Class: RDF::N3::Algebra::ListOperator

Inherits:
SPARQL::Algebra::Operator::Binary show all
Includes:
Builtin, SPARQL::Algebra::Query, SPARQL::Algebra::Update
Defined in:
vendor/bundler/ruby/3.0.0/bundler/gems/rdf-n3-7f928f0a0762/lib/rdf/n3/algebra/list_operator.rb

Overview

This is a generic operator where the subject is a list or binds to a list and the object is either a constant that equals the evaluation of the subject, or a variable to which the result is bound in a solution

Constant Summary collapse

NAME =
:listOperator

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, SPARQL::Algebra::Operator::URI

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 included from Builtin

#each, #evaluate, #hash, #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, #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, #ndvars, #node?, #operand, #optimize, #optimize!, #parent, #parent=, #prefixes, prefixes, prefixes=, #rewrite, #to_binary, #to_sxp, #to_sxp_bin, #validate!, #variable?, #vars

Methods included from SPARQL::Algebra::Expression

cast, #constant?, #evaluate, 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

#as_literal(object) ⇒ Object

Returns a literal for the numeric argument.



85
86
87
88
89
90
91
92
93
94
# File 'vendor/bundler/ruby/3.0.0/bundler/gems/rdf-n3-7f928f0a0762/lib/rdf/n3/algebra/list_operator.rb', line 85

def as_literal(object)
  case object
  when Float
    literal = RDF::Literal(object, canonicalize: true)
    literal.instance_variable_set(:@string, literal.to_s.downcase)
    literal
  else
    RDF::Literal(object, canonicalize: true)
  end
end

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

The operator takes a list and provides a mechanism for subclasses to operate over (and validate) that list argument.

Parameters:

Returns:



19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
# File 'vendor/bundler/ruby/3.0.0/bundler/gems/rdf-n3-7f928f0a0762/lib/rdf/n3/algebra/list_operator.rb', line 19

def execute(queryable, solutions:, **options)
  RDF::Query::Solutions(solutions.map do |solution|
    # Might be a variable or node evaluating to a list in queryable, or might be a list with variables
    subject = operand(0).evaluate(solution.bindings, formulae: formulae)
    next unless subject
    # If it evaluated to a BNode, re-expand as a list
    subject = RDF::N3::List.try_list(subject, queryable).evaluate(solution.bindings, formulae: formulae)
    object = operand(1).evaluate(solution.bindings, formulae: formulae) || operand(1)
    object = formulae.fetch(object, object) if object.node?

    log_info(self.class.const_get(:NAME), "subject") {SXP::Generator.string(subject.to_sxp_bin).strip}
    log_info(self.class.const_get(:NAME), "object") {SXP::Generator.string(object.to_sxp_bin).strip}
    next unless validate(subject)

    lhs = resolve(subject)
    if lhs.nil?
      log_error(self.class.const_get(:NAME), "subject evaluates to null") {subject.inspect}
      next
    end

    if object.variable?
      log_debug(self.class.const_get(:NAME), "result") {SXP::Generator.string(lhs.to_sxp_bin).strip}
      solution.merge(object.to_sym => lhs)
    elsif object != lhs
      log_debug(self.class.const_get(:NAME), "result: false")
      nil
    else
      log_debug(self.class.const_get(:NAME), "result: true")
      solution
    end
  end.compact.uniq)
end

#input_operandRDF::Term

Input is generically the subject

Returns:



56
57
58
# File 'vendor/bundler/ruby/3.0.0/bundler/gems/rdf-n3-7f928f0a0762/lib/rdf/n3/algebra/list_operator.rb', line 56

def input_operand
  operand(0)
end

#resolve(list) ⇒ RDF::Term

Subclasses implement resolve.

Parameters:

Returns:

Raises:



65
66
67
# File 'vendor/bundler/ruby/3.0.0/bundler/gems/rdf-n3-7f928f0a0762/lib/rdf/n3/algebra/list_operator.rb', line 65

def resolve(list)
  raise NotImplemented
end

#validate(list) ⇒ Boolean

Subclasses may override or supplement validate to perform validation on the list subject

Parameters:

Returns:

  • (Boolean)


74
75
76
77
78
79
80
81
# File 'vendor/bundler/ruby/3.0.0/bundler/gems/rdf-n3-7f928f0a0762/lib/rdf/n3/algebra/list_operator.rb', line 74

def validate(list)
  if list.list? && list.valid?
    true
  else
    log_error(NAME) {"operand is not a list: #{list.to_sxp}"}
    false
  end
end