class RDF::NTriples::Reader

N-Triples parser.

@example Obtaining an NTriples reader class

RDF::Reader.for(:ntriples)     #=> RDF::NTriples::Reader
RDF::Reader.for("etc/doap.nt")
RDF::Reader.for(file_name:      "etc/doap.nt")
RDF::Reader.for(file_extension: "nt")
RDF::Reader.for(content_type:   "application/n-triples")

@example Parsing RDF statements from an NTriples file

RDF::NTriples::Reader.open("etc/doap.nt") do |reader|
  reader.each_statement do |statement|
    puts statement.inspect
  end
end

@example Parsing RDF statements from an NTriples string

data = StringIO.new(File.read("etc/doap.nt"))
RDF::NTriples::Reader.new(data) do |reader|
  reader.each_statement do |statement|
    puts statement.inspect
  end
end

@see www.w3.org/TR/rdf-testcases/#ntriples @see www.w3.org/TR/n-triples/

Constants

BLANK_NODE_LABEL

141s

COMMENT

@see www.w3.org/TR/rdf-testcases/#ntrip_grammar

DATATYPE_URI
ECHAR

159s

END_OF_STATEMENT
ESCAPE_CHARS

@see www.w3.org/TR/rdf-testcases/#ntrip_strings

IRIREF

18

IRI_RANGE
LANGTAG

144s

LITERAL
LITERAL_PLAIN
LITERAL_WITH_DATATYPE
LITERAL_WITH_LANGUAGE
NODEID
OBJECT
PN_CHARS

166s

PN_CHARS_BASE

163s

PN_CHARS_U

164s

PREDICATE
STRING_LITERAL_QUOTE

22

SUBJECT
UCHAR
UCHAR4
UCHAR8
URIREF
U_CHARS1

Terminals from rdf-turtle.

@see www.w3.org/TR/n-triples/ @see www.w3.org/TR/turtle/

Unicode regular expressions.

U_CHARS2

Public Class Methods

parse_literal(input, options = {}) click to toggle source

(see unserialize) @return [RDF::Literal]

# File lib/rdf/ntriples/reader.rb, line 143
def self.parse_literal(input, options = {})
  case input
    when LITERAL_WITH_LANGUAGE
      RDF::Literal.new(unescape($1), language: $4)
    when LITERAL_WITH_DATATYPE
      RDF::Literal.new(unescape($1), datatype: $4)
    when LITERAL_PLAIN
      RDF::Literal.new(unescape($1))
  end
end
parse_node(input, options = {}) click to toggle source

(see unserialize) @return [RDF::Node]

# File lib/rdf/ntriples/reader.rb, line 124
def self.parse_node(input, options = {})
  if input =~ NODEID
    RDF::Node.new($1)
  end
end
parse_object(input, options = {}) click to toggle source

(see unserialize)

# File lib/rdf/ntriples/reader.rb, line 117
def self.parse_object(input, options = {})
  parse_uri(input, options) || parse_node(input, options) || parse_literal(input, options)
end
parse_predicate(input, options = {}) click to toggle source

(see unserialize) @return [RDF::URI]

# File lib/rdf/ntriples/reader.rb, line 111
def self.parse_predicate(input, options = {})
  parse_uri(input, intern: true)
end
parse_subject(input, options = {}) click to toggle source

(see unserialize) @return [RDF::Resource]

# File lib/rdf/ntriples/reader.rb, line 104
def self.parse_subject(input, options = {})
  parse_uri(input, options) || parse_node(input, options)
end
parse_uri(input, options = {}) click to toggle source

(see unserialize) @return [RDF::URI]

# File lib/rdf/ntriples/reader.rb, line 133
def self.parse_uri(input, options = {})
  if input =~ URIREF
    uri_str = unescape($1)
    RDF::URI.send(options[:intern] ? :intern : :new, unescape($1))
  end
end
unescape(string) click to toggle source

@param [String] string @return [String] @see www.w3.org/TR/rdf-testcases/#ntrip_strings @see blog.grayproductions.net/articles/understanding_m17n @see yehudakatz.com/2010/05/17/encodings-unabridged/

# File lib/rdf/ntriples/reader.rb, line 160
def self.unescape(string)
  string = string.dup.force_encoding(Encoding::UTF_8)

  # Decode \t|\n|\r|\"|\\ character escapes:
  ESCAPE_CHARS.each { |escape| string.gsub!(escape.inspect[1...-1], escape) }

  # Decode \uXXXX and \UXXXXXXXX code points:
  string.gsub!(UCHAR) do
    [($1 || $2).hex].pack('U*')
  end

  string
end
unserialize(input, options = {}) click to toggle source

Reconstructs an RDF value from its serialized N-Triples representation.

@param [String] input @param [{Symbol => Object}] options

From {RDF::Reader#initialize}

@return [RDF::Term]

# File lib/rdf/ntriples/reader.rb, line 94
def self.unserialize(input, options = {})
  case input
    when nil then nil
    else self.new(input, {logger: []}.merge(options)).read_value
  end
end

Public Instance Methods

read_comment() click to toggle source

@return [Boolean] @see www.w3.org/TR/rdf-testcases/#ntrip_grammar (comment)

# File lib/rdf/ntriples/reader.rb, line 215
def read_comment
  match(COMMENT)
end
read_eos() click to toggle source

@return [Boolean] @see www.w3.org/TR/rdf-testcases/#ntrip_grammar (triple)

# File lib/rdf/ntriples/reader.rb, line 267
def read_eos
  match(END_OF_STATEMENT)
end
read_literal() click to toggle source

@return [RDF::Literal] @see www.w3.org/TR/rdf-testcases/#ntrip_grammar (literal)

# File lib/rdf/ntriples/reader.rb, line 247
def read_literal
  if literal_str = match(LITERAL_PLAIN)
    literal_str = self.class.unescape(literal_str)
    literal = case
      when language = match(LANGTAG)
        RDF::Literal.new(literal_str, language: language)
      when datatype = match(/^(\^\^)/) # FIXME
        RDF::Literal.new(literal_str, datatype: read_uriref || fail_object)
      else
        RDF::Literal.new(literal_str) # plain string literal
    end
    literal.validate!     if validate?
    literal.canonicalize! if canonicalize?
    literal
  end
end
read_node() click to toggle source

@return [RDF::Node] @see www.w3.org/TR/rdf-testcases/#ntrip_grammar (nodeID)

# File lib/rdf/ntriples/reader.rb, line 237
def read_node
   if node_id = match(NODEID)
    @nodes ||= {}
    @nodes[node_id] ||= RDF::Node.new(node_id)
  end
end
read_triple() click to toggle source

@return [Array] @see www.w3.org/TR/rdf-testcases/#ntrip_grammar

# File lib/rdf/ntriples/reader.rb, line 189
def read_triple
  loop do
    readline.strip! # EOFError thrown on end of input
    line = @line    # for backtracking input in case of parse error

    begin
      unless blank? || read_comment
        subject   = read_uriref || read_node || fail_subject
        predicate = read_uriref(intern: true) || fail_predicate
        object    = read_uriref || read_node || read_literal || fail_object

        if validate? && !read_eos
          log_error("Expected end of statement (found: #{current_line.inspect})", lineno: lineno, exception: RDF::ReaderError)
        end
        return [subject, predicate, object]
      end
    rescue RDF::ReaderError => e
      @line = line  # this allows #read_value to work
      raise e
    end
  end
end
read_uriref(options = {}) click to toggle source

@return [RDF::URI] @see www.w3.org/TR/rdf-testcases/#ntrip_grammar (uriref)

# File lib/rdf/ntriples/reader.rb, line 222
def read_uriref(options = {})
  if uri_str = match(URIREF)
    uri_str = self.class.unescape(uri_str)
    uri = RDF::URI.send(intern? && options[:intern] ? :intern : :new, uri_str)
    uri.validate!     if validate?
    uri.canonicalize! if canonicalize?
    uri
  end
rescue ArgumentError => e
  log_error("Invalid URI (found: \"<#{uri_str}>\")", lineno: lineno, token: "<#{uri_str}>", exception: RDF::ReaderError)
end
read_value() click to toggle source

@return [RDF::Term]

# File lib/rdf/ntriples/reader.rb, line 176
def read_value
  begin
    read_statement
  rescue RDF::ReaderError
    value = read_uriref || read_node || read_literal
    log_recover
    value
  end
end