class RBS::VarianceCalculator::Result

Result contains the set of type variables and it’s variance in a occurrence.

# Enumerates recorded type variables
result.each do |name, variance|
  # name is the name of a type variable
  # variance is one of :unused | :covariant | :contravariant | :invariant
end

You can test with compatible? method if the type variable occurrences are compatible with specified (annotated) variance.

# When T is declared as `out T`
result.compatible?(:T, with_annotation: :covariant)

# When T is declared as `in T`
result.compatible?(:T, with_annotation: :contravariant)

# When T is declared as `T`
result.compatible?(:T, with_annotation: :invariant)

Attributes

result [R] Hash[Symbol, variance]

Public Class Methods

new (variables:)

(variables: Array[Symbol]) → void

Source

# File vendor/bundle/ruby/4.0.0/gems/rbs-4.0.3/lib/rbs/variance_calculator.rb, line 8
def initialize(variables:)
  @result = {}
  variables.each do |x|
    result[x] = :unused
  end
end

Public Instance Methods

compatible? (var, with_annotation:)

(Symbol, with_annotation: variance) → bool

Source

# File vendor/bundle/ruby/4.0.0/gems/rbs-4.0.3/lib/rbs/variance_calculator.rb, line 45
def compatible?(var, with_annotation:)
  variance = result[var]

  case
  when variance == :unused
    true
  when with_annotation == :invariant
    true
  when variance == with_annotation
    true
  else
    false
  end
end

contravariant (x)

(Symbol) → void

Source

# File vendor/bundle/ruby/4.0.0/gems/rbs-4.0.3/lib/rbs/variance_calculator.rb, line 24
def contravariant(x)
  case result[x]
  when :unused
    result[x] = :contravariant
  when :covariant
    result[x] = :invariant
  end
end

covariant (x)

(Symbol) → void

Source

# File vendor/bundle/ruby/4.0.0/gems/rbs-4.0.3/lib/rbs/variance_calculator.rb, line 15
def covariant(x)
  case result[x]
  when :unused
    result[x] = :covariant
  when :contravariant
    result[x] = :invariant
  end
end

each (&block)

() { ([ Symbol, variance ]) → void } → void

Source

# File vendor/bundle/ruby/4.0.0/gems/rbs-4.0.3/lib/rbs/variance_calculator.rb, line 37
def each(&block)
  result.each(&block)
end

include? (name)

(Symbol) → bool

Source

# File vendor/bundle/ruby/4.0.0/gems/rbs-4.0.3/lib/rbs/variance_calculator.rb, line 41
def include?(name)
  result.key?(name)
end

incompatible? (params)

(Array[AST::TypeParam]) → Set[Symbol]?

Source

# File vendor/bundle/ruby/4.0.0/gems/rbs-4.0.3/lib/rbs/variance_calculator.rb, line 60
def incompatible?(params)
  # @type set: Hash[Symbol]
  set = Set[]

  params.each do |param|
    unless compatible?(param.name, with_annotation: param.variance)
      set << param.name
    end
  end

  unless set.empty?
    set
  end
end

invariant (x)

(Symbol) → void

Source

# File vendor/bundle/ruby/4.0.0/gems/rbs-4.0.3/lib/rbs/variance_calculator.rb, line 33
def invariant(x)
  result[x] = :invariant
end