Class: SPARQL::Algebra::Operator::Hours

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

Overview

The SPARQL logical hours operator.

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

Examples:

SPARQL Grammar

PREFIX : <http://example.org/>
SELECT ?s (HOURS(?date) AS ?x) WHERE {
  ?s :date ?date
}

SSE

(prefix
 ((: <http://example.org/>))
 (project (?s ?x)
  (extend ((?x (hours ?date)))
   (bgp (triple ?s :date ?date)))))

See Also:

Constant Summary collapse

NAME = 
:hours

Instance Method Summary collapse

Methods included from Evaluatable

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

Instance Method Details

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

Returns the hours part of arg as an integer. The value is as given in the lexical form of the XSD dateTime.

Parameters:

  • operand (RDF::Literal) —

    the operand

Returns:

  • (RDF::Literal::Temporal)

Raises:

  • (TypeError) —

    if the operand is not a simple literal



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# File 'lib/sparql/algebra/operator/hours.rb', line 34

def apply(operand, **options)
  raise TypeError, "expected an RDF::Literal::Temporal, but got #{operand.inspect}" unless operand.is_a?(RDF::Literal::Temporal)
  RDF::Literal(operand.object.hour)
end

#to_sparql(**options) ⇒ String

Returns a partial SPARQL grammar for this operator.

Returns:

  • (String) 


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# File 'lib/sparql/algebra/operator/hours.rb', line 44

def to_sparql(**options)
  "HOURS(#{operands.last.to_sparql(**options)})"
end