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Contents
module SPARQL; module Algebra
class Operator
##
# The SPARQL numeric unary `-` (negation) operator.
#
# [118] UnaryExpression ::= ... | '-' PrimaryExpression
#
# @example SPARQL Grammar
# PREFIX : <http://example.org/>
# SELECT ?s WHERE {
# ?s :p ?o .
# FILTER(-?o = -2) .
# }
#
# @example SSE
# (prefix ((: <http://example.org/>))
# (project (?s)
# (filter (= (- ?o) -2)
# (bgp (triple ?s :p ?o)))))
#
# @see https://www.w3.org/TR/xpath-functions/#func-numeric-unary-minus
class Negate < Operator::Unary
include Evaluatable
NAME = [:-, :negate]
##
# Returns the operand with its sign reversed.
#
# @param [RDF::Literal::Numeric] term
# a numeric literal
# @return [RDF::Literal::Numeric]
# @raise [TypeError] if the operand is not a numeric literal
def apply(term, **options)
case term
when RDF::Literal::Numeric then -term
else raise TypeError, "expected an RDF::Literal::Numeric, but got #{term.inspect}"
end
end
##
#
# Returns a partial SPARQL grammar for this operator.
#
# @return [String]
def to_sparql(**options)
"(-#{operands.to_sparql(**options)})"
end
end # Negate
end # Operator
end; end # SPARQL::Algebra
Version data entries
8 entries across 8 versions & 1 rubygems