js/src/vm/DateObject.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
   2  * vim: set ts=8 sts=2 et sw=2 tw=80:
   3  * This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef vm_DateObject_h_
   8 #define vm_DateObject_h_
   9
  10 #include "js/Date.h"
  11 #include "js/Value.h"
  12 #include "vm/DateTime.h"
  13 #include "vm/NativeObject.h"
  14
  15 namespace js {
  16
  17 class DateObject : public NativeObject {
  18   // Time in milliseconds since the (Unix) epoch.
  19   static const uint32_t UTC_TIME_SLOT = 0;
  20
  21   // Raw time zone offset in seconds, i.e. without daylight saving adjustment,
  22   // of the current system zone.
  23   //
  24   // This value is exclusively used to verify the cached slots are still valid.
  25   //
  26   // It is NOT the return value of Date.prototype.getTimezoneOffset()!
  27   static const uint32_t UTC_TIME_ZONE_OFFSET_SLOT = 1;
  28
  29   /*
  30    * Cached slots holding local properties of the date.
  31    * These are undefined until the first actual lookup occurs
  32    * and are reset to undefined whenever the date's time is modified.
  33    */
  34   static const uint32_t COMPONENTS_START_SLOT = 2;
  35
  36   static const uint32_t LOCAL_TIME_SLOT = COMPONENTS_START_SLOT + 0;
  37   static const uint32_t LOCAL_YEAR_SLOT = COMPONENTS_START_SLOT + 1;
  38   static const uint32_t LOCAL_MONTH_SLOT = COMPONENTS_START_SLOT + 2;
  39   static const uint32_t LOCAL_DATE_SLOT = COMPONENTS_START_SLOT + 3;
  40   static const uint32_t LOCAL_DAY_SLOT = COMPONENTS_START_SLOT + 4;
  41
  42   /*
  43    * Unlike the above slots that hold LocalTZA-adjusted component values,
  44    * LOCAL_SECONDS_INTO_YEAR_SLOT holds a composite value that can be used
  45    * to compute LocalTZA-adjusted hours, minutes, and seconds values.
  46    * Specifically, LOCAL_SECONDS_INTO_YEAR_SLOT holds the number of
  47    * LocalTZA-adjusted seconds into the year. Unix timestamps ignore leap
  48    * seconds, so recovering hours/minutes/seconds requires only trivial
  49    * division/modulus operations.
  50    */
  51   static const uint32_t LOCAL_SECONDS_INTO_YEAR_SLOT =
  52       COMPONENTS_START_SLOT + 5;
  53
  54   static const uint32_t RESERVED_SLOTS = LOCAL_SECONDS_INTO_YEAR_SLOT + 1;
  55
  56  public:
  57   static const JSClass class_;
  58   static const JSClass protoClass_;
  59
  60   js::DateTimeInfo::ForceUTC forceUTC() const;
  61
  62   JS::ClippedTime clippedTime() const {
  63     double t = getFixedSlot(UTC_TIME_SLOT).toDouble();
  64     JS::ClippedTime clipped = JS::TimeClip(t);
  65     MOZ_ASSERT(mozilla::NumbersAreIdentical(clipped.toDouble(), t));
  66     return clipped;
  67   }
  68
  69   const js::Value& UTCTime() const { return getFixedSlot(UTC_TIME_SLOT); }
  70   const js::Value& localTime() const {
  71     return getReservedSlot(LOCAL_TIME_SLOT);
  72   }
  73
  74   // Set UTC time to a given time and invalidate cached local time.
  75   void setUTCTime(JS::ClippedTime t);
  76   void setUTCTime(JS::ClippedTime t, MutableHandleValue vp);
  77
  78   // Cache the local time, year, month, and so forth of the object.
  79   // If UTC time is not finite (e.g., NaN), the local time
  80   // slots will be set to the UTC time without conversion.
  81   void fillLocalTimeSlots();
  82
  83   const js::Value& localYear() const {
  84     return getReservedSlot(LOCAL_YEAR_SLOT);
  85   }
  86   const js::Value& localMonth() const {
  87     return getReservedSlot(LOCAL_MONTH_SLOT);
  88   }
  89   const js::Value& localDate() const {
  90     return getReservedSlot(LOCAL_DATE_SLOT);
  91   }
  92   const js::Value& localDay() const { return getReservedSlot(LOCAL_DAY_SLOT); }
  93
  94   const js::Value& localSecondsIntoYear() const {
  95     return getReservedSlot(LOCAL_SECONDS_INTO_YEAR_SLOT);
  96   }
  97 };
  98
  99 }  // namespace js
 100
 101 #endif  // vm_DateObject_h_