Class: RDF::N3::Algebra::List::Iterate

Inherits:
RDF::N3::Algebra::ListOperator show all
Defined in:
vendor/bundler/ruby/3.3.0/bundler/gems/rdf-n3-a6ef81a7e1ce/lib/rdf/n3/algebra/list/iterate.rb

Overview

Generates a list of lists when each constituent list is composed of the index and value of each element in the subject.

Binds variables in the object list.

Examples:

{ (1 2 3) list:iterate ((0 1) (1 2) (2 3)) } => { :test4a a :SUCCESS }.

Constant Summary collapse

NAME = 
:listIterate
URI = 
RDF::N3::List.iterate

Constants included from Util::Logger

Util::Logger::IOWrapper

Constants inherited from SPARQL::Algebra::Operator::Binary

SPARQL::Algebra::Operator::Binary::ARITY

Constants inherited from SPARQL::Algebra::Operator

SPARQL::Algebra::Operator::ARITY, SPARQL::Algebra::Operator::IsURI

Constants included from SPARQL::Algebra::Expression

SPARQL::Algebra::Expression::PATTERN_PARENTS

Instance Attribute Summary

Attributes included from Enumerable

#existentials, #universals

Attributes included from SPARQL::Algebra::Query

#solutions

Attributes inherited from SPARQL::Algebra::Operator

#operands

Instance Method Summary collapse

Methods inherited from RDF::N3::Algebra::ListOperator

#as_literal, #input_operand, #resolve, #validate

Methods included from Builtin

#each, #evaluate, #hash, #input_operand, #rank, #to_uri

Methods included from Util::Logger

#log_debug, #log_depth, #log_error, #log_fatal, #log_info, #log_recover, #log_recovering?, #log_statistics, #log_warn, #logger

Methods included from Enumerable

add_entailment, #canonicalize, #canonicalize!, #dump, #each_graph, #each_object, #each_predicate, #each_quad, #each_statement, #each_subject, #each_term, #each_triple, #entail, #enum_graph, #enum_object, #enum_predicate, #enum_quad, #enum_statement, #enum_subject, #enum_term, #enum_triple, #graph?, #graph_names, #invalid?, #method_missing, #object?, #objects, #predicate?, #predicates, #project_graph, #quad?, #quads, #respond_to_missing?, #statement?, #statements, #subject?, #subjects, #supports?, #term?, #terms, #to_a, #to_h, #to_set, #triple?, #triples, #valid?, #validate!

Methods included from Util::Aliasing::LateBound

#alias_method

Methods included from Isomorphic

#bijection_to, #isomorphic_with?

Methods included from Countable

#count, #empty?

Methods included from SPARQL::Algebra::Update

#graph_name=, #unshift, #variables

Methods included from SPARQL::Algebra::Query

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

Methods inherited from SPARQL::Algebra::Operator::Binary

#initialize

Methods inherited from SPARQL::Algebra::Operator

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

Methods included from SPARQL::Algebra::Expression

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

Constructor Details

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

Dynamic Method Handling

This class handles dynamic methods through the method_missing method in the class RDF::Enumerable

Instance Method Details

#execute(queryable, solutions:, **options) ⇒ RDF::Query::Solutions

Evaluates this operator using the given variable bindings. The subject MUST evaluate to a list and the object to a list composed of two components: index and value.

Examples:

{(1 2 3) list:iterate (?x ?y)} => {:solution :is (?x ?y)} .
{(1 2 3) list:iterate ?L} => {:solution :is ?L} .
{(1 2 3) list:iterate (1 ?y)} => {:value :is ?y} .
{(1 2 3) list:iterate (?x 2)} => {:index :is ?x} .

Parameters:

Returns:



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# File 'vendor/bundler/ruby/3.3.0/bundler/gems/rdf-n3-a6ef81a7e1ce/lib/rdf/n3/algebra/list/iterate.rb', line 34

def execute(queryable, solutions:, **options)
  RDF::Query::Solutions(solutions.map do |solution|
    subject = operand(0).evaluate(solution.bindings, formulae: formulae) || operand(0)
    # Might be a variable or node evaluating to a list in queryable, or might be a list with variables
    # If subject evaluated to a BNode, re-expand as a list
    subject = RDF::N3::List.try_list(subject, queryable).evaluate(solution.bindings, formulae: formulae)
    next unless validate(subject)

    object = operand(1).evaluate(solution.bindings, formulae: formulae) || operand(1)
    next unless object
    # If object evaluated to a BNode, re-expand as a list
    object = RDF::N3::List.try_list(object, queryable).evaluate(solution.bindings, formulae: formulae) || object

    if object.list? && object.variable?
      # Create a solution for those entries in subject that match object
      if object.length != 2
        log_error(NAME) {"object is not a list with two entries: #{object.to_sxp}"}
        next
      end
      if object.first.variable? && object.last.variable?
        solutions = RDF::Query::Solutions.new
        subject.each_with_index do |r, i|
          s = solution.merge(object.first.to_sym => RDF::Literal(i), object.last.to_sym => r)
          log_debug(self.class.const_get(:NAME), "result: #{s.to_sxp}")
          solutions << s
        end
        solutions
      elsif object.first.variable?
        # Solution binds indexes to all matching values
        solutions = RDF::Query::Solutions.new
        subject.each_with_index do |r, i|
          next unless r == object.last
          s = solution.merge(object.first.to_sym => RDF::Literal(i))
          log_debug(self.class.const_get(:NAME), "result: #{s.to_sxp}")
          solutions << s
        end
        solutions
      elsif object.last.variable?
        # Solution binds value at specified index
        next unless v = subject.at(object.first)
        s = solution.merge(object.last.to_sym => v)
        log_debug(self.class.const_get(:NAME), "result: #{s.to_sxp}")
        s
      end
    elsif object.variable?
      # Create a solution for each index/value pair in subject
      solutions = RDF::Query::Solutions.new
      subject.each_with_index do |r, i|
        s = solution.merge(object.to_sym => RDF::N3::List[RDF::Literal(i), r])
        log_debug(self.class.const_get(:NAME), "result: #{s.to_sxp}")
        solutions << s
      end
      solutions
    else
      # Evaluates to true if the subject has a matching entry
      same = subject.at(object.first) == object.last
      log_debug(self.class.const_get(:NAME), "result: #{same.inspect}")
      solution if same
    end
  end.flatten.compact.uniq)
end