Class: RDF::Turtle::Reader

Inherits:
Reader show all
Includes:
EBNF::LL1::Parser, Terminals, Util::Logger
Defined in:
vendor/bundler/ruby/2.7.0/bundler/gems/rdf-turtle-3ac5e1bd6dcc/lib/rdf/turtle/reader.rb

Overview

A parser for the Turtle 2

Direct Known Subclasses

RDF::TriG::Reader

Defined Under Namespace

Classes: Recovery, SyntaxError

Constant Summary

Constants included from Util::Logger

Util::Logger::IOWrapper

Constants included from Terminals

Terminals::ANON, Terminals::BASE, Terminals::BLANK_NODE_LABEL, Terminals::DECIMAL, Terminals::DOUBLE, Terminals::ECHAR, Terminals::EXPONENT, Terminals::INTEGER, Terminals::IRIREF, Terminals::IRI_RANGE, Terminals::LANGTAG, Terminals::PERCENT, Terminals::PLX, Terminals::PNAME_LN, Terminals::PNAME_NS, Terminals::PN_CHARS, Terminals::PN_CHARS_BASE, Terminals::PN_CHARS_BODY, Terminals::PN_CHARS_U, Terminals::PN_LOCAL, Terminals::PN_LOCAL_BODY, Terminals::PN_LOCAL_ESC, Terminals::PN_PREFIX, Terminals::PREFIX, Terminals::STRING_LITERAL_LONG_QUOTE, Terminals::STRING_LITERAL_LONG_SINGLE_QUOTE, Terminals::STRING_LITERAL_QUOTE, Terminals::STRING_LITERAL_SINGLE_QUOTE, Terminals::UCHAR, Terminals::U_CHARS1, Terminals::U_CHARS2, Terminals::WS

Instance Attribute Summary

Attributes inherited from Reader

#options

Attributes included from Enumerable

#existentials, #universals

Class Method Summary collapse

Instance Method Summary collapse

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 inherited from Reader

#base_uri, #canonicalize?, #close, each, #each_pg_statement, #encoding, #fail_object, #fail_predicate, #fail_subject, for, format, #intern?, #lineno, open, #prefixes, #prefixes=, #read_triple, #rewind, #to_sym, to_sym, #valid?, #validate?

Methods included from Util::Aliasing::LateBound

#alias_method

Methods included from Enumerable

add_entailment, #contain?, #dump, #each_graph, #each_object, #each_predicate, #each_quad, #each_subject, #each_term, #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, #valid?, #validate!

Methods included from Countable

#count, #empty?

Methods included from Isomorphic

#bijection_to, #isomorphic_with?

Methods included from Readable

#readable?

Constructor Details

#initialize(input = nil, **options, &block) ⇒ RDF::Turtle::Reader

Initializes a new reader instance.

Note, the spec does not define a default mapping for the empty prefix, but it is so commonly used in examples that we define it to be the empty string anyway, except when validating.

Parameters:

Options Hash (**options):

  • :prefixes (Hash) — default: Hash.new —

    the prefix mappings to use (for acessing intermediate parser productions)

  • :base_uri (#to_s) — default: nil —

    the base URI to use when resolving relative URIs (for acessing intermediate parser productions)

  • :anon_base (#to_s) — default: "b0" —

    Basis for generating anonymous Nodes

  • :validate (Boolean) — default: false —

    whether to validate the parsed statements and values. If not validating, the parser will attempt to recover from errors.

  • :logger (Logger, #write, #<<) —

    Record error/info/debug output

  • :freebase (Boolean) — default: false —

    Use optimized Freebase reader



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# File 'vendor/bundler/ruby/2.7.0/bundler/gems/rdf-turtle-3ac5e1bd6dcc/lib/rdf/turtle/reader.rb', line 85

def initialize(input = nil, **options, &block)
  super do
    @options = {
      anon_base:  "b0",
      whitespace:  WS,
      depth: 0,
    }.merge(@options)
    @prod_stack = []

    @options[:base_uri] = RDF::URI(base_uri || "")
    log_debug("base IRI") {base_uri.inspect}
    
    log_debug("validate") {validate?.inspect}
    log_debug("canonicalize") {canonicalize?.inspect}
    log_debug("intern") {intern?.inspect}

    @lexer = EBNF::LL1::Lexer.new(input, self.class.patterns, **@options)

    if block_given?
      case block.arity
        when 0 then instance_eval(&block)
        else block.call(self)
      end
    end
  end
end

Dynamic Method Handling

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

Class Method Details

.options ⇒ Object

Reader options

See Also:



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# File 'vendor/bundler/ruby/2.7.0/bundler/gems/rdf-turtle-3ac5e1bd6dcc/lib/rdf/turtle/reader.rb', line 37

def self.options
  super + [
    RDF::CLI::Option.new(
      symbol: :freebase,
      datatype: TrueClass,
      on: ["--freebase"],
      description: "Use optimized Freebase reader.") {true},
  ]
end

Instance Method Details

#add_statement(production, statement) ⇒ RDF::Statement

add a statement, object can be literal or URI or bnode

Parameters:

Returns:

Raises:

  • (RDF::ReaderError) —

    Checks parameter types and raises if they are incorrect if parsing mode is validate.



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# File 'vendor/bundler/ruby/2.7.0/bundler/gems/rdf-turtle-3ac5e1bd6dcc/lib/rdf/turtle/reader.rb', line 165

def add_statement(production, statement)
  error("Statement is invalid: #{statement.inspect.inspect}", production: produciton) if validate? && statement.invalid?
  @callback.call(statement) if statement.subject &&
                               statement.predicate &&
                               statement.object &&
                               (validate? ? statement.valid? : true)
end

#bnode(value = nil) ⇒ Object

Keep track of allocated BNodes



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# File 'vendor/bundler/ruby/2.7.0/bundler/gems/rdf-turtle-3ac5e1bd6dcc/lib/rdf/turtle/reader.rb', line 229

def bnode(value = nil)
  return RDF::Node.new unless value
  @bnode_cache ||= {}
  @bnode_cache[value.to_s] ||= RDF::Node.new(value)
end

#each_statement {|statement| ... }

This method returns an undefined value.

Iterates the given block for each RDF statement in the input.

Yields:

  • (statement)

Yield Parameters:



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# File 'vendor/bundler/ruby/2.7.0/bundler/gems/rdf-turtle-3ac5e1bd6dcc/lib/rdf/turtle/reader.rb', line 122

def each_statement(&block)
  if block_given?
    log_recover
    @callback = block

    begin
      while (@lexer.first rescue true)
        read_statement
      end
    rescue EBNF::LL1::Lexer::Error, SyntaxError, EOFError, Recovery
      # Terminate loop if EOF found while recovering
    end

    if validate? && log_statistics[:error]
      raise RDF::ReaderError, "Errors found during processing"
    end
  end
  enum_for(:each_statement)
end

#each_triple {|subject, predicate, object| ... }

This method returns an undefined value.

Iterates the given block for each RDF triple in the input.

Yields:

  • (subject, predicate, object)

Yield Parameters:



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# File 'vendor/bundler/ruby/2.7.0/bundler/gems/rdf-turtle-3ac5e1bd6dcc/lib/rdf/turtle/reader.rb', line 150

def each_triple(&block)
  if block_given?
    each_statement do |statement|
      block.call(*statement.to_triple)
    end
  end
  enum_for(:each_triple)
end

#error(node, message, options) ⇒ Object (protected)

Error information, used as level 0 debug messages.

Parameters:

  • node (String) —

    Relevant location associated with message

  • message (String) —

    Error string

  • options (Hash)

Options Hash (options):

  • :production (URI, #to_s)
  • :token (Token)

See Also:

  • RDF::Turtle::Reader.{{#debug}


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# File 'vendor/bundler/ruby/2.7.0/bundler/gems/rdf-turtle-3ac5e1bd6dcc/lib/rdf/turtle/reader.rb', line 572

def error(*args)
  ctx = ""
  ctx += "(found #{options[:token].inspect})" if options[:token]
  ctx += ", production = #{options[:production].inspect}" if options[:production]
  lineno = @lineno || (options[:token].lineno if options[:token].respond_to?(:lineno)) || @lexer.lineno
  log_error(*args, ctx,
    lineno:     lineno,
    token:      options[:token],
    production: options[:production],
    depth:      options[:depth],
    exception:  SyntaxError,)
end

#inspect ⇒ Object 



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# File 'vendor/bundler/ruby/2.7.0/bundler/gems/rdf-turtle-3ac5e1bd6dcc/lib/rdf/turtle/reader.rb', line 112

def inspect
  sprintf("#<%s:%#0x(%s)>", self.class.name, __id__, base_uri.to_s)
end

#literal(value, **options) ⇒ Object

Create a literal



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# File 'vendor/bundler/ruby/2.7.0/bundler/gems/rdf-turtle-3ac5e1bd6dcc/lib/rdf/turtle/reader.rb', line 187

def literal(value, **options)
  log_debug("literal", depth: @options[:depth]) do
    "value: #{value.inspect}, " +
    "options: #{options.inspect}, " +
    "validate: #{validate?.inspect}, " +
    "c14n?: #{canonicalize?.inspect}"
  end
  RDF::Literal.new(value, validate:  validate?, canonicalize:  canonicalize?, **options)
rescue ArgumentError => e
  error("Argument Error #{e.message}", production: :literal, token: @lexer.first)
end

#pname(prefix, suffix) ⇒ Object

Expand a PNAME using string concatenation



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# File 'vendor/bundler/ruby/2.7.0/bundler/gems/rdf-turtle-3ac5e1bd6dcc/lib/rdf/turtle/reader.rb', line 213

def pname(prefix, suffix)
  # Prefixes must be defined, except special case for empty prefix being alias for current @base
  base = if prefix(prefix)
    prefix(prefix).to_s
  elsif prefix.to_s.empty? && !validate?
    base_uri.to_s
  else
    error("undefined prefix", production: :pname, token: prefix)
    ''
  end
  suffix = suffix.to_s.sub(/^\#/, "") if base.index("#")
  log_debug("pname", depth: options[:depth]) {"base: '#{base}', suffix: '#{suffix}'"}
  process_iri(base + suffix.to_s)
end

#prefix(prefix, iri = nil) ⇒ Object

Override #prefix to take a relative IRI

prefix directives map a local name to an IRI, also resolved against the current In-Scope Base URI. Spec confusion, presume that an undefined empty prefix has an empty relative IRI, which uses string contatnation rules against the in-scope IRI at the time of use



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# File 'vendor/bundler/ruby/2.7.0/bundler/gems/rdf-turtle-3ac5e1bd6dcc/lib/rdf/turtle/reader.rb', line 205

def prefix(prefix, iri = nil)
  # Relative IRIs are resolved against @base
  iri = process_iri(iri) if iri
  super(prefix, iri)
end

#process_iri(iri) ⇒ Object

Process a URI against base



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# File 'vendor/bundler/ruby/2.7.0/bundler/gems/rdf-turtle-3ac5e1bd6dcc/lib/rdf/turtle/reader.rb', line 174

def process_iri(iri)
  iri = iri.value[1..-2] if iri === :IRIREF
  value = RDF::URI(iri)
  value = base_uri.join(value) if value.relative?
  value.validate! if validate?
  value.canonicalize! if canonicalize? && !value.frozen?
  value = RDF::URI.intern(value) if intern?
  value
rescue ArgumentError => e
  error("process_iri", e)
end

#prod(production, recover_to = []) ⇒ Object (protected) 



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# File 'vendor/bundler/ruby/2.7.0/bundler/gems/rdf-turtle-3ac5e1bd6dcc/lib/rdf/turtle/reader.rb', line 508

def prod(production, recover_to = [])
  @prod_stack << {prod: production, recover_to: recover_to}
  @options[:depth] += 1
  log_recover("#{production}(start)", depth: options[:depth]) {"token: #{@lexer.first.inspect}"}
  yield
rescue EBNF::LL1::Lexer::Error, SyntaxError, Recovery =>  e
  # Lexer encountered an illegal token or the parser encountered
  # a terminal which is inappropriate for the current production.
  # Perform error recovery to find a reasonable terminal based
  # on the follow sets of the relevant productions. This includes
  # remaining terms from the current production and the stacked
  # productions
  case e
  when EBNF::LL1::Lexer::Error
    @lexer.recover
    begin
      error("Lexer error", "With input '#{e.input}': #{e.message}",
        production: production,
        token: e.token)
    rescue SyntaxError
    end
  end
  raise EOFError, "End of input found when recovering" if @lexer.first.nil?
  log_debug("recovery", "current token: #{@lexer.first.inspect}", depth: options[:depth])

  unless e.is_a?(Recovery)
    # Get the list of follows for this sequence, this production and the stacked productions.
    log_debug("recovery", "stack follows:", depth: options[:depth])
    @prod_stack.reverse.each do |prod|
      log_debug("recovery", level: 4, depth: options[:depth]) {"  #{prod[:prod]}: #{prod[:recover_to].inspect}"}
    end
  end

  # Find all follows to the top of the stack
  follows = @prod_stack.map {|prod| Array(prod[:recover_to])}.flatten.compact.uniq

  # Skip tokens until one is found in follows
  while (token = (@lexer.first rescue @lexer.recover)) && follows.none? {|t| token === t}
    skipped = @lexer.shift
    log_debug("recovery", depth: options[:depth]) {"skip #{skipped.inspect}"}
  end
  log_debug("recovery", depth: options[:depth]) {"found #{token.inspect} in follows"}

  # Re-raise the error unless token is a follows of this production
  raise Recovery unless Array(recover_to).any? {|t| token === t}

  # Skip that token to get something reasonable to start the next production with
  @lexer.shift
ensure
  log_info("#{production}(finish)", depth: options[:depth])
  @options[:depth] -= 1
  @prod_stack.pop
end

#read_BlankNode ⇒ RDF::Node (protected)

Returns:



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# File 'vendor/bundler/ruby/2.7.0/bundler/gems/rdf-turtle-3ac5e1bd6dcc/lib/rdf/turtle/reader.rb', line 500

def read_BlankNode
  token = @lexer.first
  case token && token.type
  when :BLANK_NODE_LABEL then prod(:BlankNode) {bnode(@lexer.shift.value[2..-1])}
  when :ANON then @lexer.shift && prod(:BlankNode) {bnode}
  end
end

#read_blankNodePropertyList ⇒ RDF::Node (protected)

Returns:



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# File 'vendor/bundler/ruby/2.7.0/bundler/gems/rdf-turtle-3ac5e1bd6dcc/lib/rdf/turtle/reader.rb', line 453

def read_blankNodePropertyList
  token = @lexer.first
  if token === '['
    prod(:blankNodePropertyList, %{]}) do
      @lexer.shift
      log_info("blankNodePropertyList", depth: options[:depth]) {"token: #{token.inspect}"}
      node = bnode
      read_predicateObjectList(node)
      error("blankNodePropertyList", "Expected closing ']'") unless @lexer.first === ']'
      @lexer.shift
      node
    end
  end
end

#read_collection ⇒ RDF::Node (protected)

Returns:



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# File 'vendor/bundler/ruby/2.7.0/bundler/gems/rdf-turtle-3ac5e1bd6dcc/lib/rdf/turtle/reader.rb', line 469

def read_collection
  if @lexer.first === '('
    prod(:collection, %{)}) do
      @lexer.shift
      token = @lexer.first
      log_info("collection", depth: options[:depth]) {"token: #{token.inspect}"}
      objects = []
      while object = read_object
        objects << object
      end
      list = RDF::List.new(values: objects)
      list.each_statement do |statement|
        add_statement("collection", statement)
      end
      error("collection", "Expected closing ')'") unless @lexer.first === ')'
      @lexer.shift
      list.subject
    end
  end
end

#read_directive (protected)

This method returns an undefined value.



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# File 'vendor/bundler/ruby/2.7.0/bundler/gems/rdf-turtle-3ac5e1bd6dcc/lib/rdf/turtle/reader.rb', line 257

def read_directive
  prod(:directive, %w{.}) do
    token = @lexer.first
    case token.type
    when :BASE
      prod(:base) do
        @lexer.shift
        terminated = token.value == '@base'
        iri = @lexer.shift
        error("Expected IRIREF", production: :base, token: iri) unless iri === :IRIREF
        @options[:base_uri] = process_iri(iri)
        error("base", "#{token} should be downcased") if token.value.start_with?('@') && token.value != '@base'

        if terminated
          error("base", "Expected #{token} to be terminated") unless @lexer.first === '.'
          @lexer.shift
        elsif @lexer.first === '.'
          error("base", "Expected #{token} not to be terminated") 
        else
          true
        end
      end
    when :PREFIX
      prod(:prefixID, %w{.}) do
        @lexer.shift
        pfx, iri = @lexer.shift, @lexer.shift
        terminated = token.value == '@prefix'
        error("Expected PNAME_NS", production: :prefix, token: pfx) unless pfx === :PNAME_NS
        error("Expected IRIREF", production: :prefix, token: iri) unless iri === :IRIREF
        log_debug("prefixID", depth: options[:depth]) {"Defined prefix #{pfx.inspect} mapping to #{iri.inspect}"}
        prefix(pfx.value[0..-2], process_iri(iri))
        error("prefixId", "#{token} should be downcased") if token.value.start_with?('@') && token.value != '@prefix'

        if terminated
          error("prefixID", "Expected #{token} to be terminated") unless @lexer.first === '.'
          @lexer.shift
        elsif @lexer.first === '.'
          error("prefixID", "Expected #{token} not to be terminated") 
        else
          true
        end
      end
    end
  end
end

#read_iri ⇒ RDF::URI (protected)

Returns:



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# File 'vendor/bundler/ruby/2.7.0/bundler/gems/rdf-turtle-3ac5e1bd6dcc/lib/rdf/turtle/reader.rb', line 491

def read_iri
  token = @lexer.first
  case token && token.type
  when :IRIREF then prod(:iri)  {process_iri(@lexer.shift)}
  when :PNAME_LN, :PNAME_NS then prod(:iri) {pname(*@lexer.shift.value.split(':', 2))}
  end
end

#read_literal ⇒ RDF::Literal (protected)

Returns:



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# File 'vendor/bundler/ruby/2.7.0/bundler/gems/rdf-turtle-3ac5e1bd6dcc/lib/rdf/turtle/reader.rb', line 409

def read_literal
  error("Unexpected end of file", production: :literal) unless token = @lexer.first
  case token.type || token.value
  when :INTEGER then prod(:literal) {literal(@lexer.shift.value, datatype:  RDF::XSD.integer)}
  when :DECIMAL
    prod(:litearl) do
      value = @lexer.shift.value
      value = "0#{value}" if value.start_with?(".")
      literal(value, datatype:  RDF::XSD.decimal)
    end
  when :DOUBLE then prod(:literal) {literal(@lexer.shift.value.sub(/\.([eE])/, '.0\1'), datatype:  RDF::XSD.double)}
  when "true", "false" then prod(:literal) {literal(@lexer.shift.value, datatype: RDF::XSD.boolean)}
  when :STRING_LITERAL_QUOTE, :STRING_LITERAL_SINGLE_QUOTE
    prod(:literal) do
      value = @lexer.shift.value[1..-2]
      error("read_literal", "Unexpected end of file") unless token = @lexer.first
      case token.type || token.value
      when :LANGTAG
        literal(value, language: @lexer.shift.value[1..-1].to_sym)
      when '^^'
        @lexer.shift
        literal(value, datatype: read_iri)
      else
        literal(value)
      end
    end
  when :STRING_LITERAL_LONG_QUOTE, :STRING_LITERAL_LONG_SINGLE_QUOTE
    prod(:literal) do
      value = @lexer.shift.value[3..-4]
      error("read_literal", "Unexpected end of file") unless token = @lexer.first
      case token.type || token.value
      when :LANGTAG
        literal(value, language: @lexer.shift.value[1..-1].to_sym)
      when '^^'
        @lexer.shift
        literal(value, datatype: read_iri)
      else
        literal(value)
      end
    end
  end
end

#read_object(subject = nil, predicate = nil) (protected)

This method returns an undefined value.



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# File 'vendor/bundler/ruby/2.7.0/bundler/gems/rdf-turtle-3ac5e1bd6dcc/lib/rdf/turtle/reader.rb', line 371

def read_object(subject = nil, predicate = nil)
  prod(:object) do
    if object = read_iri ||
      read_BlankNode ||
      read_collection ||
      read_blankNodePropertyList ||
      read_literal ||
      read_rdfstar

      add_statement(:object, RDF::Statement(subject, predicate, object)) if subject && predicate
      object
    end
  end
end

#read_objectList(subject, predicate) ⇒ RDF::Term (protected)

Returns the last matched subject.

Returns:



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# File 'vendor/bundler/ruby/2.7.0/bundler/gems/rdf-turtle-3ac5e1bd6dcc/lib/rdf/turtle/reader.rb', line 338

def read_objectList(subject, predicate)
  prod(:objectList, %{,}) do
    last_object = nil
    while object = prod(:_objectList_2) {read_object(subject, predicate)}
      last_object = object
      break unless @lexer.first === ','
      @lexer.shift while @lexer.first === ','
    end
    last_object
  end
end

#read_predicateObjectList(subject) ⇒ RDF::URI (protected)

Returns the last matched verb.

Parameters:

Returns:



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# File 'vendor/bundler/ruby/2.7.0/bundler/gems/rdf-turtle-3ac5e1bd6dcc/lib/rdf/turtle/reader.rb', line 322

def read_predicateObjectList(subject)
  prod(:predicateObjectList, %{;}) do
    last_verb = nil
    while verb = read_verb
      last_verb = verb
      prod(:_predicateObjectList_5) do
        read_objectList(subject, verb) || error("Expected objectList", production: :predicateObjectList, token: @lexer.first)
      end
      break unless @lexer.first === ';'
      @lexer.shift while @lexer.first === ';'
    end
    last_verb
  end
end

#read_rdfstar ⇒ RDF::Statement (protected)

Read an RDF* reified statement

Returns:



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# File 'vendor/bundler/ruby/2.7.0/bundler/gems/rdf-turtle-3ac5e1bd6dcc/lib/rdf/turtle/reader.rb', line 388

def read_rdfstar
  return unless @options[:rdfstar]
  if @lexer.first.value == '<<'
    prod(:rdfstar) do
      @lexer.shift # eat <<
      subject = read_subject || error("Failed to parse subject", production: :rdfstar, token: @lexer.first)
      predicate = read_verb || error("Failed to parse predicate", production: :rdfstar, token: @lexer.first)
      object = read_object || error("Failed to parse object", production: :rdfstar, token: @lexer.first)
      unless @lexer.first.value == '>>'
        error("Failed to end of embedded triple", production: :rdfstar, token: @lexer.first)
      end
      @lexer.shift
      statement = RDF::Statement(subject, predicate, object)
      # Emit the statement if in Property Graph mode
      add_statement(:rdfstar, statement) if @options[:rdfstar] == :PG
      statement
    end
  end
end

#read_statement (protected)

This method returns an undefined value.



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# File 'vendor/bundler/ruby/2.7.0/bundler/gems/rdf-turtle-3ac5e1bd6dcc/lib/rdf/turtle/reader.rb', line 237

def read_statement
  prod(:statement, %w{.}) do
    error("read_statement", "Unexpected end of file") unless token = @lexer.first
    case token.type
    when :BASE, :PREFIX
      read_directive || error("Failed to parse directive", production: :directive, token: token)
    else
      read_triples || error("Expected token", production: :statement, token: token)
      if !log_recovering? || @lexer.first === '.'
        # If recovering, we will have eaten the closing '.'
        token = @lexer.shift
        unless token && token.value == '.'
          error("Expected '.' following triple", production: :statement, token: token)
        end
      end
    end
  end
end

#read_subject ⇒ RDF::Resource (protected)

Returns:



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# File 'vendor/bundler/ruby/2.7.0/bundler/gems/rdf-turtle-3ac5e1bd6dcc/lib/rdf/turtle/reader.rb', line 360

def read_subject
  prod(:subject) do
    read_iri ||
    read_BlankNode ||
    read_collection ||
    read_rdfstar ||
    error( "Expected subject", production: :subject, token: @lexer.first)
  end
end

#read_triples ⇒ Object (protected)

Returns the last verb matched, or subject BNode on predicateObjectList?

Returns:

  • (Object) —

    returns the last verb matched, or subject BNode on predicateObjectList?



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# File 'vendor/bundler/ruby/2.7.0/bundler/gems/rdf-turtle-3ac5e1bd6dcc/lib/rdf/turtle/reader.rb', line 304

def read_triples
  prod(:triples, %w{.}) do
    error("read_triples", "Unexpected end of file") unless token = @lexer.first
    case token.type || token.value
    when '['
      # blankNodePropertyList predicateObjectList? 
      subject = read_blankNodePropertyList || error("Failed to parse blankNodePropertyList", production: :triples, token: @lexer.first)
      read_predicateObjectList(subject) || subject
    else
      # subject predicateObjectList
      subject = read_subject || error("Failed to parse subject", production: :triples, token: @lexer.first)
      read_predicateObjectList(subject) || error("Expected predicateObjectList", production: :triples, token: @lexer.first)
    end
  end
end

#read_verb ⇒ RDF::URI (protected)

Returns:



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# File 'vendor/bundler/ruby/2.7.0/bundler/gems/rdf-turtle-3ac5e1bd6dcc/lib/rdf/turtle/reader.rb', line 351

def read_verb
  error("read_verb", "Unexpected end of file") unless token = @lexer.first
  case token.type || token.value
  when 'a' then prod(:verb) {@lexer.shift && RDF.type}
  else prod(:verb) {read_iri}
  end
end