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module RDF::N3::Algebra::Math
##
# The subject is a pair of numbers. The object is calculated by subtracting the second number of the pair from the first.
#
# @example
# { ("8" "3") math:difference ?x} => { ?x :valueOf "8 - 3" } .
# { ("8") math:difference ?x } => { ?x :valueOf "8 - (error?)" } .
# { (8 3) math:difference ?x} => { ?x :valueOf "8 - 3" } .
#
# @see https://www.w3.org/TR/xpath-functions/#func-numeric-subtract
class Difference < RDF::N3::Algebra::ListOperator
NAME = :mathDifference
URI = RDF::N3::Math.difference
##
# The math:difference operator takes a pair of strings or numbers and calculates their difference.
#
# @param [RDF::N3::List] list
# @return [RDF::Term]
# @see RDF::N3::ListOperator#evaluate
def resolve(list)
list.to_a.map(&:as_number).reduce(&:-)
end
##
# The list argument must be a pair of literals.
#
# @param [RDF::N3::List] list
# @return [Boolean]
# @see RDF::N3::ListOperator#validate
def validate(list)
if super && list.all?(&:literal?) && list.length == 2
true
else
log_error(NAME) {"list is not a pair of literals: #{list.to_sxp}"}
false
end
end
end
end
Version data entries
4 entries across 4 versions & 1 rubygems