Class: Alf::Algebra::Operand::Named

Inherits:
Object
  • Object
show all
Includes:
Alf::Algebra::Operand
Defined in:
lib/alf/algebra/operand/named.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from Alf::Algebra::Operand

#attr_list, coerce, #resulting_type, #to_ascii_tree, #to_relation

Constructor Details

#initialize(name, connection = nil) ⇒ Named

Returns a new instance of Named


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# File 'lib/alf/algebra/operand/named.rb', line 7

def initialize(name, connection = nil)
  @name = name
  @connection = connection
end

Instance Attribute Details

#connection ⇒ Object (readonly)

Returns the value of attribute connection


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# File 'lib/alf/algebra/operand/named.rb', line 11

def connection
  @connection
end

#name ⇒ Object (readonly)

Returns the value of attribute name


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# File 'lib/alf/algebra/operand/named.rb', line 11

def name
  @name
end

Instance Method Details

#==(other) ⇒ Object Also known as: eql? 


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# File 'lib/alf/algebra/operand/named.rb', line 35

def ==(other)
  super || (other.is_a?(Named) &&
            other.name==name   &&
            other.connection == connection)
end

#connection! ⇒ Object

Raises:


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# File 'lib/alf/algebra/operand/named.rb', line 13

def connection!
  raise UnboundError, "Expression not bound `#{name}`" unless connection
  connection
end

#hash ⇒ Object 


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# File 'lib/alf/algebra/operand/named.rb', line 31

def hash
  @hash ||= name.hash + 37*connection.hash
end

#heading ⇒ Object 


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# File 'lib/alf/algebra/operand/named.rb', line 27

def heading
  connection!.heading(name)
end

#inspect ⇒ Object 


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# File 'lib/alf/algebra/operand/named.rb', line 54

def inspect
  "Operand::Named(#{name.inspect})"
end

#keys ⇒ Object 


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# File 'lib/alf/algebra/operand/named.rb', line 23

def keys
  connection!.keys(name)
end

#to_cog(plan = Alf::Compiler::Plan.new) ⇒ Object 


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# File 'lib/alf/algebra/operand/named.rb', line 42

def to_cog(plan = Alf::Compiler::Plan.new)
  connection!.cog(plan, self)
end

#to_lispy ⇒ Object 


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# File 'lib/alf/algebra/operand/named.rb', line 58

def to_lispy
  name.to_s
end

#to_relvar ⇒ Object 


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# File 'lib/alf/algebra/operand/named.rb', line 46

def to_relvar
  Relvar::Base.new(self)
end

#to_s ⇒ Object 


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# File 'lib/alf/algebra/operand/named.rb', line 50

def to_s
  name.to_s
end

#type_check(options = {strict: false}) ⇒ Object

Raises:


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# File 'lib/alf/algebra/operand/named.rb', line 18

def type_check(options = {strict: false})
  return heading if connection!.knows?(name)
  raise TypeCheckError, "No such relvar `#{name}`"
end