Class: Redlander::Query::Results Private

Inherits:
Object
  • Object
show all
Includes:
Enumerable
Defined in:
lib/redlander/query/results.rb

This class is part of a private API. You should avoid using this class if possible, as it may be removed or be changed in the future.

Instance Method Summary collapse

Constructor Details

#initialize(q, options = {}) ⇒ void

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Note:

The returned value is determined by the type of the query:

  • Boolean

    for SPARQL ASK queries (ignores block, if given)

  • Redlander::Model

    for SPARQL CONSTRUCT queries

    if given a block, yields the constructed statements to it instead

  • Array<Hash>

    for SPARQL SELECT queries

    where hash values are Redlander::Node instances; if given a block, yields each binding hash to it

  • nil, if query fails

Query the model RDF graph using a query language

Parameters:

  • q (String) —

    the text of the query

  • options (Hash<Symbol => [String, URI]>) (defaults to: {}) —

    options for the query

Options Hash (options):

  • :language (String) —

    language of the query, one of:

    • “sparql10” SPARQL 1.0 W3C RDF Query Language (default)

    • “sparql” SPARQL 1.1 (DRAFT) Query and Update Languages

    • “sparql11-query” SPARQL 1.1 (DRAFT) Query Language

    • “sparql11-update” SPARQL 1.1 (DRAFT) Update Language

    • “laqrs” LAQRS adds to Querying RDF in SPARQL

    • “rdql” RDF Data Query Language (RDQL)

  • :language_uri (String) —

    URI of the query language, if applicable

  • :base_uri (String) —

    base URI of the query, if applicable

Raises:



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# File 'lib/redlander/query/results.rb', line 17

def initialize(q, options = {})
  language = options[:language] || "sparql10"
  language_uri = options[:language_uri] && options[:language_uri].to_s
  base_uri = options[:base_uri] && options[:base_uri].to_s

  @rdf_query = Redland.librdf_new_query(Redlander.rdf_world, language, language_uri, q, base_uri)
  raise RedlandError, "Failed to create a #{language.upcase} query from '#{q}'" if @rdf_query.null?

  ObjectSpace.define_finalizer(self, self.class.send(:finalize_query, @rdf_query))
end

Instance Method Details

#bindings? ⇒ Boolean

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Returns:

  • (Boolean) 


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# File 'lib/redlander/query/results.rb', line 72

def bindings?
  !Redland.librdf_query_results_is_bindings(@rdf_results).zero?
end

#boolean? ⇒ Boolean

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Returns:

  • (Boolean) 


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# File 'lib/redlander/query/results.rb', line 76

def boolean?
  !Redland.librdf_query_results_is_boolean(@rdf_results).zero?
end

#each ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future. 



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# File 'lib/redlander/query/results.rb', line 61

def each
  if block_given?
    while Redland.librdf_query_results_finished(@rdf_results).zero?
      yield self
      Redland.librdf_query_results_next(@rdf_results)
    end
  else
    enum_for(:each)
  end
end

#graph? ⇒ Boolean

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Returns:

  • (Boolean) 


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# File 'lib/redlander/query/results.rb', line 80

def graph?
  !Redland.librdf_query_results_is_graph(@rdf_results).zero?
end

#process(model) ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future. 



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# File 'lib/redlander/query/results.rb', line 28

def process(model)
  @rdf_results = Redland.librdf_model_query_execute(model.rdf_model, @rdf_query)

  begin
    case
    when bindings?
      if block_given?
        return nil if @rdf_results.null?
        each { yield process_bindings }
      else
        return [] if @rdf_results.null?
        map { process_bindings }
      end
    when boolean?
      return nil if @rdf_results.null?
      process_boolean
    when graph?
      return nil if @rdf_results.null?
      if block_given?
        process_graph { |statement| yield statement }
      else
        process_graph
      end
    when syntax?
      process_syntax
    else
      raise RedlandError, "Cannot determine the type of query results"
    end
  ensure
    Redland.librdf_free_query_results(@rdf_results)
  end
end

#syntax? ⇒ Boolean

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Returns:

  • (Boolean) 


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# File 'lib/redlander/query/results.rb', line 84

def syntax?
  !Redland.librdf_query_results_is_syntax(@rdf_results).zero?
end