Source/platform/DateComponents.cpp

/* [<][>][^][v][top][bottom][index][help] */
This source file includes following definitions.
maxDayOfMonth
dayOfWeek
maxWeekNumberInYear
countDigits
toInt
parseYear
withinHTMLDateLimits
withinHTMLDateLimits
withinHTMLDateLimits
addDay
addMinute
parseTimeZone
parseMonth
parseDate
parseWeek
parseTime
parseDateTimeLocal
parseDateTime
positiveFmod
setMillisecondsSinceMidnightInternal
setMillisecondsSinceEpochForDateInternal
setMillisecondsSinceEpochForDate
setMillisecondsSinceEpochForDateTime
setMillisecondsSinceEpochForDateTimeLocal
setMillisecondsSinceEpochForMonth
setMillisecondsSinceMidnight
setMonthsSinceEpoch
offsetTo1stWeekStart
setMillisecondsSinceEpochForWeek
millisecondsSinceEpochForTime
millisecondsSinceEpoch
monthsSinceEpoch
toStringForTime
toString
/*
 * Copyright (C) 2009 Google Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *     * 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.
 *     * Neither the name of Google Inc. nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * 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.
 */

#include "config.h"
#include "platform/DateComponents.h"

#include <limits.h>
#include "wtf/ASCIICType.h"
#include "wtf/DateMath.h"
#include "wtf/MathExtras.h"
#include "wtf/text/WTFString.h"

using namespace std;

namespace WebCore {

// HTML5 specification defines minimum week of year is one.
const int DateComponents::minimumWeekNumber = 1;

// HTML5 specification defines maximum week of year is 53.
const int DateComponents::maximumWeekNumber = 53;

static const int maximumMonthInMaximumYear = 8; // This is September, since months are 0 based.
static const int maximumDayInMaximumMonth = 13;
static const int maximumWeekInMaximumYear = 37; // The week of 275760-09-13

static const int daysInMonth[12] = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};

// 'month' is 0-based.
static int maxDayOfMonth(int year, int month)
{
    if (month != 1) // February?
        return daysInMonth[month];
    return isLeapYear(year) ? 29 : 28;
}

// 'month' is 0-based.
static int dayOfWeek(int year, int month, int day)
{
    int shiftedMonth = month + 2;
    // 2:January, 3:Feburuary, 4:March, ...

    // Zeller's congruence
    if (shiftedMonth <= 3) {
        shiftedMonth += 12;
        year--;
    }
    // 4:March, ..., 14:January, 15:February

    int highYear = year / 100;
    int lowYear = year % 100;
    // We add 6 to make the result Sunday-origin.
    int result = (day + 13 * shiftedMonth / 5 + lowYear + lowYear / 4 + highYear / 4 + 5 * highYear + 6) % 7;
    return result;
}

int DateComponents::maxWeekNumberInYear() const
{
    int day = dayOfWeek(m_year, 0, 1); // January 1.
    return day == Thursday || (day == Wednesday && isLeapYear(m_year)) ? maximumWeekNumber : maximumWeekNumber - 1;
}

static unsigned countDigits(const String& src, unsigned start)
{
    unsigned index = start;
    for (; index < src.length(); ++index) {
        if (!isASCIIDigit(src[index]))
            break;
    }
    return index - start;
}

// Very strict integer parser. Do not allow leading or trailing whitespace unlike charactersToIntStrict().
static bool toInt(const String& src, unsigned parseStart, unsigned parseLength, int& out)
{
    if (parseStart + parseLength > src.length() || !parseLength)
        return false;
    int value = 0;
    unsigned current = parseStart;
    unsigned end = current + parseLength;

    // We don't need to handle negative numbers for ISO 8601.
    for (; current < end; ++current) {
        if (!isASCIIDigit(src[current]))
            return false;
        int digit = src[current] - '0';
        if (value > (INT_MAX - digit) / 10) // Check for overflow.
            return false;
        value = value * 10 + digit;
    }
    out = value;
    return true;
}

bool DateComponents::parseYear(const String& src, unsigned start, unsigned& end)
{
    unsigned digitsLength = countDigits(src, start);
    // Needs at least 4 digits according to the standard.
    if (digitsLength < 4)
        return false;
    int year;
    if (!toInt(src, start, digitsLength, year))
        return false;
    if (year < minimumYear() || year > maximumYear())
        return false;
    m_year = year;
    end = start + digitsLength;
    return true;
}

static bool withinHTMLDateLimits(int year, int month)
{
    if (year < DateComponents::minimumYear())
        return false;
    if (year < DateComponents::maximumYear())
        return true;
    return month <= maximumMonthInMaximumYear;
}

static bool withinHTMLDateLimits(int year, int month, int monthDay)
{
    if (year < DateComponents::minimumYear())
        return false;
    if (year < DateComponents::maximumYear())
        return true;
    if (month < maximumMonthInMaximumYear)
        return true;
    return monthDay <= maximumDayInMaximumMonth;
}

static bool withinHTMLDateLimits(int year, int month, int monthDay, int hour, int minute, int second, int millisecond)
{
    if (year < DateComponents::minimumYear())
        return false;
    if (year < DateComponents::maximumYear())
        return true;
    if (month < maximumMonthInMaximumYear)
        return true;
    if (monthDay < maximumDayInMaximumMonth)
        return true;
    if (monthDay > maximumDayInMaximumMonth)
        return false;
    // (year, month, monthDay) = (maximumYear, maximumMonthInMaximumYear, maximumDayInMaximumMonth)
    return !hour && !minute && !second && !millisecond;
}

bool DateComponents::addDay(int dayDiff)
{
    ASSERT(m_monthDay);

    int day = m_monthDay + dayDiff;
    if (day > maxDayOfMonth(m_year, m_month)) {
        day = m_monthDay;
        int year = m_year;
        int month = m_month;
        int maxDay = maxDayOfMonth(year, month);
        for (; dayDiff > 0; --dayDiff) {
            ++day;
            if (day > maxDay) {
                day = 1;
                ++month;
                if (month >= 12) { // month is 0-origin.
                    month = 0;
                    ++year;
                }
                maxDay = maxDayOfMonth(year, month);
            }
        }
        if (!withinHTMLDateLimits(year, month, day))
            return false;
        m_year = year;
        m_month = month;
    } else if (day < 1) {
        int month = m_month;
        int year = m_year;
        day = m_monthDay;
        for (; dayDiff < 0; ++dayDiff) {
            --day;
            if (day < 1) {
                --month;
                if (month < 0) {
                    month = 11;
                    --year;
                }
                day = maxDayOfMonth(year, month);
            }
        }
        if (!withinHTMLDateLimits(year, month, day))
            return false;
        m_year = year;
        m_month = month;
    } else {
        if (!withinHTMLDateLimits(m_year, m_month, day))
            return false;
    }
    m_monthDay = day;
    return true;
}

bool DateComponents::addMinute(int minute)
{
    // This function is used to adjust timezone offset. So m_year, m_month,
    // m_monthDay have values between the lower and higher limits.
    ASSERT(withinHTMLDateLimits(m_year, m_month, m_monthDay));

    int carry;
    // minute can be negative or greater than 59.
    minute += m_minute;
    if (minute > 59) {
        carry = minute / 60;
        minute = minute % 60;
    } else if (minute < 0) {
        carry = (59 - minute) / 60;
        minute += carry * 60;
        carry = -carry;
        ASSERT(minute >= 0 && minute <= 59);
    } else {
        if (!withinHTMLDateLimits(m_year, m_month, m_monthDay, m_hour, minute, m_second, m_millisecond))
            return false;
        m_minute = minute;
        return true;
    }

    int hour = m_hour + carry;
    if (hour > 23) {
        carry = hour / 24;
        hour = hour % 24;
    } else if (hour < 0) {
        carry = (23 - hour) / 24;
        hour += carry * 24;
        carry = -carry;
        ASSERT(hour >= 0 && hour <= 23);
    } else {
        if (!withinHTMLDateLimits(m_year, m_month, m_monthDay, hour, minute, m_second, m_millisecond))
            return false;
        m_minute = minute;
        m_hour = hour;
        return true;
    }
    if (!addDay(carry))
        return false;
    if (!withinHTMLDateLimits(m_year, m_month, m_monthDay, hour, minute, m_second, m_millisecond))
        return false;
    m_minute = minute;
    m_hour = hour;
    return true;
}

// Parses a timezone part, and adjust year, month, monthDay, hour, minute, second, millisecond.
bool DateComponents::parseTimeZone(const String& src, unsigned start, unsigned& end)
{
    if (start >= src.length())
        return false;
    unsigned index = start;
    if (src[index] == 'Z') {
        end = index + 1;
        return true;
    }

    bool minus;
    if (src[index] == '+')
        minus = false;
    else if (src[index] == '-')
        minus = true;
    else
        return false;
    ++index;

    int hour;
    int minute;
    if (!toInt(src, index, 2, hour) || hour < 0 || hour > 23)
        return false;
    index += 2;

    if (index >= src.length() || src[index] != ':')
        return false;
    ++index;

    if (!toInt(src, index, 2, minute) || minute < 0 || minute > 59)
        return false;
    index += 2;

    if (minus) {
        hour = -hour;
        minute = -minute;
    }

    // Subtract the timezone offset.
    if (!addMinute(-(hour * 60 + minute)))
        return false;
    end = index;
    return true;
}

bool DateComponents::parseMonth(const String& src, unsigned start, unsigned& end)
{
    unsigned index;
    if (!parseYear(src, start, index))
        return false;
    if (index >= src.length() || src[index] != '-')
        return false;
    ++index;

    int month;
    if (!toInt(src, index, 2, month) || month < 1 || month > 12)
        return false;
    --month;
    if (!withinHTMLDateLimits(m_year, month))
        return false;
    m_month = month;
    end = index + 2;
    m_type = Month;
    return true;
}

bool DateComponents::parseDate(const String& src, unsigned start, unsigned& end)
{
    unsigned index;
    if (!parseMonth(src, start, index))
        return false;
    // '-' and 2-digits are needed.
    if (index + 2 >= src.length())
        return false;
    if (src[index] != '-')
        return false;
    ++index;

    int day;
    if (!toInt(src, index, 2, day) || day < 1 || day > maxDayOfMonth(m_year, m_month))
        return false;
    if (!withinHTMLDateLimits(m_year, m_month, day))
        return false;
    m_monthDay = day;
    end = index + 2;
    m_type = Date;
    return true;
}

bool DateComponents::parseWeek(const String& src, unsigned start, unsigned& end)
{
    unsigned index;
    if (!parseYear(src, start, index))
        return false;

    // 4 characters ('-' 'W' digit digit) are needed.
    if (index + 3 >= src.length())
        return false;
    if (src[index] != '-')
        return false;
    ++index;
    if (src[index] != 'W')
        return false;
    ++index;

    int week;
    if (!toInt(src, index, 2, week) || week < minimumWeekNumber || week > maxWeekNumberInYear())
        return false;
    if (m_year == maximumYear() && week > maximumWeekInMaximumYear)
        return false;
    m_week = week;
    end = index + 2;
    m_type = Week;
    return true;
}

bool DateComponents::parseTime(const String& src, unsigned start, unsigned& end)
{
    int hour;
    if (!toInt(src, start, 2, hour) || hour < 0 || hour > 23)
        return false;
    unsigned index = start + 2;
    if (index >= src.length())
        return false;
    if (src[index] != ':')
        return false;
    ++index;

    int minute;
    if (!toInt(src, index, 2, minute) || minute < 0 || minute > 59)
        return false;
    index += 2;

    int second = 0;
    int millisecond = 0;
    // Optional second part.
    // Do not return with false because the part is optional.
    if (index + 2 < src.length() && src[index] == ':') {
        if (toInt(src, index + 1, 2, second) && second >= 0 && second <= 59) {
            index += 3;

            // Optional fractional second part.
            if (index < src.length() && src[index] == '.') {
                unsigned digitsLength = countDigits(src, index + 1);
                if (digitsLength >  0) {
                    ++index;
                    bool ok;
                    if (digitsLength == 1) {
                        ok = toInt(src, index, 1, millisecond);
                        millisecond *= 100;
                    } else if (digitsLength == 2) {
                        ok = toInt(src, index, 2, millisecond);
                        millisecond *= 10;
                    } else { // digitsLength >= 3
                        ok = toInt(src, index, 3, millisecond);
                    }
                    ASSERT_UNUSED(ok, ok);
                    index += digitsLength;
                }
            }
        }
    }
    m_hour = hour;
    m_minute = minute;
    m_second = second;
    m_millisecond = millisecond;
    end = index;
    m_type = Time;
    return true;
}

bool DateComponents::parseDateTimeLocal(const String& src, unsigned start, unsigned& end)
{
    unsigned index;
    if (!parseDate(src, start, index))
        return false;
    if (index >= src.length())
        return false;
    if (src[index] != 'T')
        return false;
    ++index;
    if (!parseTime(src, index, end))
        return false;
    if (!withinHTMLDateLimits(m_year, m_month, m_monthDay, m_hour, m_minute, m_second, m_millisecond))
        return false;
    m_type = DateTimeLocal;
    return true;
}

bool DateComponents::parseDateTime(const String& src, unsigned start, unsigned& end)
{
    unsigned index;
    if (!parseDate(src, start, index))
        return false;
    if (index >= src.length())
        return false;
    if (src[index] != 'T')
        return false;
    ++index;
    if (!parseTime(src, index, index))
        return false;
    if (!parseTimeZone(src, index, end))
        return false;
    if (!withinHTMLDateLimits(m_year, m_month, m_monthDay, m_hour, m_minute, m_second, m_millisecond))
        return false;
    m_type = DateTime;
    return true;
}

static inline double positiveFmod(double value, double divider)
{
    double remainder = fmod(value, divider);
    return remainder < 0 ? remainder + divider : remainder;
}

void DateComponents::setMillisecondsSinceMidnightInternal(double msInDay)
{
    ASSERT(msInDay >= 0 && msInDay < msPerDay);
    m_millisecond = static_cast<int>(fmod(msInDay, msPerSecond));
    double value = floor(msInDay / msPerSecond);
    m_second = static_cast<int>(fmod(value, secondsPerMinute));
    value = floor(value / secondsPerMinute);
    m_minute = static_cast<int>(fmod(value, minutesPerHour));
    m_hour = static_cast<int>(value / minutesPerHour);
}

bool DateComponents::setMillisecondsSinceEpochForDateInternal(double ms)
{
    m_year = msToYear(ms);
    int yearDay = dayInYear(ms, m_year);
    m_month = monthFromDayInYear(yearDay, isLeapYear(m_year));
    m_monthDay = dayInMonthFromDayInYear(yearDay, isLeapYear(m_year));
    return true;
}

bool DateComponents::setMillisecondsSinceEpochForDate(double ms)
{
    m_type = Invalid;
    if (!std::isfinite(ms))
        return false;
    if (!setMillisecondsSinceEpochForDateInternal(round(ms)))
        return false;
    if (!withinHTMLDateLimits(m_year, m_month, m_monthDay))
        return false;
    m_type = Date;
    return true;
}

bool DateComponents::setMillisecondsSinceEpochForDateTime(double ms)
{
    m_type = Invalid;
    if (!std::isfinite(ms))
        return false;
    ms = round(ms);
    setMillisecondsSinceMidnightInternal(positiveFmod(ms, msPerDay));
    if (!setMillisecondsSinceEpochForDateInternal(ms))
        return false;
    if (!withinHTMLDateLimits(m_year, m_month, m_monthDay, m_hour, m_minute, m_second, m_millisecond))
        return false;
    m_type = DateTime;
    return true;
}

bool DateComponents::setMillisecondsSinceEpochForDateTimeLocal(double ms)
{
    // Internal representation of DateTimeLocal is the same as DateTime except m_type.
    if (!setMillisecondsSinceEpochForDateTime(ms))
        return false;
    m_type = DateTimeLocal;
    return true;
}

bool DateComponents::setMillisecondsSinceEpochForMonth(double ms)
{
    m_type = Invalid;
    if (!std::isfinite(ms))
        return false;
    if (!setMillisecondsSinceEpochForDateInternal(round(ms)))
        return false;
    if (!withinHTMLDateLimits(m_year, m_month))
        return false;
    m_type = Month;
    return true;
}

bool DateComponents::setMillisecondsSinceMidnight(double ms)
{
    m_type = Invalid;
    if (!std::isfinite(ms))
        return false;
    setMillisecondsSinceMidnightInternal(positiveFmod(round(ms), msPerDay));
    m_type = Time;
    return true;
}

bool DateComponents::setMonthsSinceEpoch(double months)
{
    if (!std::isfinite(months))
        return false;
    months = round(months);
    double doubleMonth = positiveFmod(months, 12);
    double doubleYear = 1970 + (months - doubleMonth) / 12;
    if (doubleYear < minimumYear() || maximumYear() < doubleYear)
        return false;
    int year = static_cast<int>(doubleYear);
    int month = static_cast<int>(doubleMonth);
    if (!withinHTMLDateLimits(year, month))
        return false;
    m_year = year;
    m_month = month;
    m_type = Month;
    return true;
}

// Offset from January 1st to Monday of the ISO 8601's first week.
//   ex. If January 1st is Friday, such Monday is 3 days later. Returns 3.
static int offsetTo1stWeekStart(int year)
{
    int offsetTo1stWeekStart = 1 - dayOfWeek(year, 0, 1);
    if (offsetTo1stWeekStart <= -4)
        offsetTo1stWeekStart += 7;
    return offsetTo1stWeekStart;
}

bool DateComponents::setMillisecondsSinceEpochForWeek(double ms)
{
    m_type = Invalid;
    if (!std::isfinite(ms))
        return false;
    ms = round(ms);

    m_year = msToYear(ms);
    if (m_year < minimumYear() || m_year > maximumYear())
        return false;

    int yearDay = dayInYear(ms, m_year);
    int offset = offsetTo1stWeekStart(m_year);
    if (yearDay < offset) {
        // The day belongs to the last week of the previous year.
        m_year--;
        if (m_year <= minimumYear())
            return false;
        m_week = maxWeekNumberInYear();
    } else {
        m_week = ((yearDay - offset) / 7) + 1;
        if (m_week > maxWeekNumberInYear()) {
            m_year++;
            m_week = 1;
        }
        if (m_year > maximumYear() || (m_year == maximumYear() && m_week > maximumWeekInMaximumYear))
            return false;
    }
    m_type = Week;
    return true;
}

double DateComponents::millisecondsSinceEpochForTime() const
{
    ASSERT(m_type == Time || m_type == DateTime || m_type == DateTimeLocal);
    return ((m_hour * minutesPerHour + m_minute) * secondsPerMinute + m_second) * msPerSecond + m_millisecond;
}

double DateComponents::millisecondsSinceEpoch() const
{
    switch (m_type) {
    case Date:
        return dateToDaysFrom1970(m_year, m_month, m_monthDay) * msPerDay;
    case DateTime:
    case DateTimeLocal:
        return dateToDaysFrom1970(m_year, m_month, m_monthDay) * msPerDay + millisecondsSinceEpochForTime();
    case Month:
        return dateToDaysFrom1970(m_year, m_month, 1) * msPerDay;
    case Time:
        return millisecondsSinceEpochForTime();
    case Week:
        return (dateToDaysFrom1970(m_year, 0, 1) + offsetTo1stWeekStart(m_year) + (m_week - 1) * 7) * msPerDay;
    case Invalid:
        break;
    }
    ASSERT_NOT_REACHED();
    return invalidMilliseconds();
}

double DateComponents::monthsSinceEpoch() const
{
    ASSERT(m_type == Month);
    return (m_year - 1970) * 12 + m_month;
}

String DateComponents::toStringForTime(SecondFormat format) const
{
    ASSERT(m_type == DateTime || m_type == DateTimeLocal || m_type == Time);
    SecondFormat effectiveFormat = format;
    if (m_millisecond)
        effectiveFormat = Millisecond;
    else if (format == None && m_second)
        effectiveFormat = Second;

    switch (effectiveFormat) {
    default:
        ASSERT_NOT_REACHED();
        // Fallback to None.
    case None:
        return String::format("%02d:%02d", m_hour, m_minute);
    case Second:
        return String::format("%02d:%02d:%02d", m_hour, m_minute, m_second);
    case Millisecond:
        return String::format("%02d:%02d:%02d.%03d", m_hour, m_minute, m_second, m_millisecond);
    }
}

String DateComponents::toString(SecondFormat format) const
{
    switch (m_type) {
    case Date:
        return String::format("%04d-%02d-%02d", m_year, m_month + 1, m_monthDay);
    case DateTime:
        return String::format("%04d-%02d-%02dT", m_year, m_month + 1, m_monthDay)
            + toStringForTime(format) + String("Z");
    case DateTimeLocal:
        return String::format("%04d-%02d-%02dT", m_year, m_month + 1, m_monthDay)
            + toStringForTime(format);
    case Month:
        return String::format("%04d-%02d", m_year, m_month + 1);
    case Time:
        return toStringForTime(format);
    case Week:
        return String::format("%04d-W%02d", m_year, m_week);
    case Invalid:
        break;
    }
    ASSERT_NOT_REACHED();
    return String("(Invalid DateComponents)");
}

} // namespace WebCore
/* [<][>][^][v][top][bottom][index][help] */
root/Source/platform/DateComponents.cpp

DEFINITIONS
