Class: SPARQL::Algebra::Operator::PathStar

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

Overview

Examples:

SPARQL Grammar

PREFIX : <http://example/> 
SELECT * WHERE {
  :a :p* ?z
}

SSE

(prefix ((: <http://example/>))
 (path :a (path* :p) ?z))

See Also:

Constant Summary collapse

NAME = 
:"path*"

Instance Attribute Summary

Attributes included from Query

#solutions

Instance Method Summary collapse

Methods included from Query

#each_solution, #empty?, #failed?, #graph_name=, #matched?, #query_yields_boolean?, #query_yields_solutions?, #query_yields_statements?, #unshift, #variables

Instance Method Details

#execute(queryable, **options) {|solution| ... } ⇒ Object

Path including at zero length:

(path :a (path* :p) :b)

into

(path :a (path? (path+ :p)) :b)

Parameters:

  • queryable (RDF::Queryable) —

    the graph or repository to query

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

    any additional keyword options

Options Hash (**options):

Yields:

  • (solution) —

    each matching solution

Yield Parameters:

Yield Returns:

  • (void) —

    ignored

See Also:



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# File 'lib/sparql/algebra/operator/path_star.rb', line 45

def execute(queryable, **options, &block)
  subject, object = options[:subject], options[:object]
  debug(options) {"Path* #{[subject, operands, object].to_sse}"}

  # (:x :p* :y) => (:x (:p+)? :y)
  query = PathOpt.new(PathPlus.new(*operands))
  query.execute(queryable, **options.merge(depth: options[:depth].to_i + 1), &block)
end

#to_sparql(**options) ⇒ String

Returns a partial SPARQL grammar for this operator.

Returns:

  • (String) 


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# File 'lib/sparql/algebra/operator/path_star.rb', line 58

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