1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
|
# 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.
class TimeZone
include Comparable
attr_reader :name, :utc_offset
# 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).
def initialize(name, utc_offset)
@name = name
@utc_offset = utc_offset
end
# 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.
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
# Compute and return the current time, in the time zone represented by
# +self+.
def now
adjust(Time.now)
end
# Return the current date in this time zone.
def today
now.to_date
end
# Adjust the given time to the time zone represented by +self+.
def adjust(time)
time = time.to_time
time + utc_offset - time.utc_offset
end
# 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.
def unadjust(time)
time = Time.local(*time.to_time.to_a)
time - utc_offset + time.utc_offset
end
# Compare this time zone to the parameter. The two are comapred first on
# their offsets, and then by name.
def <=>(zone)
result = (utc_offset <=> zone.utc_offset)
result = (name <=> zone.name) if result == 0
result
end
# Returns a textual representation of this time zone.
def to_s
"(GMT#{formatted_offset}) #{name}"
end
@@zones = nil
class << self
# Create a new TimeZone instance with the given name and offset.
def create(name, offset)
zone = allocate
zone.send!(:initialize, name, offset)
zone
end
# 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.)
def new(name)
self[name]
end
# 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.
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", "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
# 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.
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
# A regular expression that matches the names of all time zones in
# the USA.
US_ZONES = /US|Arizona|Indiana|Hawaii|Alaska/ unless defined?(US_ZONES)
# A convenience method for returning a collection of TimeZone objects
# for time zones in the USA.
def us_zones
all.find_all { |z| z.name =~ US_ZONES }
end
end
end
|
