Class: RdfContext::RdfaParser

Inherits:
Parser
  • Object
show all
Defined in:
lib/rdf_context/rdfaparser.rb

Overview

An RDFa parser in Ruby

Based on processing rules described here:

See Also:

Author:

  • Ben Adida

  • Gregg Kellogg

Constant Summary collapse

SafeCURIEorCURIEorURI = 
{
  :rdfa_1_0 => [:term, :safe_curie, :uri, :bnode],
  :rdfa_1_1 => [:safe_curie, :curie, :term, :uri, :bnode],
}
TERMorCURIEorAbsURI = 
{
  :rdfa_1_0 => [:term, :curie],
  :rdfa_1_1 => [:term, :curie, :absuri],
}
TERMorCURIEorAbsURIprop = 
{
  :rdfa_1_0 => [:curie],
  :rdfa_1_1 => [:term, :curie, :absuri],
}

Instance Attribute Summary collapse

Attributes inherited from Parser

#debug, #doc, #graph, #processor_graph, #uri

Instance Method Summary collapse

Methods inherited from Parser

#add_debug, #add_error, #add_info, #add_processor_message, #add_triple, #add_warning, #detect_format, n3_parser, #node_path, parse, rdfa_parser, rdfxml_parser

Constructor Details

#initialize(options = {}) ⇒ RdfaParser

Creates a new parser for RDFa.

Parameters:

  • options (Hash) (defaults to: {}) —

    a customizable set of options

Options Hash (options):

  • :graph (Graph) — default: nil —

    Graph to parse into, otherwise a new RdfContext::Graph instance is created

  • :processor_graph (Graph) — default: nil —

    Graph to record information, warnings and errors.

  • :profile_graph (Graph) — default: nil —

    Graph to save profile graphs.

  • :debug (Array) — default: nil —

    Array to place debug messages

  • :type (:rdfxml, :html, :n3) — default: nil
  • :strict (Boolean) — default: false —

    Raise Error if true, continue with lax parsing, otherwise



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# File 'lib/rdf_context/rdfaparser.rb', line 154

def initialize(options = {})
  super
  @profile_graph = options[:profile_graph]
  @@vocabulary_cache ||= {}
end

Instance Attribute Details

#host_language ⇒ :xhtml (readonly)

Host language

Returns:

  • (:xhtml) 


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# File 'lib/rdf_context/rdfaparser.rb', line 30

def host_language
  @host_language
end

#profile_graph ⇒ RdfContext::Graph

Graph instance containing parsed profiles

Returns:



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# File 'lib/rdf_context/rdfaparser.rb', line 38

def profile_graph
  @profile_graph
end

#version ⇒ :rdfa_1_0, :rdfa_1_1 (readonly)

Version

Returns:

  • (:rdfa_1_0, :rdfa_1_1) 


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# File 'lib/rdf_context/rdfaparser.rb', line 34

def version
  @version
end

Instance Method Details

#parse(stream, uri = nil, options = {}) {|triple| ... } ⇒ Graph

Parse XHTML+RDFa document from a string or input stream to closure or graph.

If the parser is called with a block, triples are passed to the block rather than added to the graph.

Optionally, the stream may be a Nokogiri::HTML::Document or Nokogiri::XML::Document With a block, yeilds each statement with URIRef, BNode or Literal elements

Parameters:

  • stream (Nokogiri::HTML::Document, Nokogiri::XML::Document, #read, #to_s) —

    the HTML+RDFa IO stream, string, Nokogiri::HTML::Document or Nokogiri::XML::Document

  • uri (String) (defaults to: nil) —

    (nil) the URI of the document

  • options (Hash) (defaults to: {}) —

    a customizable set of options

Options Hash (options):

  • :graph (Graph) — default: Graph.new —

    Graph to parse into, otherwise a new Graph

  • :processor_graph (Graph) — default: nil —

    Graph to record information, warnings and errors.

  • :profile_graph (ConjunctiveGraph) — default: nil —

    Graph to save profile graphs.

  • :debug (Array) — default: nil —

    Array to place debug messages

  • :version (:rdfa_1_0, :rdfa_1_1) — default: :rdfa_1_1 —

    Parser version information

  • :host_language (:xhtml) — default: :xhtml —

    Host Language

  • :strict (Boolean) — default: false —

    Raise Error if true, continue with lax parsing, otherwise

Yields:

  • (triple)

Yield Parameters:

Returns:

  • (Graph) —

    Returns the graph containing parsed triples

Raises:

  • (Error) —

    Raises RdfError if strict



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# File 'lib/rdf_context/rdfaparser.rb', line 181

def parse(stream, uri = nil, options = {}, &block) # :yields: triple
  super

  @doc = case stream
  when Nokogiri::HTML::Document then stream
  when Nokogiri::XML::Document  then stream
  else                               Nokogiri::XML.parse(stream, uri.to_s)
  end
  
  add_error(nil, "Empty document", RDFA_NS.DocumentError) if @doc.nil?
  add_warning(nil, "Synax errors:\n#{@doc.errors}", RDFA_NS.DocumentError) unless @doc.errors.empty?
  
  @callback = block

  @version = options[:version] ? options[:version].to_sym : :rdfa_1_1
  @host_language = options[:host_language] || case @doc.root.name.downcase.to_sym
  when :html  then :xhtml
  when :svg   then :svg
  else             :xhtml
  end

  # Section 4.2 RDFa Host Language Conformance
  #
  # The Host Language may define a default RDFa Profile. If it does, the RDFa Profile triples that establish term or
  # URI mappings associated with that profile must not change without changing the profile URI. RDFa Processors may
  # embed, cache, or retrieve the RDFa Profile triples associated with that profile.
  @host_defaults = case @host_language
  when :xhtml
    @graph.bind(XHV_NS)
    {
      :vocabulary => nil,
      :prefix     => XHV_NS,
      :uri_mappings => {"xhv" => XHV_NS}, # RDF::XHTML is wrong
      :term_mappings => %w(
        alternate appendix bookmark cite chapter contents copyright first glossary help icon index
        last license meta next p3pv1 prev role section stylesheet subsection start top up
        ).inject({}) { |hash, term| hash[term] = XHV_NS.send("#{term}_"); hash },
    }
  else
    {}
  end

  @profile_graph ||= options[:profile_graph] if options.has_key?(:profile_graph)
  
  add_debug(@doc.root, "version = #{@version.inspect},  host_language = #{@host_language}")
  # parse
  parse_whole_document(@doc, @uri)

  @graph
end