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Contents
module SPARQL; module Algebra
class Operator
##
# The SPARQL logical `abs` operator.
#
# [121] BuiltInCall ::= ... | 'ABS' '(' Expression ')'
#
# @example SPARQL Grammar
# PREFIX : <http://example.org/>
# SELECT * WHERE {
# ?s :num ?num
# FILTER(ABS(?num) >= 2)
# }
#
# @example SSE
# (prefix ((: <http://example.org/>))
# (filter (>= (abs ?num) 2)
# (bgp (triple ?s :num ?num))))
#
# @see https://www.w3.org/TR/sparql11-query/#func-abs
# @see https://www.w3.org/TR/xpath-functions/#func-abs
class Abs < Operator::Unary
include Evaluatable
NAME = [:abs]
##
# Returns the absolute value of `arg`. An error is raised if `arg` is not a numeric value.
#
# @param [RDF::Literal] operand
# the operand
# @return [RDF::Literal] literal of same type
# @raise [TypeError] if the operand is not a numeric value
def apply(operand, **options)
case operand
when RDF::Literal::Numeric then operand.abs
else raise TypeError, "expected an RDF::Literal::Numeric, but got #{operand.inspect}"
end
end
##
#
# Returns a partial SPARQL grammar for this operator.
#
# @return [String]
def to_sparql(**options)
"ABS(#{operands.first.to_sparql(**options)})"
end
end # Abs
end # Operator
end; end # SPARQL::Algebra
Version data entries
7 entries across 7 versions & 1 rubygems