Module: Alf::Relvar

Extended by:
Forwardable
Includes:
Algebra::Operand, Lang::ObjectOriented
Included in:
Base, Fake, ReadOnly, Virtual
Defined in:
lib/alf/relvar.rb,
lib/alf/relvar/base.rb,
lib/alf/relvar/fake.rb,
lib/alf/relvar/virtual.rb,
lib/alf/relvar/read_only.rb

Defined Under Namespace

Classes: Base, Fake, ReadOnly, Virtual

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from Lang::ObjectOriented

new

Methods included from Lang::ObjectOriented::RenderingMethods

def_renderer_method, #to_a, #to_array

Methods included from Lang::ObjectOriented::AlgebraMethods

#!~, #&, #*, #+, #-, #=~, def_operator_method, #tuple_extract

Methods included from Lang::ObjectOriented::AggregationMethods

def_aggregator_method

Methods included from Algebra::Operand

#attr_list, coerce, #heading, #keys, #resulting_type, #to_ascii_tree, #to_cog, #type_check

Instance Attribute Details

#expr ⇒ Object (readonly)

Returns the value of attribute expr.



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# File 'lib/alf/relvar.rb', line 10

def expr
  @expr
end

Instance Method Details

#affect(value) ⇒ Object 



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# File 'lib/alf/relvar.rb', line 50

def affect(value)
  delete
  insert(value)
end

#delete(predicate = Predicate.tautology) ⇒ Object

Raises:



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# File 'lib/alf/relvar.rb', line 59

def delete(predicate = Predicate.tautology)
  raise NotSupportedError
end

#each(&bl) ⇒ Object 



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# File 'lib/alf/relvar.rb', line 23

def each(&bl)
  to_cog.each(&bl)
end

#empty!(msg = "relvar is empty") ⇒ Object

Raises:



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# File 'lib/alf/relvar.rb', line 32

def empty!(msg = "relvar is empty")
  raise FactAssertionError, msg unless empty?
  self
end

#empty? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/alf/relvar.rb', line 27

def empty?
  to_cog.each{|_| return false }
  true
end

#initialize(expr = nil) ⇒ Object 



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# File 'lib/alf/relvar.rb', line 7

def initialize(expr = nil)
  @expr = expr
end

#insert(tuples) ⇒ Object

Raises:



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# File 'lib/alf/relvar.rb', line 55

def insert(tuples)
  raise NotSupportedError
end

#lock ⇒ Object

Raises:



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# File 'lib/alf/relvar.rb', line 46

def lock(*)
  raise NotSupportedError
end

#not_empty!(msg = "relvar is not empty") ⇒ Object

Raises:



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# File 'lib/alf/relvar.rb', line 37

def not_empty!(msg = "relvar is not empty")
  raise FactAssertionError, msg if empty?
  self
end

#safe(*args, &bl) ⇒ Object 



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# File 'lib/alf/relvar.rb', line 71

def safe(*args, &bl)
  Safe.new(self, *args, &bl)
end

#to_relation ⇒ Object 



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# File 'lib/alf/relvar.rb', line 79

def to_relation
  to_cog.to_relation
end

#to_relvar ⇒ Object 



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# File 'lib/alf/relvar.rb', line 75

def to_relvar
  self
end

#type ⇒ Object 



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# File 'lib/alf/relvar.rb', line 17

def type
  @type ||= Relation[heading]
end

#update(updating, predicate = Predicate.tautology) ⇒ Object

Raises:



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# File 'lib/alf/relvar.rb', line 63

def update(updating, predicate = Predicate.tautology)
  raise NotSupportedError
end

#upsert(tuples) ⇒ Object 



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# File 'lib/alf/relvar.rb', line 67

def upsert(tuples)
  empty? ? insert(tuples) : update(tuples)
end

#value ⇒ Object 



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# File 'lib/alf/relvar.rb', line 42

def value
  to_relation
end