Class: CoreExt::TimeZone

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

Overview

The TimeZone class serves as a wrapper around TZInfo::Timezone instances. It allows us to do the following:

  • Limit the set of zones provided by TZInfo to a meaningful subset of 146 zones.

  • Retrieve and display zones with a friendlier name (e.g., “Eastern Time (US & Canada)” instead of “America/New_York”).

  • Lazily load TZInfo::Timezone instances only when they’re needed.

  • Create CoreExt::TimeWithZone instances via TimeZone’s local, parse, at and now methods.

If you set config.time_zone in the Rails Application, you can access this TimeZone object via Time.zone:

# application.rb:
class Application < Rails::Application
  config.time_zone = 'Eastern Time (US & Canada)'
end

Time.zone      # => #<CoreExt::TimeZone:0x514834...>
Time.zone.name # => "Eastern Time (US & Canada)"
Time.zone.now  # => Sun, 18 May 2008 14:30:44 EDT -04:00

Constant Summary collapse

MAPPING =

Keys are Rails TimeZone names, values are TZInfo identifiers.

{
  "International Date Line West" => "Pacific/Midway",
  "Midway Island"                => "Pacific/Midway",
  "American Samoa"               => "Pacific/Pago_Pago",
  "Hawaii"                       => "Pacific/Honolulu",
  "Alaska"                       => "America/Juneau",
  "Pacific Time (US & Canada)"   => "America/Los_Angeles",
  "Tijuana"                      => "America/Tijuana",
  "Mountain Time (US & Canada)"  => "America/Denver",
  "Arizona"                      => "America/Phoenix",
  "Chihuahua"                    => "America/Chihuahua",
  "Mazatlan"                     => "America/Mazatlan",
  "Central Time (US & Canada)"   => "America/Chicago",
  "Saskatchewan"                 => "America/Regina",
  "Guadalajara"                  => "America/Mexico_City",
  "Mexico City"                  => "America/Mexico_City",
  "Monterrey"                    => "America/Monterrey",
  "Central America"              => "America/Guatemala",
  "Eastern Time (US & Canada)"   => "America/New_York",
  "Indiana (East)"               => "America/Indiana/Indianapolis",
  "Bogota"                       => "America/Bogota",
  "Lima"                         => "America/Lima",
  "Quito"                        => "America/Lima",
  "Atlantic Time (Canada)"       => "America/Halifax",
  "Caracas"                      => "America/Caracas",
  "La Paz"                       => "America/La_Paz",
  "Santiago"                     => "America/Santiago",
  "Newfoundland"                 => "America/St_Johns",
  "Brasilia"                     => "America/Sao_Paulo",
  "Buenos Aires"                 => "America/Argentina/Buenos_Aires",
  "Montevideo"                   => "America/Montevideo",
  "Georgetown"                   => "America/Guyana",
  "Greenland"                    => "America/Godthab",
  "Mid-Atlantic"                 => "Atlantic/South_Georgia",
  "Azores"                       => "Atlantic/Azores",
  "Cape Verde Is."               => "Atlantic/Cape_Verde",
  "Dublin"                       => "Europe/Dublin",
  "Edinburgh"                    => "Europe/London",
  "Lisbon"                       => "Europe/Lisbon",
  "London"                       => "Europe/London",
  "Casablanca"                   => "Africa/Casablanca",
  "Monrovia"                     => "Africa/Monrovia",
  "UTC"                          => "Etc/UTC",
  "Belgrade"                     => "Europe/Belgrade",
  "Bratislava"                   => "Europe/Bratislava",
  "Budapest"                     => "Europe/Budapest",
  "Ljubljana"                    => "Europe/Ljubljana",
  "Prague"                       => "Europe/Prague",
  "Sarajevo"                     => "Europe/Sarajevo",
  "Skopje"                       => "Europe/Skopje",
  "Warsaw"                       => "Europe/Warsaw",
  "Zagreb"                       => "Europe/Zagreb",
  "Brussels"                     => "Europe/Brussels",
  "Copenhagen"                   => "Europe/Copenhagen",
  "Madrid"                       => "Europe/Madrid",
  "Paris"                        => "Europe/Paris",
  "Amsterdam"                    => "Europe/Amsterdam",
  "Berlin"                       => "Europe/Berlin",
  "Bern"                         => "Europe/Berlin",
  "Rome"                         => "Europe/Rome",
  "Stockholm"                    => "Europe/Stockholm",
  "Vienna"                       => "Europe/Vienna",
  "West Central Africa"          => "Africa/Algiers",
  "Bucharest"                    => "Europe/Bucharest",
  "Cairo"                        => "Africa/Cairo",
  "Helsinki"                     => "Europe/Helsinki",
  "Kyiv"                         => "Europe/Kiev",
  "Riga"                         => "Europe/Riga",
  "Sofia"                        => "Europe/Sofia",
  "Tallinn"                      => "Europe/Tallinn",
  "Vilnius"                      => "Europe/Vilnius",
  "Athens"                       => "Europe/Athens",
  "Istanbul"                     => "Europe/Istanbul",
  "Minsk"                        => "Europe/Minsk",
  "Jerusalem"                    => "Asia/Jerusalem",
  "Harare"                       => "Africa/Harare",
  "Pretoria"                     => "Africa/Johannesburg",
  "Kaliningrad"                  => "Europe/Kaliningrad",
  "Moscow"                       => "Europe/Moscow",
  "St. Petersburg"               => "Europe/Moscow",
  "Volgograd"                    => "Europe/Volgograd",
  "Samara"                       => "Europe/Samara",
  "Kuwait"                       => "Asia/Kuwait",
  "Riyadh"                       => "Asia/Riyadh",
  "Nairobi"                      => "Africa/Nairobi",
  "Baghdad"                      => "Asia/Baghdad",
  "Tehran"                       => "Asia/Tehran",
  "Abu Dhabi"                    => "Asia/Muscat",
  "Muscat"                       => "Asia/Muscat",
  "Baku"                         => "Asia/Baku",
  "Tbilisi"                      => "Asia/Tbilisi",
  "Yerevan"                      => "Asia/Yerevan",
  "Kabul"                        => "Asia/Kabul",
  "Ekaterinburg"                 => "Asia/Yekaterinburg",
  "Islamabad"                    => "Asia/Karachi",
  "Karachi"                      => "Asia/Karachi",
  "Tashkent"                     => "Asia/Tashkent",
  "Chennai"                      => "Asia/Kolkata",
  "Kolkata"                      => "Asia/Kolkata",
  "Mumbai"                       => "Asia/Kolkata",
  "New Delhi"                    => "Asia/Kolkata",
  "Kathmandu"                    => "Asia/Kathmandu",
  "Astana"                       => "Asia/Dhaka",
  "Dhaka"                        => "Asia/Dhaka",
  "Sri Jayawardenepura"          => "Asia/Colombo",
  "Almaty"                       => "Asia/Almaty",
  "Novosibirsk"                  => "Asia/Novosibirsk",
  "Rangoon"                      => "Asia/Rangoon",
  "Bangkok"                      => "Asia/Bangkok",
  "Hanoi"                        => "Asia/Bangkok",
  "Jakarta"                      => "Asia/Jakarta",
  "Krasnoyarsk"                  => "Asia/Krasnoyarsk",
  "Beijing"                      => "Asia/Shanghai",
  "Chongqing"                    => "Asia/Chongqing",
  "Hong Kong"                    => "Asia/Hong_Kong",
  "Urumqi"                       => "Asia/Urumqi",
  "Kuala Lumpur"                 => "Asia/Kuala_Lumpur",
  "Singapore"                    => "Asia/Singapore",
  "Taipei"                       => "Asia/Taipei",
  "Perth"                        => "Australia/Perth",
  "Irkutsk"                      => "Asia/Irkutsk",
  "Ulaanbaatar"                  => "Asia/Ulaanbaatar",
  "Seoul"                        => "Asia/Seoul",
  "Osaka"                        => "Asia/Tokyo",
  "Sapporo"                      => "Asia/Tokyo",
  "Tokyo"                        => "Asia/Tokyo",
  "Yakutsk"                      => "Asia/Yakutsk",
  "Darwin"                       => "Australia/Darwin",
  "Adelaide"                     => "Australia/Adelaide",
  "Canberra"                     => "Australia/Melbourne",
  "Melbourne"                    => "Australia/Melbourne",
  "Sydney"                       => "Australia/Sydney",
  "Brisbane"                     => "Australia/Brisbane",
  "Hobart"                       => "Australia/Hobart",
  "Vladivostok"                  => "Asia/Vladivostok",
  "Guam"                         => "Pacific/Guam",
  "Port Moresby"                 => "Pacific/Port_Moresby",
  "Magadan"                      => "Asia/Magadan",
  "Srednekolymsk"                => "Asia/Srednekolymsk",
  "Solomon Is."                  => "Pacific/Guadalcanal",
  "New Caledonia"                => "Pacific/Noumea",
  "Fiji"                         => "Pacific/Fiji",
  "Kamchatka"                    => "Asia/Kamchatka",
  "Marshall Is."                 => "Pacific/Majuro",
  "Auckland"                     => "Pacific/Auckland",
  "Wellington"                   => "Pacific/Auckland",
  "Nuku'alofa"                   => "Pacific/Tongatapu",
  "Tokelau Is."                  => "Pacific/Fakaofo",
  "Chatham Is."                  => "Pacific/Chatham",
  "Samoa"                        => "Pacific/Apia"
}
UTC_OFFSET_WITH_COLON = 
'%s%02d:%02d'
UTC_OFFSET_WITHOUT_COLON = 
UTC_OFFSET_WITH_COLON.tr(':', '')

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(name, utc_offset = nil, tzinfo = nil) ⇒ 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/core_ext/time_zone.rb', line 265

def initialize(name, utc_offset = nil, tzinfo = nil)
  @name = name
  @utc_offset = utc_offset
  @tzinfo = tzinfo || TimeZone.find_tzinfo(name)
  @current_period = nil
end

Instance Attribute Details

#name ⇒ Object (readonly)

Returns the value of attribute name.



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# File 'lib/core_ext/time_zone.rb', line 258

def name
  @name
end

#tzinfo ⇒ Object (readonly)

Returns the value of attribute tzinfo.



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# File 'lib/core_ext/time_zone.rb', line 259

def tzinfo
  @tzinfo
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/core_ext/time_zone.rb', line 226

def [](arg)
  case arg
    when String
    begin
      @lazy_zones_map[arg] ||= create(arg)
    rescue TZInfo::InvalidTimezoneIdentifier
      nil
    end
    when Numeric, CoreExt::Duration
      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

.all ⇒ Object

Returns 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/core_ext/time_zone.rb', line 217

def all
  @zones ||= zones_map.values.sort
end

.create ⇒ Object 



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# File 'lib/core_ext/time_zone.rb', line 205

alias_method :create, :new

.find_tzinfo(name) ⇒ Object 



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# File 'lib/core_ext/time_zone.rb', line 201

def find_tzinfo(name)
  TZInfo::Timezone.new(MAPPING[name] || name)
end

.new(name) ⇒ Object

Returns 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/core_ext/time_zone.rb', line 210

def new(name)
  self[name]
end

.seconds_to_utc_offset(seconds, colon = true) ⇒ Object

Assumes self represents an offset from UTC in seconds (as returned from Time#utc_offset) and turns this into an +HH:MM formatted string.

CoreExt::TimeZone.seconds_to_utc_offset(-21_600) # => "-06:00"



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# File 'lib/core_ext/time_zone.rb', line 193

def seconds_to_utc_offset(seconds, colon = true)
  format = colon ? UTC_OFFSET_WITH_COLON : UTC_OFFSET_WITHOUT_COLON
  sign = (seconds < 0 ? '-' : '+')
  hours = seconds.abs / 3600
  minutes = (seconds.abs % 3600) / 60
  format % [sign, hours, minutes]
end

.us_zones ⇒ Object

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



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# File 'lib/core_ext/time_zone.rb', line 244

def us_zones
  @us_zones ||= all.find_all { |z| z.name =~ /US|Arizona|Indiana|Hawaii|Alaska/ }
end

Instance Method Details

#<=>(zone) ⇒ Object

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



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# File 'lib/core_ext/time_zone.rb', line 294

def <=>(zone)
  return unless zone.respond_to? :utc_offset
  result = (utc_offset <=> zone.utc_offset)
  result = (name <=> zone.name) if result == 0
  result
end

#=~(re) ⇒ Object

Compare #name and TZInfo identifier to a supplied regexp, returning true if a match is found.



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# File 'lib/core_ext/time_zone.rb', line 303

def =~(re)
  re === name || re === MAPPING[name]
end

#at(secs) ⇒ Object

Method for creating new CoreExt::TimeWithZone instance in time zone of self from number of seconds since the Unix epoch.

Time.zone = 'Hawaii'        # => "Hawaii"
Time.utc(2000).to_f         # => 946684800.0
Time.zone.at(946684800.0)   # => Fri, 31 Dec 1999 14:00:00 HST -10:00



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# File 'lib/core_ext/time_zone.rb', line 328

def at(secs)
  Time.at(secs).utc.in_time_zone(self)
end

#encode_with(coder) ⇒ Object

:nodoc:



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# File 'lib/core_ext/time_zone.rb', line 433

def encode_with(coder) #:nodoc:
  coder.tag ="!ruby/object:#{self.class}"
  coder.map = { 'name' => tzinfo.name }
end

#formatted_offset(colon = true, alternate_utc_string = nil) ⇒ Object

Returns a formatted string of the offset from UTC, or an alternative string if the time zone is already UTC.

zone = CoreExt::TimeZone['Central Time (US & Canada)']
zone.formatted_offset        # => "-06:00"
zone.formatted_offset(false) # => "-0600"



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# File 'lib/core_ext/time_zone.rb', line 288

def formatted_offset(colon=true, alternate_utc_string = nil)
  utc_offset == 0 && alternate_utc_string || self.class.seconds_to_utc_offset(utc_offset, colon)
end

#init_with(coder) ⇒ Object

:nodoc:



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# File 'lib/core_ext/time_zone.rb', line 429

def init_with(coder) #:nodoc:
  initialize(coder['name'])
end

#local(*args) ⇒ Object

Method for creating new CoreExt::TimeWithZone instance in time zone of self from given values.

Time.zone = 'Hawaii'                    # => "Hawaii"
Time.zone.local(2007, 2, 1, 15, 30, 45) # => Thu, 01 Feb 2007 15:30:45 HST -10:00



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# File 'lib/core_ext/time_zone.rb', line 317

def local(*args)
  time = Time.utc(*args)
  CoreExt::TimeWithZone.new(nil, self, time)
end

#local_to_utc(time, dst = true) ⇒ Object

Adjust the given time to the simultaneous time in UTC. Returns a Time.utc() instance.



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# File 'lib/core_ext/time_zone.rb', line 409

def local_to_utc(time, dst=true)
  tzinfo.local_to_utc(time, dst)
end

#now ⇒ Object

Returns an CoreExt::TimeWithZone instance representing the current time in the time zone represented by self.

Time.zone = 'Hawaii'  # => "Hawaii"
Time.zone.now         # => Wed, 23 Jan 2008 20:24:27 HST -10:00



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# File 'lib/core_ext/time_zone.rb', line 381

def now
  time_now.utc.in_time_zone(self)
end

#parse(str, now = now()) ⇒ Object

Method for creating new CoreExt::TimeWithZone instance in time zone of self from parsed string.

Time.zone = 'Hawaii'                   # => "Hawaii"
Time.zone.parse('1999-12-31 14:00:00') # => Fri, 31 Dec 1999 14:00:00 HST -10:00

If upper components are missing from the string, they are supplied from TimeZone#now:

Time.zone.now               # => Fri, 31 Dec 1999 14:00:00 HST -10:00
Time.zone.parse('22:30:00') # => Fri, 31 Dec 1999 22:30:00 HST -10:00

However, if the date component is not provided, but any other upper components are supplied, then the day of the month defaults to 1:

Time.zone.parse('Mar 2000') # => Wed, 01 Mar 2000 00:00:00 HST -10:00



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# File 'lib/core_ext/time_zone.rb', line 348

def parse(str, now=now())
  parts_to_time(Date._parse(str, false), now)
end

#period_for_local(time, dst = true) ⇒ Object

Available so that TimeZone instances respond like TZInfo::Timezone instances.



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# File 'lib/core_ext/time_zone.rb', line 421

def period_for_local(time, dst=true)
  tzinfo.period_for_local(time, dst)
end

#period_for_utc(time) ⇒ Object

Available so that TimeZone instances respond like TZInfo::Timezone instances.



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# File 'lib/core_ext/time_zone.rb', line 415

def period_for_utc(time)
  tzinfo.period_for_utc(time)
end

#periods_for_local(time) ⇒ Object

:nodoc:



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# File 'lib/core_ext/time_zone.rb', line 425

def periods_for_local(time) #:nodoc:
  tzinfo.periods_for_local(time)
end

#strptime(str, format, now = now()) ⇒ Object

Parses str according to format and returns an CoreExt::TimeWithZone.

Assumes that str is a time in the time zone self, unless format includes an explicit time zone. (This is the same behavior as parse.) In either case, the returned TimeWithZone has the timezone of self.

Time.zone = 'Hawaii'                   # => "Hawaii"
Time.zone.strptime('1999-12-31 14:00:00', '%Y-%m-%d %H:%M:%S') # => Fri, 31 Dec 1999 14:00:00 HST -10:00

If upper components are missing from the string, they are supplied from TimeZone#now:

Time.zone.now                              # => Fri, 31 Dec 1999 14:00:00 HST -10:00
Time.zone.strptime('22:30:00', '%H:%M:%S') # => Fri, 31 Dec 1999 22:30:00 HST -10:00

However, if the date component is not provided, but any other upper components are supplied, then the day of the month defaults to 1:

Time.zone.strptime('Mar 2000', '%b %Y') # => Wed, 01 Mar 2000 00:00:00 HST -10:00



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# File 'lib/core_ext/time_zone.rb', line 372

def strptime(str, format, now=now())
  parts_to_time(DateTime._strptime(str, format), now)
end

#to_s ⇒ Object

Returns a textual representation of this time zone.



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# File 'lib/core_ext/time_zone.rb', line 308

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

#today ⇒ Object

Returns the current date in this time zone.



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# File 'lib/core_ext/time_zone.rb', line 386

def today
  tzinfo.now.to_date
end

#tomorrow ⇒ Object

Returns the next date in this time zone.



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# File 'lib/core_ext/time_zone.rb', line 391

def tomorrow
  today + 1
end

#utc_offset ⇒ Object

Returns the offset of this time zone from UTC in seconds.



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# File 'lib/core_ext/time_zone.rb', line 273

def utc_offset
  if @utc_offset
    @utc_offset
  else
    @current_period ||= tzinfo.current_period if tzinfo
    @current_period.utc_offset if @current_period
  end
end

#utc_to_local(time) ⇒ Object

Adjust the given time to the simultaneous time in the time zone represented by self. Returns a Time.utc() instance – if you want an CoreExt::TimeWithZone instance, use Time#in_time_zone() instead.



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# File 'lib/core_ext/time_zone.rb', line 403

def utc_to_local(time)
  tzinfo.utc_to_local(time)
end

#yesterday ⇒ Object

Returns the previous date in this time zone.



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# File 'lib/core_ext/time_zone.rb', line 396

def yesterday
  today - 1
end