vendor/rails/activesupport/lib/active_support/vendor/tzinfo-0.3.12/tzinfo/data_timezone_info.rb

   1 #--
   2 # Copyright (c) 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/time_or_datetime'
  24 require 'tzinfo/timezone_info'
  25 require 'tzinfo/timezone_offset_info'
  26 require 'tzinfo/timezone_period'
  27 require 'tzinfo/timezone_transition_info'
  28
  29 module TZInfo
  30   # Thrown if no offsets have been defined when calling period_for_utc or
  31   # periods_for_local. Indicates an error in the timezone data.
  32   class NoOffsetsDefined < StandardError
  33   end
  34
  35   # Represents a (non-linked) timezone defined in a data module.
  36   class DataTimezoneInfo < TimezoneInfo #:nodoc:
  37
  38     # Constructs a new TimezoneInfo with its identifier.
  39     def initialize(identifier)
  40       super(identifier)
  41       @offsets = {}
  42       @transitions = []
  43       @previous_offset = nil
  44       @transitions_index = nil
  45     end
  46
  47     # Defines a offset. The id uniquely identifies this offset within the
  48     # timezone. utc_offset and std_offset define the offset in seconds of
  49     # standard time from UTC and daylight savings from standard time
  50     # respectively. abbreviation describes the timezone offset (e.g. GMT, BST,
  51     # EST or EDT).
  52     #
  53     # The first offset to be defined is treated as the offset that applies
  54     # until the first transition. This will usually be in Local Mean Time (LMT).
  55     #
  56     # ArgumentError will be raised if the id is already defined.
  57     def offset(id, utc_offset, std_offset, abbreviation)
  58       raise ArgumentError, 'Offset already defined' if @offsets.has_key?(id)
  59
  60       offset = TimezoneOffsetInfo.new(utc_offset, std_offset, abbreviation)
  61       @offsets[id] = offset
  62       @previous_offset = offset unless @previous_offset
  63     end
  64
  65     # Defines a transition. Transitions must be defined in chronological order.
  66     # ArgumentError will be raised if a transition is added out of order.
  67     # offset_id refers to an id defined with offset. ArgumentError will be
  68     # raised if the offset_id cannot be found. numerator_or_time and
  69     # denomiator specify the time the transition occurs as. See
  70     # TimezoneTransitionInfo for more detail about specifying times.
  71     def transition(year, month, offset_id, numerator_or_time, denominator = nil)
  72       offset = @offsets[offset_id]
  73       raise ArgumentError, 'Offset not found' unless offset
  74
  75       if @transitions_index
  76         if year < @last_year || (year == @last_year && month < @last_month)
  77           raise ArgumentError, 'Transitions must be increasing date order'
  78         end
  79
  80         # Record the position of the first transition with this index.
  81         index = transition_index(year, month)
  82         @transitions_index[index] ||= @transitions.length
  83
  84         # Fill in any gaps
  85         (index - 1).downto(0) do |i|
  86           break if @transitions_index[i]
  87           @transitions_index[i] = @transitions.length
  88         end
  89       else
  90         @transitions_index = [@transitions.length]
  91         @start_year = year
  92         @start_month = month
  93       end
  94
  95       @transitions << TimezoneTransitionInfo.new(offset, @previous_offset,
  96         numerator_or_time, denominator)
  97       @last_year = year
  98       @last_month = month
  99       @previous_offset = offset
 100     end
 101
 102     # Returns the TimezonePeriod for the given UTC time.
 103     # Raises NoOffsetsDefined if no offsets have been defined.
 104     def period_for_utc(utc)
 105       unless @transitions.empty?
 106         utc = TimeOrDateTime.wrap(utc)
 107         index = transition_index(utc.year, utc.mon)
 108
 109         start_transition = nil
 110         start = transition_before_end(index)
 111         if start
 112           start.downto(0) do |i|
 113             if @transitions[i].at <= utc
 114               start_transition = @transitions[i]
 115               break
 116             end
 117           end
 118         end
 119
 120         end_transition = nil
 121         start = transition_after_start(index)
 122         if start
 123           start.upto(@transitions.length - 1) do |i|
 124             if @transitions[i].at > utc
 125               end_transition = @transitions[i]
 126               break
 127             end
 128           end
 129         end
 130
 131         if start_transition || end_transition
 132           TimezonePeriod.new(start_transition, end_transition)
 133         else
 134           # Won't happen since there are transitions. Must always find one
 135           # transition that is either >= or < the specified time.
 136           raise 'No transitions found in search'
 137         end
 138       else
 139         raise NoOffsetsDefined, 'No offsets have been defined' unless @previous_offset
 140         TimezonePeriod.new(nil, nil, @previous_offset)
 141       end
 142     end
 143
 144     # Returns the set of TimezonePeriods for the given local time as an array.
 145     # Results returned are ordered by increasing UTC start date.
 146     # Returns an empty array if no periods are found for the given time.
 147     # Raises NoOffsetsDefined if no offsets have been defined.
 148     def periods_for_local(local)
 149       unless @transitions.empty?
 150         local = TimeOrDateTime.wrap(local)
 151         index = transition_index(local.year, local.mon)
 152
 153         result = []
 154
 155         start_index = transition_after_start(index - 1)
 156         if start_index && @transitions[start_index].local_end > local
 157           if start_index > 0
 158             if @transitions[start_index - 1].local_start <= local
 159               result << TimezonePeriod.new(@transitions[start_index - 1], @transitions[start_index])
 160             end
 161           else
 162             result << TimezonePeriod.new(nil, @transitions[start_index])
 163           end
 164         end
 165
 166         end_index = transition_before_end(index + 1)
 167
 168         if end_index
 169           start_index = end_index unless start_index
 170
 171           start_index.upto(transition_before_end(index + 1)) do |i|
 172             if @transitions[i].local_start <= local
 173               if i + 1 < @transitions.length
 174                 if @transitions[i + 1].local_end > local
 175                   result << TimezonePeriod.new(@transitions[i], @transitions[i + 1])
 176                 end
 177               else
 178                 result << TimezonePeriod.new(@transitions[i], nil)
 179               end
 180             end
 181           end
 182         end
 183
 184         result
 185       else
 186         raise NoOffsetsDefined, 'No offsets have been defined' unless @previous_offset
 187         [TimezonePeriod.new(nil, nil, @previous_offset)]
 188       end
 189     end
 190
 191     private
 192       # Returns the index into the @transitions_index array for a given year
 193       # and month.
 194       def transition_index(year, month)
 195         index = (year - @start_year) * 2
 196         index += 1 if month > 6
 197         index -= 1 if @start_month > 6
 198         index
 199       end
 200
 201       # Returns the index into @transitions of the first transition that occurs
 202       # on or after the start of the given index into @transitions_index.
 203       # Returns nil if there are no such transitions.
 204       def transition_after_start(index)
 205         if index >= @transitions_index.length
 206           nil
 207         else
 208           index = 0 if index < 0
 209           @transitions_index[index]
 210         end
 211       end
 212
 213       # Returns the index into @transitions of the first transition that occurs
 214       # before the end of the given index into @transitions_index.
 215       # Returns nil if there are no such transitions.
 216       def transition_before_end(index)
 217         index = index + 1
 218
 219         if index <= 0
 220           nil
 221         elsif index >= @transitions_index.length
 222           @transitions.length - 1
 223         else
 224           @transitions_index[index] - 1
 225         end
 226       end
 227   end
 228 end