Class: SPARQL::Algebra::Operator::Equal

Inherits:
Compare show all
Defined in:
lib/sparql/algebra/operator/equal.rb

Overview

The SPARQL relational = (equal) comparison operator.

[114] RelationalExpression ::= NumericExpression (‘=’ NumericExpression)?

Examples:

SPARQL Grammar

PREFIX  xsd: <http://www.w3.org/2001/XMLSchema#>
PREFIX  : <http://example.org/things#>
SELECT  ?x
WHERE { ?x :p ?v . FILTER ( ?v = 1 ) }

SSE

(prefix
 ((xsd: <http://www.w3.org/2001/XMLSchema#>) (: <http://example.org/things#>))
 (project (?x) (filter (= ?v 1) (bgp (triple ?x :p ?v)))))

See Also:

Direct Known Subclasses

NotEqual

Constant Summary collapse

NAME = 
:'='

Constants inherited from Binary

Binary::ARITY

Constants inherited from SPARQL::Algebra::Operator

ARITY, IsURI, URI

Constants included from Expression

Expression::PATTERN_PARENTS

Instance Attribute Summary

Attributes inherited from SPARQL::Algebra::Operator

#operands

Instance Method Summary collapse

Methods inherited from Compare

#to_sparql

Methods included from Evaluatable

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

Methods inherited from Binary

#initialize

Methods inherited from SPARQL::Algebra::Operator

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

Methods included from Expression

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

Constructor Details

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

Instance Method Details

#apply(term1, term2, **options) ⇒ RDF::Literal::Boolean

Returns TRUE if term1 and term2 are the same RDF term as defined in Resource Description Framework (RDF): Concepts and Abstract Syntax [CONCEPTS]; produces a type error if the arguments are both literal but are not the same RDF term *; returns FALSE otherwise. term1 and term2 are the same if any of the following is true:

  • term1 and term2 are equivalent IRIs as defined in 6.4 RDF URI References of [CONCEPTS].

  • term1 and term2 are equivalent literals as defined in 6.5.1 Literal Equality of [CONCEPTS].

  • term1 and term2 are the same blank node as described in 6.6 Blank Nodes of [CONCEPTS].

Parameters:

Returns:

  • (RDF::Literal::Boolean) —

    true or false

Raises:

  • (TypeError) —

    if either operand is not an RDF term or operands are not comperable

See Also:

  • RDF::Term#==


39
40
41
42
43
 
# File 'lib/sparql/algebra/operator/equal.rb', line 39

def apply(term1, term2, **options)
  term1 = term1.dup.extend(RDF::TypeCheck)
  term2 = term2.dup.extend(RDF::TypeCheck)
  RDF::Literal(term1 == term2)
end