Class: SPARQL::Algebra::Operator::StrLen

Inherits:

Unary

• Object
• SPARQL::Algebra::Operator
• Unary
• SPARQL::Algebra::Operator::StrLen

Includes:

Evaluatable

Defined in:

vendor/bundler/ruby/2.5.0/bundler/gems/sparql-bb59900f675b/lib/sparql/algebra/operator/strlen.rb

Overview

The SPARQL strlen operator.

Examples:

(strlen ?x)

See Also:

• http://www.w3.org/TR/sparql11-query/#func-strlen
• http://www.w3.org/TR/xpath-functions/#func-string-length

Constant Summary

NAME =

:strlen

Constants inherited from Unary

Unary::ARITY

Constants inherited from SPARQL::Algebra::Operator

ARITY, IsURI, URI

Instance Attribute Summary

Attributes inherited from SPARQL::Algebra::Operator

#operands

Instance Method Summary

• #apply(operand) ⇒ RDF::Literal::Integer

  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.

Methods included from Evaluatable

#evaluate, #memoize, #replace_aggregate!, #replace_vars!

Methods inherited from Unary

#initialize

Methods inherited from SPARQL::Algebra::Operator

#aggregate?, arity, #base_uri, base_uri, base_uri=, #boolean, #constant?, #each_descendant, #eql?, #evaluatable?, evaluate, #executable?, #first_ancestor, for, #initialize, #inspect, #ndvars, #node?, #operand, #optimize, #parent, #parent=, prefixes, #prefixes, prefixes=, #rewrite, #to_binary, #to_sxp, #to_sxp_bin, #validate!, #variable?, #vars

Methods included from Expression

cast, #constant?, #evaluate, extension, extensions, for, #invalid?, new, #node?, open, #optimize, parse, register_extension, #to_sxp_bin, #valid?, #validate!, #variable?

Constructor Details

This class inherits a constructor from SPARQL::Algebra::Operator::Unary

Instance Method Details

#apply(operand) ⇒ RDF::Literal::Integer

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.

Examples:

strlen("chat")	4
strlen("chat"@en)	4
strlen("chat"^^xsd:string)	4

Parameters:

• operand (RDF::Literal) —

  the operand

Returns:

• (RDF::Literal::Integer) —

  length of string

Raises:

• (TypeError) —

  if the operand is not a numeric value

# File 'vendor/bundler/ruby/2.5.0/bundler/gems/sparql-bb59900f675b/lib/sparql/algebra/operator/strlen.rb', line 28

def apply(operand)
  raise TypeError, "expected a plain RDF::Literal, but got #{operand.inspect}" unless operand.literal? && operand.plain?
  RDF::Literal(operand.to_s.length)
end