1 #--
2 # Copyright (c) 2005-2006 Philip Ross
3 #
4 # Permission is hereby granted, free of charge, to any person obtaining a copy
5 # of this software and associated documentation files (the "Software"), to deal
6 # in the Software without restriction, including without limitation the rights
7 # to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
8 # copies of the Software, and to permit persons to whom the Software is
9 # furnished to do so, subject to the following conditions:
10 #
11 # The above copyright notice and this permission notice shall be included in all
12 # copies or substantial portions of the Software.
13 #
14 # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
15 # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
16 # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
17 # AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
18 # LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
19 # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
20 # THE SOFTWARE.
21 #++
22
23 require 'tzinfo/offset_rationals'
24 require 'tzinfo/time_or_datetime'
25
26 module TZInfo
27 # A period of time in a timezone where the same offset from UTC applies.
28 #
29 # All the methods that take times accept instances of Time, DateTime or
30 # integer timestamps.
31 class TimezonePeriod
32 # The TimezoneTransitionInfo that defines the start of this TimezonePeriod
33 # (may be nil if unbounded).
34 attr_reader :start_transition
35
36 # The TimezoneTransitionInfo that defines the end of this TimezonePeriod
37 # (may be nil if unbounded).
38 attr_reader :end_transition
39
40 # The TimezoneOffsetInfo for this period.
41 attr_reader :offset
42
43 # Initializes a new TimezonePeriod.
44 def initialize(start_transition, end_transition, offset = nil)
45 @start_transition = start_transition
46 @end_transition = end_transition
47
48 if offset
49 raise ArgumentError, 'Offset specified with transitions' if @start_transition || @end_transition
50 @offset = offset
51 else
52 if @start_transition
53 @offset = @start_transition.offset
54 elsif @end_transition
55 @offset = @end_transition.previous_offset
56 else
57 raise ArgumentError, 'No offset specified and no transitions to determine it from'
58 end
59 end
60
61 @utc_total_offset_rational = nil
62 end
63
64 # Base offset of the timezone from UTC (seconds).
65 def utc_offset
66 @offset.utc_offset
67 end
68
69 # Offset from the local time where daylight savings is in effect (seconds).
70 # E.g.: utc_offset could be -5 hours. Normally, std_offset would be 0.
71 # During daylight savings, std_offset would typically become +1 hours.
72 def std_offset
73 @offset.std_offset
74 end
75
76 # The identifier of this period, e.g. "GMT" (Greenwich Mean Time) or "BST"
77 # (British Summer Time) for "Europe/London". The returned identifier is a
78 # symbol.
79 def abbreviation
80 @offset.abbreviation
81 end
82 alias :zone_identifier :abbreviation
83
84 # Total offset from UTC (seconds). Equal to utc_offset + std_offset.
85 def utc_total_offset
86 @offset.utc_total_offset
87 end
88
89 # Total offset from UTC (days). Result is a Rational.
90 def utc_total_offset_rational
91 unless @utc_total_offset_rational
92 @utc_total_offset_rational = OffsetRationals.rational_for_offset(utc_total_offset)
93 end
94 @utc_total_offset_rational
95 end
96
97 # The start time of the period in UTC as a DateTime. May be nil if unbounded.
98 def utc_start
99 @start_transition ? @start_transition.at.to_datetime : nil
100 end
101
102 # The end time of the period in UTC as a DateTime. May be nil if unbounded.
103 def utc_end
104 @end_transition ? @end_transition.at.to_datetime : nil
105 end
106
107 # The start time of the period in local time as a DateTime. May be nil if
108 # unbounded.
109 def local_start
110 @start_transition ? @start_transition.local_start.to_datetime : nil
111 end
112
113 # The end time of the period in local time as a DateTime. May be nil if
114 # unbounded.
115 def local_end
116 @end_transition ? @end_transition.local_end.to_datetime : nil
117 end
118
119 # true if daylight savings is in effect for this period; otherwise false.
120 def dst?
121 @offset.dst?
122 end
123
124 # true if this period is valid for the given UTC DateTime; otherwise false.
125 def valid_for_utc?(utc)
126 utc_after_start?(utc) && utc_before_end?(utc)
127 end
128
129 # true if the given UTC DateTime is after the start of the period
130 # (inclusive); otherwise false.
131 def utc_after_start?(utc)
132 !@start_transition || @start_transition.at <= utc
133 end
134
135 # true if the given UTC DateTime is before the end of the period
136 # (exclusive); otherwise false.
137 def utc_before_end?(utc)
138 !@end_transition || @end_transition.at > utc
139 end
140
141 # true if this period is valid for the given local DateTime; otherwise false.
142 def valid_for_local?(local)
143 local_after_start?(local) && local_before_end?(local)
144 end
145
146 # true if the given local DateTime is after the start of the period
147 # (inclusive); otherwise false.
148 def local_after_start?(local)
149 !@start_transition || @start_transition.local_start <= local
150 end
151
152 # true if the given local DateTime is before the end of the period
153 # (exclusive); otherwise false.
154 def local_before_end?(local)
155 !@end_transition || @end_transition.local_end > local
156 end
157
158 # Converts a UTC DateTime to local time based on the offset of this period.
159 def to_local(utc)
160 @offset.to_local(utc)
161 end
162
163 # Converts a local DateTime to UTC based on the offset of this period.
164 def to_utc(local)
165 @offset.to_utc(local)
166 end
167
168 # Returns true if this TimezonePeriod is equal to p. This compares the
169 # start_transition, end_transition and offset using ==.
170 def ==(p)
171 p.respond_to?(:start_transition) && p.respond_to?(:end_transition) &&
172 p.respond_to?(:offset) && start_transition == p.start_transition &&
173 end_transition == p.end_transition && offset == p.offset
174 end
175
176 # Returns true if this TimezonePeriods is equal to p. This compares the
177 # start_transition, end_transition and offset using eql?
178 def eql?(p)
179 p.respond_to?(:start_transition) && p.respond_to?(:end_transition) &&
180 p.respond_to?(:offset) && start_transition.eql?(p.start_transition) &&
181 end_transition.eql?(p.end_transition) && offset.eql?(p.offset)
182 end
183
184 # Returns a hash of this TimezonePeriod.
185 def hash
186 result = @start_transition.hash ^ @end_transition.hash
187 result ^= @offset.hash unless @start_transition || @end_transition
188 result
189 end
190
191 # Returns internal object state as a programmer-readable string.
192 def inspect
193 result = "#<#{self.class}: #{@start_transition.inspect},#{@end_transition.inspect}"
194 result << ",#{@offset.inspect}>" unless @start_transition || @end_transition
195 result + '>'
196 end
197 end
198 end