Class: RDF::Writer Abstract

Inherits:

Object

Object
RDF::Writer

show all

Extended by:

Enumerable, Util::Aliasing::LateBound

Includes:

Writable

Defined in:

lib/rdf/writer.rb

Overview

This class is abstract.

The base class for RDF serializers.

Examples:

Loading an RDF writer implementation

require 'rdf/ntriples'

Iterating over known RDF writer classes

RDF::Writer.each { |klass| puts klass.name }

Obtaining an RDF writer class

RDF::Writer.for(:ntriples)     #=> RDF::NTriples::Writer
RDF::Writer.for("spec/data/output.nt")
RDF::Writer.for(:file_name      => "spec/data/output.nt")
RDF::Writer.for(:file_extension => "nt")
RDF::Writer.for(:content_type   => "text/plain")

Instantiating an RDF writer class

RDF::Writer.for(:ntriples).new($stdout) { |writer| ... }

Serializing RDF statements into a file

RDF::Writer.open("spec/data/output.nt") do |writer|
  graph.each_statement do |statement|
    writer << statement
  end
end

Serializing RDF statements into a string

RDF::Writer.for(:ntriples).buffer do |writer|
  graph.each_statement do |statement|
    writer << statement
  end
end

Direct Known Subclasses

NTriples::Writer

Instance Attribute Summary (collapse)

- (Hash) options readonly
Any additional options for this writer.

Class Method Summary (collapse)

+ (String) buffer(*args) {|writer| ... }
Buffers output into a string buffer.
+ dump(data, io = nil, options = {})
+ (Enumerator) each {|klass| ... }
Enumerates known RDF writer classes.
+ (Class) for(options = {})
Finds an RDF writer class based on the given criteria.
+ (Class) format(klass = nil) (also: format_class)
Retrieves the RDF serialization format class for this writer class.
+ (RDF::Writer) open(filename, options = {}, &block)
Writes output to the given filename.
+ (Symbol) to_sym
Returns a symbol appropriate to use with RDF::Writer.for().

Instance Method Summary (collapse)

- (Hash{Symbol => RDF::URI}) base_uri
Returns the base URI used for this writer.
- (String) escaped(string) protected
- flush (also: #flush!)
Flushes the underlying output buffer.
- (String) format_list(value, options = {}) abstract
- (String) format_literal(value, options = {}) abstract
- (String) format_node(value, options = {}) abstract
- (String) format_term(term, options = {}) (also: #format_value)
- (String) format_uri(value, options = {}) abstract
- (Writer) initialize(output = $stdout, options = {}) {|writer| ... } constructor
Initializes the writer.
- (String) node_id protected
- (RDF::URI) prefix(name, uri = nil) (also: #prefix!)
Defines the given named URI prefix for this writer.
- (Hash{Symbol => RDF::URI}) prefixes
Returns the URI prefixes currently defined for this writer.
- (Hash{Symbol => RDF::URI}) prefixes=(prefixes)
Defines the given URI prefixes for this writer.
- puts(*args) protected
- (String) quoted(string) protected
- (Symbol) to_sym
Returns a symbol appropriate to use with RDF::Writer.for().
- (String) uri_for(uriref) protected
- write_comment(text) abstract
self.
- write_epilogue abstract
self.
- write_graph(graph) deprecated Deprecated.
replace by RDF::Writable#insert_graph
- write_prologue abstract
self.
- write_statement(statement) (also: #insert_statement)
self.
- write_statements(*statements) deprecated Deprecated.
replace by RDF::Writable#insert_statements
- write_triple(subject, predicate, object) abstract
self.
- write_triples(*triples)
self.

Methods included from Util::Aliasing::LateBound

alias_method

Methods included from Writable

#<<, #insert, #insert_graph, #insert_reader, #insert_statements, #writable?

Constructor Details

- (`Writer`) initialize(output = $stdout, options = {}) {|writer| ... }

Initializes the writer.

Parameters:

output (IO, File) (defaults to: $stdout) —
the output stream
options (Hash{Symbol => Object}) (defaults to: {}) —
any additional options

Options Hash (options):

:encoding (Encoding) — default: Encoding::UTF_8 —
the encoding to use on the output stream (Ruby 1.9+)
:canonicalize (Boolean) — default: false —
whether to canonicalize literals when serializing
:prefixes (Hash) — default: Hash.new —
the prefix mappings to use (not supported by all writers)
:base_uri (#to_s) — default: nil —
the base URI to use when constructing relative URIs (not supported by all writers)

Yields:

(writer) —
self

Yield Parameters:

writer (RDF::Writer)

Yield Returns:

(void)

# File 'lib/rdf/writer.rb', line 197

def initialize(output = $stdout, options = {}, &block)
  @output, @options = output, options.dup
  @nodes, @node_id  = {}, 0

  if block_given?
    write_prologue
    case block.arity
      when 1 then block.call(self)
      else instance_eval(&block)
    end
    write_epilogue
  end
end

Instance Attribute Details

- (`Hash`) options (readonly)

Any additional options for this writer.

Returns:

(Hash)

Since:

0.2.2



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# File 'lib/rdf/writer.rb', line 216

def options
  @options
end

Class Method Details

+ (`String`) buffer(*args) {|writer| ... }

Buffers output into a string buffer.

Yields:

(writer)

Yield Parameters:

writer (RDF::Writer)

Yield Returns:

(void)

Returns:

(String)

# File 'lib/rdf/writer.rb', line 138

def self.buffer(*args, &block)
  StringIO.open do |buffer|
    self.new(buffer, *args) { |writer| block.call(writer) }
    buffer.string
  end
end

+ dump(data, io = nil, options = {})

This method returns an undefined value.

Parameters:

data (RDF::Enumerable, #each) —
the graph or repository to dump
io (IO, File) (defaults to: nil) —
the output stream or file to write to
options (Hash{Symbol => Object}) (defaults to: {}) —
passed to #initialize or buffer

# File 'lib/rdf/writer.rb', line 112

def self.dump(data, io = nil, options = {})
  io = File.open(io, 'w') if io.is_a?(String)
  method = data.respond_to?(:each_statement) ? :each_statement : :each
  if io
    new(io, options) do |writer|
      data.send(method) do |statement|
        writer << statement
      end
      writer.flush
    end
  else
    buffer(options) do |writer|
      data.send(method) do |statement|
        writer << statement
      end
    end
  end
end

+ (`Enumerator`) each {|klass| ... }

Enumerates known RDF writer classes.

Yields:

(klass)

Yield Parameters:

klass (Class)

Yield Returns:

(void) —
ignored

Returns:

(Enumerator)



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# File 'lib/rdf/writer.rb', line 50

def self.each(&block)
  @@subclasses.each(&block)
end

+ (`Class`) for(format) + (`Class`) for(filename) + (`Class`) for(options = {})

Finds an RDF writer class based on the given criteria.

Overloads:

+ (Class) for(format)

Finds an RDF writer class based on a symbolic name.
Parameters:
- format (Symbol)
Returns:
- (Class)
+ (Class) for(filename)

Finds an RDF writer class based on a file name.
Parameters:
- filename (String)
Returns:
- (Class)
+ (Class) for(options = {})

Finds an RDF writer class based on various options.
Parameters:
- options (Hash{Symbol => Object})
Options Hash (options):
- :file_name (String, #to_s) — default: nil
- :file_extension (Symbol, #to_sym) — default: nil
- :content_type (String, #to_s) — default: nil
Returns:
- (Class)

Returns:

(Class)

# File 'lib/rdf/writer.rb', line 79

def self.for(options = {})
  if format = self.format || Format.for(options)
    format.writer
  end
end

+ (`Class`) format(klass = nil) Also known as: format_class

Retrieves the RDF serialization format class for this writer class.

Returns:

(Class)

# File 'lib/rdf/writer.rb', line 89

def self.format(klass = nil)
  if klass.nil?
    Format.each do |format|
      if format.writer == self
        return format
      end
    end
    nil # not found
  end
end

+ (`RDF::Writer`) open(filename, options = {}, &block)

Writes output to the given filename.

Parameters:

filename (String, #to_s)
options (Hash{Symbol => Object}) (defaults to: {}) —
any additional options (see #initialize and Format.for)

Options Hash (options):

:format (Symbol) — default: nil

Returns:

(RDF::Writer)

# File 'lib/rdf/writer.rb', line 153

def self.open(filename, options = {}, &block)
  File.open(filename, 'wb') do |file|
    format_options = options.dup
    format_options[:file_name] ||= filename
    self.for(options[:format] || format_options).new(file, options, &block)
  end
end

+ (`Symbol`) to_sym

Returns a symbol appropriate to use with RDF::Writer.for()

Returns:

(Symbol)

# File 'lib/rdf/writer.rb', line 164

def self.to_sym
  elements = self.to_s.split("::")
  sym = elements.pop
  sym = elements.pop if sym == 'Writer'
  sym.downcase.to_s.to_sym
end

Instance Method Details

- (`Hash{Symbol => RDF::URI}`) base_uri

Returns the base URI used for this writer.

Examples:

reader.prefixes[:dc]  #=> RDF::URI('http://purl.org/dc/terms/')

Returns:

(Hash{Symbol => RDF::URI})

Since:

0.3.4



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# File 'lib/rdf/writer.rb', line 226

def base_uri
  @options[:base_uri]
end

- (`String`) escaped(string) (protected)

Parameters:

string (String)

Returns:

(String)

# File 'lib/rdf/writer.rb', line 445

def escaped(string)
  string.gsub('\\', '\\\\').gsub("\t", '\\t').
    gsub("\n", '\\n').gsub("\r", '\\r').gsub('"', '\\"')
end

- flush Also known as: flush!

This method returns an undefined value.

Flushes the underlying output buffer.

# File 'lib/rdf/writer.rb', line 284

def flush
  @output.flush if @output.respond_to?(:flush)
  self
end

- (`String`) format_list(value, options = {})

This method is abstract.

Parameters:

value (RDF::List)
options (Hash{Symbol => Object}) (defaults to: {})

Returns:

(String)

Since:

0.2.3



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# File 'lib/rdf/writer.rb', line 410

def format_list(value, options = {})
  format_term(value.subject, options)
end

- (`String`) format_literal(value, options = {})

This method is abstract.

Parameters:

value (RDF::Literal, String, #to_s)
options (Hash{Symbol => Object}) (defaults to: {})

Returns:

(String)

Raises:

(NotImplementedError) —
unless implemented in subclass



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# File 'lib/rdf/writer.rb', line 400

def format_literal(value, options = {})
  raise NotImplementedError.new("#{self.class}#format_literal") # override in subclasses
end

- (`String`) format_node(value, options = {})

This method is abstract.

Parameters:

value (RDF::Node)
options (Hash{Symbol => Object}) (defaults to: {})

Returns:

(String)

Raises:

(NotImplementedError) —
unless implemented in subclass



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# File 'lib/rdf/writer.rb', line 380

def format_node(value, options = {})
  raise NotImplementedError.new("#{self.class}#format_node") # override in subclasses
end

- (`String`) format_term(term, options = {}) Also known as: format_value

Parameters:

term (RDF::Term)

Returns:

(String)

Since:

0.3.0

# File 'lib/rdf/writer.rb', line 362

def format_term(term, options = {})
  case term
    when String       then format_literal(RDF::Literal(term, options), options)
    when RDF::List    then format_list(term, options)
    when RDF::Literal then format_literal(term, options)
    when RDF::URI     then format_uri(term, options)
    when RDF::Node    then format_node(term, options)
    else nil
  end
end

- (`String`) format_uri(value, options = {})

This method is abstract.

Parameters:

value (RDF::URI)
options (Hash{Symbol => Object}) (defaults to: {})

Returns:

(String)

Raises:

(NotImplementedError) —
unless implemented in subclass



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# File 'lib/rdf/writer.rb', line 390

def format_uri(value, options = {})
  raise NotImplementedError.new("#{self.class}#format_uri") # override in subclasses
end

- (`String`) node_id (protected)

Returns:

(String)



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# File 'lib/rdf/writer.rb', line 438

def node_id
  "_:n#{@node_id += 1}"
end

- (`RDF::URI`) prefix(name, uri) - (`RDF::URI`) prefix(name) Also known as: prefix!

Defines the given named URI prefix for this writer.

Examples:

Defining a URI prefix

writer.prefix :dc, RDF::URI('http://purl.org/dc/terms/')

Returning a URI prefix

writer.prefix(:dc)    #=> RDF::URI('http://purl.org/dc/terms/')

Overloads:

- (RDF::URI) prefix(name, uri)
Parameters:
- name (Symbol, #to_s)
- uri (RDF::URI, #to_s)
- (RDF::URI) prefix(name)
Parameters:
- name (Symbol, #to_s)

Returns:

(RDF::URI)

# File 'lib/rdf/writer.rb', line 274

def prefix(name, uri = nil)
  name = name.to_s.empty? ? nil : (name.respond_to?(:to_sym) ? name.to_sym : name.to_s.to_sym)
  uri.nil? ? prefixes[name] : prefixes[name] = uri
end

- (`Hash{Symbol => RDF::URI}`) prefixes

Returns the URI prefixes currently defined for this writer.

Examples:

writer.prefixes[:dc]  #=> RDF::URI('http://purl.org/dc/terms/')

Returns:

(Hash{Symbol => RDF::URI})

Since:

0.2.2



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# File 'lib/rdf/writer.rb', line 238

def prefixes
  @options[:prefixes] ||= {}
end

- (`Hash{Symbol => RDF::URI}`) prefixes=(prefixes)

Defines the given URI prefixes for this writer.

Examples:

writer.prefixes = {
  :dc => RDF::URI('http://purl.org/dc/terms/'),
}

Parameters:

prefixes (Hash{Symbol => RDF::URI})

Returns:

(Hash{Symbol => RDF::URI})

Since:

0.3.0



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# File 'lib/rdf/writer.rb', line 253

def prefixes=(prefixes)
  @options[:prefixes] = prefixes
end

- puts(*args) (protected)

This method returns an undefined value.



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# File 'lib/rdf/writer.rb', line 418

def puts(*args)
  @output.puts(*args)
end

- (`String`) quoted(string) (protected)

Parameters:

string (String)

Returns:

(String)



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# File 'lib/rdf/writer.rb', line 453

def quoted(string)
  "\"#{string}\""
end

- (`Symbol`) to_sym

Returns a symbol appropriate to use with RDF::Writer.for()

Returns:

(Symbol)



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# File 'lib/rdf/writer.rb', line 174

def to_sym
  self.class.to_sym
end

- (`String`) uri_for(uriref) (protected)

Parameters:

uriref (RDF::Resource)

Returns:

(String)

# File 'lib/rdf/writer.rb', line 425

def uri_for(uriref)
  case
    when uriref.is_a?(RDF::Node)
      @nodes[uriref]
    when uriref.respond_to?(:to_uri)
      uriref.to_uri.to_s
    else
      uriref.to_s
  end
end

- write_comment(text)

This method is abstract.

This method returns an undefined value.

self

Parameters:

text (String)



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# File 'lib/rdf/writer.rb', line 308

def write_comment(text)
  self
end

- write_epilogue

This method is abstract.

This method returns an undefined value.

self



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# File 'lib/rdf/writer.rb', line 300

def write_epilogue
  self
end

- write_graph(graph)

Deprecated.

replace by RDF::Writable#insert_graph

This method returns an undefined value.

self

Parameters:

graph (RDF::Graph)

# File 'lib/rdf/writer.rb', line 316

def write_graph(graph)
  graph.each_triple { |*triple| write_triple(*triple) }
  self
end

- write_prologue

This method is abstract.

This method returns an undefined value.

self



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# File 'lib/rdf/writer.rb', line 293

def write_prologue
  self
end

- write_statement(statement) Also known as: insert_statement

This method returns an undefined value.

self

Parameters:

statement (RDF::Statement)

# File 'lib/rdf/writer.rb', line 333

def write_statement(statement)
  write_triple(*statement.to_triple)
  self
end

- write_statements(*statements)

Deprecated.

replace by RDF::Writable#insert_statements

This method returns an undefined value.

self

Parameters:

statements (Array<RDF::Statement>)

# File 'lib/rdf/writer.rb', line 325

def write_statements(*statements)
  statements.flatten.each { |statement| write_statement(statement) }
  self
end

- write_triple(subject, predicate, object)

This method is abstract.

This method returns an undefined value.

self

Parameters:

subject (RDF::Resource)
predicate (RDF::URI)
object (RDF::Term)

Raises:

(NotImplementedError) —
unless implemented in subclass



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# File 'lib/rdf/writer.rb', line 354

def write_triple(subject, predicate, object)
  raise NotImplementedError.new("#{self.class}#write_triple") # override in subclasses
end

- write_triples(*triples)

This method returns an undefined value.

self

Parameters:

triples (Array<Array(RDF::Resource, RDF::URI, RDF::Term)>)

# File 'lib/rdf/writer.rb', line 342

def write_triples(*triples)
  triples.each { |triple| write_triple(*triple) }
  self
end

Class: RDF::Writer Abstract

Overview

Direct Known Subclasses

Instance Attribute Summary (collapse)

Class Method Summary (collapse)

Instance Method Summary (collapse)

Methods included from Util::Aliasing::LateBound

Methods included from Writable

Constructor Details

- (Writer) initialize(output = $stdout, options = {}) {|writer| ... }

Instance Attribute Details

- (Hash) options (readonly)

Class Method Details

+ (String) buffer(*args) {|writer| ... }

+ dump(data, io = nil, options = {})

+ (Enumerator) each {|klass| ... }

+ (Class) for(format) + (Class) for(filename) + (Class) for(options = {})

+ (Class) format(klass = nil) Also known as: format_class

+ (RDF::Writer) open(filename, options = {}, &block)

+ (Symbol) to_sym

Instance Method Details

- (Hash{Symbol => RDF::URI}) base_uri

- (String) escaped(string) (protected)

- flush Also known as: flush!

- (String) format_list(value, options = {})

- (String) format_literal(value, options = {})

- (String) format_node(value, options = {})

- (String) format_term(term, options = {}) Also known as: format_value

- (String) format_uri(value, options = {})

- (String) node_id (protected)

- (RDF::URI) prefix(name, uri) - (RDF::URI) prefix(name) Also known as: prefix!

- (Hash{Symbol => RDF::URI}) prefixes

- (Hash{Symbol => RDF::URI}) prefixes=(prefixes)

- puts(*args) (protected)

- (String) quoted(string) (protected)

- (Symbol) to_sym

- (String) uri_for(uriref) (protected)

- write_comment(text)

- write_epilogue

- write_graph(graph)

- write_prologue

- write_statement(statement) Also known as: insert_statement

- write_statements(*statements)

- write_triple(subject, predicate, object)

- write_triples(*triples)

- (`Writer`) initialize(output = $stdout, options = {}) {|writer| ... }

- (`Hash`) options (readonly)

+ (`String`) buffer(*args) {|writer| ... }

+ (`Enumerator`) each {|klass| ... }

+ (`Class`) for(format) + (`Class`) for(filename) + (`Class`) for(options = {})

+ (`Class`) format(klass = nil) Also known as: format_class

+ (`RDF::Writer`) open(filename, options = {}, &block)

+ (`Symbol`) to_sym

- (`Hash{Symbol => RDF::URI}`) base_uri

- (`String`) escaped(string) (protected)

- (`String`) format_list(value, options = {})

- (`String`) format_literal(value, options = {})

- (`String`) format_node(value, options = {})

- (`String`) format_term(term, options = {}) Also known as: format_value

- (`String`) format_uri(value, options = {})

- (`String`) node_id (protected)

- (`RDF::URI`) prefix(name, uri) - (`RDF::URI`) prefix(name) Also known as: prefix!

- (`Hash{Symbol => RDF::URI}`) prefixes

- (`Hash{Symbol => RDF::URI}`) prefixes=(prefixes)

- (`String`) quoted(string) (protected)

- (`Symbol`) to_sym

- (`String`) uri_for(uriref) (protected)