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123 lines
3.4 KiB
Ruby
123 lines
3.4 KiB
Ruby
# frozen_string_literal: true
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require "strscan"
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module ActiveSupport
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class Duration
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# Parses a string formatted according to ISO 8601 Duration into the hash.
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#
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# See {ISO 8601}[https://en.wikipedia.org/wiki/ISO_8601#Durations] for more information.
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#
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# This parser allows negative parts to be present in pattern.
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class ISO8601Parser # :nodoc:
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class ParsingError < ::ArgumentError; end
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PERIOD_OR_COMMA = /\.|,/
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PERIOD = "."
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COMMA = ","
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SIGN_MARKER = /\A-|\+|/
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DATE_MARKER = /P/
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TIME_MARKER = /T/
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DATE_COMPONENT = /(-?\d+(?:[.,]\d+)?)(Y|M|D|W)/
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TIME_COMPONENT = /(-?\d+(?:[.,]\d+)?)(H|M|S)/
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DATE_TO_PART = { "Y" => :years, "M" => :months, "W" => :weeks, "D" => :days }
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TIME_TO_PART = { "H" => :hours, "M" => :minutes, "S" => :seconds }
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DATE_COMPONENTS = [:years, :months, :days]
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TIME_COMPONENTS = [:hours, :minutes, :seconds]
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attr_reader :parts, :scanner
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attr_accessor :mode, :sign
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def initialize(string)
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@scanner = StringScanner.new(string)
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@parts = {}
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@mode = :start
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@sign = 1
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end
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def parse!
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while !finished?
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case mode
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when :start
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if scan(SIGN_MARKER)
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self.sign = (scanner.matched == "-") ? -1 : 1
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self.mode = :sign
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else
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raise_parsing_error
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end
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when :sign
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if scan(DATE_MARKER)
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self.mode = :date
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else
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raise_parsing_error
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end
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when :date
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if scan(TIME_MARKER)
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self.mode = :time
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elsif scan(DATE_COMPONENT)
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parts[DATE_TO_PART[scanner[2]]] = number * sign
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else
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raise_parsing_error
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end
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when :time
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if scan(TIME_COMPONENT)
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parts[TIME_TO_PART[scanner[2]]] = number * sign
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else
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raise_parsing_error
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end
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end
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end
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validate!
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parts
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end
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private
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def finished?
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scanner.eos?
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end
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# Parses number which can be a float with either comma or period.
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def number
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PERIOD_OR_COMMA.match?(scanner[1]) ? scanner[1].tr(COMMA, PERIOD).to_f : scanner[1].to_i
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end
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def scan(pattern)
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scanner.scan(pattern)
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end
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def raise_parsing_error(reason = nil)
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raise ParsingError, "Invalid ISO 8601 duration: #{scanner.string.inspect} #{reason}".strip
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end
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# Checks for various semantic errors as stated in ISO 8601 standard.
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def validate!
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raise_parsing_error("is empty duration") if parts.empty?
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# Mixing any of Y, M, D with W is invalid.
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if parts.key?(:weeks) && (parts.keys & DATE_COMPONENTS).any?
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raise_parsing_error("mixing weeks with other date parts not allowed")
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end
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# Specifying an empty T part is invalid.
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if mode == :time && (parts.keys & TIME_COMPONENTS).empty?
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raise_parsing_error("time part marker is present but time part is empty")
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end
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fractions = parts.values.reject(&:zero?).select { |a| (a % 1) != 0 }
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unless fractions.empty? || (fractions.size == 1 && fractions.last == @parts.values.reject(&:zero?).last)
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raise_parsing_error "(only last part can be fractional)"
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end
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true
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end
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end
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end
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end
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