Class: SPARQL::Algebra::Operator::StrLang

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

Overview

The SPARQL strlang operator.

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

Examples:

SPARQL Grammar

PREFIX : <http://example.org/>
SELECT ?s (STRLANG(?str,"en-US") AS ?s2) WHERE {
  ?s :str ?str
  FILTER(LANGMATCHES(LANG(?str), "en"))
}

SSE

(prefix ((: <http://example.org/>))
  (project (?s ?s2)
    (extend ((?s2 (strlang ?str "en-US")))
      (filter (langMatches (lang ?str) "en")
        (bgp (triple ?s :str ?str))))))

See Also:

Constant Summary collapse

NAME = 
:strlang

Instance Method Summary collapse

Methods included from Evaluatable

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

Instance Method Details

#apply(value, langTag, **options) ⇒ RDF::Literal

Constructs a literal with lexical form and type as specified by the arguments.

Parameters:

  • value (RDF::Literal) —

    a literal

  • langTag (RDF::Literal) —

    datatype

Returns:

  • (RDF::Literal) —

    a datatyped literal

Raises:

  • (TypeError)

See Also:



37
38
39
40
 
# File 'lib/sparql/algebra/operator/strlang.rb', line 37

def apply(value, langTag, **options)
  raise TypeError, "Literal #{value.inspect} is not simple" unless value.simple?
  RDF::Literal.new(value.to_s, language: langTag.to_s)
end

#to_sparql(**options) ⇒ String

Returns a partial SPARQL grammar for this operator.

Returns:

  • (String) 


47
48
49
 
# File 'lib/sparql/algebra/operator/strlang.rb', line 47

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