Class: Steep::Interface::Builder

Inherits:
Object
  • Object
show all
Defined in:
lib/steep/interface/builder.rb

Defined Under Namespace

Classes: Config

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(factory, implicitly_returns_nil:) ⇒ Builder

Returns a new instance of Builder.



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# File 'lib/steep/interface/builder.rb', line 59

def initialize(factory, implicitly_returns_nil:)
  @factory = factory
  @object_shape_cache = {}
  @union_shape_cache = {}
  @singleton_shape_cache = {}
  @implicitly_returns_nil = implicitly_returns_nil
end

Instance Attribute Details

#factory ⇒ Object (readonly)

Returns the value of attribute factory.



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# File 'lib/steep/interface/builder.rb', line 57

def factory
  @factory
end

#implicitly_returns_nil ⇒ Object (readonly)

Returns the value of attribute implicitly_returns_nil.



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# File 'lib/steep/interface/builder.rb', line 57

def implicitly_returns_nil
  @implicitly_returns_nil
end

#object_shape_cache ⇒ Object (readonly)

Returns the value of attribute object_shape_cache.



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# File 'lib/steep/interface/builder.rb', line 57

def object_shape_cache
  @object_shape_cache
end

#singleton_shape_cache ⇒ Object (readonly)

Returns the value of attribute singleton_shape_cache.



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# File 'lib/steep/interface/builder.rb', line 57

def singleton_shape_cache
  @singleton_shape_cache
end

#union_shape_cache ⇒ Object (readonly)

Returns the value of attribute union_shape_cache.



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# File 'lib/steep/interface/builder.rb', line 57

def union_shape_cache
  @union_shape_cache
end

Instance Method Details

#add_implicitly_returns_nil(annotations, method_type) ⇒ Object 



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# File 'lib/steep/interface/builder.rb', line 862

def add_implicitly_returns_nil(annotations, method_type)
  return method_type unless implicitly_returns_nil

  if annotations.find { _1.string == "implicitly-returns-nil" }
    return_type = method_type.type.return_type
    method_type = method_type.with(
      type: method_type.type.with(return_type: AST::Types::Union.build(types: [return_type, AST::Builtin.nil_type]))
    )
  else
    method_type
  end
end

#app_subst(type) ⇒ Object 



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# File 'lib/steep/interface/builder.rb', line 234

def app_subst(type)
  if type.args.empty?
    return Substitution.empty
  end

  vars =
    case type
    when AST::Types::Name::Instance
      entry = factory.env.module_class_entry(type.name, normalized: true) or raise
      entry.primary_decl.type_params.map { _1.name }
    when AST::Types::Name::Interface
      entry = factory.env.interface_decls.fetch(type.name)
      entry.decl.type_params.map { _1.name }
    when AST::Types::Name::Alias
      entry = factory.env.type_alias_decls.fetch(type.name)
      entry.decl.type_params.map { _1.name }
    end

  Substitution.build(vars, type.args)
end

#class_subst(type) ⇒ Object 



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# File 'lib/steep/interface/builder.rb', line 255

def class_subst(type)
  case type
  when AST::Types::Name::Singleton
    self_type = type
    singleton_type = type
    instance_type = factory.instance_type(type.name)
  when AST::Types::Name::Instance
    self_type = type
    singleton_type = type.to_module
    instance_type = factory.instance_type(type.name)
  end

  Substitution.build([], self_type: self_type, module_type: singleton_type, instance_type: instance_type)
end

#fetch_cache(cache, key) ⇒ Object 



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# File 'lib/steep/interface/builder.rb', line 84

def fetch_cache(cache, key)
  if cache.key?(key) # steep:ignore ArgumentTypeMismatch
    return cache.fetch(key)
  end

  cache[key] = yield
end

#interface_subst(type) ⇒ Object 



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# File 'lib/steep/interface/builder.rb', line 270

def interface_subst(type)
  Substitution.build([], self_type: type)
end

#intersection_shape(type, shapes) ⇒ Object 



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# File 'lib/steep/interface/builder.rb', line 392

def intersection_shape(type, shapes)
  shape = Interface::Shape.new(type: type, private: true)

  shapes.each do |s|
    shape.methods.merge!(s.methods) do |name, old_entry, new_entry|
      if old_entry.public_method? && new_entry.private_method?
        old_entry
      else
        new_entry
      end
    end
  end

  shape
end

#method_name_for(type_def, name) ⇒ Object 



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# File 'lib/steep/interface/builder.rb', line 408

def method_name_for(type_def, name)
  type_name = type_def.implemented_in || type_def.defined_in

  if name == :new
    case type_def.member
    when RBS::AST::Members::MethodDefinition
      if type_def.member.name == :initialize
        return SingletonMethodName.new(type_name: type_name, method_name: name)
      end
    when RBS::AST::Ruby::Members::DefMember
      if type_def.member.name == :initialize
        return SingletonMethodName.new(type_name: type_name, method_name: name)
      end
    end
  end

  case type_def.member
  when RBS::AST::Members::Base
    case type_def.member.kind
    when :instance
      InstanceMethodName.new(type_name: type_name, method_name: name)
    when :singleton
      SingletonMethodName.new(type_name: type_name, method_name: name)
    when :singleton_instance
      # Assume it a instance method, because `module_function` methods are typically defined with `def`
      InstanceMethodName.new(type_name: type_name, method_name: name)
    else
      raise
    end
  when RBS::AST::Ruby::Members::DefMember, RBS::AST::Ruby::Members::AttributeMember
    InstanceMethodName.new(type_name: type_name, method_name: name)
  end
end

#object_shape(type_name) ⇒ Object 



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# File 'lib/steep/interface/builder.rb', line 298

def object_shape(type_name)
  object_shape_cache[type_name] ||= begin
    shape = Interface::Shape.new(type: AST::Builtin.bottom_type, private: true)

    case
    when type_name.class?
      definition = factory.definition_builder.build_instance(type_name)
    when type_name.interface?
      definition = factory.definition_builder.build_interface(type_name)
    end

    definition or raise

    definition.methods.each do |name, method|
      Steep.logger.tagged "method = #{type_name}##{name}" do
        overloads = method.defs.map do |type_def|
          method_name = method_name_for(type_def, name)
          method_type = factory.method_type(type_def.type)
          method_type = replace_primitive_method(method_name, type_def, method_type)
          if type_name.class?
            method_type = replace_kernel_class(method_name, type_def, method_type) { AST::Types::Name::Singleton.new(name: type_name) }
          end
          method_type = add_implicitly_returns_nil(type_def.each_annotation, method_type)
          Shape::MethodOverload.new(method_type, [type_def])
        end

        shape.methods[name] = Interface::Shape::Entry.new(method_name: name, private_method: method.private?, overloads: overloads)
      end
    end

    shape
  end
end

#proc_shape(proc, proc_shape) ⇒ Object 



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# File 'lib/steep/interface/builder.rb', line 719

def proc_shape(proc, proc_shape)
  shape = Shape.new(type: proc, private: true)
  shape.methods.merge!(proc_shape.methods)

  overload = Shape::MethodOverload.new(
    MethodType.new(type_params: [], type: proc.type, block: proc.block),
    []
  )

  shape.methods[:[]] = Shape::Entry.new(
    method_name: :[],
    private_method: false,
    overloads: [overload]
  )
  shape.methods[:call] = Shape::Entry.new(
    method_name: :call,
    private_method: false,
    overloads: [overload]
  )

  shape
end

#raw_shape(type, config) ⇒ Object 



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# File 'lib/steep/interface/builder.rb', line 92

def raw_shape(type, config)
  case type
  when AST::Types::Self
    config.validate_self_type
    self_type = config.self_type or raise
    self_shape(self_type, config)
  when AST::Types::Instance
    config.validate_instance_type
    instance_type = config.instance_type or raise
    raw_shape(instance_type, config)
  when AST::Types::Class
    config.validate_class_type
    klass_type = config.class_type or raise
    raw_shape(klass_type, config)
  when AST::Types::Name::Singleton
    singleton_shape(type.name).subst(class_subst(type))
  when AST::Types::Name::Instance
    object_shape(type.name).subst(class_subst(type).merge(app_subst(type)), type: type)
  when AST::Types::Name::Interface
    object_shape(type.name).subst(interface_subst(type).merge(app_subst(type)), type: type)
  when AST::Types::Union
    groups = type.types.group_by do |type|
      if type.is_a?(AST::Types::Literal)
        type.back_type
      else
        nil
      end
    end

    shapes = [] #: Array[Shape]
    groups.each do |name, types|
      if name
        union = AST::Types::Union.build(types: types)
        subst = class_subst(name).update(self_type: union)
        shapes << object_shape(name.name).subst(subst, type: union)
      else
        shapes.concat(types.map {|ty| raw_shape(ty, config) or return })
      end
    end

    fetch_cache(union_shape_cache, type) do
      union_shape(type, shapes)
    end
  when AST::Types::Intersection
    shapes = type.types.map do |type|
      raw_shape(type, config) or return
    end
    intersection_shape(type, shapes)
  when AST::Types::Name::Alias
    expanded = factory.expand_alias(type)
    if shape = raw_shape(expanded, config)
      shape.update(type: type)
    end
  when AST::Types::Literal
    instance_type = type.back_type
    subst = class_subst(instance_type).update(self_type: type)
    object_shape(instance_type.name).subst(subst, type: type)
  when AST::Types::Boolean
    true_shape =
      (object_shape(RBS::BuiltinNames::TrueClass.name)).
        subst(class_subst(AST::Builtin::TrueClass.instance_type).update(self_type: type))
    false_shape =
      (object_shape(RBS::BuiltinNames::FalseClass.name)).
        subst(class_subst(AST::Builtin::FalseClass.instance_type).update(self_type: type))
    union_shape(type, [true_shape, false_shape])
  when AST::Types::Proc
    shape = object_shape(AST::Builtin::Proc.module_name).subst(class_subst(AST::Builtin::Proc.instance_type).update(self_type: type))
    proc_shape(type, shape)
  when AST::Types::Tuple
    tuple_shape(type) do |array|
      object_shape(array.name).subst(
        class_subst(array).update(self_type: type).merge(app_subst(array))
      )
    end
  when AST::Types::Record
    record_shape(type) do |hash|
      object_shape(hash.name).subst(
        class_subst(hash).update(self_type: type).merge(app_subst(hash))
      )
    end
  when AST::Types::Var
    if bound = config.upper_bound(type.name)
      new_config = Config.new(self_type: bound, variable_bounds: config.variable_bounds)
      sub = Substitution.build([], self_type: type)
      # We have to use `self_shape` instead of `raw_shape` here.
      # Keep the `self` types included in the `bound`'s shape, and replace it to the type variable.
      self_shape(bound, new_config)&.subst(sub, type: type)
    end
  when AST::Types::Nil
    subst = class_subst(AST::Builtin::NilClass.instance_type).update(self_type: type)
    object_shape(AST::Builtin::NilClass.module_name).subst(subst, type: type)
  when AST::Types::Logic::Base
    true_shape =
      (object_shape(RBS::BuiltinNames::TrueClass.name)).
        subst(class_subst(AST::Builtin::TrueClass.instance_type).update(self_type: type))
    false_shape =
      (object_shape(RBS::BuiltinNames::FalseClass.name)).
        subst(class_subst(AST::Builtin::FalseClass.instance_type).update(self_type: type))
    union_shape(type, [true_shape, false_shape])
  else
    nil
  end
end

#record_shape(record) ⇒ Object 



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# File 'lib/steep/interface/builder.rb', line 604

def record_shape(record)
  all_key_type = AST::Types::Union.build(
    types: record.elements.each_key.map {|value| AST::Types::Literal.new(value: value).back_type }
  )
  all_value_type = AST::Types::Union.build(types: record.elements.values)
  hash_type = AST::Builtin::Hash.instance_type(all_key_type, all_value_type)

  hash_shape = yield(hash_type) or raise
  shape = Shape.new(type: record, private: true)
  shape.methods.merge!(hash_shape.methods)

  shape.methods[:[]] = hash_shape.methods[:[]].yield_self do |aref|
    aref or raise
    Shape::Entry.new(
      method_name: :[],
      private_method: false,
      overloads: record.elements.map do |key_value, value_type|
        key_type = AST::Types::Literal.new(value: key_value)

        if record.optional?(key_value)
          value_type = AST::Builtin.optional(value_type)
        end

        Shape::MethodOverload.new(
          MethodType.new(
            type_params: [],
            type: Function.new(
              params: Function::Params.build(required: [key_type]),
              return_type: value_type,
              location: nil
            ),
            block: nil
          ),
          []
        )
      end + aref.overloads
    )
  end

  shape.methods[:[]=] = hash_shape.methods[:[]=].yield_self do |update|
    update or raise

    Shape::Entry.new(
      method_name: :[]=,
      private_method: false,
      overloads: record.elements.map do |key_value, value_type|
        key_type = AST::Types::Literal.new(value: key_value)
        Shape::MethodOverload.new(
          MethodType.new(
            type_params: [],
            type: Function.new(
              params: Function::Params.build(required: [key_type, value_type]),
              return_type: value_type,
              location: nil),
            block: nil
          ),
          []
        )
      end + update.overloads
    )
  end

  shape.methods[:fetch] = hash_shape.methods[:fetch].yield_self do |update|
    update or raise

    Shape::Entry.new(
      method_name: :fetch,
      private_method: false,
      overloads: record.elements.flat_map {|key_value, value_type|
        key_type = AST::Types::Literal.new(value: key_value)

        [
          MethodType.new(
            type_params: [],
            type: Function.new(
              params: Function::Params.build(required: [key_type]),
              return_type: value_type,
              location: nil
            ),
            block: nil
          ),
          MethodType.new(
            type_params: [TypeParam.new(name: :T, upper_bound: nil, variance: :invariant, unchecked: false, default_type: nil)],
            type: Function.new(
              params: Function::Params.build(required: [key_type, AST::Types::Var.new(name: :T)]),
              return_type: AST::Types::Union.build(types: [value_type, AST::Types::Var.new(name: :T)]),
              location: nil
            ),
            block: nil
          ),
          MethodType.new(
            type_params: [TypeParam.new(name: :T, upper_bound: nil, variance: :invariant, unchecked: false, default_type: nil)],
            type: Function.new(
              params: Function::Params.build(required: [key_type]),
              return_type: AST::Types::Union.build(types: [value_type, AST::Types::Var.new(name: :T)]),
              location: nil
            ),
            block: Block.new(
              type: Function.new(
                params: Function::Params.build(required: [all_key_type]),
                return_type: AST::Types::Var.new(name: :T),
                location: nil
              ),
              optional: false,
              self_type: nil
            )
          )
        ].map { Shape::MethodOverload.new(_1, []) }
      } + update.overloads
    )
  end

  shape
end

#replace_kernel_class(method_name, method_def, method_type) ⇒ Object 



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# File 'lib/steep/interface/builder.rb', line 845

def replace_kernel_class(method_name, method_def, method_type)
  defined_in = method_def.defined_in
  member = method_def.member

  if member.is_a?(RBS::AST::Members::MethodDefinition)
    case method_name.method_name
    when :class
      case defined_in
      when AST::Builtin::Kernel.module_name
        return method_type.with(type: method_type.type.with(return_type: yield))
      end
    end
  end

  method_type
end

#replace_primitive_method(method_name, method_def, method_type) ⇒ Object 



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# File 'lib/steep/interface/builder.rb', line 742

def replace_primitive_method(method_name, method_def, method_type)
  defined_in = method_def.defined_in
  member = method_def.member

  if member.is_a?(RBS::AST::Members::MethodDefinition)
    case method_name.method_name
    when :is_a?, :kind_of?, :instance_of?
      case
      when RBS::BuiltinNames::Object.name,
        RBS::BuiltinNames::Kernel.name
        if member.instance?
          return method_type.with(
            type: method_type.type.with(
              return_type: AST::Types::Logic::ReceiverIsArg.instance()
            )
          )
        end
      end

    when :nil?
      case defined_in
      when RBS::BuiltinNames::Object.name,
        AST::Builtin::NilClass.module_name,
        RBS::BuiltinNames::Kernel.name
        if member.instance?
          return method_type.with(
            type: method_type.type.with(
              return_type: AST::Types::Logic::ReceiverIsNil.instance()
            )
          )
        end
      end

    when :!
      case defined_in
      when RBS::BuiltinNames::BasicObject.name,
        RBS::BuiltinNames::TrueClass.name,
        RBS::BuiltinNames::FalseClass.name,
        AST::Builtin::NilClass.module_name
        return method_type.with(
          type: method_type.type.with(
            return_type: AST::Types::Logic::Not.instance()
          )
        )
      end

    when :===
      case defined_in
      when RBS::BuiltinNames::Module.name
        return method_type.with(
          type: method_type.type.with(
            return_type: AST::Types::Logic::ArgIsReceiver.instance()
          )
        )
      when RBS::BuiltinNames::BasicObject.name,
        RBS::BuiltinNames::Object.name,
        RBS::BuiltinNames::Kernel.name,
        RBS::BuiltinNames::String.name,
        RBS::BuiltinNames::Integer.name,
        RBS::BuiltinNames::Symbol.name,
        RBS::BuiltinNames::TrueClass.name,
        RBS::BuiltinNames::FalseClass.name,
        RBS::TypeName.parse("::NilClass")
        # Value based type-case works on literal types which is available for String, Integer, Symbol, TrueClass, FalseClass, and NilClass
        return method_type.with(
          type: method_type.type.with(
            return_type: AST::Types::Logic::ArgEqualsReceiver.instance()
          )
        )
      end
    when :==
      case defined_in
      when RBS::BuiltinNames::BasicObject.name,
        RBS::BuiltinNames::Object.name,
        RBS::BuiltinNames::Kernel.name,
        RBS::BuiltinNames::String.name,
        RBS::BuiltinNames::Integer.name,
        RBS::BuiltinNames::Symbol.name,
        RBS::BuiltinNames::TrueClass.name,
        RBS::BuiltinNames::FalseClass.name,
        RBS::TypeName.parse("::NilClass")
        # For ==, we use ReceiverIsArg to narrow the receiver based on the argument
        return method_type.with(
          type: method_type.type.with(
            return_type: AST::Types::Logic::ReceiverIsArg.instance()
          )
        )
      end
    when :<, :<=
      case defined_in
      when RBS::BuiltinNames::Module.name
        return method_type.with(
          type: method_type.type.with(
            return_type: AST::Types::Logic::ArgIsAncestor.instance()
          )
        )
      end
    end
  end

  method_type
end

#self_shape(type, config) ⇒ Object 



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# File 'lib/steep/interface/builder.rb', line 196

def self_shape(type, config)
  case type
  when AST::Types::Self, AST::Types::Instance, AST::Types::Class
    raise
  when AST::Types::Name::Singleton
    singleton_shape(type.name).subst(class_subst(type).update(self_type: nil))
  when AST::Types::Name::Instance
    object_shape(type.name)
      .subst(
        class_subst(type).update(self_type: nil).merge(app_subst(type)),
        type: type
      )
  when AST::Types::Name::Interface
    object_shape(type.name).subst(app_subst(type), type: type)
  when AST::Types::Literal
    instance_type = type.back_type
    subst = class_subst(instance_type).update(self_type: nil)
    object_shape(instance_type.name).subst(subst, type: type)
  when AST::Types::Boolean
    true_shape =
      (object_shape(RBS::BuiltinNames::TrueClass.name)).
        subst(class_subst(AST::Builtin::TrueClass.instance_type).update(self_type: nil))
    false_shape =
      (object_shape(RBS::BuiltinNames::FalseClass.name)).
        subst(class_subst(AST::Builtin::FalseClass.instance_type).update(self_type: nil))
    union_shape(type, [true_shape, false_shape])
  when AST::Types::Proc
    shape = object_shape(AST::Builtin::Proc.module_name).subst(class_subst(AST::Builtin::Proc.instance_type).update(self_type: nil))
    proc_shape(type, shape)
  when AST::Types::Var
    if bound = config.upper_bound(type.name)
      self_shape(bound, config)&.update(type: type)
    end
  else
    raw_shape(type, config)
  end
end

#shape(type, config) ⇒ Object 



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# File 'lib/steep/interface/builder.rb', line 67

def shape(type, config)
  Steep.logger.tagged "shape(#{type})" do
    if shape = raw_shape(type, config)
      # Optimization that skips unnecessary substitution
      if type.free_variables.include?(AST::Types::Self.instance)
        shape
      else
        if s = config.subst
          shape.subst(s)
        else
          shape
        end
      end
    end
  end
end

#singleton_shape(type_name) ⇒ Object 



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# File 'lib/steep/interface/builder.rb', line 274

def singleton_shape(type_name)
  singleton_shape_cache[type_name] ||= begin
    shape = Interface::Shape.new(type: AST::Types::Name::Singleton.new(name: type_name), private: true)
    definition = factory.definition_builder.build_singleton(type_name)

    definition.methods.each do |name, method|
      Steep.logger.tagged "method = #{type_name}.#{name}" do
        overloads = method.defs.map do |type_def|
          method_name = method_name_for(type_def, name)
          method_type = factory.method_type(type_def.type)
          method_type = replace_primitive_method(method_name, type_def, method_type)
          method_type = replace_kernel_class(method_name, type_def, method_type) { AST::Builtin::Class.instance_type }
          method_type = add_implicitly_returns_nil(type_def.each_annotation, method_type)
          Shape::MethodOverload.new(method_type, [type_def])
        end

        shape.methods[name] = Interface::Shape::Entry.new(method_name: name, private_method: method.private?, overloads: overloads)
      end
    end

    shape
  end
end

#subtyping ⇒ Object 



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# File 'lib/steep/interface/builder.rb', line 442

def subtyping
  @subtyping ||= Subtyping::Check.new(builder: self)
end

#tuple_shape(tuple) ⇒ Object 



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# File 'lib/steep/interface/builder.rb', line 446

def tuple_shape(tuple)
  element_type = AST::Types::Union.build(types: tuple.types)
  array_type = AST::Builtin::Array.instance_type(element_type)

  array_shape = yield(array_type) or raise
  shape = Shape.new(type: tuple, private: true)
  shape.methods.merge!(array_shape.methods)

  aref_entry = array_shape.methods[:[]].yield_self do |aref|
    raise unless aref

    Shape::Entry.new(
      method_name: :[],
      private_method: false,
      overloads: tuple.types.map.with_index {|elem_type, index|
        Shape::MethodOverload.new(
          MethodType.new(
            type_params: [],
            type: Function.new(
              params: Function::Params.build(required: [AST::Types::Literal.new(value: index)]),
              return_type: elem_type,
              location: nil
            ),
            block: nil
          ),
          []
        )
      } + aref.overloads
    )
  end

  aref_update_entry = array_shape.methods[:[]=].yield_self do |update|
    raise unless update

    Shape::Entry.new(
      method_name: :[]=,
      private_method: false,
      overloads: tuple.types.map.with_index {|elem_type, index|
        Shape::MethodOverload.new(
          MethodType.new(
            type_params: [],
            type: Function.new(
              params: Function::Params.build(required: [AST::Types::Literal.new(value: index), elem_type]),
              return_type: elem_type,
              location: nil
            ),
            block: nil
          ),
          []
        )
      } + update.overloads
    )
  end

  fetch_entry = array_shape.methods[:fetch].yield_self do |fetch|
    raise unless fetch

    Shape::Entry.new(
      method_name: :fetch,
      private_method: false,
      overloads: tuple.types.flat_map.with_index {|elem_type, index|
        [
          MethodType.new(
            type_params: [],
            type: Function.new(
              params: Function::Params.build(required: [AST::Types::Literal.new(value: index)]),
              return_type: elem_type,
              location: nil
            ),
            block: nil
          ),
          MethodType.new(
            type_params: [TypeParam.new(name: :T, upper_bound: nil, variance: :invariant, unchecked: false, default_type: nil)],
            type: Function.new(
              params: Function::Params.build(
                required: [
                  AST::Types::Literal.new(value: index),
                  AST::Types::Var.new(name: :T)
                ]
              ),
              return_type: AST::Types::Union.build(types: [elem_type, AST::Types::Var.new(name: :T)]),
              location: nil
            ),
            block: nil
          ),
          MethodType.new(
            type_params: [TypeParam.new(name: :T, upper_bound: nil, variance: :invariant, unchecked: false, default_type: nil)],
            type: Function.new(
              params: Function::Params.build(required: [AST::Types::Literal.new(value: index)]),
              return_type: AST::Types::Union.build(types: [elem_type, AST::Types::Var.new(name: :T)]),
              location: nil
            ),
            block: Block.new(
              type: Function.new(
                params: Function::Params.build(required: [AST::Builtin::Integer.instance_type]),
                return_type: AST::Types::Var.new(name: :T),
                location: nil
              ),
              optional: false,
              self_type: nil
            )
          )
        ].map { Shape::MethodOverload.new(_1, []) }
      } + fetch.overloads
    )
  end

  first_entry = array_shape.methods[:first].yield_self do |first|
    Shape::Entry.new(
      method_name: :first,
      private_method: false,
      overloads: [
        Shape::MethodOverload.new(
          MethodType.new(
            type_params: [],
            type: Function.new(
              params: Function::Params.empty,
              return_type: tuple.types[0] || AST::Builtin.nil_type,
              location: nil
            ),
            block: nil
          ),
          []
        )
      ]
    )
  end

  last_entry = array_shape.methods[:last].yield_self do |last|
    Shape::Entry.new(
      method_name: :last,
      private_method: false,
      overloads: [
        Shape::MethodOverload.new(
          MethodType.new(
            type_params: [],
            type: Function.new(
              params: Function::Params.empty,
              return_type: tuple.types.last || AST::Builtin.nil_type,
              location: nil
            ),
            block: nil
          ),
          []
        )
      ]
    )
  end

  shape.methods[:[]] = aref_entry
  shape.methods[:[]=] = aref_update_entry
  shape.methods[:fetch] = fetch_entry
  shape.methods[:first] = first_entry
  shape.methods[:last] = last_entry

  shape
end

#union_shape(shape_type, shapes) ⇒ Object 



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# File 'lib/steep/interface/builder.rb', line 332

def union_shape(shape_type, shapes)
  s0, *sx = shapes
  s0 or raise
  all_common_methods = Set.new(s0.methods.each_name)
  sx.each do |shape|
    all_common_methods &= shape.methods.each_name
  end

  shape = Interface::Shape.new(type: shape_type, private: true)
  all_common_methods.each do |method_name|
    overloadss = [] #: Array[Array[Shape::MethodOverload]]
    private_method = false
    shapes.each do |shape|
      entry = shape.methods[method_name] || raise
      overloadss << entry.overloads
      private_method ||= entry.private_method?
    end

    shape.methods[method_name] = Interface::Shape::Entry.new(method_name: method_name, private_method: private_method) do
      overloadss.inject do |overloads1, overloads2|
        # @type break: nil

        types1 = overloads1.map(&:method_type)
        types2 = overloads2.map(&:method_type)

        if types1 == types2
          defs1 = overloads1.flat_map(&:method_defs)
          defs2 = overloads2.flat_map(&:method_defs)

          if defs1 == defs2
            next overloads1
          end
        end

        method_overloads = {} #: Hash[Shape::MethodOverload, bool]

        overloads1.each do |overload1|
          overloads2.each do |overload2|
            if overload1.method_type == overload2.method_type
              overload = Shape::MethodOverload.new(overload1.method_type, overload1.method_defs + overload2.method_defs)
              method_overloads[overload] = true
            else
              if type = MethodType.union(overload1.method_type, overload2.method_type, subtyping)
                overload = Shape::MethodOverload.new(type, overload1.method_defs + overload2.method_defs)
                method_overloads[overload] = true
              end
            end
          end
        end

        break nil if method_overloads.empty?

        method_overloads.keys
      end
    end
  end

  shape
end