Class: TimeZone

Inherits:
Object show all
Includes:
Comparable
Defined in:
lib/active_support/values/time_zone.rb

Overview

A value object representing a time zone. A time zone is simply a named offset (in seconds) from GMT. Note that two time zone objects are only equivalent if they have both the same offset, and the same name.

A TimeZone instance may be used to convert a Time value to the corresponding time zone.

The class also includes #all, which returns a list of all TimeZone objects.

Constant Summary collapse

US_ZONES =

A regular expression that matches the names of all time zones in the USA.

/US|Arizona|Indiana|Hawaii|Alaska/
@@zones =
nil

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(name, utc_offset) ⇒ TimeZone

Create a new TimeZone object with the given name and offset. The offset is the number of seconds that this time zone is offset from UTC (GMT). Seconds were chosen as the offset unit because that is the unit that Ruby uses to represent time zone offsets (see Time#utc_offset).


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# File 'lib/active_support/values/time_zone.rb', line 18

def initialize(name, utc_offset)
  @name = name
  @utc_offset = utc_offset
end

Instance Attribute Details

#nameObject (readonly)

Returns the value of attribute name


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# File 'lib/active_support/values/time_zone.rb', line 12

def name
  @name
end

#utc_offsetObject (readonly)

Returns the value of attribute utc_offset


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# File 'lib/active_support/values/time_zone.rb', line 12

def utc_offset
  @utc_offset
end

Class Method Details

.[](arg) ⇒ Object

Locate a specific time zone object. If the argument is a string, it is interpreted to mean the name of the timezone to locate. If it is a numeric value it is either the hour offset, or the second offset, of the timezone to find. (The first one with that offset will be returned.) Returns nil if no such time zone is known to the system.


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# File 'lib/active_support/values/time_zone.rb', line 158

def [](arg)
  case arg
    when String
      all.find { |z| z.name == arg }
    when Numeric
      arg *= 3600 if arg.abs <= 13
      all.find { |z| z.utc_offset == arg.to_i }
    else
      raise ArgumentError, "invalid argument to TimeZone[]: #{arg.inspect}"
  end
end

.allObject

Return an array of all TimeZone objects. There are multiple TimeZone objects per time zone, in many cases, to make it easier for users to find their own time zone.


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# File 'lib/active_support/values/time_zone.rb', line 93

def all
  unless @@zones
    @@zones = []
    [[-43_200, "International Date Line West" ],
     [-39_600, "Midway Island", "Samoa" ],
     [-36_000, "Hawaii" ],
     [-32_400, "Alaska" ],
     [-28_800, "Pacific Time (US & Canada)", "Tijuana" ],
     [-25_200, "Mountain Time (US & Canada)", "Chihuahua", "La Paz",
               "Mazatlan", "Arizona" ],
     [-21_600, "Central Time (US & Canada)", "Saskatchewan", "Guadalajara",
               "Mexico City", "Monterrey", "Central America" ],
     [-18_000, "Eastern Time (US & Canada)", "Indiana (East)", "Bogota",
               "Lima", "Quito" ],
     [-14_400, "Atlantic Time (Canada)", "Caracas", "La Paz", "Santiago" ],
     [-12_600, "Newfoundland" ],
     [-10_800, "Brasilia", "Buenos Aires", "Georgetown", "Greenland" ],
     [ -7_200, "Mid-Atlantic" ],
     [ -3_600, "Azores", "Cape Verde Is." ],
     [      0, "Dublin", "Edinburgh", "Lisbon", "London", "Casablanca",
               "Monrovia" ],
     [  3_600, "Belgrade", "Bratislava", "Budapest", "Ljubljana", "Prague",
               "Sarajevo", "Skopje", "Warsaw", "Zagreb", "Brussels",
               "Copenhagen", "Madrid", "Paris", "Amsterdam", "Berlin",
               "Bern", "Rome", "Stockholm", "Vienna",
               "West Central Africa" ],
     [  7_200, "Bucharest", "Cairo", "Helsinki", "Kyev", "Riga", "Sofia",
               "Tallinn", "Vilnius", "Athens", "Istanbul", "Minsk",
               "Jerusalem", "Harare", "Pretoria" ],
     [ 10_800, "Moscow", "St. Petersburg", "Volgograd", "Kuwait", "Riyadh",
               "Nairobi", "Baghdad" ],
     [ 12_600, "Tehran" ],
     [ 14_400, "Abu Dhabi", "Muscat", "Baku", "Tbilisi", "Yerevan" ],
     [ 16_200, "Kabul" ],
     [ 18_000, "Ekaterinburg", "Islamabad", "Karachi", "Tashkent" ],
     [ 19_800, "Chennai", "Kolkata", "Mumbai", "New Delhi" ],
     [ 20_700, "Kathmandu" ],
     [ 21_600, "Astana", "Dhaka", "Sri Jayawardenepura", "Almaty",
               "Novosibirsk" ],
     [ 23_400, "Rangoon" ],
     [ 25_200, "Bangkok", "Hanoi", "Jakarta", "Krasnoyarsk" ],
     [ 28_800, "Beijing", "Chongqing", "Hong Kong", "Urumqi",
               "Kuala Lumpur", "Singapore", "Taipei", "Perth", "Irkutsk",
               "Ulaan Bataar" ],
     [ 32_400, "Seoul", "Osaka", "Sapporo", "Tokyo", "Yakutsk" ],
     [ 34_200, "Darwin", "Adelaide" ],
     [ 36_000, "Canberra", "Melbourne", "Sydney", "Brisbane", "Hobart",
               "Vladivostok", "Guam", "Port Moresby" ],
     [ 39_600, "Magadan", "Solomon Is.", "New Caledonia" ],
     [ 43_200, "Fiji", "Kamchatka", "Marshall Is.", "Auckland",
               "Wellington" ],
     [ 46_800, "Nuku'alofa" ]].
    each do |offset, *places|
      places.each { |place| @@zones << create(place, offset).freeze }
    end
    @@zones.sort!
  end
  @@zones
end

.create(name, offset) ⇒ Object

Create a new TimeZone instance with the given name and offset.


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# File 'lib/active_support/values/time_zone.rb', line 77

def create(name, offset)
  zone = allocate
  zone.send :initialize, name, offset
  zone
end

.new(name) ⇒ Object

Return a TimeZone instance with the given name, or nil if no such TimeZone instance exists. (This exists to support the use of this class with the #composed_of macro.)


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# File 'lib/active_support/values/time_zone.rb', line 86

def new(name)
  self[name]
end

.us_zonesObject

A convenience method for returning a collection of TimeZone objects for time zones in the USA.


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# File 'lib/active_support/values/time_zone.rb', line 176

def us_zones
  all.find_all { |z| z.name =~ US_ZONES }
end

Instance Method Details

#<=>(zone) ⇒ Object

Compare this time zone to the parameter. The two are comapred first on their offsets, and then by name.


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# File 'lib/active_support/values/time_zone.rb', line 62

def <=>(zone)
  result = (utc_offset <=> zone.utc_offset)
  result = (name <=> zone.name) if result == 0
  result
end

#adjust(time) ⇒ Object

Adjust the given time to the time zone represented by self.


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# File 'lib/active_support/values/time_zone.rb', line 47

def adjust(time)
  time = time.to_time
  time + utc_offset - time.utc_offset
end

#formatted_offset(colon = true) ⇒ Object

Returns the offset of this time zone as a formatted string, of the format “+HH:MM”. If the offset is zero, this returns the empty string. If colon is false, a colon will not be inserted into the result.


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# File 'lib/active_support/values/time_zone.rb', line 27

def formatted_offset( colon=true )
  return "" if utc_offset == 0
  sign = (utc_offset < 0 ? -1 : 1)
  hours = utc_offset.abs / 3600
  minutes = (utc_offset.abs % 3600) / 60
  "%+03d%s%02d" % [ hours * sign, colon ? ":" : "", minutes ]
end

#nowObject

Compute and return the current time, in the time zone represented by self.


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# File 'lib/active_support/values/time_zone.rb', line 37

def now
  adjust(Time.now)
end

#to_sObject

Returns a textual representation of this time zone.


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# File 'lib/active_support/values/time_zone.rb', line 69

def to_s
  "(GMT#{formatted_offset}) #{name}"
end

#todayObject

Return the current date in this time zone.


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# File 'lib/active_support/values/time_zone.rb', line 42

def today
  now.to_date
end

#unadjust(time) ⇒ Object

Reinterprets the given time value as a time in the current time zone, and then adjusts it to return the corresponding time in the local time zone.


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# File 'lib/active_support/values/time_zone.rb', line 55

def unadjust(time)
  time = Time.local(*time.to_time.to_a)
  time - utc_offset + time.utc_offset
end