Source/WTF/wtf/DateMath.h

/*
 * Copyright (C) 1999-2000 Harri Porten (porten@kde.org)
 * Copyright (C) 2006, 2007 Apple Inc. All rights reserved.
 * Copyright (C) 2009 Google Inc. All rights reserved.
 * Copyright (C) 2010 Research In Motion Limited. All rights reserved.
 *
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is Mozilla Communicator client code, released
 * March 31, 1998.
 *
 * The Initial Developer of the Original Code is
 * Netscape Communications Corporation.
 * Portions created by the Initial Developer are Copyright (C) 1998
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either of the GNU General Public License Version 2 or later (the "GPL"),
 * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 *
 */

#pragma once

#include <math.h>
#include <stdint.h>
#include <string.h>
#include <time.h>
#include <wtf/WallTime.h>
#include <wtf/text/WTFString.h>

namespace WTF {

enum TimeType {
    UTCTime = 0,
    LocalTime
};

struct LocalTimeOffset {
    WTF_MAKE_STRUCT_FAST_ALLOCATED;

    LocalTimeOffset()
        : isDST(false)
        , offset(0)
    {
    }

    LocalTimeOffset(bool isDST, int offset)
        : isDST(isDST)
        , offset(offset)
    {
    }

    bool operator==(const LocalTimeOffset& other)
    {
        return isDST == other.isDST && offset == other.offset;
    }

    bool operator!=(const LocalTimeOffset& other)
    {
        return isDST != other.isDST || offset != other.offset;
    }

    bool isDST;
    int offset;
};

void initializeDates();
int equivalentYearForDST(int year);

// Not really math related, but this is currently the only shared place to put these.
WTF_EXPORT_PRIVATE double parseES5DateFromNullTerminatedCharacters(const char* dateString);
WTF_EXPORT_PRIVATE double parseDateFromNullTerminatedCharacters(const char* dateString);
WTF_EXPORT_PRIVATE double parseDateFromNullTerminatedCharacters(const char* dateString, bool& haveTZ, int& offset);
WTF_EXPORT_PRIVATE double timeClip(double);
// dayOfWeek: [0, 6] 0 being Monday, day: [1, 31], month: [0, 11], year: ex: 2011, hours: [0, 23], minutes: [0, 59], seconds: [0, 59], utcOffset: [-720,720]. 
String makeRFC2822DateString(unsigned dayOfWeek, unsigned day, unsigned month, unsigned year, unsigned hours, unsigned minutes, unsigned seconds, int utcOffset);

inline double jsCurrentTime()
{
    // JavaScript doesn't recognize fractions of a millisecond.
    return floor(WallTime::now().secondsSinceEpoch().milliseconds());
}

const char* const weekdayName[7] = { "Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun" };
const char* const monthName[12] = { "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec" };
const char* const monthFullName[12] = { "January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December" };

const double hoursPerDay = 24.0;
const double minutesPerHour = 60.0;
const double secondsPerMinute = 60.0;
const double msPerSecond = 1000.0;
const double msPerMonth = 2592000000.0;
const double secondsPerHour = secondsPerMinute * minutesPerHour;
const double secondsPerDay = secondsPerHour * hoursPerDay;
const double msPerMinute = msPerSecond * secondsPerMinute;
const double msPerHour = msPerSecond * secondsPerHour;
const double msPerDay = msPerSecond * secondsPerDay;

WTF_EXPORT_PRIVATE bool isLeapYear(int year);

// Returns the number of days from 1970-01-01 to the specified date.
WTF_EXPORT_PRIVATE double dateToDaysFrom1970(int year, int month, int day);
WTF_EXPORT_PRIVATE int msToYear(double ms);
WTF_EXPORT_PRIVATE double msToDays(double ms);
WTF_EXPORT_PRIVATE int msToMinutes(double ms);
WTF_EXPORT_PRIVATE int msToHours(double ms);
WTF_EXPORT_PRIVATE int dayInYear(int year, int month, int day);
WTF_EXPORT_PRIVATE int dayInYear(double ms, int year);
WTF_EXPORT_PRIVATE int monthFromDayInYear(int dayInYear, bool leapYear);
WTF_EXPORT_PRIVATE int dayInMonthFromDayInYear(int dayInYear, bool leapYear);

// Returns combined offset in millisecond (UTC + DST).
WTF_EXPORT_PRIVATE LocalTimeOffset calculateLocalTimeOffset(double utcInMilliseconds, TimeType = UTCTime);

} // namespace WTF

using WTF::isLeapYear;
using WTF::dateToDaysFrom1970;
using WTF::dayInMonthFromDayInYear;
using WTF::dayInYear;
using WTF::minutesPerHour;
using WTF::monthFromDayInYear;
using WTF::msPerDay;
using WTF::msPerHour;
using WTF::msPerMinute;
using WTF::msPerSecond;
using WTF::msToYear;
using WTF::msToDays;
using WTF::msToMinutes;
using WTF::msToHours;
using WTF::secondsPerDay;
using WTF::secondsPerMinute;
using WTF::parseDateFromNullTerminatedCharacters;
using WTF::makeRFC2822DateString;
using WTF::LocalTimeOffset;
using WTF::calculateLocalTimeOffset;