Class: SPARQL::Algebra::Operator::Exprlist

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

Overview

The SPARQL GraphPattern exprlist operator.

Used for filters with more than one expression.

[72] ExpressionList ::= NIL | '(' Expression ( ',' Expression )* ')'

Examples:

SPARQL Grammar

PREFIX : <http://example.org/>

SELECT ?v ?w
{ 
  FILTER (?v = 2)
  FILTER (?w = 3)
  ?s :p ?v . 
  ?s :q ?w .
}

SSE

(prefix ((: <http://example.org/>))
  (project (?v ?w)
    (filter (exprlist (= ?v 2) (= ?w 3))
      (bgp
        (triple ?s :p ?v)
        (triple ?s :q ?w)
      ))))

See Also:

Constant Summary collapse

NAME = 
[:exprlist]

Instance Method Summary collapse

Methods included from Evaluatable

#apply, #memoize, #replace_aggregate!, #replace_vars!

Instance Method Details

#evaluate(bindings, **options) ⇒ RDF::Literal::Boolean

Returns true if all operands evaluate to true.

Note that this operator operates on the effective boolean value (EBV) of its operands.

Examples:


(exprlist (= 1 1) (!= 1 0))

Parameters:

  • bindings (RDF::Query::Solution) —

    a query solution containing zero or more variable bindings

  • options (Hash{Symbol => Object}) —

    ({}) options passed from query

Returns:

  • (RDF::Literal::Boolean) —

    true or false

Raises:

  • (TypeError) —

    if the operands could not be coerced to a boolean literal



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# File 'lib/sparql/algebra/operator/exprlist.rb', line 52

def evaluate(bindings, **options)
  res = operands.all? {|op| boolean(op.evaluate(bindings, **options.merge(depth: options[:depth].to_i + 1))).true? }
  RDF::Literal(res) # FIXME: error handling
end