class RBS::TypeAliasRegularity

# File rbs-2.1.0/lib/rbs/type_alias_regularity.rb, line 14
def initialize(env:)
  @env = env
  @builder = DefinitionBuilder.new(env: env)
  @diagnostics = {}
end

# File rbs-2.1.0/lib/rbs/type_alias_regularity.rb, line 109
def self.validate(env:)
  self.new(env: env).tap do |validator|
    validator.validate()
  end
end

# File rbs-2.1.0/lib/rbs/type_alias_regularity.rb, line 57
def build_alias_type(name)
  entry = env.alias_decls[name] or raise "Unknown alias name: #{name}"
  unless entry.decl.type_params.empty?
    as = entry.decl.type_params.each.map {|param| Types::Variable.new(name: param.name, location: nil) }
    Types::Alias.new(name: name, args: as, location: nil)
  end
end

# File rbs-2.1.0/lib/rbs/type_alias_regularity.rb, line 65
def compatible_args?(args1, args2)
  if args1.size == args2.size
    args1.zip(args2).all? do |t1, t2|
      t1.is_a?(Types::Bases::Any) ||
        t2.is_a?(Types::Bases::Any) ||
        t1 == t2
    end
  end
end

# File rbs-2.1.0/lib/rbs/type_alias_regularity.rb, line 99
def each_alias_type(type, &block)
  if type.is_a?(RBS::Types::Alias)
    yield type
  end

  type.each_type do |ty|
    each_alias_type(ty, &block)
  end
end

# File rbs-2.1.0/lib/rbs/type_alias_regularity.rb, line 79
def each_mutual_alias_defs(&block)
  # @type var each_node: TSort::_EachNode[TypeName]
  each_node = __skip__ = -> (&block) do
    env.alias_decls.each_value do |decl|
      block[decl.name]
    end
  end
  # @type var each_child: TSort::_EachChild[TypeName]
  each_child = __skip__ = -> (name, &block) do
    type = builder.expand_alias1(name)
    each_alias_type(type) do |ty|
      block[ty.name]
    end
  end

  TSort.each_strongly_connected_component(each_node, each_child) do |names|
    yield Set.new(names)
  end
end

# File rbs-2.1.0/lib/rbs/type_alias_regularity.rb, line 75
def nonregular?(type_name)
  diagnostics[type_name]
end

# File rbs-2.1.0/lib/rbs/type_alias_regularity.rb, line 20
def validate
  diagnostics.clear

  each_mutual_alias_defs do |names|
    # Find the first generic type alias in strongly connected component.
    # This is to skip the regularity check when the alias is not generic.
    names.each do |name|
      # @type break: nil
      if type = build_alias_type(name)
        # Running validation only once from the first generic type is enough, because they are mutual recursive definition.
        validate_alias_type(type, names, {})
        break
      end
    end
  end
end

# File rbs-2.1.0/lib/rbs/type_alias_regularity.rb, line 37
def validate_alias_type(alias_type, names, types)
  if names.include?(alias_type.name)
    if ex_type = types[alias_type.name]
      unless compatible_args?(ex_type.args, alias_type.args)
        diagnostics[alias_type.name] ||=
          Diagnostic.new(type_name: alias_type.name, nonregular_type: alias_type)
      end

      return
    else
      types[alias_type.name] = alias_type
    end

    expanded = builder.expand_alias2(alias_type.name, alias_type.args)
    each_alias_type(expanded) do |at|
      validate_alias_type(at, names, types)
    end
  end
end