Class: SPARQL::Algebra::Operator::Bound

Inherits:

Unary

• Object
• SPARQL::Algebra::Operator
• Unary
• SPARQL::Algebra::Operator::Bound

show all

Includes:

Evaluatable

Defined in:

lib/sparql/algebra/operator/bound.rb

Overview

(prefix ((: <http://example.org/ns#>))
  (project (?a ?c)
    (filter (! (bound ?e))
      (leftjoin
        (bgp (triple ?a :b ?c))
        (bgp (triple ?c :d ?e))))))

Constant Summary

NAME =

:bound

Constants inherited from Unary

Unary::ARITY

Constants inherited from SPARQL::Algebra::Operator

ARITY

Instance Attribute Summary

Attributes inherited from SPARQL::Algebra::Operator

#operands, #options

Instance Method Summary (collapse)

• - (RDF::Literal::Boolean) evaluate(bindings = {})

  Returns true if the operand is a variable that is bound to a value in the given bindings, false otherwise.

• - (Bound) initialize(var, options = {}) constructor

  Initializes a new operator instance.

Methods included from Evaluatable

#apply, #memoize

Methods inherited from SPARQL::Algebra::Operator

arity, base_uri, #base_uri, base_uri=, #boolean, #constant?, #eql?, #evaluatable?, evaluate, #executable?, for, #inspect, #operand, #optimize, prefixes, #prefixes, prefixes=, #to_sse, #to_sxp, #variable?

Methods included from Expression

cast, #constant?, for, new, open, #optimize, parse, #to_sse, #variable?

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# File 'lib/sparql/algebra/operator/bound.rb', line 28

def initialize(var, options = {})
  super
end

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# File 'lib/sparql/algebra/operator/bound.rb', line 39

def evaluate(bindings = {})
  case var = operand
    when Variable
      operand.evaluate(bindings) ? RDF::Literal::TRUE : RDF::Literal::FALSE
    else raise TypeError, "expected an RDF::Query::Variable, but got #{var.inspect}"
  end
end