vendor/rails/activesupport/lib/active_support/vendor/tzinfo-0.3.12/tzinfo/offset_rationals.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 'rational'
  24 require 'tzinfo/ruby_core_support'
  25
  26 module TZInfo
  27
  28   # Provides a method for getting Rationals for a timezone offset in seconds.
  29   # Pre-reduced rationals are returned for all the half-hour intervals between
  30   # -14 and +14 hours to avoid having to call gcd at runtime.
  31   module OffsetRationals #:nodoc:
  32     @@rational_cache = {
  33       -50400 => RubyCoreSupport.rational_new!(-7,12),
  34       -48600 => RubyCoreSupport.rational_new!(-9,16),
  35       -46800 => RubyCoreSupport.rational_new!(-13,24),
  36       -45000 => RubyCoreSupport.rational_new!(-25,48),
  37       -43200 => RubyCoreSupport.rational_new!(-1,2),
  38       -41400 => RubyCoreSupport.rational_new!(-23,48),
  39       -39600 => RubyCoreSupport.rational_new!(-11,24),
  40       -37800 => RubyCoreSupport.rational_new!(-7,16),
  41       -36000 => RubyCoreSupport.rational_new!(-5,12),
  42       -34200 => RubyCoreSupport.rational_new!(-19,48),
  43       -32400 => RubyCoreSupport.rational_new!(-3,8),
  44       -30600 => RubyCoreSupport.rational_new!(-17,48),
  45       -28800 => RubyCoreSupport.rational_new!(-1,3),
  46       -27000 => RubyCoreSupport.rational_new!(-5,16),
  47       -25200 => RubyCoreSupport.rational_new!(-7,24),
  48       -23400 => RubyCoreSupport.rational_new!(-13,48),
  49       -21600 => RubyCoreSupport.rational_new!(-1,4),
  50       -19800 => RubyCoreSupport.rational_new!(-11,48),
  51       -18000 => RubyCoreSupport.rational_new!(-5,24),
  52       -16200 => RubyCoreSupport.rational_new!(-3,16),
  53       -14400 => RubyCoreSupport.rational_new!(-1,6),
  54       -12600 => RubyCoreSupport.rational_new!(-7,48),
  55       -10800 => RubyCoreSupport.rational_new!(-1,8),
  56        -9000 => RubyCoreSupport.rational_new!(-5,48),
  57        -7200 => RubyCoreSupport.rational_new!(-1,12),
  58        -5400 => RubyCoreSupport.rational_new!(-1,16),
  59        -3600 => RubyCoreSupport.rational_new!(-1,24),
  60        -1800 => RubyCoreSupport.rational_new!(-1,48),
  61            0 => RubyCoreSupport.rational_new!(0,1),
  62         1800 => RubyCoreSupport.rational_new!(1,48),
  63         3600 => RubyCoreSupport.rational_new!(1,24),
  64         5400 => RubyCoreSupport.rational_new!(1,16),
  65         7200 => RubyCoreSupport.rational_new!(1,12),
  66         9000 => RubyCoreSupport.rational_new!(5,48),
  67        10800 => RubyCoreSupport.rational_new!(1,8),
  68        12600 => RubyCoreSupport.rational_new!(7,48),
  69        14400 => RubyCoreSupport.rational_new!(1,6),
  70        16200 => RubyCoreSupport.rational_new!(3,16),
  71        18000 => RubyCoreSupport.rational_new!(5,24),
  72        19800 => RubyCoreSupport.rational_new!(11,48),
  73        21600 => RubyCoreSupport.rational_new!(1,4),
  74        23400 => RubyCoreSupport.rational_new!(13,48),
  75        25200 => RubyCoreSupport.rational_new!(7,24),
  76        27000 => RubyCoreSupport.rational_new!(5,16),
  77        28800 => RubyCoreSupport.rational_new!(1,3),
  78        30600 => RubyCoreSupport.rational_new!(17,48),
  79        32400 => RubyCoreSupport.rational_new!(3,8),
  80        34200 => RubyCoreSupport.rational_new!(19,48),
  81        36000 => RubyCoreSupport.rational_new!(5,12),
  82        37800 => RubyCoreSupport.rational_new!(7,16),
  83        39600 => RubyCoreSupport.rational_new!(11,24),
  84        41400 => RubyCoreSupport.rational_new!(23,48),
  85        43200 => RubyCoreSupport.rational_new!(1,2),
  86        45000 => RubyCoreSupport.rational_new!(25,48),
  87        46800 => RubyCoreSupport.rational_new!(13,24),
  88        48600 => RubyCoreSupport.rational_new!(9,16),
  89        50400 => RubyCoreSupport.rational_new!(7,12)}
  90
  91     # Returns a Rational expressing the fraction of a day that offset in
  92     # seconds represents (i.e. equivalent to Rational(offset, 86400)).
  93     def rational_for_offset(offset)
  94       @@rational_cache[offset] || Rational(offset, 86400)
  95     end
  96     module_function :rational_for_offset
  97   end
  98 end