/
posix_time_zone_parser.rb
177 lines (159 loc) · 6.88 KB
/
posix_time_zone_parser.rb
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# encoding: UTF-8
# frozen_string_literal: true
require 'strscan'
module TZInfo
module DataSources
# An {InvalidPosixTimeZone} exception is raised if an invalid POSIX-style
# time zone string is encountered.
#
# @private
class InvalidPosixTimeZone < StandardError #:nodoc:
end
private_constant :InvalidPosixTimeZone
# A parser for POSIX-style TZ strings used in zoneinfo files and specified
# by tzfile.5 and tzset.3.
#
# @private
class PosixTimeZoneParser #:nodoc:
# Initializes a new {PosixTimeZoneParser}.
#
# @param string_deduper [StringDeduper] a {StringDeduper} instance to use
# to dedupe abbreviations.
def initialize(string_deduper)
@string_deduper = string_deduper
end
# Parses a POSIX-style TZ string.
#
# @param tz_string [String] the string to parse.
# @return [Object] either a {TimezoneOffset} for a constantly applied
# offset or an {AnnualRules} instance representing the rules.
# @raise [InvalidPosixTimeZone] if `tz_string` is not a `String`.
# @raise [InvalidPosixTimeZone] if `tz_string` is is not valid.
def parse(tz_string)
raise InvalidPosixTimeZone unless tz_string.kind_of?(String)
return nil if tz_string.empty?
s = StringScanner.new(tz_string)
check_scan(s, /([^-+,\d<][^-+,\d]*) | <([^>]+)>/x)
std_abbrev = @string_deduper.dedupe(RubyCoreSupport.untaint(s[1] || s[2]))
check_scan(s, /([-+]?\d+)(?::(\d+)(?::(\d+))?)?/)
std_offset = get_offset_from_hms(s[1], s[2], s[3])
if s.scan(/([^-+,\d<][^-+,\d]*) | <([^>]+)>/x)
dst_abbrev = @string_deduper.dedupe(RubyCoreSupport.untaint(s[1] || s[2]))
if s.scan(/([-+]?\d+)(?::(\d+)(?::(\d+))?)?/)
dst_offset = get_offset_from_hms(s[1], s[2], s[3])
else
# POSIX is negative for ahead of UTC.
dst_offset = std_offset - 3600
end
dst_difference = std_offset - dst_offset
start_rule = parse_rule(s, 'start')
end_rule = parse_rule(s, 'end')
raise InvalidPosixTimeZone, "Expected the end of a POSIX-style time zone string but found '#{s.rest}'." if s.rest?
if start_rule.is_always_first_day_of_year? && start_rule.transition_at == 0 &&
end_rule.is_always_last_day_of_year? && end_rule.transition_at == 86400 + dst_difference
# Constant daylight savings time.
# POSIX is negative for ahead of UTC.
TimezoneOffset.new(-std_offset, dst_difference, dst_abbrev)
else
AnnualRules.new(
TimezoneOffset.new(-std_offset, 0, std_abbrev),
TimezoneOffset.new(-std_offset, dst_difference, dst_abbrev),
start_rule,
end_rule)
end
elsif !s.rest?
# Constant standard time.
# POSIX is negative for ahead of UTC.
TimezoneOffset.new(-std_offset, 0, std_abbrev)
else
raise InvalidPosixTimeZone, "Expected the end of a POSIX-style time zone string but found '#{s.rest}'."
end
end
private
# Parses a rule.
#
# @param s [StringScanner] the `StringScanner` to read the rule from.
# @param type [String] the type of rule (either `'start'` or `'end'`).
# @raise [InvalidPosixTimeZone] if the rule is not valid.
# @return [TransitionRule] the parsed rule.
def parse_rule(s, type)
check_scan(s, /,(?: (?: J(\d+) ) | (\d+) | (?: M(\d+)\.(\d)\.(\d) ) )/x)
julian_day_of_year = s[1]
absolute_day_of_year = s[2]
month = s[3]
week = s[4]
day_of_week = s[5]
if s.scan(/\//)
check_scan(s, /([-+]?\d+)(?::(\d+)(?::(\d+))?)?/)
transition_at = get_seconds_after_midnight_from_hms(s[1], s[2], s[3])
else
transition_at = 7200
end
begin
if julian_day_of_year
JulianDayOfYearTransitionRule.new(julian_day_of_year.to_i, transition_at)
elsif absolute_day_of_year
AbsoluteDayOfYearTransitionRule.new(absolute_day_of_year.to_i, transition_at)
elsif week == '5'
LastDayOfMonthTransitionRule.new(month.to_i, day_of_week.to_i, transition_at)
else
DayOfMonthTransitionRule.new(month.to_i, week.to_i, day_of_week.to_i, transition_at)
end
rescue ArgumentError => e
raise InvalidPosixTimeZone, "Invalid #{type} rule in POSIX-style time zone string: #{e}"
end
end
# Returns an offset in seconds from hh:mm:ss values. The value can be
# negative. -02:33:12 would represent 2 hours, 33 minutes and 12 seconds
# ahead of UTC.
#
# @param h [String] the hours.
# @param m [String] the minutes.
# @param s [String] the seconds.
# @return [Integer] the offset.
# @raise [InvalidPosixTimeZone] if the mm and ss values are greater than
# 59.
def get_offset_from_hms(h, m, s)
h = h.to_i
m = m.to_i
s = s.to_i
raise InvalidPosixTimeZone, "Invalid minute #{m} in offset for POSIX-style time zone string." if m > 59
raise InvalidPosixTimeZone, "Invalid second #{s} in offset for POSIX-style time zone string." if s > 59
magnitude = (h.abs * 60 + m) * 60 + s
h < 0 ? -magnitude : magnitude
end
# Returns the seconds from midnight from hh:mm:ss values. Hours can exceed
# 24 for a time on the following day. Hours can be negative to subtract
# hours from midnight on the given day. -02:33:12 represents 22:33:12 on
# the prior day.
#
# @param h [String] the hour.
# @param m [String] the minutes past the hour.
# @param s [String] the seconds past the minute.
# @return [Integer] the number of seconds after midnight.
# @raise [InvalidPosixTimeZone] if the mm and ss values are greater than
# 59.
def get_seconds_after_midnight_from_hms(h, m, s)
h = h.to_i
m = m.to_i
s = s.to_i
raise InvalidPosixTimeZone, "Invalid minute #{m} in time for POSIX-style time zone string." if m > 59
raise InvalidPosixTimeZone, "Invalid second #{s} in time for POSIX-style time zone string." if s > 59
(h * 3600) + m * 60 + s
end
# Scans for a pattern and raises an exception if the pattern does not
# match the input.
#
# @param s [StringScanner] the `StringScanner` to scan.
# @param pattern [Regexp] the pattern to match.
# @return [String] the result of the scan.
# @raise [InvalidPosixTimeZone] if the pattern does not match the input.
def check_scan(s, pattern)
result = s.scan(pattern)
raise InvalidPosixTimeZone, "Expected '#{s.rest}' to match #{pattern} in POSIX-style time zone string." unless result
result
end
end
private_constant :PosixTimeZoneParser
end
end