ladybird/AK/Time.cpp
Nico Weber 1ab8939077 AK+LibC+LibCore: Have fewer implementations of day_of_week
The implementation in LibC did a timestamp->day-of-week conversion
which looks like a valuable thing to have. But we only need it in
time_to_tm, where we already computed year/month/day -- so let's
consolidate on the day_of_week function in DateTime (which is
getting extracted to AK).
2020-08-26 08:52:07 +02:00

65 lines
2.4 KiB
C++

/*
* Copyright (c) 2020, The SerenityOS developers.
* 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 HOLDER 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.
*/
#include <AK/Assertions.h>
#include <AK/Time.h>
namespace AK {
int day_of_year(int year, unsigned month, int day)
{
ASSERT(month >= 1 && month <= 12);
static const int seek_table[] = { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334 };
int day_of_year = seek_table[month - 1] + day - 1;
if (is_leap_year(year) && month >= 3)
day_of_year++;
return day_of_year;
}
int days_in_month(int year, unsigned month)
{
ASSERT(month >= 1 && month <= 12);
if (month == 2)
return is_leap_year(year) ? 29 : 28;
bool is_long_month = (month == 1 || month == 3 || month == 5 || month == 7 || month == 8 || month == 10 || month == 12);
return is_long_month ? 31 : 30;
}
unsigned day_of_week(int year, unsigned month, int day)
{
ASSERT(month >= 1 && month <= 12);
static const int seek_table[] = { 0, 3, 2, 5, 0, 3, 5, 1, 4, 6, 2, 4 };
if (month < 3)
--year;
return (year + year / 4 - year / 100 + year / 400 + seek_table[month - 1] + day) % 7;
}
}