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Contents
module SPARQL; module Algebra
class Operator
##
# The SPARQL `strlen` operator.
#
# [121] BuiltInCall ::= ... 'STRLEN' '(' Expression ')'
#
# @example SPARQL Grammar
# PREFIX : <http://example.org/>
# SELECT ?str (STRLEN(?str) AS ?len) WHERE {
# ?s :str ?str
# }
#
# @example SSE
# (prefix
# ((: <http://example.org/>))
# (project (?str ?len)
# (extend ((?len (strlen ?str)))
# (bgp (triple ?s :str ?str)))))
#
# @see https://www.w3.org/TR/sparql11-query/#func-strlen
# @see https://www.w3.org/TR/xpath-functions/#func-string-length
class StrLen < Operator::Unary
include Evaluatable
NAME = :strlen
##
# The strlen function corresponds to the XPath fn:string-length function and returns an xsd:integer equal to the length in characters of the lexical form of the literal.
#
# @example
# strlen("chat") 4
# strlen("chat"@en) 4
# strlen("chat"^^xsd:string) 4
#
# @param [RDF::Literal] operand
# the operand
# @return [RDF::Literal::Integer] length of string
# @raise [TypeError] if the operand is not a numeric value
def apply(operand, **options)
raise TypeError, "expected a plain RDF::Literal, but got #{operand.inspect}" unless operand.literal? && operand.plain?
RDF::Literal(operand.to_s.length)
end
##
#
# Returns a partial SPARQL grammar for this operator.
#
# @return [String]
def to_sparql(**options)
"STRLEN(" + operands.to_sparql(delimiter: ', ', **options) + ")"
end
end # StrLen
end # Operator
end; end # SPARQL::Algebra
Version data entries
8 entries across 8 versions & 1 rubygems