Class: RDF::TriG::Reader

Inherits:
RDF::Turtle::Reader
  • Object
show all
Defined in:
lib/rdf/trig/reader.rb

Overview

A parser for the TriG

Leverages the Turtle reader

Instance Method Summary collapse

Instance Method Details

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

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

Parameters:

  • production (Symbol)
  • statement (RDF::Statement) —

    the subject of the statement

Returns:

  • (RDF::Statement) —

    Added statement

Raises:

  • (RDF::ReaderError) —

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



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# File 'lib/rdf/trig/reader.rb', line 91

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

#each_quad {|subject, predicate, object, graph_name| ... }

This method returns an undefined value.

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

Yields:

  • (subject, predicate, object, graph_name)

Yield Parameters:

  • subject (RDF::Resource)
  • predicate (RDF::URI)
  • object (RDF::Value)
  • graph_name (RDF::URI) 


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# File 'lib/rdf/trig/reader.rb', line 76

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

  • statement (RDF::Statement) 


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# File 'lib/rdf/trig/reader.rb', line 47

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

    begin
      while (@lexer.first rescue true)
        read_trigDoc
      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

#read_block ⇒ Object (protected)

Returns:

  • (Object) 


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# File 'lib/rdf/trig/reader.rb', line 109

def read_block
  prod(:block, %(})) do
    @graph_name = nil
    token = @lexer.first
    case token && (token.type || token.value)
    when :GRAPH
      @lexer.shift
      @graph_name = read_labelOrSubject || error("Expected label or subject", production: :block, token: @lexer.first)
      read_wrappedGraph || error("Expected wrappedGraph", production: :block, token: @lexer.first)
      @graph_name = nil
    when :IRIREF, :BLANK_NODE_LABEL, :ANON, :PNAME_LN, :PNAME_NS
      read_triplesOrGraph || error("Expected triplesOrGraph", production: :block, token: @lexer.first)
    when '{'
      read_wrappedGraph || error("Expected wrappedGraph", production: :block, token: @lexer.first)
    when '(', '[', '<<'
      read_triples2 || error("Expected collection or blankNodePropertyList", production: :block, token: @lexer.first)
    when nil
      # End of input
    else
      error("Unexpected token: #{@lexer.first.inspect}", production: :block, token: @lexer.first)
    end
  end
end

#read_labelOrSubject ⇒ RDF::Resource (protected)

Returns:

  • (RDF::Resource) 


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# File 'lib/rdf/trig/reader.rb', line 248

def read_labelOrSubject
  prod(:labelOrSubject) do
    read_iri || read_BlankNode
  end
end

#read_trigDoc ⇒ Object (protected)

Returns:

  • (Object) 


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# File 'lib/rdf/trig/reader.rb', line 102

def read_trigDoc
  prod(:trigDoc, %(} .)) do
    read_directive || read_block
  end
end

#read_triples2 ⇒ Object (protected)

Returns:

  • (Object) 


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# File 'lib/rdf/trig/reader.rb', line 160

def read_triples2
  token = @lexer.first
  case token && token.value
  when '['
    prod(:triples2) do
      # blankNodePropertyList predicateObjectList? 
      subject = read_blankNodePropertyList || error("Failed to parse blankNodePropertyList", production: :triples2, token: @lexer.first)
      read_predicateObjectList(subject)
      if !@recovering || @lexer.first === '.'
        # If recovering, we will have eaten the closing '.'
        token = @lexer.shift
        unless token && token.value == '.'
          error("Expected '.' following triple", production: :triples2, token: token)
        end
      end
      true
    end
  when '('
    prod(:triples2) do
      subject = read_collection || error("Failed to parse read_collection", production: :triples2, token: @lexer.first)
      token = @lexer.first
      case token && (token.type || token.value)
      when 'a', :IRIREF, :PNAME_LN, :PNAME_NS then read_predicateObjectList(subject)
      else error("Expected predicateObjectList after collection subject", production: :triples2, token: token)
      end
      if !@recovering || @lexer.first === '.'
        # If recovering, we will have eaten the closing '.'
        token = @lexer.shift
        unless token && token.value == '.'
          error("Expected '.' following triple", production: :triples2, token: token)
        end
      end
      true
    end
  when '<<'
    prod(:triples2) do
      subject = read_quotedTriple || error("Failed to parse embedded triple", production: :triples2, token: @lexer.first)
      token = @lexer.first
      case token && (token.type || token.value)
      when 'a', :IRIREF, :PNAME_LN, :PNAME_NS then read_predicateObjectList(subject)
      else error("Expected predicateObjectList after collection subject", production: :triples2, token: token)
      end
      if !@recovering || @lexer.first === '.'
        # If recovering, we will have eaten the closing '.'
        token = @lexer.shift
        unless token && token.value == '.'
          error("Expected '.' following triple", production: :triples2, token: token)
        end
      end
      true
    end
  end
end

#read_triplesBlock ⇒ Object (protected)

Returns:

  • (Object) 


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# File 'lib/rdf/trig/reader.rb', line 236

def read_triplesBlock
  prod(:triplesBlock, %w(.)) do
    while (token = @lexer.first) && token.value != '}' && read_triples
      unless log_recovering?
        break unless @lexer.first === '.'
        @lexer.shift
      end
    end
  end
end

#read_triplesOrGraph ⇒ Object (protected)

Returns:

  • (Object) 


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# File 'lib/rdf/trig/reader.rb', line 134

def read_triplesOrGraph
  while name = read_labelOrSubject
    prod(:triplesOrGraph, %(} .)) do
      token = @lexer.first
      case token && token.value
      when '{'
        @graph_name = name
        read_wrappedGraph || error("Expected wrappedGraph", production: :triplesOrGraph, token: @lexer.first)
        @graph_name = nil
        true
      else
        read_predicateObjectList(name) || error("Expected predicateObjectList", production: :triplesOrGraph, token: @lexer.first)
        unless @recovering
          # If recovering, we will have eaten the closing '.'
          token = @lexer.shift
          unless token && token.value == '.'
            error("Expected '.' following triple", production: :triplesOrGraph, token: token)
          end
        end
      end
    end
  end
  true
end

#read_wrappedGraph ⇒ Object (protected)

Returns:

  • (Object) 


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# File 'lib/rdf/trig/reader.rb', line 215

def read_wrappedGraph
  token = @lexer.first
  if token && token.value == '{'
    prod(:wrappedGraph, %w(})) do
      @lexer.shift
      while read_triplesBlock
        # Read until nothing found
      end
      if !@recovering || @lexer.first === '}'
        # If recovering, we will have eaten the closing '}'
        token = @lexer.shift
        unless token && token.value == '}'
          error("Expected '}' following triple", production: :wrappedGraph, token: token)
        end
      end
      true
    end
  end
end