Class: SPARQL::Algebra::Operator::Not

Inherits:
Operator::Unary
  • Object
show all
Includes:
Evaluatable
Defined in:
lib/sparql/algebra/operator/not.rb

Overview

The SPARQL logical not operator.

[118] UnaryExpression ::= ... | '!' PrimaryExpression

Examples:

SPARQL Grammar

PREFIX  : <http://example.org/ns#>
SELECT  ?a
WHERE {
  ?a :p ?v . 
  FILTER ( ! ?v ) .
}

SSE

(prefix ((: <http://example.org/ns#>))
 (project (?a)
  (filter (! ?v)
   (bgp (triple ?a :p ?v)))))

See Also:

Constant Summary collapse

NAME = 
[:'!', :not]

Instance Method Summary collapse

Methods included from Evaluatable

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

Instance Method Details

#apply(operand, **options) ⇒ RDF::Literal::Boolean

Returns the logical NOT (inverse) of the operand.

Note that this operator operates on the effective boolean value (EBV) of its operand.

Parameters:

  • operand (RDF::Literal::Boolean) —

    the operand

Returns:

  • (RDF::Literal::Boolean) —

    true or false

Raises:

  • (TypeError) —

    if the operand could not be coerced to a boolean literal



38
39
40
41
42
43
44
 
# File 'lib/sparql/algebra/operator/not.rb', line 38

def apply(operand, **options)
  case bool = boolean(operand)
    when RDF::Literal::Boolean
      RDF::Literal(bool.false?)
    else super
  end
end

#to_sparql(**options) ⇒ String

Returns a partial SPARQL grammar for this operator.

Returns:

  • (String) 


51
52
53
 
# File 'lib/sparql/algebra/operator/not.rb', line 51

def to_sparql(**options)
  "(!" + operands.first.to_sparql(**options) + ")"
end