class/corlib/System.Globalization/Calendar.cs

   1 // System.Globalization.Calendar.cs
   2 //
   3 // (C) Ulrich Kunitz 2002
   4 //
   5
   6 //
   7 // Copyright (C) 2004 Novell, Inc (http://www.novell.com)
   8 //
   9 // Permission is hereby granted, free of charge, to any person obtaining
  10 // a copy of this software and associated documentation files (the
  11 // "Software"), to deal in the Software without restriction, including
  12 // without limitation the rights to use, copy, modify, merge, publish,
  13 // distribute, sublicense, and/or sell copies of the Software, and to
  14 // permit persons to whom the Software is furnished to do so, subject to
  15 // the following conditions:
  16 //
  17 // The above copyright notice and this permission notice shall be
  18 // included in all copies or substantial portions of the Software.
  19 //
  20 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  21 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  22 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  23 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  24 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  25 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  26 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  27 //
  28
  29 namespace System.Globalization {
  30
  31 using System;
  32 using System.IO;
  33 using System.Runtime.InteropServices;
  34
  35 /// <remarks>
  36 /// The class serves as a base class for calendar classes.
  37 /// </remarks>
  38 [Serializable]
  39 [ComVisible (true)]
  40 public abstract class Calendar : ICloneable
  41 {
  42         /// <value>An protected integer property that gives the number of
  43         /// days in a week. It might be overridden.</value>
  44         internal virtual int M_DaysInWeek
  45         {
  46                 get { return 7; }
  47         }
  48
  49         /// <summary>
  50         /// The protected method creates the string used in the
  51         /// <see cref="T:System.ArgumentOutOfRangeException"/>
  52         /// </summary>
  53         /// <param name="a">An object that represents the smallest
  54         /// allowable value.</param>
  55         /// <param name="b">An object that represents the greatest allowable
  56         /// value.</param>
  57         /// <returns>The string used in the
  58         /// <see cref="T:System.ArgumentOutOfRangeException"/>
  59         /// </returns>
  60         internal string M_ValidValues(object a, object b)
  61         {
  62                 StringWriter sw = new StringWriter();
  63                 sw.Write("Valid values are between {0} and {1}, inclusive.",
  64                         a, b);
  65                 return sw.ToString();
  66         }
  67
  68         /// <summary>
  69         /// The protected method checks wether the parameter
  70         /// <paramref name="arg"/> is in the allowed range.
  71         /// </summary>
  72         /// <param name="param">A string that gives the name of the
  73         /// parameter to check.</param>
  74         /// <param name="arg">An integer that gives the value to check.
  75         /// </param>
  76         /// <param name="a">An integer that represents the smallest allowed
  77         /// value.</param>
  78         /// <param name="b">An integer that represents the greatest allowed
  79         /// value.</param>
  80         /// <exception cref="T:System.ArgumentOutOfRangeException">
  81         /// The exception is thrown, if the <paramref name="arg"/> is outside
  82         /// the allowed range.
  83         /// </exception>
  84         internal void M_ArgumentInRange(string param, int arg, int a, int b)
  85         {
  86                 if (a <= arg && arg <= b)
  87                         return;
  88                 throw new ArgumentOutOfRangeException(param, M_ValidValues(a, b));
  89         }
  90
  91         /// <summary>
  92         /// The protected method, that checks whether
  93         /// <paramref name="hour"/>, <paramref name="minute"/>,
  94         /// <paramref name="second"/>, and <parameref name="millisecond"/>
  95         /// are in their valid ranges
  96         /// </summary>
  97         /// <param name="hour">An integer that represents a hour,
  98         /// should be between 0 and 23.</param>
  99         /// <param name="minute">An integer that represents a minute,
 100         /// should be between 0 and 59.</param>
 101         /// <param name="second">An integer that represents a second,
 102         /// should be between 0 and 59.</param>
 103         /// <param name="milliseconds">An integer that represents a number
 104         /// of milliseconds, should be between 0 and 999999.</param>
 105         /// <exception cref="T:System.ArgumentOutOfRangeException">
 106         /// The Exception is thrown, if one of the parameter is outside the
 107         /// allowed the range.
 108         /// </exception>
 109         internal void M_CheckHMSM(int hour, int minute, int second,
 110                 int milliseconds)
 111         {
 112                 M_ArgumentInRange("hour", hour, 0, 23);
 113                 M_ArgumentInRange("minute", minute, 0, 59);
 114                 M_ArgumentInRange("second", second, 0, 59);
 115                 M_ArgumentInRange("milliseconds", milliseconds, 0, 999999);
 116         }
 117
 118         /// <value>
 119         /// A represantation of the CurrentEra.
 120         /// </value>
 121         public const int CurrentEra = 0;
 122
 123         /// <value>When overridden gives the eras supported by the
 124         /// calendar as an array of integers.
 125         /// </value>
 126         public abstract int[] Eras { get; }
 127
 128         [NonSerialized]
 129         bool m_isReadOnly;
 130
 131 #if !MOONLIGHT
 132         [System.Runtime.InteropServices.ComVisible(false)]
 133         public virtual CalendarAlgorithmType AlgorithmType {
 134                 get {
 135                         return CalendarAlgorithmType.Unknown;
 136                 }
 137         }
 138 #endif
 139
 140         [System.Runtime.InteropServices.ComVisible(false)]
 141         public virtual DateTime MaxSupportedDateTime {
 142                 get {
 143                         return DateTime.MaxValue;
 144                 }
 145         }
 146
 147         [System.Runtime.InteropServices.ComVisible(false)]
 148         public virtual DateTime MinSupportedDateTime {
 149                 get {
 150                         return DateTime.MinValue;
 151                 }
 152         }
 153
 154         // LAMESPEC: huh, why not Calendar but Object?
 155         [ComVisible (false)]
 156         public virtual object Clone ()
 157         {
 158                 Calendar c = (Calendar) MemberwiseClone ();
 159                 c.m_isReadOnly = false;
 160                 return c;
 161         }
 162
 163         [ComVisible (false)]
 164         public virtual int GetLeapMonth (int year)
 165         {
 166                 return GetLeapMonth (year, GetEra (ToDateTime (year, 1, 1, 0, 0, 0, 0)));
 167         }
 168
 169         [ComVisible (false)]
 170         public virtual int GetLeapMonth (int year, int era)
 171         {
 172                 int max = GetMonthsInYear (year, era);
 173                 for (int i = 1; i <= max; i++)
 174                         if (IsLeapMonth (year, i, era))
 175                                 return i;
 176                 return 0;
 177         }
 178
 179         [ComVisible (false)]
 180         public bool IsReadOnly {
 181                 get { return m_isReadOnly; }
 182         }
 183
 184         [ComVisible (false)]
 185         public static Calendar ReadOnly (Calendar calendar)
 186         {
 187                 if (calendar.m_isReadOnly)
 188                         return calendar;
 189                 Calendar c = (Calendar) calendar.Clone ();
 190                 c.m_isReadOnly = true;
 191                 return c;
 192         }
 193
 194         internal void CheckReadOnly ()
 195         {
 196                 if (m_isReadOnly)
 197                         throw new InvalidOperationException ("This Calendar is read-only.");
 198         }
 199
 200         /// <summary>
 201         /// The protected member stores the value for the
 202         /// <see cref="P:TwoDigitYearMax"/>
 203         /// property.
 204         /// </summary>
 205         [NonSerialized]
 206         internal int twoDigitYearMax;
 207
 208
 209         /// <summary>
 210         /// Private field containing the maximum year for the calendar.
 211         /// </summary>
 212         [NonSerialized]
 213         private int M_MaxYearValue = 0;
 214
 215         /// <value>
 216         /// Get-only property returing the maximum allowed year for this
 217         /// class.
 218         /// </value>
 219         internal virtual int M_MaxYear {
 220                 get {
 221                         if (M_MaxYearValue == 0) {
 222                                 M_MaxYearValue = GetYear(DateTime.MaxValue);
 223                         }
 224                         return M_MaxYearValue;
 225                 }
 226         }
 227
 228         /// <summary>
 229         /// Checks whether the year is the era is valid, if era = CurrentEra
 230         /// the right value is set.
 231         /// </summary>
 232         /// <param name="year">The year to check.</param>
 233         /// <param name="era">The era to check.</Param>
 234         /// <exception cref="T:ArgumentOutOfRangeException">
 235         /// The exception will be thrown, if the year is not valid.
 236         /// </exception>
 237         internal virtual void M_CheckYE(int year, ref int era)
 238         {
 239                 //
 240                 // By default, we do nothing.
 241                 //
 242                 // This used to be an abstract method in Mono's implementation,
 243                 // but that means that end-user code could not create their
 244                 // own calendars.
 245                 //
 246                 // Binaries would also crash in this condition.
 247         }
 248
 249         /// <value>
 250         /// <para>The property gives the maximum value for years with two
 251         /// digits. If the property has the value 2029, than the two-digit
 252         /// integer 29 results in the year 2029 and 30 in the
 253         /// year 1930.</para>
 254         /// <para>It might be overridden.</para>
 255         /// </value>
 256         public virtual int TwoDigitYearMax {
 257                 get { return twoDigitYearMax; }
 258                 set {
 259                         CheckReadOnly ();
 260                         M_ArgumentInRange("year", value, 100, M_MaxYear);
 261                         int era = CurrentEra;
 262                         M_CheckYE(value, ref era);
 263                         twoDigitYearMax = value;
 264                 }
 265         }
 266
 267         /// <summary>
 268         /// The virtual method adds days to a given date.
 269         /// </summary>
 270         /// <param name="time">The
 271         /// <see cref="T:System.DateTime"/> to which to add
 272         /// days.
 273         /// </param>
 274         /// <param name="days">The number of days to add.</param>
 275         /// <returns>A new <see cref="T:System.DateTime"/> value, that
 276         /// results from adding <paramref name="days"/> to the specified
 277         /// DateTime.</returns>
 278         public virtual DateTime AddDays(DateTime time, int days) {
 279                 return time.Add(TimeSpan.FromDays(days));
 280         }
 281
 282         /// <summary>
 283         /// The virtual method adds hours to a given date.
 284         /// </summary>
 285         /// <param name="time">The
 286         /// <see cref="T:System.DateTime"/> to which to add
 287         /// hours.
 288         /// </param>
 289         /// <param name="hours">The number of hours to add.</param>
 290         /// <returns>A new <see cref="T:System.DateTime"/> value, that
 291         /// results from adding <paramref name="hours"/> to the specified
 292         /// DateTime.</returns>
 293         public virtual DateTime AddHours(DateTime time, int hours) {
 294                 return time.Add(TimeSpan.FromHours(hours));
 295         }
 296
 297         /// <summary>
 298         /// The virtual method adds milliseconds to a given date.
 299         /// </summary>
 300         /// <param name="time">The
 301         /// <see cref="T:System.DateTime"/> to which to add
 302         /// milliseconds.
 303         /// </param>
 304         /// <param name="milliseconds">The number of milliseconds given as
 305         /// double to add. Keep in mind the 100 nanosecond resolution of
 306         /// <see cref="T:System.DateTime"/>.
 307         /// </param>
 308         /// <returns>A new <see cref="T:System.DateTime"/> value, that
 309         /// results from adding <paramref name="milliseconds"/> to the specified
 310         /// DateTime.</returns>
 311         public virtual DateTime AddMilliseconds(DateTime time,
 312                 double milliseconds)
 313         {
 314                 return time.Add(TimeSpan.FromMilliseconds(milliseconds));
 315         }
 316
 317         /// <summary>
 318         /// The virtual method adds minutes to a given date.
 319         /// </summary>
 320         /// <param name="time">The
 321         /// <see cref="T:System.DateTime"/> to which to add
 322         /// minutes.
 323         /// </param>
 324         /// <param name="minutes">The number of minutes to add.</param>
 325         /// <returns>A new <see cref="T:System.DateTime"/> value, that
 326         /// results from adding <paramref name="minutes"/> to the specified
 327         /// DateTime.</returns>
 328         public virtual DateTime AddMinutes(DateTime time, int minutes) {
 329                 return time.Add(TimeSpan.FromMinutes(minutes));
 330         }
 331
 332         /// <summary>
 333         /// When overrideden adds months to a given date.
 334         /// </summary>
 335         /// <param name="time">The
 336         /// <see cref="T:System.DateTime"/> to which to add
 337         /// months.
 338         /// </param>
 339         /// <param name="months">The number of months to add.</param>
 340         /// <returns>A new <see cref="T:System.DateTime"/> value, that
 341         /// results from adding <paramref name="months"/> to the specified
 342         /// DateTime.</returns>
 343         public abstract DateTime AddMonths(DateTime time, int months);
 344
 345         /// <summary>
 346         /// The virtual method adds seconds to a given date.
 347         /// </summary>
 348         /// <param name="time">The
 349         /// <see cref="T:System.DateTime"/> to which to add
 350         /// seconds.
 351         /// </param>
 352         /// <param name="seconds">The number of seconds to add.</param>
 353         /// <returns>A new <see cref="T:System.DateTime"/> value, that
 354         /// results from adding <paramref name="seconds"/> to the specified
 355         /// DateTime.</returns>
 356         public virtual DateTime AddSeconds(DateTime time, int seconds) {
 357                 return time.Add(TimeSpan.FromSeconds(seconds));
 358         }
 359
 360         /// <summary>
 361         /// A wirtual method that adds weeks to a given date.
 362         /// </summary>
 363         /// <param name="time">The
 364         /// <see cref="T:System.DateTime"/> to which to add
 365         /// weeks.
 366         /// </param>
 367         /// <param name="weeks">The number of weeks to add.</param>
 368         /// <returns>A new <see cref="T:System.DateTime"/> value, that
 369         /// results from adding <paramref name="weeks"/> to the specified
 370         /// DateTime.</returns>
 371         public virtual DateTime AddWeeks(DateTime time, int weeks) {
 372                 return time.AddDays(weeks * M_DaysInWeek);
 373         }
 374
 375         /// <summary>
 376         /// When overrideden adds years to a given date.
 377         /// </summary>
 378         /// <param name="time">The
 379         /// <see cref="T:System.DateTime"/> to which to add
 380         /// years.
 381         /// </param>
 382         /// <param name="years">The number of years to add.</param>
 383         /// <returns>A new <see cref="T:System.DateTime"/> value, that
 384         /// results from adding <paramref name="years"/> to the specified
 385         /// DateTime.</returns>
 386         public abstract DateTime AddYears(DateTime time, int years);
 387
 388         /// <summary>
 389         /// When overriden gets the day of the month from
 390         /// <paramref name="time"/>.
 391         /// </summary>
 392         /// <param name="time">The
 393         /// <see cref="T:System.DateTime"/> that specifies a
 394         /// date.
 395         /// </param>
 396         /// <returns>An integer giving the day of months, starting with 1.
 397         /// </returns>
 398         public abstract int GetDayOfMonth(DateTime time);
 399
 400         /// <summary>
 401         /// When overriden gets the day of the week from the specified date.
 402         /// </summary>
 403         /// <param name="time">The
 404         /// <see cref="T:System.DateTime"/> that specifies a
 405         /// date.
 406         /// </param>
 407         /// <returns>An integer giving the day of months, starting with 1.
 408         /// </returns>
 409         public abstract DayOfWeek GetDayOfWeek(DateTime time);
 410
 411         /// <summary>
 412         /// When overridden gives the number of the day in the year.
 413         /// </summary>
 414         /// <param name="time">The
 415         /// <see cref="T:System.DateTime"/> that specifies a
 416         /// date.
 417         /// </param>
 418         /// <returns>An integer representing the day of the year,
 419         /// starting with 1.</returns>
 420         public abstract int GetDayOfYear(DateTime time);
 421
 422         /// <summary>
 423         /// A virtual method that gives the number of days of the specified
 424         /// month of the <paramref name="year"/> and the
 425         /// <see cref="P:CurrentEra"/>.
 426         /// </summary>
 427         /// <param name="year">An integer that gives the year in the current
 428         /// era.</param>
 429         /// <param name="month">An integer that gives the month, starting
 430         /// with 1.</param>
 431         /// <returns>An integer that gives the number of days of the
 432         /// specified month.</returns>
 433         /// <exception cref="T:System.ArgumentOutOfRangeException">
 434         /// The exception is thrown, if <paramref name="month"/> or
 435         /// <paramref name="year"/> is outside the allowed range.
 436         /// </exception>
 437         public virtual int GetDaysInMonth(int year, int month) {
 438                 return GetDaysInMonth(year, month, CurrentEra);
 439         }
 440
 441         /// <summary>
 442         /// When overridden gives the number of days in the specified month
 443         /// of the given year and era.
 444         /// </summary>
 445         /// <param name="year">An integer that gives the year.
 446         /// </param>
 447         /// <param name="month">An integer that gives the month, starting
 448         /// with 1.</param>
 449         /// <param name="era">An intger that gives the era of the specified
 450         /// year.</param>
 451         /// <returns>An integer that gives the number of days of the
 452         /// specified month.</returns>
 453         /// <exception cref="T:System.ArgumentOutOfRangeException">
 454         /// The exception is thrown, if <paramref name="month"/>,
 455         /// <paramref name="year"/> ,or <paramref name="era"/> is outside
 456         /// the allowed range.
 457         /// </exception>
 458         public abstract int GetDaysInMonth(int year, int month, int era);
 459
 460         /// <summary>
 461         /// A virtual method that gives the number of days of the specified
 462         /// year of the <see cref="P:CurrentEra"/>.
 463         /// </summary>
 464         /// <param name="year">An integer that gives the year in the current
 465         /// era.</param>
 466         /// <returns>An integer that gives the number of days of the
 467         /// specified year.</returns>
 468         /// <exception cref="T:System.ArgumentOutOfRangeException">
 469         /// The exception is thrown, if
 470         /// <paramref name="year"/> is outside the allowed range.
 471         /// </exception>
 472         public virtual int GetDaysInYear(int year) {
 473                 return GetDaysInYear(year, CurrentEra);
 474         }
 475
 476         /// <summary>
 477         /// When overridden gives the number of days of the specified
 478         /// year of the given era..
 479         /// </summary>
 480         /// <param name="year">An integer that specifies the year.
 481         /// </param>
 482         /// <param name="era">An ineger that specifies the era.
 483         /// </param>
 484         /// <returns>An integer that gives the number of days of the
 485         /// specified year.</returns>
 486         /// <exception cref="T:System.ArgumentOutOfRangeExceiption">
 487         /// The exception is thrown, if
 488         /// <paramref name="year"/> is outside the allowed range.
 489         /// </exception>
 490         public abstract int GetDaysInYear(int year, int era);
 491
 492         /// <summary>
 493         /// When overridden gives the era of the specified date.
 494         /// </summary>
 495         /// <param name="time">The
 496         /// <see cref="T:System.DateTime"/> that specifies a
 497         /// date.
 498         /// </param>
 499         /// <returns>An integer representing the era of the calendar.
 500         /// </returns>
 501         public abstract int GetEra(DateTime time);
 502
 503         /// <summary>
 504         /// Virtual method that gives the hour of the specified time.
 505         /// </summary>
 506         /// <param name="time">The
 507         /// <see cref="T:System.DateTime"/> that specifies the
 508         /// time.
 509         /// </param>
 510         /// <returns>An integer that gives the hour of the specified time,
 511         /// starting with 0.</returns>
 512         public virtual int GetHour(DateTime time) {
 513                 return time.TimeOfDay.Hours;
 514         }
 515
 516         /// <summary>
 517         /// Virtual method that gives the milliseconds in the current second
 518         /// of the specified time.
 519         /// </summary>
 520         /// <param name="time">The
 521         /// <see cref="T:System.DateTime"/> that specifies the
 522         /// time.
 523         /// </param>
 524         /// <returns>An integer that gives the milliseconds in the seconds
 525         /// of the specified time, starting with 0.</returns>
 526         public virtual double GetMilliseconds(DateTime time) {
 527                 return time.TimeOfDay.Milliseconds;
 528         }
 529
 530         /// <summary>
 531         /// Virtual method that gives the minute of the specified time.
 532         /// </summary>
 533         /// <param name="time">The
 534         /// <see cref="T:System.DateTime"/> that specifies the
 535         /// time.
 536         /// </param>
 537         /// <returns>An integer that gives the minute of the specified time,
 538         /// starting with 0.</returns>
 539         public virtual int GetMinute(DateTime time) {
 540                 return time.TimeOfDay.Minutes;
 541         }
 542
 543         /// <summary>
 544         /// When overridden gives the number of the month of the specified
 545         /// date.
 546         /// </summary>
 547         /// <param name="time">The
 548         /// <see cref="T:System.DateTime"/> that specifies a
 549         /// date.
 550         /// </param>
 551         /// <returns>An integer representing the month,
 552         /// starting with 1.</returns>
 553         public abstract int GetMonth(DateTime time);
 554
 555         /// <summary>
 556         /// Virtual method that gives the number of months of the specified
 557         /// year of the <see cref="M:CurrentEra"/>.
 558         /// </summary>
 559         /// <param name="year">An integer that specifies the year in the
 560         /// current era.
 561         /// </param>
 562         /// <returns>An integer that gives the number of the months in the
 563         /// specified year.</returns>
 564         /// <exception cref="T:System.ArgumentOutOfRangeException">
 565         /// The exception is thrown, if the year is not allowed in the
 566         /// current era.
 567         /// </exception>
 568         public virtual int GetMonthsInYear(int year) {
 569                 return GetMonthsInYear(year, CurrentEra);
 570         }
 571
 572         /// <summary>
 573         /// When overridden gives the number of months in the specified year
 574         /// and era.
 575         /// </summary>
 576         /// <param name="year">An integer that specifies the year.
 577         /// </param>
 578         /// <param name="era">An integer that specifies the era.
 579         /// </param>
 580         /// <returns>An integer that gives the number of the months in the
 581         /// specified year.</returns>
 582         /// <exception cref="T:System.ArgumentOutOfRangeException">
 583         /// The exception is thrown, if the year or the era are not valid.
 584         /// </exception>
 585         public abstract int GetMonthsInYear(int year, int era);
 586
 587         /// <summary>
 588         /// Virtual method that gives the second of the specified time.
 589         /// </summary>
 590         /// <param name="time">The
 591         /// <see cref="T:System.DateTime"/> that specifies the
 592         /// time.
 593         /// </param>
 594         /// <returns>An integer that gives the second of the specified time,
 595         /// starting with 0.</returns>
 596         public virtual int GetSecond(DateTime time) {
 597                 return time.TimeOfDay.Seconds;
 598         }
 599
 600         /// <summary>
 601         /// A protected method to calculate the number of days between two
 602         /// dates.
 603         /// </summary>
 604         /// <param name="timeA">A <see cref="T:System.DateTime"/>
 605         /// representing the first date.
 606         /// </param>
 607         /// <param name="timeB">A <see cref="T:System.DateTime"/>
 608         /// representing the second date.
 609         /// </param>
 610         /// <returns>An integer that represents the difference of days
 611         /// between <paramref name="timeA"/> and <paramref name="timeB"/>.
 612         /// </returns>
 613         internal int M_DiffDays(DateTime timeA, DateTime timeB) {
 614                 long diff = timeA.Ticks - timeB.Ticks;
 615
 616                 if (diff >= 0) {
 617                         return (int)(diff/TimeSpan.TicksPerDay);
 618                 }
 619
 620                 diff += 1;
 621                 return -1 + (int)(diff/TimeSpan.TicksPerDay);
 622         }
 623
 624         /// <summary>
 625         /// A protected method that gives the first day of the second week of
 626         /// the year.
 627         /// </summary>
 628         /// <param name="year">An integer that represents the year.</param>
 629         /// <param name="rule">The
 630         /// <see cref="T:System.Globalization.CalendarWeekRule"/>
 631         /// to be used for the calculation.
 632         /// </param>
 633         /// <param name="firstDayOfWeek">
 634         /// The <see cref="T:System.Globalization.DayOfWeek"/>
 635         /// specifying the first day in a week.
 636         /// </param>
 637         /// <returns>The <see cref="T:System.DateTime"/> representing
 638         /// the first day of the second week of the year.
 639         /// </returns>
 640         internal DateTime M_GetFirstDayOfSecondWeekOfYear(
 641                 int year, CalendarWeekRule rule, DayOfWeek firstDayOfWeek)
 642         {
 643                 DateTime d1 = ToDateTime(year, 1, 1, 0, 0, 0, 0);
 644                 int dow1 = (int)GetDayOfWeek(d1);
 645                 int fdow = (int)firstDayOfWeek;
 646                 int d = 0;
 647
 648                 switch (rule) {
 649                 case CalendarWeekRule.FirstDay:
 650                         if (fdow > dow1) {
 651                                 d += fdow - dow1;
 652                         }
 653                         else {
 654                                 d += fdow + M_DaysInWeek - dow1;
 655                         }
 656                         break;
 657                 case CalendarWeekRule.FirstFullWeek:
 658                         d = M_DaysInWeek;
 659                         if (fdow >= dow1) {
 660                                 d += fdow - dow1;
 661                         }
 662                         else {
 663                                 d += fdow + M_DaysInWeek - dow1;
 664                         }
 665                         break;
 666                 case CalendarWeekRule.FirstFourDayWeek:
 667                         int dow4 = (dow1 + 3)%M_DaysInWeek;
 668
 669                         d = 3;
 670                         if (fdow > dow4) {
 671                                 d += fdow - dow4;
 672                         }
 673                         else {
 674                                 d += fdow + M_DaysInWeek - dow4;
 675                         }
 676                         break;
 677                 }
 678
 679                 return AddDays(d1, d);
 680         }
 681
 682         /// <summary>
 683         /// A virtual method that gives the number of the week in the year.
 684         /// </summary>
 685         /// <param name="time">A
 686         /// <see cref="T:System.DateTime"/> representing the date.
 687         /// </param>
 688         /// <param name="rule">The
 689         /// <see cref="T:System.Globalization.CalendarWeekRule"/>
 690         /// to be used for the calculation.
 691         /// </param>
 692         /// <param name="firstDayOfWeek">
 693         /// The <see cref="T:System.Globalization.DayOfWeek"/>
 694         /// specifying the first day in a week.
 695         /// </param>
 696         /// <returns>An integer representing the number of the week in the
 697         /// year, starting with 1.
 698         /// </returns>
 699         public virtual int GetWeekOfYear(DateTime time,
 700                 CalendarWeekRule rule,
 701                 DayOfWeek firstDayOfWeek)
 702         {
 703                 if (firstDayOfWeek < DayOfWeek.Sunday ||
 704                     DayOfWeek.Saturday < firstDayOfWeek)
 705                 {
 706                         throw new ArgumentOutOfRangeException("firstDayOfWeek",
 707                                 "Value is not a valid day of week.");
 708                 }
 709                 int year = GetYear(time);
 710
 711                 int days;
 712
 713                 while (true) {
 714                         DateTime secondWeek = M_GetFirstDayOfSecondWeekOfYear(
 715                                 year, rule, firstDayOfWeek);
 716                         days = M_DiffDays(time, secondWeek) + M_DaysInWeek;
 717                         if (days >= 0)
 718                                 break;
 719                         year -= 1;
 720                 }
 721
 722                 return 1 + days/M_DaysInWeek;
 723         }
 724
 725         /// <summary>
 726         /// When overridden gives the number of the year of the specified
 727         /// date.
 728         /// </summary>
 729         /// <param name="time">The
 730         /// <see cref="T:System.DateTime"/> that specifies a
 731         /// date.
 732         /// </param>
 733         /// <returns>An integer representing the year,
 734         /// starting with 1.</returns>
 735         public abstract int GetYear(DateTime time);
 736
 737         /// <summary>
 738         /// A virtual method that tells whether the given day in the
 739         /// <see cref="M:CurrentEra"/> is a leap day.
 740         /// </summary>
 741         /// <param name="year">An integer that specifies the year in the
 742         /// current era.
 743         /// </param>
 744         /// <param name="month">An integer that specifies the month.
 745         /// </param>
 746         /// <param name="day">An integer that specifies the day.
 747         /// </param>
 748         /// <returns>A boolean that tells whether the given day is a leap
 749         /// day.
 750         /// </returns>
 751         /// <exception cref="T:System.ArgumentOutOfRangeException">
 752         /// The exception is thrown, if the year, month or day is not valid
 753         /// the current era.
 754         /// </exception>
 755         public virtual bool IsLeapDay(int year, int month, int day) {
 756                 return IsLeapDay(year, month, day, CurrentEra);
 757         }
 758
 759         /// <summary>
 760         /// Tells when overridden whether the given day
 761         /// is a leap day.
 762         /// </summary>
 763         /// <param name="year">An integer that specifies the year in the
 764         /// given era.
 765         /// </param>
 766         /// <param name="month">An integer that specifies the month.
 767         /// </param>
 768         /// <param name="day">An integer that specifies the day.
 769         /// </param>
 770         /// <param name="era">An integer that specifies the era.
 771         /// </param>
 772         /// <returns>A boolean that tells whether the given day is a leap
 773         /// day.
 774         /// </returns>
 775         /// <exception cref="T:System.ArgumentOutOfRangeException">
 776         /// The exception is thrown, if the year, month, day, or era is not
 777         /// valid.
 778         /// </exception>
 779         public abstract bool IsLeapDay(int year, int month, int day, int era);
 780
 781         /// <summary>
 782         /// A virtual method that tells whether the given month of the
 783         /// specified year in the
 784         /// <see cref="M:CurrentEra"/> is a leap month.
 785         /// </summary>
 786         /// <param name="year">An integer that specifies the year in the
 787         /// current era.
 788         /// </param>
 789         /// <param name="month">An integer that specifies the month.
 790         /// </param>
 791         /// <returns>A boolean that tells whether the given month is a leap
 792         /// month.
 793         /// </returns>
 794         /// <exception cref="T:System.ArgumentOutOfRangeException">
 795         /// The exception is thrown, if the year or month is not valid
 796         /// the current era.
 797         /// </exception>
 798         public virtual bool IsLeapMonth(int year, int month) {
 799                 return IsLeapMonth(year, month, CurrentEra);
 800         }
 801
 802         /// <summary>
 803         /// Tells when overridden whether the given month
 804         /// is a leap month.
 805         /// </summary>
 806         /// <param name="year">An integer that specifies the year in the
 807         /// given era.
 808         /// </param>
 809         /// <param name="month">An integer that specifies the month.
 810         /// </param>
 811         /// <param name="era">An integer that specifies the era.
 812         /// </param>
 813         /// <returns>A boolean that tells whether the given month is a leap
 814         /// month.
 815         /// </returns>
 816         /// <exception cref="T:System.ArgumentOutOfRangeException">
 817         /// The exception is thrown, if the year, month, or era is not
 818         /// valid.
 819         /// </exception>
 820         public abstract bool IsLeapMonth(int year, int month, int era);
 821
 822         /// <summary>
 823         /// A virtual method that tells whether the given year
 824         /// in the
 825         /// <see cref="M:CurrentEra"/> is a leap year.
 826         /// </summary>
 827         /// <param name="year">An integer that specifies the year in the
 828         /// current era.
 829         /// </param>
 830         /// <returns>A boolean that tells whether the given year is a leap
 831         /// year.
 832         /// </returns>
 833         /// <exception cref="T:System.ArgumentOutOfRangeException">
 834         /// The exception is thrown, if the year is not valid
 835         /// the current era.
 836         /// </exception>
 837         public virtual bool IsLeapYear(int year) {
 838                 return IsLeapYear(year, CurrentEra);
 839         }
 840
 841         /// <summary>
 842         /// Tells when overridden whether the given year
 843         /// is a leap year.
 844         /// </summary>
 845         /// <param name="year">An integer that specifies the year in the
 846         /// given era.
 847         /// </param>
 848         /// <param name="era">An integer that specifies the era.
 849         /// </param>
 850         /// <returns>A boolean that tells whether the given year is a leap
 851         /// year.
 852         /// </returns>
 853         /// <exception cref="T:System.ArgumentOutOfRangeException">
 854         /// The exception is thrown, if the year or era is not
 855         /// valid.
 856         /// </exception>
 857         public abstract bool IsLeapYear(int year, int era);
 858
 859         /// <summary>
 860         /// A virtual method that creates the
 861         /// <see cref="T:System.DateTime"/> from the parameters.
 862         /// </summary>
 863         /// <param name="year">An integer that gives the year in the
 864         /// <see cref="M:CurrentEra"/>.
 865         /// </param>
 866         /// <param name="month">An integer that specifies the month.
 867         /// </param>
 868         /// <param name="day">An integer that specifies the day.
 869         /// </param>
 870         /// <param name="hour">An integer that specifies the hour.
 871         /// </param>
 872         /// <param name="minute">An integer that specifies the minute.
 873         /// </param>
 874         /// <param name="second">An integer that gives the second.
 875         /// </param>
 876         /// <param name="milliseconds">An integer that gives the
 877         /// milliseconds.
 878         /// </param>
 879         /// <returns>A
 880         /// <see cref="T:system.DateTime"/> representig the date and time.
 881         /// </returns>
 882         /// <exception cref="T:System.ArgumentOutOfRangeException">
 883         /// The exception is thrown, if at least one of the parameters
 884         /// is out of range.
 885         /// </exception>
 886         public virtual DateTime ToDateTime(int year, int month, int day,
 887                 int hour, int minute, int second, int millisecond)
 888         {
 889                 return ToDateTime (year, month, day, hour, minute, second,
 890                         millisecond, CurrentEra);
 891         }
 892
 893
 894         /// <summary>
 895         /// When overridden creates the
 896         /// <see cref="T:System.DateTime"/> from the parameters.
 897         /// </summary>
 898         /// <param name="year">An integer that gives the year in the
 899         /// <paramref name="era"/>.
 900         /// </param>
 901         /// <param name="month">An integer that specifies the month.
 902         /// </param>
 903         /// <param name="day">An integer that specifies the day.
 904         /// </param>
 905         /// <param name="hour">An integer that specifies the hour.
 906         /// </param>
 907         /// <param name="minute">An integer that specifies the minute.
 908         /// </param>
 909         /// <param name="second">An integer that gives the second.
 910         /// </param>
 911         /// <param name="milliseconds">An integer that gives the
 912         /// milliseconds.
 913         /// </param>
 914         /// <param name="era">An integer that specifies the era.
 915         /// </param>
 916         /// <returns>A
 917         /// <see cref="T:system.DateTime"/> representig the date and time.
 918         /// </returns>
 919         /// <exception cref="T:System.ArgumentOutOfRangeException">
 920         /// The exception is thrown, if at least one of the parameters
 921         /// is out of range.
 922         /// </exception>
 923         public abstract DateTime ToDateTime(int year, int month, int day,
 924                 int hour, int minute, int second, int millisecond,
 925                 int era);
 926
 927         /// <summary>
 928         /// A virtual method that converts a two-digit year to a four-digit
 929         /// year. It uses the <see cref="M:TwoDigitYearMax"/> property.
 930         /// </summary>
 931         /// <param name="year">An integer that gives the two-digit year.
 932         /// </param>
 933         /// <returns>An integer giving the four digit year.
 934         /// </returns>
 935         /// <exception cref="T:System.ArgumentOutOfRangeException">
 936         /// The exception is thrown if the year is negative or the resulting
 937         /// year is invalid.
 938         /// </exception>
 939         public virtual int ToFourDigitYear(int year) {
 940                 if (year < 0)
 941                         throw new ArgumentOutOfRangeException(
 942                                 "year", "Non-negative number required.");
 943                 /* seems not to be the right thing to do, but .NET is
 944                  * doing it this way.
 945                  */
 946                 if (year <= 99) {
 947                         int year2 = TwoDigitYearMax%100;
 948                         int d = year - year2;
 949                         year = TwoDigitYearMax + d + (d <= 0 ? 0 : -100);
 950                 }
 951                 int era = CurrentEra;
 952                 M_CheckYE(year, ref era);
 953                 return year;
 954         }
 955
 956         // TwoDigitYearMax: Windows reads it from the Registry, we
 957         // should have an XML file with the defaults
 958         /// <summary>
 959         /// The default constructor, is sets the TwoDigitYearMax to 2029.
 960         /// </summary>
 961         /// <remarks>
 962         /// The .NET framework reads the value from the registry.
 963         /// We should implement it here. Currently I set the default values
 964         /// in the ctors of the derived classes, if it is 99.
 965         /// </remarks>
 966         protected Calendar() {
 967                 twoDigitYearMax = 99;
 968         }
 969
 970         /// <summary>Protected field storing the abbreviated era names.
 971         /// </summary>
 972         [NonSerialized]
 973         internal string[] M_AbbrEraNames;
 974         /// <summary>Protected field storing the era names.
 975         /// </summary>
 976         [NonSerialized]
 977         internal string[] M_EraNames;
 978
 979         /// <value>
 980         /// The property stores the era names. It might be overwritten by
 981         /// CultureInfo.
 982         /// </value>
 983         internal string[] AbbreviatedEraNames {
 984                 get {
 985                         if (M_AbbrEraNames == null ||
 986                             M_AbbrEraNames.Length != Eras.Length)
 987                                 throw new Exception(
 988                                         "Internal: M_AbbrEraNames " +
 989                                         "wrong initialized!");
 990                         return (string[])M_AbbrEraNames.Clone();
 991                 }
 992                 set {
 993                         CheckReadOnly ();
 994                         if (value.Length != Eras.Length) {
 995                                 StringWriter sw = new StringWriter();
 996                                 sw.Write("Array length must be equal Eras " +
 997                                         "length {0}.", Eras.Length);
 998                                 throw new ArgumentException(
 999                                         sw.ToString());
1000                         }
1001                         M_AbbrEraNames = (string[])value.Clone();
1002                 }
1003         }
1004
1005         /// <value>
1006         /// The property stores the era names. It might be overwritten by
1007         /// CultureInfo.
1008         /// </value>
1009         internal string[] EraNames {
1010                 get {
1011                         if (M_EraNames == null ||
1012                             M_EraNames.Length != Eras.Length)
1013                                 throw new Exception(
1014                                         "Internal: M_EraNames " +
1015                                         "not initialized!");
1016                         return (string[])M_EraNames.Clone();
1017                 }
1018                 set {
1019                         CheckReadOnly ();
1020                         if (value.Length != Eras.Length) {
1021                                 StringWriter sw = new StringWriter();
1022                                 sw.Write("Array length must be equal Eras " +
1023                                         "length {0}.", Eras.Length);
1024                                 throw new ArgumentException(
1025                                         sw.ToString());
1026                         }
1027                         M_EraNames = (string[])value.Clone();
1028                 }
1029         }
1030
1031         internal int m_currentEraValue; // Unused, by MS serializes this
1032
1033 } // class Calendar
1034
1035 } // namespace System.Globalization