Class: SPARQL::Algebra::Operator::Project

Inherits:
Binary show all
Includes:
Query
Defined in:
lib/sparql/algebra/operator/project.rb

Overview

The SPARQL GraphPattern order operator.

Examples:

(select (?v)
  (project (?v)
    (filter (= ?v 2)
      (bgp (triple ?s <http://example/p> ?v)))))

See Also:

Constant Summary

NAME =
[:project]

Constants inherited from Binary

Binary::ARITY

Constants inherited from SPARQL::Algebra::Operator

ARITY

Instance Attribute Summary

Attributes included from Query

#solutions

Attributes inherited from SPARQL::Algebra::Operator

#operands, #options

Instance Method Summary (collapse)

Methods included from Query

#context=, #each_solution, #failed?, #matched?, #unshift, #variables

Methods inherited from Binary

#initialize

Methods inherited from SPARQL::Algebra::Operator

arity, base_uri, #base_uri, base_uri=, #boolean, #constant?, #eql?, #evaluatable?, evaluate, #executable?, for, #initialize, #inspect, #operand, prefixes, #prefixes, prefixes=, #to_sse, #to_sxp, #variable?

Methods included from Evaluatable

#apply, #evaluate, #memoize

Methods included from Expression

cast, #constant?, #evaluate, for, new, open, parse, #to_sse, #variable?

Constructor Details

This class inherits a constructor from SPARQL::Algebra::Operator::Binary

Instance Method Details

- (RDF::Query::Solutions) execute(queryable, options = {})

Executes this query on the given queryable graph or repository. Reduces the result set to the variables listed in the first operand

Parameters:

  • queryable (RDF::Queryable)

    the graph or repository to query

  • options (Hash{Symbol => Object}) (defaults to: {})

    any additional keyword options

Returns:

See Also:



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# File 'lib/sparql/algebra/operator/project.rb', line 29

def execute(queryable, options = {})
  @solutions = operands.last.
    execute(queryable, options.merge(:depth => options[:depth].to_i + 1)).
    project(*(operands.first))
end

- (Union, RDF::Query) optimize

Returns an optimized version of this query.

Return optimized query

Returns:



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# File 'lib/sparql/algebra/operator/project.rb', line 41

def optimize
  operands = operands.map(&:optimize)
end