Method: Puppet::Pops::Types::TypeCalculator#common_type

Defined in:

lib/puppet/pops/types/type_calculator.rb

#common_type(t1, t2) ⇒ Object

Answers, ‘What is the common type of t1 and t2?’

TODO: The current implementation should be optimized for performance

Raises:

• (ArgumentError)

# File 'lib/puppet/pops/types/type_calculator.rb', line 330

def common_type(t1, t2)
  raise ArgumentError, 'two types expected' unless (is_ptype?(t1) || is_pnil?(t1)) && (is_ptype?(t2) || is_pnil?(t2))

  # TODO: This is not right since Scalar U Undef is Any
  # if either is nil, the common type is the other
  if is_pnil?(t1)
    return t2
  elsif is_pnil?(t2)
    return t1
  end

  # If either side is Unit, it is the other type
  if t1.is_a?(PUnitType)
    return t2
  elsif t2.is_a?(PUnitType)
    return t1
  end

  # Simple case, one is assignable to the other
  if assignable?(t1, t2)
    return t1
  elsif assignable?(t2, t1)
    return t2
  end

  # when both are arrays, return an array with common element type
  if t1.is_a?(PArrayType) && t2.is_a?(PArrayType)
    return PArrayType.new(common_type(t1.element_type, t2.element_type))
  end

  # when both are hashes, return a hash with common key- and element type
  if t1.is_a?(PHashType) && t2.is_a?(PHashType)
    key_type = common_type(t1.key_type, t2.key_type)
    value_type = common_type(t1.value_type, t2.value_type)
    return PHashType.new(key_type, value_type)
  end

  # when both are host-classes, reduce to PHostClass[] (since one was not assignable to the other)
  if t1.is_a?(PClassType) && t2.is_a?(PClassType)
    return PClassType::DEFAULT
  end

  # when both are resources, reduce to Resource[T] or Resource[] (since one was not assignable to the other)
  if t1.is_a?(PResourceType) && t2.is_a?(PResourceType)
    # only Resource[] unless the type name is the same
    return t1.type_name == t2.type_name ? PResourceType.new(t1.type_name, nil) : PResourceType::DEFAULT
  end

  # Integers have range, expand the range to the common range
  if t1.is_a?(PIntegerType) && t2.is_a?(PIntegerType)
    return PIntegerType.new([t1.numeric_from, t2.numeric_from].min, [t1.numeric_to, t2.numeric_to].max)
  end

  # Floats have range, expand the range to the common range
  if t1.is_a?(PFloatType) && t2.is_a?(PFloatType)
    return PFloatType.new([t1.numeric_from, t2.numeric_from].min, [t1.numeric_to, t2.numeric_to].max)
  end

  if t1.is_a?(PStringType) && (t2.is_a?(PStringType) || t2.is_a?(PEnumType))
    if t2.is_a?(PEnumType)
      return t1.value.nil? ? PEnumType::DEFAULT : PEnumType.new(t2.values | [t1.value])
    end

    if t1.size_type.nil? || t2.size_type.nil?
      return t1.value.nil? || t2.value.nil? ? PStringType::DEFAULT : PEnumType.new([t1.value, t2.value])
    end

    return PStringType.new(common_type(t1.size_type, t2.size_type))
  end

  if t1.is_a?(PPatternType) && t2.is_a?(PPatternType)
    return PPatternType.new(t1.patterns | t2.patterns)
  end

  if t1.is_a?(PEnumType) && (t2.is_a?(PStringType) || t2.is_a?(PEnumType))
    # The common type is one that complies with either set
    if t2.is_a?(PEnumType)
      return PEnumType.new(t1.values | t2.values)
    end

    return t2.value.nil? ? PEnumType::DEFAULT : PEnumType.new(t1.values | [t2.value])
  end

  if t1.is_a?(PVariantType) && t2.is_a?(PVariantType)
    # The common type is one that complies with either set
    return PVariantType.maybe_create(t1.types | t2.types)
  end

  if t1.is_a?(PRegexpType) && t2.is_a?(PRegexpType)
    # if they were identical, the general rule would return a parameterized regexp
    # since they were not, the result is a generic regexp type
    return PRegexpType::DEFAULT
  end

  if t1.is_a?(PCallableType) && t2.is_a?(PCallableType)
    # They do not have the same signature, and one is not assignable to the other,
    # what remains is the most general form of Callable
    return PCallableType::DEFAULT
  end

  # Common abstract types, from most specific to most general
  if common_numeric?(t1, t2)
    return PNumericType::DEFAULT
  end

  if common_scalar_data?(t1, t2)
    return PScalarDataType::DEFAULT
  end

  if common_scalar?(t1, t2)
    return PScalarType::DEFAULT
  end

  if common_data?(t1, t2)
    return TypeFactory.data
  end

  # Meta types Type[Integer] + Type[String] => Type[Data]
  if t1.is_a?(PTypeType) && t2.is_a?(PTypeType)
    return PTypeType.new(common_type(t1.type, t2.type))
  end

  if common_rich_data?(t1, t2)
    return TypeFactory.rich_data
  end

  # If both are Runtime types
  if t1.is_a?(PRuntimeType) && t2.is_a?(PRuntimeType)
    if t1.runtime == t2.runtime && t1.runtime_type_name == t2.runtime_type_name
      return t1
    end

    # finding the common super class requires that names are resolved to class
    # NOTE: This only supports runtime type of :ruby
    c1 = ClassLoader.provide_from_type(t1)
    c2 = ClassLoader.provide_from_type(t2)
    if c1 && c2
      c2_superclasses = superclasses(c2)
      superclasses(c1).each do |c1_super|
        c2_superclasses.each do |c2_super|
          if c1_super == c2_super
            return PRuntimeType.new(:ruby, c1_super.name)
          end
        end
      end
    end
  end

  # They better both be Any type, or the wrong thing was asked and nil is returned
  t1.is_a?(PAnyType) && t2.is_a?(PAnyType) ? PAnyType::DEFAULT : nil
end