Class: SPARQL::Algebra::Operator::Contains

Inherits:
Operator::Binary
  • Object
show all
Includes:
Evaluatable
Defined in:
lib/sparql/algebra/operator/contains.rb

Overview

A SPARQL contains operator.

[121] BuiltInCall ::= ... | 'CONTAINS' '(' Expression ',' Expression ')'

Examples:

SPARQL Grammar

PREFIX : <http://example.org/>
SELECT ?s ?str WHERE {
  ?s :str ?str
  FILTER CONTAINS(?str, "a")
}

SSE

(prefix
 ((: <http://example.org/>))
 (project (?s ?str)
  (filter (contains ?str "a")
   (bgp (triple ?s :str ?str)))))

See Also:

Constant Summary collapse

NAME = 
:contains

Instance Method Summary collapse

Methods included from Evaluatable

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

Instance Method Details

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

The CONTAINS function corresponds to the XPath fn:contains. The arguments must be argument compatible otherwise an error is raised.

Examples:

contains("foobar", "bar") #=> true
contains("foobar"@en, "foo"@en) #=> true
contains("foobar"^^xsd:string, "bar"^^xsd:string) #=> true
contains("foobar"^^xsd:string, "foo") #=> true
contains("foobar", "bar"^^xsd:string) #=> true
contains("foobar"@en, "foo") #=> true
contains("foobar"@en, "bar"^^xsd:string) #=> true

Parameters:

  • left (RDF::Literal) —

    a literal

  • right (RDF::Literal) —

    a literal

Returns:

  • (RDF::Literal::Boolean)

Raises:

  • (TypeError) —

    if operands are not compatible



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# File 'lib/sparql/algebra/operator/contains.rb', line 47

def apply(left, right, **options)
  case
  when !left.compatible?(right)
    raise TypeError, "expected two RDF::Literal operands, but got #{left.inspect} and #{right.inspect}"
  when left.to_s.include?(right.to_s) then RDF::Literal::TRUE
  else RDF::Literal::FALSE
  end
end

#to_sparql(**options) ⇒ String

Returns a partial SPARQL grammar for this operator.

Returns:

  • (String) 


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# File 'lib/sparql/algebra/operator/contains.rb', line 61

def to_sparql(**options)
  "contains(" + operands.to_sparql(delimiter: ', ', **options) + ")"
end