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#--
# Copyright (c) 2006 Philip Ross
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in all
# copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.
#++
module TZInfo
# Provides a method for getting Rationals for a timezone offset in seconds.
# Pre-reduced rationals are returned for all the half-hour intervals between
# -14 and +14 hours to avoid having to call gcd at runtime.
module OffsetRationals #:nodoc:
@@rational_cache = {
-50400 => Rational(-7,12),
-48600 => Rational(-9,16),
-46800 => Rational(-13,24),
-45000 => Rational(-25,48),
-43200 => Rational(-1,2),
-41400 => Rational(-23,48),
-39600 => Rational(-11,24),
-37800 => Rational(-7,16),
-36000 => Rational(-5,12),
-34200 => Rational(-19,48),
-32400 => Rational(-3,8),
-30600 => Rational(-17,48),
-28800 => Rational(-1,3),
-27000 => Rational(-5,16),
-25200 => Rational(-7,24),
-23400 => Rational(-13,48),
-21600 => Rational(-1,4),
-19800 => Rational(-11,48),
-18000 => Rational(-5,24),
-16200 => Rational(-3,16),
-14400 => Rational(-1,6),
-12600 => Rational(-7,48),
-10800 => Rational(-1,8),
-9000 => Rational(-5,48),
-7200 => Rational(-1,12),
-5400 => Rational(-1,16),
-3600 => Rational(-1,24),
-1800 => Rational(-1,48),
0 => Rational(0,1),
1800 => Rational(1,48),
3600 => Rational(1,24),
5400 => Rational(1,16),
7200 => Rational(1,12),
9000 => Rational(5,48),
10800 => Rational(1,8),
12600 => Rational(7,48),
14400 => Rational(1,6),
16200 => Rational(3,16),
18000 => Rational(5,24),
19800 => Rational(11,48),
21600 => Rational(1,4),
23400 => Rational(13,48),
25200 => Rational(7,24),
27000 => Rational(5,16),
28800 => Rational(1,3),
30600 => Rational(17,48),
32400 => Rational(3,8),
34200 => Rational(19,48),
36000 => Rational(5,12),
37800 => Rational(7,16),
39600 => Rational(11,24),
41400 => Rational(23,48),
43200 => Rational(1,2),
45000 => Rational(25,48),
46800 => Rational(13,24),
48600 => Rational(9,16),
50400 => Rational(7,12)}
# Returns a Rational expressing the fraction of a day that offset in
# seconds represents (i.e. equivalent to Rational(offset, 86400)).
def rational_for_offset(offset)
@@rational_cache[offset] || Rational(offset, 86400)
end
module_function :rational_for_offset
end
end
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