;
    // Alternative representation:
    case 'E': {
      if (ptr == end)
        throw format_error("invalid format");
      c = *ptr++;
      switch (c) {
      case 'c':
        handler.on_datetime(numeric_system::alternative);
        break;
      case 'x':
        handler.on_loc_date(numeric_system::alternative);
        break;
      case 'X':
        handler.on_loc_time(numeric_system::alternative);
        break;
      default:
        throw format_error("invalid format");
      }
      break;
    }
    case 'O':
      if (ptr == end)
        throw format_error("invalid format");
      c = *ptr++;
      switch (c) {
      case 'w':
        handler.on_dec0_weekday(numeric_system::alternative);
        break;
      case 'u':
        handler.on_dec1_weekday(numeric_system::alternative);
        break;
      case 'H':
        handler.on_24_hour(numeric_system::alternative);
        break;
      case 'I':
        handler.on_12_hour(numeric_system::alternative);
        break;
      case 'M':
        handler.on_minute(numeric_system::alternative);
        break;
      case 'S':
        handler.on_second(numeric_system::alternative);
        break;
      default:
        throw format_error("invalid format");
      }
      break;
    default:
      throw format_error("invalid format");
    }
    begin = ptr;
  }
  if (begin != ptr)
    handler.on_text(begin, ptr);
  return ptr;
}

struct chrono_format_checker {
  void report_no_date() { throw format_error("no date"); }

  template <typename Char>
  void on_text(const Char *, const Char *) {}
  void on_abbr_weekday() { report_no_date(); }
  void on_full_weekday() { report_no_date(); }
  void on_dec0_weekday(numeric_system) { report_no_date(); }
  void on_dec1_weekday(numeric_system) { report_no_date(); }
  void on_abbr_month() { report_no_date(); }
  void on_full_month() { report_no_date(); }
  void on_24_hour(numeric_system) {}
  void on_12_hour(numeric_system) {}
  void on_minute(numeric_system) {}
  void on_second(numeric_system) {}
  void on_datetime(numeric_system) { report_no_date(); }
  void on_loc_date(numeric_system) { report_no_date(); }
  void on_loc_time(numeric_system) { report_no_date(); }
  void on_us_date() { report_no_date(); }
  void on_iso_date() { report_no_date(); }
  void on_12_hour_time() {}
  void on_24_hour_time() {}
  void on_iso_time() {}
  void on_am_pm() {}
  void on_utc_offset() { report_no_date(); }
  void on_tz_name() { report_no_date(); }
};

template <typename Int>
inline int to_int(Int value) {
  FMT_ASSERT(value >= (std::numeric_limits<int>::min)() &&
             value <= (std::numeric_limits<int>::max)(), "invalid value");
  return static_cast<int>(value);
}

template <typename FormatContext, typename OutputIt>
struct chrono_formatter {
  FormatContext &context;
  OutputIt out;
  std::chrono::seconds s;
  std::chrono::milliseconds ms;

  typedef typename FormatContext::char_type char_type;

  explicit chrono_formatter(FormatContext &ctx, OutputIt o)
    : context(ctx), out(o) {}

  int hour() const { return to_int((s.count() / 3600) % 24); }

  int hour12() const {
    auto hour = to_int((s.count() / 3600) % 12);
    return hour > 0 ? hour : 12;
  }

  int minute() const { return to_int((s.count() / 60) % 60); }
  int second() const { return to_int(s.count() % 60); }

  std::tm time() const {
    auto time = std::tm();
    time.tm_hour = hour();
    time.tm_min = minute();
    time.tm_sec = second();
    return time;
  }

  void write(int value, int width) {
    typedef typename int_traits<int>::main_type main_type;
    main_type n = to_unsigned(value);
    int num_digits = internal::count_digits(n);
    if (width > num_digits)
      out = std::fill_n(out, width - num_digits, '0');
    out = format_decimal<char_type>(out, n, num_digits);
  }

  void format_localized(const tm &time, const char *format) {
    auto locale = context.locale().template get<std::locale>();
    auto &facet = std::use_facet<std::time_put<char_type>>(locale);
    std::basic_ostringstream<char_type> os;
    os.imbue(locale);
    facet.put(os, os, ' ', &time, format, format + std::strlen(format));
    auto str = os.str();
    std::copy(str.begin(), str.end(), out);
  }

  void on_text(const char_type *begin, const char_type *end) {
    std::copy(begin, end, out);
  }

  // These are not implemented because durations don't have date information.
  void on_abbr_weekday() {}
  void on_full_weekday() {}
  void on_dec0_weekday(numeric_system) {}
  void on_dec1_weekday(numeric_system) {}
  void on_abbr_month() {}
  void on_full_month() {}
  void on_datetime(numeric_system) {}
  void on_loc_date(numeric_system) {}
  void on_loc_time(numeric_system) {}
  void on_us_date() {}
  void on_iso_date() {}
  void on_utc_offset() {}
  void on_tz_name() {}

  void on_24_hour(numeric_system ns) {
    if (ns == numeric_system::standard)
      return write(hour(), 2);
    auto time = tm();
    time.tm_hour = hour();
    format_localized(time, "%OH");
  }

  void on_12_hour(numeric_system ns) {
    if (ns == numeric_system::standard)
      return write(hour12(), 2);
    auto time = tm();
    time.tm_hour = hour();
    format_localized(time, "%OI");
  }

  void on_minute(numeric_system ns) {
    if (ns == numeric_system::standard)
      return write(minute(), 2);
    auto time = tm();
    time.tm_min = minute();
    format_localized(time, "%OM");
  }

  void on_second(numeric_system ns) {
    if (ns == numeric_system::standard) {
      write(second(), 2);
      if (ms != std::chrono::milliseconds(0)) {
        *out++ = '.';
        write(to_int(ms.count()), 3);
      }
      return;
    }
    auto time = tm();
    time.tm_sec = second();
    format_localized(time, "%OS");
  }

  void on_12_hour_time() { format_localized(time(), "%r"); }

  void on_24_hour_time() {
    write(hour(), 2);
    *out++ = ':';
    write(minute(), 2);
  }

  void on_iso_time() {
    on_24_hour_time();
    *out++ = ':';
    write(second(), 2);
  }

  void on_am_pm() { format_localized(time(), "%p"); }
};
}  // namespace internal

template <typename Period> FMT_CONSTEXPR const char *get_units() {
  return FMT_NULL;
}
template <> FMT_CONSTEXPR const char *get_units<std::atto>() { return "as"; }
template <> FMT_CONSTEXPR const char *get_units<std::femto>() { return "fs"; }
template <> FMT_CONSTEXPR const char *get_units<std::pico>() { return "ps"; }
template <> FMT_CONSTEXPR const char *get_units<std::nano>() { return "ns"; }
template <> FMT_CONSTEXPR const char *get_units<std::micro>() { return "µs"; }
template <> FMT_CONSTEXPR const char *get_units<std::milli>() { return "ms"; }
template <> FMT_CONSTEXPR const char *get_units<std::centi>() { return "cs"; }
template <> FMT_CONSTEXPR const char *get_units<std::deci>() { return "ds"; }
template <> FMT_CONSTEXPR const char *get_units<std::ratio<1>>() { return "s"; }
template <> FMT_CONSTEXPR const char *get_units<std::deca>() { return "das"; }
template <> FMT_CONSTEXPR const char *get_units<std::hecto>() { return "hs"; }
template <> FMT_CONSTEXPR const char *get_units<std::kilo>() { return "ks"; }
template <> FMT_CONSTEXPR const char *get_units<std::mega>() { return "Ms"; }
template <> FMT_CONSTEXPR const char *get_units<std::giga>() { return "Gs"; }
template <> FMT_CONSTEXPR const char *get_units<std::tera>() { return "Ts"; }
template <> FMT_CONSTEXPR const char *get_units<std::peta>() { return "Ps"; }
template <> FMT_CONSTEXPR const char *get_units<std::exa>() { return "Es"; }
template <> FMT_CONSTEXPR const char *get_units<std::ratio<60>>() {
  return "m";
}
template <> FMT_CONSTEXPR const char *get_units<std::ratio<3600>>() {
  return "h";
}

template <typename Rep, typename Period, typename Char>
struct formatter<std::chrono::duration<Rep, Period>, Char> {
 private:
  align_spec spec;
  internal::arg_ref<Char> width_ref;
  mutable basic_string_view<Char> format_str;
  typedef std::chrono::duration<Rep, Period> duration;

  struct spec_handler {
    formatter &f;
    basic_parse_context<Char> &context;

    typedef internal::arg_ref<Char> arg_ref_type;

    template <typename Id>
    FMT_CONSTEXPR arg_ref_type make_arg_ref(Id arg_id) {
      context.check_arg_id(arg_id);
      return arg_ref_type(arg_id);
    }

    FMT_CONSTEXPR arg_ref_type make_arg_ref(internal::auto_id) {
      return arg_ref_type(context.next_arg_id());
    }

    void on_error(const char *msg) { throw format_error(msg); }
    void on_fill(Char fill) { f.spec.fill_ = fill; }
    void on_align(alignment align) { f.spec.align_ = align; }
    void on_width(unsigned width) { f.spec.width_ = width; }

    template <typename Id>
    void on_dynamic_width(Id arg_id) {
      f.width_ref = make_arg_ref(arg_id);
    }
  };

 public:
  formatter() : spec() {}

  FMT_CONSTEXPR auto parse(basic_parse_context<Char> &ctx)
      -> decltype(ctx.begin()) {
    auto begin = ctx.begin(), end = ctx.end();
    if (begin == end) return begin;
    spec_handler handler{*this, ctx};
    begin = internal::parse_align(begin, end, handler);
    if (begin == end) return begin;
    begin = internal::parse_width(begin, end, handler);
    end = parse_chrono_format(begin, end, internal::chrono_format_checker());
    format_str = basic_string_view<Char>(&*begin, internal::to_unsigned(end - begin));
    return end;
  }

  template <typename FormatContext>
  auto format(const duration &d, FormatContext &ctx)
      -> decltype(ctx.out()) {
    auto begin = format_str.begin(), end = format_str.end();
    memory_buffer buf;
    typedef output_range<decltype(ctx.out()), Char> range;
    basic_writer<range> w(range(ctx.out()));
    if (begin == end || *begin == '}') {
      if (const char *unit = get_units<Period>())
        format_to(buf, "{}{}", d.count(), unit);
      else if (Period::den == 1)
        format_to(buf, "{}[{}]s", d.count(), Period::num);
      else
        format_to(buf, "{}[{}/{}]s", d.count(), Period::num, Period::den);
      internal::handle_dynamic_spec<internal::width_checker>(
        spec.width_, width_ref, ctx);
    } else {
      auto out = std::back_inserter(buf);
      internal::chrono_formatter<FormatContext, decltype(out)> f(ctx, out);
      f.s = std::chrono::duration_cast<std::chrono::seconds>(d);
      f.ms = std::chrono::duration_cast<std::chrono::milliseconds>(d - f.s);
      parse_chrono_format(begin, end, f);
    }
    w.write(buf.data(), buf.size(), spec);
    return w.out();
  }
};

FMT_END_NAMESPACE

#endif  // FMT_CHRONO_H_