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