Class: RDF::Query

Inherits:
Object show all
Includes:
Enumerable
Defined in:
vendor/bundler/ruby/2.6.0/bundler/gems/rdf-02340e834fe8/lib/rdf/query.rb,
vendor/bundler/ruby/2.6.0/bundler/gems/rdf-02340e834fe8/lib/rdf/query/solutions.rb,
vendor/bundler/ruby/2.6.0/bundler/gems/rdf-02340e834fe8/lib/rdf/query/variable.rb,
vendor/bundler/ruby/2.6.0/bundler/gems/rdf-02340e834fe8/lib/rdf/query/pattern.rb,
vendor/bundler/ruby/2.6.0/bundler/gems/rdf-02340e834fe8/lib/rdf/query/hash_pattern_normalizer.rb,
vendor/bundler/ruby/2.6.0/bundler/gems/rdf-02340e834fe8/lib/rdf/query/solution.rb,
vendor/bundler/ruby/2.6.0/bundler/gems/rdf-spec-1b54f9c9555a/lib/rdf/spec/inspects.rb,
vendor/bundler/ruby/2.6.0/bundler/gems/sparql-407aaf052a45/lib/sparql/algebra/extensions.rb

Overview

An RDF basic graph pattern (BGP) query.

Named queries either match against a specifically named graph if the name is an RDF::Resource or bound RDF::Query::Variable. Names that are against unbound variables match either default or named graphs. The name of false will only match against the default graph.

Variable names cause the variable to be added to the solution set elements.

Examples:

Constructing a basic graph pattern query (1)

query = RDF::Query.new do
  pattern [:person, RDF.type,  FOAF.Person]
  pattern [:person, FOAF.name, :name]
  pattern [:person, FOAF.mbox, :email]
end

Constructing a basic graph pattern query (2)

query = RDF::Query.new({
  person: {
    RDF.type  => FOAF.Person,
    FOAF.name => :name,
    FOAF.mbox => :email,
  }
})

Executing a basic graph pattern query

graph = RDF::Graph.load('etc/doap.nt')
query.execute(graph).each do |solution|
  puts solution.inspect
end

Constructing and executing a query in one go (1)

solutions = RDF::Query.execute(graph) do
  pattern [:person, RDF.type, FOAF.Person]
end

Constructing and executing a query in one go (2)

solutions = RDF::Query.execute(graph, {
  person: {
    RDF.type => FOAF.Person,
  }
})

In this example, the default graph contains the names of the publishers of two named graphs. The triples in the named graphs are not visible in the default graph in this example.

# default graph
@prefix dc: <http://purl.org/dc/elements/1.1/

<http://example.org/bob>    dc:publisher  "Bob" .
<http://example.org/alice>  dc:publisher  "Alice" .

# Named graph: http://example.org/bob
@prefix foaf: <http://xmlns.com/foaf/0.1/> .

_:a foaf:name "Bob" .
_:a foaf:mbox <mailto:bob@oldcorp.example.org> .

# Named graph: http://example.org/alice
@prefix foaf: <http://xmlns.com/foaf/0.1/> .

_:a foaf:name "Alice" .
_:a foaf:mbox <mailto:alice@work.example.org> .

See Also:

Since:

  • 0.3.0

Direct Known Subclasses

SPARQL::Client::Query

Defined Under Namespace

Classes: HashPatternNormalizer, Pattern, Solution, Solutions, Variable

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Enumerable

add_entailment, #dump, #each_graph, #each_object, #each_predicate, #each_quad, #each_subject, #each_term, #each_triple, #entail, #enum_graph, #enum_object, #enum_predicate, #enum_quad, #enum_statement, #enum_subject, #enum_term, #enum_triple, #graph_names, #has_graph?, #has_object?, #has_predicate?, #has_quad?, #has_statement?, #has_subject?, #has_term?, #has_triple?, #invalid?, #method_missing, #objects, #predicates, #project_graph, #quads, #respond_to_missing?, #statements, #subjects, #supports?, #terms, #to_a, #to_h, #to_set, #triples

Methods included from Util::Aliasing::LateBound

#alias_method

Methods included from Countable

#count

Methods included from Isomorphic

#bijection_to, #isomorphic_with?

Constructor Details

#initialize(patterns = [], **options) {|query| ... } ⇒ Query #initialize(patterns, **options) ⇒ Query

Initializes a new basic graph pattern query.

Overloads:

  • #initialize(patterns = [], **options) {|query| ... } ⇒ Query

    Parameters:

    Options Hash (**options):

    • :solutions (RDF::Query::Solutions) — default: Solutions.new
    • :graph_name (RDF::Resource, RDF::Query::Variable, false) — default: nil

      Default graph name for matching against queryable. Named queries either match against a specifically named graphs if the name is an Resource or bound Variable. Names that are against unbound variables match either default or named graphs. The name of false will only match against the default graph.

    • :name (RDF::Resource, RDF::Query::Variable, false) — default: nil

      Alias for :graph_name.

    Yields:

    • (query)

    Yield Parameters:

    Yield Returns:

    • (void)

      ignored

  • #initialize(patterns, **options) ⇒ Query

    Parameters:

Parameters:

  • options (Hash)

    a customizable set of options

Options Hash (**options):

  • validate (Boolean) — default: false

    validate patterns @yield [query] @yieldparam [RDF::Query] query @yieldreturn [void] ignored

Since:

  • 0.3.0



179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
# File 'vendor/bundler/ruby/2.6.0/bundler/gems/rdf-02340e834fe8/lib/rdf/query.rb', line 179

def initialize(*patterns, solutions: nil, graph_name: nil, name: nil, validate: false, **options, &block)
  @options = options.dup
  @solutions = Query::Solutions(solutions)
  graph_name = name if graph_name.nil?

  patterns << @options if patterns.empty?

  @patterns  = case patterns.first
    when Hash  then compile_hash_patterns(HashPatternNormalizer.normalize!(patterns.first.dup, @options))
    when Array then patterns.first
    else patterns
  end

  self.graph_name = graph_name

  if block_given?
    case block.arity
      when 1 then block.call(self)
      else instance_eval(&block)
    end
  end

  validate! if validate
end

Dynamic Method Handling

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

Instance Attribute Details

#optionsHash (readonly)

Any additional options for this query.

Returns:

Since:

  • 0.3.0



135
136
137
# File 'vendor/bundler/ruby/2.6.0/bundler/gems/rdf-02340e834fe8/lib/rdf/query.rb', line 135

def options
  @options
end

#patternsArray<RDF::Query::Pattern> (readonly)

The patterns that constitute this query.

Returns:

Since:

  • 0.3.0



123
124
125
# File 'vendor/bundler/ruby/2.6.0/bundler/gems/rdf-02340e834fe8/lib/rdf/query.rb', line 123

def patterns
  @patterns
end

#solutionsRDF::Query::Solutions (readonly)

The solution sequence for this query.

Returns:

Since:

  • 0.3.0



129
130
131
# File 'vendor/bundler/ruby/2.6.0/bundler/gems/rdf-02340e834fe8/lib/rdf/query.rb', line 129

def solutions
  @solutions
end

Class Method Details

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

Executes a query on the given queryable graph or repository.

Parameters:

Yields:

  • (query)

Yield Parameters:

Yield Returns:

  • (void)

    ignored

Returns:

See Also:

Since:

  • 0.3.0



92
93
94
# File 'vendor/bundler/ruby/2.6.0/bundler/gems/rdf-02340e834fe8/lib/rdf/query.rb', line 92

def self.execute(queryable, patterns = {}, options = {}, &block)
  self.new(patterns, options, &block).execute(queryable, options)
end

.SolutionsSolutions .Solutions(solutions) ⇒ Solutions .Solutions(array) ⇒ Solutions .Solutions(*args) ⇒ Solutions

Cast values as Solutions

Overloads:

  • .SolutionsSolutions

    Returns Solutions.new()

    Returns:

  • .Solutions(solutions) ⇒ Solutions

    Returns the argument

    Returns:

  • .Solutions(array) ⇒ Solutions

    Returns the array extended with solutions

    Parameters:

    Returns:

    • (Solutions)

      returns the array extended with solutions

  • .Solutions(*args) ⇒ Solutions

    Returns new solutions including the arguments, which must each be a Solution

    Parameters:

    Returns:

    • (Solutions)

      returns new solutions including the arguments, which must each be a Solution

Since:

  • 0.3.0



111
112
113
114
115
116
117
# File 'vendor/bundler/ruby/2.6.0/bundler/gems/rdf-02340e834fe8/lib/rdf/query.rb', line 111

def self.Solutions(*args)
  if args.length == 1
    return args[0] if args[0].is_a?(Solutions)
    args = args[0] if args[0].is_a?(Array)
  end
  return Solutions.new(args)
end

Instance Method Details

#+(other) ⇒ RDF::Query

Add patterns from another query to form a new Query

Parameters:

Returns:

Since:

  • 0.3.0



403
404
405
# File 'vendor/bundler/ruby/2.6.0/bundler/gems/rdf-02340e834fe8/lib/rdf/query.rb', line 403

def +(other)
  Query.new(self.patterns + other.patterns)
end

#<<(pattern)

This method returns an undefined value.

Appends the given query pattern to this query.

Parameters:

Since:

  • 0.3.0



210
211
212
213
# File 'vendor/bundler/ruby/2.6.0/bundler/gems/rdf-02340e834fe8/lib/rdf/query.rb', line 210

def <<(pattern)
  @patterns << Pattern.from(pattern)
  self
end

#==(other) ⇒ Boolean

Equivalence for Queries: Same Patterns Same Context

Returns:

  • (Boolean)

Since:

  • 0.3.0



281
282
283
284
# File 'vendor/bundler/ruby/2.6.0/bundler/gems/sparql-407aaf052a45/lib/sparql/algebra/extensions.rb', line 281

def ==(other)
  # FIXME: this should be graph_name == other.graph_name
  other.is_a?(RDF::Query) && patterns == other.patterns && graph_name == graph_name
end

#apply_graph_name(graph_name = options[:graph_name]) ⇒ Object

Apply the graph name specified (or configured) to all patterns that have no graph name

Parameters:

Since:

  • 0.3.0



441
442
443
# File 'vendor/bundler/ruby/2.6.0/bundler/gems/rdf-02340e834fe8/lib/rdf/query.rb', line 441

def apply_graph_name(graph_name = options[:graph_name])
  patterns.each {|pattern| pattern.graph_name = graph_name if pattern.graph_name.nil?} unless graph_name.nil?
end

#default?Boolean

Is this query scoped to the default graph?

Returns:

  • (Boolean)

Since:

  • 0.3.0



415
416
417
# File 'vendor/bundler/ruby/2.6.0/bundler/gems/rdf-02340e834fe8/lib/rdf/query.rb', line 415

def default?
  options[:graph_name] == false
end

#dupRDF::Query

Duplicate query, including patterns and solutions

Returns:

Since:

  • 0.3.0



516
517
518
519
520
# File 'vendor/bundler/ruby/2.6.0/bundler/gems/rdf-02340e834fe8/lib/rdf/query.rb', line 516

def dup
  patterns = @patterns.map {|p| p.dup}
  patterns << @options.merge(solutions: @solutions.dup)
  Query.new(*patterns)
end

#each_solution {|solution| ... } ⇒ Enumerator Also known as: each

Enumerates over each matching query solution.

Yields:

  • (solution)

Yield Parameters:

Returns:

Since:

  • 0.3.0



497
498
499
# File 'vendor/bundler/ruby/2.6.0/bundler/gems/rdf-02340e834fe8/lib/rdf/query.rb', line 497

def each_solution(&block)
  @solutions.each(&block)
end

#each_statement {|RDF::Query::Pattern| ... } ⇒ Enumerator

Enumerates over each statement (pattern).

Yields:

Yield Parameters:

  • pattern (::Query::Pattern)

Returns:

Since:

  • 0.3.0



508
509
510
511
# File 'vendor/bundler/ruby/2.6.0/bundler/gems/rdf-02340e834fe8/lib/rdf/query.rb', line 508

def each_statement(&block)
  apply_graph_name
  patterns.each(&block)
end

#empty?Boolean

Query has no patterns

Returns:

  • (Boolean)

Since:

  • 0.3.0



486
487
488
# File 'vendor/bundler/ruby/2.6.0/bundler/gems/rdf-02340e834fe8/lib/rdf/query.rb', line 486

def empty?
  patterns.empty?
end

#executable?Boolean

Returns true if this is executable (i.e., contains a graph patterns), false otherwise.

Returns:

  • (Boolean)

    true or false

Since:

  • 0.3.0



346
# File 'vendor/bundler/ruby/2.6.0/bundler/gems/sparql-407aaf052a45/lib/sparql/algebra/extensions.rb', line 346

def executable?; true; end

#execute(queryable, solutions: Solution.new, graph_name: nil, name: nil, **options) {|solution| ... } ⇒ RDF::Query::Solutions

Note:

solutions could be an Iterator, but this algorithm cycles over solutions, which requires them to be an array internally.

Executes this query on the given queryable graph or repository.

Named queries either match against a specifically named graphs if the name is an RDF::Resource or bound RDF::Query::Variable. Names that are against unbound variables match either detault or named graphs. The name of false will only match against the default graph.

If the query nas no patterns, it returns a single empty solution as per SPARQL 1.1 Empty Group Pattern.

Parameters:

Options Hash (**options):

Yields:

  • (solution)

    each matching solution

Yield Parameters:

Yield Returns:

  • (void)

    ignored

Returns:

See Also:

Since:

  • 0.3.0



297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
# File 'vendor/bundler/ruby/2.6.0/bundler/gems/rdf-02340e834fe8/lib/rdf/query.rb', line 297

def execute(queryable, solutions: Solution.new, graph_name: nil, name: nil, **options, &block)
  options = {bindings: {}}.merge(options)

  # Use provided solutions to allow for query chaining
  # Otherwise, a quick empty solution simplifies the logic below; no special case for
  # the first pattern
  @solutions = Query::Solutions(solutions)

  # If there are no patterns, just return the empty solution
  if empty?
    @solutions.each(&block) if block_given?
    return @solutions
  end

  patterns = @patterns
  graph_name = name if graph_name.nil?
  graph_name = self.graph_name if graph_name.nil?
  options[:graph_name] = graph_name unless graph_name.nil?

  # Add graph_name to pattern, if necessary
  unless graph_name.nil?
    if patterns.empty?
      patterns = [Pattern.new(nil, nil, nil, graph_name: graph_name)]
    else
      apply_graph_name(graph_name)
    end
  end

  patterns.each do |pattern|

    old_solutions, @solutions = @solutions, Query::Solutions()

    options[:bindings].each_key do |variable|
      if pattern.variables.include?(variable)
        unbound_solutions, old_solutions = old_solutions, Query::Solutions()
        options[:bindings][variable].each do |binding|
          unbound_solutions.each do |solution|
            old_solutions << solution.merge(variable => binding)
          end
        end
        options[:bindings].delete(variable)
      end
    end

    old_solutions.each do |solution|
      found_match = false
      pattern.execute(queryable, solution) do |statement|
        found_match = true
        @solutions << solution.merge(pattern.solution(statement))
      end
      # If this pattern was optional, and we didn't find any matches,
      # just copy it over as-is.
      if !found_match && pattern.optional?
        @solutions << solution
      end
    end

    #puts "solutions after #{pattern} are #{@solutions.to_a.inspect}"

    # It's important to abort failed queries quickly because later patterns
    # that can have constraints are often broad without them.
    # We have no solutions at all:
    return @solutions if @solutions.empty?

    if !pattern.optional?
      # We have no solutions for variables we should have solutions for
      # (excludes non-distinguished variables):
      need_vars = pattern.variables.select {|k,v| v.distinguished?}.keys
      @solutions.each do |solution|
        break if need_vars.empty?
        need_vars -= solution.bindings.keys
      end
      return Query::Solutions() unless need_vars.empty?
    end
  end
  @solutions.each(&block) if block_given?
  @solutions
end

#failed?Boolean

Returns true if this query did not match when last executed.

When the solution sequence is empty, this method can be used to determine whether the query failed to match or not.

Returns:

  • (Boolean)

See Also:

Since:

  • 0.3.0



384
385
386
# File 'vendor/bundler/ruby/2.6.0/bundler/gems/rdf-02340e834fe8/lib/rdf/query.rb', line 384

def failed?
  @solutions.empty?
end

#graph_nameRDF::IRI, RDF::Query::Variable

Scope of this query, if any

Returns:

Since:

  • 0.3.0



435
436
437
# File 'vendor/bundler/ruby/2.6.0/bundler/gems/rdf-02340e834fe8/lib/rdf/query.rb', line 435

def graph_name
  options[:graph_name]
end

#graph_name=(value) ⇒ RDF::IRI, RDF::Query::Variable

Scope the query to named graphs matching value

Parameters:

Returns:

Since:

  • 0.3.0



429
430
431
# File 'vendor/bundler/ruby/2.6.0/bundler/gems/rdf-02340e834fe8/lib/rdf/query.rb', line 429

def graph_name=(value)
  options[:graph_name] = value
end

#inspectObject

Since:

  • 0.3.0



29
30
31
# File 'vendor/bundler/ruby/2.6.0/bundler/gems/rdf-spec-1b54f9c9555a/lib/rdf/spec/inspects.rb', line 29

def inspect
  "RDF::Query(#{graph_name ? graph_name.to_sxp : 'nil'})#{patterns.inspect}"
end

#matched?Boolean

Returns true if this query matched when last executed.

When the solution sequence is empty, this method can be used to determine whether the query matched successfully or not.

Returns:

  • (Boolean)

See Also:

Since:

  • 0.3.0



396
397
398
# File 'vendor/bundler/ruby/2.6.0/bundler/gems/rdf-02340e834fe8/lib/rdf/query.rb', line 396

def matched?
  !failed?
end

#named?Boolean

Is this query scoped to a named graph?

Returns:

  • (Boolean)

Since:

  • 0.3.0



409
410
411
# File 'vendor/bundler/ruby/2.6.0/bundler/gems/rdf-02340e834fe8/lib/rdf/query.rb', line 409

def named?
  !!options[:graph_name]
end

#ndvarsArray<RDF::Query::Variable>

Return the non-destinguished variables contained within patterns and graph name

Returns:

Since:

  • 0.3.0



330
331
332
# File 'vendor/bundler/ruby/2.6.0/bundler/gems/sparql-407aaf052a45/lib/sparql/algebra/extensions.rb', line 330

def ndvars
  vars.reject(&:distinguished?)
end

#node?Boolean Also known as: has_blank_nodes?

Returns true if any pattern contains a blank node.

Returns:

  • (Boolean)

Since:

  • 2.0



480
481
482
# File 'vendor/bundler/ruby/2.6.0/bundler/gems/rdf-02340e834fe8/lib/rdf/query.rb', line 480

def node?
  patterns.any?(&:node?) || graph_name && graph_name.node?
end

#optimize(**options) ⇒ RDF::Query

Returns an optimized copy of this query.

Parameters:

Returns:

Since:

  • 0.3.0



237
238
239
# File 'vendor/bundler/ruby/2.6.0/bundler/gems/rdf-02340e834fe8/lib/rdf/query.rb', line 237

def optimize(**options)
  self.dup.optimize!(options)
end

#optimize!(**options) ⇒ self

Optimizes this query by reordering its constituent triple patterns according to their cost estimates.

Parameters:

Returns:

  • (self)

See Also:

Since:

  • 0.3.0



250
251
252
253
254
255
# File 'vendor/bundler/ruby/2.6.0/bundler/gems/rdf-02340e834fe8/lib/rdf/query.rb', line 250

def optimize!(**options)
  @patterns.sort! do |a, b|
    (a.cost || 0) <=> (b.cost || 0)
  end
  self
end

#pattern(pattern, **options)

This method returns an undefined value.

Appends the given query pattern to this query.

Parameters:

Options Hash (**options):

  • :optional (Boolean) — default: false

    whether this is an optional pattern

Since:

  • 0.3.0



225
226
227
228
# File 'vendor/bundler/ruby/2.6.0/bundler/gems/rdf-02340e834fe8/lib/rdf/query.rb', line 225

def pattern(pattern, **options)
  @patterns << Pattern.from(pattern, options)
  self
end

#query_yields_boolean?Boolean

Query results in a boolean result (e.g., ASK)

Returns:

  • (Boolean)

Since:

  • 0.3.0



311
312
313
# File 'vendor/bundler/ruby/2.6.0/bundler/gems/sparql-407aaf052a45/lib/sparql/algebra/extensions.rb', line 311

def query_yields_boolean?
  false
end

#query_yields_solutions?Boolean

Query results solutions (e.g., SELECT)

Returns:

  • (Boolean)

Since:

  • 0.3.0



323
324
325
# File 'vendor/bundler/ruby/2.6.0/bundler/gems/sparql-407aaf052a45/lib/sparql/algebra/extensions.rb', line 323

def query_yields_solutions?
  true
end

#query_yields_statements?Boolean

Query results statements (e.g., CONSTRUCT, DESCRIBE, CREATE)

Returns:

  • (Boolean)

Since:

  • 0.3.0



317
318
319
# File 'vendor/bundler/ruby/2.6.0/bundler/gems/sparql-407aaf052a45/lib/sparql/algebra/extensions.rb', line 317

def query_yields_statements?
  false
end

#rewrite(&block) ⇒ SPARQL::Algebra::Expression

Don't do any more rewriting

Returns:

Since:

  • 0.3.0



289
290
291
# File 'vendor/bundler/ruby/2.6.0/bundler/gems/sparql-407aaf052a45/lib/sparql/algebra/extensions.rb', line 289

def rewrite(&block)
  self
end

#to_sxp_binArray

Transform Query into an Array form of an SSE

If Query has the as_container option set, serialize as Quads Otherwise, If Query is named, serialize as a GroupGraphPattern. Otherise, serialize as a BGP

Returns:

Since:

  • 0.3.0



300
301
302
303
304
305
306
307
# File 'vendor/bundler/ruby/2.6.0/bundler/gems/sparql-407aaf052a45/lib/sparql/algebra/extensions.rb', line 300

def to_sxp_bin
  if options[:as_container]
    [:graph, graph_name] + [patterns.map(&:to_sxp_bin)]
  else
    res = [:bgp] + patterns.map(&:to_sxp_bin)
    (graph_name ? [:graph, graph_name, res] : res)
  end
end

#unnamed?Boolean

Is this query unscoped? This indicates that it can return results from either a named graph or the default graph.

Returns:

  • (Boolean)

Since:

  • 0.3.0



422
423
424
# File 'vendor/bundler/ruby/2.6.0/bundler/gems/rdf-02340e834fe8/lib/rdf/query.rb', line 422

def unnamed?
  options[:graph_name].nil?
end

#valid?Boolean

Determine if the query containts valid patterns

Returns:

  • (Boolean)

    true or false

Since:

  • 0.3.9



527
528
529
530
531
# File 'vendor/bundler/ruby/2.6.0/bundler/gems/rdf-02340e834fe8/lib/rdf/query.rb', line 527

def valid?
  !!validate! rescue raise false
rescue
  false
end

#validate!RDF::Query

Validate this query, making sure it can be executed by our query engine. This method is public so that it may be called by implementations of RDF::Queryable#query_execute that bypass our built-in query engine.

Returns:

Raises:

  • (ArgumentError)

    This query cannot be executed.

Since:

  • 0.3.0



540
541
542
543
544
545
546
547
548
549
550
551
552
# File 'vendor/bundler/ruby/2.6.0/bundler/gems/rdf-02340e834fe8/lib/rdf/query.rb', line 540

def validate!
  # All patterns must be valid
  @patterns.each(&:validate!)

  # All optional patterns must appear after the regular patterns.
  if i = @patterns.find_index(&:optional?)
    unless @patterns[i..-1].all?(&:optional?)
      raise ArgumentError.new("Optional patterns must appear at end of query")
    end
  end

  self
end

#variable?Boolean Also known as: variables?, has_variables?

Returns true if any pattern contains a variable.

Returns:

  • (Boolean)

Since:

  • 0.3.0



449
450
451
# File 'vendor/bundler/ruby/2.6.0/bundler/gems/rdf-02340e834fe8/lib/rdf/query.rb', line 449

def variable?
  !variables.empty?
end

#variable_countInteger

Returns the number of variables in this query.

Returns:

Since:

  • 0.3.0



471
472
473
# File 'vendor/bundler/ruby/2.6.0/bundler/gems/rdf-02340e834fe8/lib/rdf/query.rb', line 471

def variable_count
  variables.keys.length
end

#variablesHash{Symbol => RDF::Query::Variable}

The variables used in this query. This includes variables used in patterns along with the graph_name itself, if it is a variable.

Returns:

Since:

  • 0.3.0



459
460
461
462
463
464
465
# File 'vendor/bundler/ruby/2.6.0/bundler/gems/rdf-02340e834fe8/lib/rdf/query.rb', line 459

def variables
  # Set variables used in query
  vars = patterns.inject({}) do |memo, pattern|
    memo.merge(pattern.variables)
  end
  graph_name.is_a?(Variable) ? vars.merge(graph_name.to_sym => graph_name) : vars
end

#varsArray<RDF::Query::Variable>

Return the variables contained within patterns and graph name

Returns:

Since:

  • 0.3.0



337
338
339
# File 'vendor/bundler/ruby/2.6.0/bundler/gems/sparql-407aaf052a45/lib/sparql/algebra/extensions.rb', line 337

def vars
  variables.values
end