Class: ActiveFacts::Metamodel::Role

Inherits:
Object
  • Object
show all
Defined in:
lib/activefacts/persistence/tables.rb,
lib/activefacts/vocabulary/metamodel.rb,
lib/activefacts/vocabulary/extensions.rb

Overview

EntityType class

Instance Method Summary collapse

Instance Method Details

#describe(highlight = nil) ⇒ Object 



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# File 'lib/activefacts/vocabulary/extensions.rb', line 153

def describe(highlight = nil)
  object_type.name + (self == highlight ? "*" : "")
end

#is_functional ⇒ Object

Return true if this role is functional (has only one instance wrt its player) A role in an objectified fact type is deemed to refer to the implicit role of the objectification.



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# File 'lib/activefacts/vocabulary/extensions.rb', line 185

def is_functional
  fact_type.entity_type or
  fact_type.all_role.size != 2 or
    all_role_ref.detect do |rr|
      rr.role_sequence.all_role_ref.size == 1 and
        rr.role_sequence.all_presence_constraint.detect do |pc|
          pc.max_frequency == 1 and !pc.enforcement   # Alethic uniqueness constraint
        end
    end
end

#is_mandatory ⇒ Object 



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# File 'lib/activefacts/vocabulary/extensions.rb', line 168

def is_mandatory
  link_fact_type ||
  all_role_ref.detect{|rr|
    rs = rr.role_sequence
    rs.all_role_ref.size == 1 and
    rs.all_presence_constraint.detect{|pc|
      pc.min_frequency and pc.min_frequency >= 1 and pc.is_mandatory
    }
  } ? true : false
end

#preferred_reference ⇒ Object 



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# File 'lib/activefacts/vocabulary/extensions.rb', line 179

def preferred_reference
  fact_type.preferred_reading.role_sequence.all_role_ref.detect{|rr| rr.role == self }
end

#role_type ⇒ Object

:nodoc:



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# File 'lib/activefacts/persistence/tables.rb', line 128

def role_type
  # TypeInheritance roles are always 1:1
  if TypeInheritance === fact_type
    return object_type == fact_type.supertype ? :supertype : :subtype
  end

  # Always N:1 if unary:
  return :unary if fact_type.all_role.size == 1

  # List the UCs on this fact type:
  all_uniqueness_constraints =
    fact_type.all_role.map do |fact_role|
      fact_role.all_role_ref.map do |rr|
        rr.role_sequence.all_presence_constraint.select do |pc|
          pc.max_frequency == 1
        end
      end
    end.flatten.uniq

  to_1 =
    all_uniqueness_constraints.
      detect do |c|
          (rr = c.role_sequence.all_role_ref.single) and
          rr.role == self
      end

  if fact_type.entity_type
    # This is a role in an objectified fact type
    from_1 = true
  else
    # It's to-1 if a UC exists over roles of this FT that doesn't cover this role:
    from_1 = all_uniqueness_constraints.detect{|uc|
      !uc.role_sequence.all_role_ref.detect{|rr| rr.role == self || rr.role.fact_type != fact_type}
    }
  end

  if from_1
    return to_1 ? :one_one : :one_many
  else
    return to_1 ? :many_one : :many_many
  end
end

#unique ⇒ Object

Is there are internal uniqueness constraint on this role only?



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# File 'lib/activefacts/vocabulary/extensions.rb', line 158

def unique
  all_role_ref.detect{|rr|
    rs = rr.role_sequence
    rs.all_role_ref.size == 1 and
    rs.all_presence_constraint.detect{|pc|
      pc.max_frequency == 1
    }
  } ? true : false
end