Class: RBS::VarianceCalculator

Inherits:
Object
  • Object
show all
Defined in:
lib/rbs/variance_calculator.rb

Defined Under Namespace

Classes: Result

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(builder:) ⇒ VarianceCalculator

Returns a new instance of VarianceCalculator.



78
79
80
 
# File 'lib/rbs/variance_calculator.rb', line 78

def initialize(builder:)
  @builder = builder
end

Instance Attribute Details

#builder ⇒ Object (readonly)

Returns the value of attribute builder.



76
77
78
 
# File 'lib/rbs/variance_calculator.rb', line 76

def builder
  @builder
end

Instance Method Details

#env ⇒ Object 



82
83
84
 
# File 'lib/rbs/variance_calculator.rb', line 82

def env
  builder.env
end

#function(type, result:, context:) ⇒ Object 



166
167
168
169
170
171
 
# File 'lib/rbs/variance_calculator.rb', line 166

def function(type, result:, context:)
  type.each_param do |param|
    type(param.type, result: result, context: negate(context))
  end
  type(type.return_type, result: result, context: context)
end

#in_inherit(name:, args:, variables:) ⇒ Object 



98
99
100
101
102
103
104
105
106
107
108
 
# File 'lib/rbs/variance_calculator.rb', line 98

def in_inherit(name:, args:, variables:)
  type = if name.class?
           Types::ClassInstance.new(name: name, args: args, location: nil)
         else
           Types::Interface.new(name: name, args: args, location: nil)
         end

  Result.new(variables: variables).tap do |result|
    type(type, result: result, context: :covariant)
  end
end

#in_method_type(method_type:, variables:) ⇒ Object 



86
87
88
89
90
91
92
93
94
95
96
 
# File 'lib/rbs/variance_calculator.rb', line 86

def in_method_type(method_type:, variables:)
  result = Result.new(variables: variables)

  function(method_type.type, result: result, context: :covariant)

  if block = method_type.block
    function(block.type, result: result, context: :contravariant)
  end

  result
end

#in_type_alias(name:) ⇒ Object 



110
111
112
113
114
115
116
 
# File 'lib/rbs/variance_calculator.rb', line 110

def in_type_alias(name:)
  decl = env.type_alias_decls[name].decl or raise
  variables = decl.type_params.each.map(&:name)
  Result.new(variables: variables).tap do |result|
    type(decl.type, result: result, context: :covariant)
  end
end

#negate(variance) ⇒ Object 



173
174
175
176
177
178
179
180
181
182
183
184
 
# File 'lib/rbs/variance_calculator.rb', line 173

def negate(variance)
  case variance
  when :invariant
    :invariant
  when :covariant
    :contravariant
  when :contravariant
    :covariant
  else
    raise
  end
end

#type(type, result:, context:) ⇒ Object 



118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
 
# File 'lib/rbs/variance_calculator.rb', line 118

def type(type, result:, context:)
  case type
  when Types::Variable
    if result.include?(type.name)
      case context
      when :covariant
        result.covariant(type.name)
      when :contravariant
        result.contravariant(type.name)
      when :invariant
        result.invariant(type.name)
      end
    end
  when Types::ClassInstance, Types::Interface, Types::Alias
    NoTypeFoundError.check!(type.name,
                            env: env,
                            location: type.location)

    type_params = case type
                  when Types::ClassInstance
                    env.class_decls[env.normalize_module_name(type.name)].type_params
                  when Types::Interface
                    env.interface_decls[type.name].decl.type_params
                  when Types::Alias
                    env.type_alias_decls[type.name].decl.type_params
                  end

    type.args.each.with_index do |ty, i|
      if var = type_params[i]
        case var.variance
        when :invariant
          type(ty, result: result, context: :invariant)
        when :covariant
          type(ty, result: result, context: context)
        when :contravariant
          type(ty, result: result, context: negate(context))
        end
      end
    end
  when Types::Proc
    function(type.type, result: result, context: context)
  else
    type.each_type do |ty|
      type(ty, result: result, context: context)
    end
  end
end