Class: SPARQL::Algebra::Operator::IsBlank

Inherits:
Unary show all
Includes:
Evaluatable
Defined in:
vendor/bundler/ruby/2.5.0/bundler/gems/sparql-7b34b4cf091a/lib/sparql/algebra/operator/is_blank.rb

Overview

The SPARQL isBlank operator.

Examples:

(prefix ((xsd: <http://www.w3.org/2001/XMLSchema#>)
         (: <http://example.org/things#>))
  (project (?x ?v)
    (filter (isBlank ?v)
      (bgp (triple ?x :p ?v)))))

See Also:

Constant Summary collapse

NAME = 
:isBlank

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 collapse

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(term) ⇒ RDF::Literal::Boolean

Returns true if the operand is an RDF::Node, false otherwise.

Parameters:

Returns:

  • (RDF::Literal::Boolean) —

    true or false

Raises:

  • (TypeError) —

    if the operand is not an RDF term



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# File 'vendor/bundler/ruby/2.5.0/bundler/gems/sparql-7b34b4cf091a/lib/sparql/algebra/operator/is_blank.rb', line 26

def apply(term)
  case term
    when RDF::Node then RDF::Literal::TRUE
    when RDF::Term then RDF::Literal::FALSE
    else raise TypeError, "expected an RDF::Term, but got #{term.inspect}"
  end
end