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

Inherits:
Binary show all
Includes:
Query
Defined in:
vendor/bundler/ruby/2.6.0/bundler/gems/sparql-78c2af8f957e/lib/sparql/algebra/operator/project.rb

Overview

The SPARQL GraphPattern project operator.

Examples:

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

See Also:

Constant Summary collapse

NAME = 
[:project]

Constants inherited from Binary

Binary::ARITY

Constants inherited from SPARQL::Algebra::Operator

ARITY, IsURI, URI

Instance Attribute Summary

Attributes included from Query

#solutions

Attributes inherited from SPARQL::Algebra::Operator

#operands

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

Methods inherited from Binary

#initialize

Methods inherited from SPARQL::Algebra::Operator

#aggregate?, arity, #base_uri, base_uri, base_uri=, #boolean, #constant?, #each_descendant, #eql?, #evaluatable?, evaluate, #executable?, #first_ancestor, for, #initialize, #inspect, #ndvars, #node?, #operand, #parent, #parent=, #prefixes, prefixes, prefixes=, #rewrite, #to_binary, #to_sxp, #to_sxp_bin, #validate!, #variable?, #vars

Methods included from Expression

cast, #constant?, #evaluate, extension, extensions, for, #invalid?, new, #node?, open, parse, register_extension, #to_sxp_bin, #valid?, #validate!, #variable?

Constructor Details

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

Instance Method Details

#execute(queryable, options = {}) {|solution| ... } ⇒ RDF::Query::Solutions

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

Yields:

  • (solution) —

    each matching solution

Yield Parameters:

Yield Returns:

  • (void) —

    ignored

Returns:

See Also:



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# File 'vendor/bundler/ruby/2.6.0/bundler/gems/sparql-78c2af8f957e/lib/sparql/algebra/operator/project.rb', line 33

def execute(queryable, options = {}, &block)
  @solutions = queryable.query(operands.last, options.merge(depth: options[:depth].to_i + 1))
  @solutions = @solutions.project(*(operands.first))
  @solutions.each(&block) if block_given?
  @solutions
end

#optimize ⇒ Union, RDF::Query

Returns an optimized version of this query.

Return optimized query

Returns:



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# File 'vendor/bundler/ruby/2.6.0/bundler/gems/sparql-78c2af8f957e/lib/sparql/algebra/operator/project.rb', line 46

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