lib/rdf/model/literal/date.rb
module RDF; class Literal
##
# A date literal.
#
# @see http://www.w3.org/TR/xmlschema11-2/#date
# @see https://www.w3.org/TR/xmlschema11-2/#rf-lexicalMappings-datetime
# @since 0.2.1
class Date < Temporal
DATATYPE = RDF::URI("http://www.w3.org/2001/XMLSchema#date")
GRAMMAR = %r(\A(#{YEARFRAG}-#{MONTHFRAG}-#{DAYFRAG})(#{TZFRAG})?\z).freeze
FORMAT = '%Y-%m-%d'.freeze
##
# Internally, a `Date` is represented using a native `::DateTime` object at midnight. If initialized from a `::Date`, there is no timezone component, If initialized from a `::DateTime`, the timezone is taken from that native object, otherwise, a timezone (or no timezone) is taken from the string representation having a matching `zzzzzz` component.
#
# @note If initialized using the `#to_datetime` method, time component is unchanged. Otherewise, it is set to 00:00 (midnight).
#
# @param [String, Date, #to_datetime] value
# @param (see Literal#initialize)
def initialize(value, datatype: nil, lexical: nil, **options)
@datatype = RDF::URI(datatype || self.class.const_get(:DATATYPE))
@string = lexical || (value if value.is_a?(String))
@object = case
when value.class == ::Date
@zone = nil
# Use midnight as midpoint of the interval
::DateTime.parse(value.strftime('%FT00:00:00'))
when value.respond_to?(:to_datetime)
dt = value.to_datetime
@zone = dt.zone
dt
else
md = value.to_s.match(GRAMMAR)
_, dt, tz = Array(md)
if tz
@zone = tz == 'Z' ? '+00:00' : tz
else
@zone = nil # No timezone
end
# Use midnight as midpoint of the interval
::DateTime.parse("#{dt}T00:00:00#{@zone}")
end rescue ::DateTime.new
end
##
# Returns a human-readable value for the literal
#
# @return [String]
# @since 1.1.6
def humanize(lang = :en)
d = object.strftime("%A, %d %B %Y")
if timezone?
d += if @zone == '+00:00'
" UTC"
else
" #{@zone}"
end
end
d
end
end # Date
end; end # RDF::Literal