libcruft-util/time/parse8601.cpp.rl

177 lines
5.1 KiB
Ragel

/*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/.
*
* Copyright 2017-2018 Danny Robson <danny@nerdcruft.net>
*/
#include "time/parse.hpp"
#include "debug/assert.hpp"
#include "posix/except.hpp"
#include <stdexcept>
#include <iostream>
// We generate some really old style C code via ragel here, so we have to
// disable some noisy warnings (doubly so given -Werror)
#pragma GCC diagnostic ignored "-Wold-style-cast"
///////////////////////////////////////////////////////////////////////////////
%%{
# based off rfc3339 rather than iso8601 because the former is public
machine iso8601;
date_fullyear = digit{4};
date_month = digit{2};
date_mday = digit{2};
time_hour = digit{2};
time_minute = digit{2};
time_second = digit{2};
time_secfrac = '.' digit{1,} ${ frac *= 10; frac += fc - '0'; };
time_numoffset = ('+' %{dir=1;} | '-' %{dir=-1;})
time_hour ${ offset.tm_hour *= 10; offset.tm_hour += fc - '0'; }
':' time_minute ${ offset.tm_min *= 10; offset.tm_min += fc - '0'; };
time_offset = 'Z' | time_numoffset;
partial_time = time_hour ${ parts.tm_hour *= 10; parts.tm_hour += fc - '0'; }
':' time_minute ${ parts.tm_min *= 10; parts.tm_min += fc - '0'; }
':' time_second ${ parts.tm_sec *= 10; parts.tm_sec += fc - '0'; }
time_secfrac?;
full_date = date_fullyear ${ parts.tm_year *= 10; parts.tm_year += fc - '0'; }
'-' date_month ${ parts.tm_mon *= 10; parts.tm_mon += fc - '0'; }
'-' date_mday ${ parts.tm_mday *= 10; parts.tm_mday += fc - '0'; };
full_time = partial_time time_offset;
date_time := (
full_date 'T' full_time
)
>{ success = false; }
%{ success = true; };
write data;
}%%
///////////////////////////////////////////////////////////////////////////////
template <>
bool
cruft::debug::validator<tm>::is_valid (const tm &val) noexcept
{
// we don't test tm_year anywhere here because there isn't a valid range
// for years, only that they are expressed as offsets from 1900;
return val.tm_sec >= 0 && val.tm_sec <= 60 &&
val.tm_min >= 0 && val.tm_min < 60 &&
val.tm_hour >= 0 && val.tm_hour < 24 &&
val.tm_mday > 0 && val.tm_mday <= 31 &&
val.tm_mon >= 0 && val.tm_mon < 12 &&
val.tm_wday >= 0 && val.tm_wday < 7 &&
val.tm_yday >= 0 && val.tm_yday <= 365;
}
//-----------------------------------------------------------------------------
std::ostream&
operator<< (std::ostream &os, const tm&)
{
return os << "{}";
}
//-----------------------------------------------------------------------------
std::chrono::seconds
to_epoch (const tm &t)
{
// TODO: it's assumed the user isn't passing in oddities like 36 months or
// similar. in the future we can account for this
CHECK_SANITY (t);
constexpr int
cumulative_days [12] = {
0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334
};
constexpr int epoch_year = 1970;
const int year = 1900 + t.tm_year;
// find the number of days since 1970. careful of leap years.
time_t secs;
secs = (year - epoch_year) * 365 + cumulative_days[t.tm_mon % 12];
secs += (year - epoch_year + epoch_year % 4) / 4;
secs -= (year - epoch_year + epoch_year % 100) / 100;
secs += (year - epoch_year + epoch_year % 400) / 400;
const bool is_leap_year = (year % 4 == 0 && (year % 100 != 0 || year % 400 == 0));
if (is_leap_year && t.tm_mon < 2)
secs--;
secs += t.tm_mday - 1;
// hours
secs *= 24;
secs += t.tm_hour;
// minutes
secs *= 60;
secs += t.tm_min;
// seconds
secs *= 60;
secs += t.tm_sec;
if (t.tm_isdst)
secs -= 60 * 60;
return std::chrono::seconds {secs};
}
//-----------------------------------------------------------------------------
std::chrono::nanoseconds
cruft::time::iso8601::parse (cruft::view<const char*> str)
{
int cs;
const char *p = std::begin (str);
const char *pe = std::end (str);
const char *eof = pe;
bool success = false;
int dir = 0;
int64_t frac = 0;
struct tm parts, offset;
memset (&parts, 0, sizeof (parts));
memset (&offset, 0, sizeof (offset));
%%write init;
%%write exec;
if (!success)
throw std::invalid_argument ("invalid date string");
parts.tm_year -= 1900;
parts.tm_mon -= 1;
// compute the timezone offset
std::chrono::seconds diff {
dir * (offset.tm_hour * 60 * 60 + offset.tm_min * 60)
};
// fractional part
auto nano_digits = cruft::digits10 (std::nano::den-1);
auto frac_digits = cruft::digits10 (frac);
auto shift = cruft::pow (10, unsigned(nano_digits - frac_digits));
// sum the time_t, timezone offset, and fractional components
return to_epoch (parts) - diff + std::chrono::nanoseconds (frac * shift);
}