Module: RDF::Value

Included in:
Graph, List, Statement, Term
Defined in:
lib/rdf/nquads.rb,
lib/rdf/ntriples.rb,
lib/rdf/model/value.rb

Overview

An RDF value.

This is the basis for the RDF.rb class hierarchy. Anything that can be a term of RDF statements should directly or indirectly include this module, but it does not define classes that can be included within a Statement, for this see Term.

Examples:

Checking if a value is a resource (blank node or URI reference)

value.resource?

Checking if a value is a blank node

value.node?

Checking if a value is a URI reference

value.uri?
value.iri?

Checking if a value is a literal

value.literal?

See Also:

Instance Method Summary collapse

Instance Method Details

#anonymous? ⇒ Boolean

Is this value named?

Returns:

  • (Boolean) —

    ‘true` or `false`



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# File 'lib/rdf/model/value.rb', line 129

def anonymous?
  false
end

#canonicalize ⇒ RDF::Value

Returns a copy of this value converted into its canonical representation.

Returns:

Since:

  • 1.0.8



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# File 'lib/rdf/model/value.rb', line 168

def canonicalize
  self.dup.canonicalize!
end

#canonicalize! ⇒ RDF::Value

Converts this value into its canonical representation.

Should be overridden by concrete classes.

Returns:

Since:

  • 1.0.8



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# File 'lib/rdf/model/value.rb', line 179

def canonicalize!
  self
end

#constant? ⇒ Boolean

Is this constant, or are all of its components constant?

Same as ‘!variable?`

Returns:

  • (Boolean) —

    ‘true` or `false`

See Also:



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# File 'lib/rdf/model/value.rb', line 121

def constant?
  !(variable?)
end

#graph? ⇒ Boolean

Returns ‘true` if `self` is a Graph.

Returns:

  • (Boolean) 


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# File 'lib/rdf/model/value.rb', line 35

def graph?
  false
end

#inspect ⇒ String

Returns a developer-friendly representation of ‘self`.

The result will be of the format ‘#<RDF::Value::0x12345678(…)>`, where `…` is the string returned by `#to_s`.

Returns:

  • (String) 


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# File 'lib/rdf/model/value.rb', line 206

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

#inspect! ⇒ void

This method returns an undefined value.

Outputs a developer-friendly representation of ‘self` to `stderr`.



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# File 'lib/rdf/model/value.rb', line 214

def inspect!
  warn(inspect)
end

#invalid? ⇒ Boolean

Is this value invalid, or is it composed of any invalid components?

Returns:

  • (Boolean) —

    ‘true` or `false`

Since:

  • 0.2.1



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# File 'lib/rdf/model/value.rb', line 147

def invalid?
  !valid?
end

#iri? ⇒ Boolean

Is this an IRI?

By default this is simply an alias for #uri?.

Returns:

  • (Boolean) 


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# File 'lib/rdf/model/value.rb', line 93

def iri?
  uri?
end

#list? ⇒ Boolean

Is this a List?

Returns:

  • (Boolean) 


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# File 'lib/rdf/model/value.rb', line 51

def list?
  false
end

#literal? ⇒ Boolean

Is this a Literal?

Returns:

  • (Boolean) 


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# File 'lib/rdf/model/value.rb', line 75

def literal?
  false
end

#node? ⇒ Boolean

Is this a Node, or does it contain a node?

Returns:

  • (Boolean) 


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# File 'lib/rdf/model/value.rb', line 83

def node?
  false
end

#resource? ⇒ Boolean

Is this a Resource?

Returns:

  • (Boolean) 


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# File 'lib/rdf/model/value.rb', line 67

def resource?
  false
end

#statement? ⇒ Boolean

Is this a Statement?

Returns:

  • (Boolean) 


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# File 'lib/rdf/model/value.rb', line 43

def statement?
  false
end

#term? ⇒ Boolean

Is this a Term?

Returns:

  • (Boolean) 


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# File 'lib/rdf/model/value.rb', line 59

def term?
  false
end

#to_nquads ⇒ String

Returns the N-Quads representation of this value.

This method is only available when the ‘rdf/nquads’ serializer has been explicitly required.

Returns:

  • (String)

Since:

  • 0.4.0



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# File 'lib/rdf/nquads.rb', line 166

def to_nquads
  RDF::NQuads.serialize(self)
end

#to_ntriples ⇒ String

Returns the N-Triples representation of this value.

This method is only available when the ‘rdf/ntriples’ serializer has been explicitly required.

Returns:

  • (String)

Since:

  • 0.2.1



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# File 'lib/rdf/ntriples.rb', line 98

def to_ntriples
  RDF::NTriples.serialize(self)
end

#to_rdf ⇒ RDF::Value

Returns an ‘RDF::Value` representation of `self`.

Returns:



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# File 'lib/rdf/model/value.rb', line 187

def to_rdf
  self
end

#to_term ⇒ RDF::Value

Returns an ‘RDF::Term` representation of `self`.

Returns:

Raises:

  • (NotImplementedError) 


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# File 'lib/rdf/model/value.rb', line 195

def to_term
  raise NotImplementedError, "#{self.class}#read_triple" # override in subclasses
end

#type_error(message) ⇒ false

Default implementation of ‘type_error`, which returns false. Classes including RDF::TypeCheck will raise TypeError instead.

Returns:

  • (false) 


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# File 'lib/rdf/model/value.rb', line 224

def type_error(message)
  false
end

#uri? ⇒ Boolean

Is this an URI?

Returns:

  • (Boolean) 


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# File 'lib/rdf/model/value.rb', line 101

def uri?
  false
end

#valid? ⇒ Boolean

Is this value valid, and composed only of valid components?

Returns:

  • (Boolean) —

    ‘true` or `false`

Since:

  • 0.3.9



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# File 'lib/rdf/model/value.rb', line 138

def valid?
  true
end

#validate! ⇒ RDF::Value Also known as: validate

Default validate! implementation, overridden in concrete classes

Returns:

Raises:

  • (ArgumentError) —

    if the value is invalid

Since:

  • 0.3.9



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# File 'lib/rdf/model/value.rb', line 156

def validate!
  raise ArgumentError, "#{self.inspect} is not valid" if invalid?
  self
end

#variable? ⇒ Boolean

Is this a Query::Variable, or does it contain a variable?

Returns:

  • (Boolean)

Since:

  • 0.1.7



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# File 'lib/rdf/model/value.rb', line 110

def variable?
  false
end