Class: Steep::Subtyping::VariableVariance

Inherits:
Object
  • Object
show all
Defined in:
lib/steep/subtyping/variable_variance.rb

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(covariants:, contravariants:) ⇒ VariableVariance

Returns a new instance of VariableVariance.



7
8
9
10
 
# File 'lib/steep/subtyping/variable_variance.rb', line 7

def initialize(covariants:, contravariants:)
  @covariants = covariants
  @contravariants = contravariants
end

Instance Attribute Details

#contravariants ⇒ Object (readonly)

Returns the value of attribute contravariants.



5
6
7
 
# File 'lib/steep/subtyping/variable_variance.rb', line 5

def contravariants
  @contravariants
end

#covariants ⇒ Object (readonly)

Returns the value of attribute covariants.



4
5
6
 
# File 'lib/steep/subtyping/variable_variance.rb', line 4

def covariants
  @covariants
end

Class Method Details

.add_params(params, block:, covariants:, contravariants:) ⇒ Object 



48
49
50
51
52
 
# File 'lib/steep/subtyping/variable_variance.rb', line 48

def self.add_params(params, block:, covariants:, contravariants:)
  params&.each_type do |type|
    add_type(type, variance: block ? :contravariant : :covariant, covariants: covariants, contravariants: contravariants)
  end
end

.add_type(type, variance:, covariants:, contravariants:) ⇒ Object 



54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
 
# File 'lib/steep/subtyping/variable_variance.rb', line 54

def self.add_type(type, variance:, covariants:, contravariants:)
  case type
  when AST::Types::Var
    case variance
    when :covariant
      covariants << type.name
    when :contravariant
      contravariants << type.name
    when :invariant
      covariants << type.name
      contravariants << type.name
    end
  when AST::Types::Proc
    type.type.params&.each_type do |type|
      add_type(type, variance: variance, covariants: contravariants, contravariants: covariants)
    end
    add_type(type.type.return_type, variance: variance, covariants: covariants, contravariants: contravariants)
    if type.block
      type.block.type.params&.each_type do |type|
        add_type(type, variance: variance, covariants: covariants, contravariants: contravariants)
      end
      add_type(type.type.return_type, variance: variance, covariants: contravariants, contravariants: covariants)
    end
  when AST::Types::Union, AST::Types::Intersection, AST::Types::Tuple
    type.types.each do |ty|
      add_type(ty, variance: variance, covariants: covariants, contravariants: contravariants)
    end
  when AST::Types::Name::Interface, AST::Types::Name::Instance, AST::Types::Name::Alias
    type.args.each do |arg|
      add_type(arg, variance: :invariant, covariants: covariants, contravariants: contravariants)
    end
  end
end

.from_method_type(method_type) ⇒ Object 



33
34
35
36
37
38
39
40
41
42
43
44
45
46
 
# File 'lib/steep/subtyping/variable_variance.rb', line 33

def self.from_method_type(method_type)
  covariants = Set.new
  contravariants = Set.new

  add_params(method_type.type.params, block: false, contravariants: contravariants, covariants: covariants)
  add_type(method_type.type.return_type, variance: :covariant, covariants: covariants, contravariants: contravariants)

  method_type.block&.type&.yield_self do |proc|
    add_params(proc.params, block: true, contravariants: contravariants, covariants: covariants)
    add_type(proc.return_type, variance: :contravariant, covariants: covariants, contravariants: contravariants)
  end

  new(covariants: covariants, contravariants: contravariants)
end

.from_type(type) ⇒ Object 



24
25
26
27
28
29
30
31
 
# File 'lib/steep/subtyping/variable_variance.rb', line 24

def self.from_type(type)
  covariants = Set.new
  contravariants = Set.new

  add_type(type, variance: :covariant, covariants: covariants, contravariants: contravariants)

  new(covariants: covariants, contravariants: contravariants)
end

Instance Method Details

#contravariant?(var) ⇒ Boolean

Returns:

  • (Boolean) 


16
17
18
 
# File 'lib/steep/subtyping/variable_variance.rb', line 16

def contravariant?(var)
  contravariants.member?(var) && !covariants.member?(var)
end

#covariant?(var) ⇒ Boolean

Returns:

  • (Boolean) 


12
13
14
 
# File 'lib/steep/subtyping/variable_variance.rb', line 12

def covariant?(var)
  covariants.member?(var) && !contravariants.member?(var)
end

#invariant?(var) ⇒ Boolean

Returns:

  • (Boolean) 


20
21
22
 
# File 'lib/steep/subtyping/variable_variance.rb', line 20

def invariant?(var)
  covariants.member?(var) && contravariants.member?(var)
end