Method: Parlour::TypeParser#parse_sig_into_methods

Defined in:

lib/parlour/type_parser.rb

#parse_sig_into_methods(path, is_within_eigenclass: false) ⇒ <RbiGenerator::Method>

Given a path to a sig in the AST, finds the associated definition and parses them into methods. This will raise an exception if the sig is invalid. Usually this will return one method; the only exception currently is for attributes, where multiple can be declared in one call, e.g. attr_reader :x, :y, :z.

Parameters:

• path (NodePath) —

  The sig to parse.

• is_within_eigenclass (Boolean) (defaults to: false) —

  Whether the method definition this sig is associated with appears inside an eigenclass definition. If true, the returned method is made a class method. If the method definition is already a class method, an exception is thrown as the method will be a class method of the eigenclass, which Parlour can’t represent.

Returns:

• (<RbiGenerator::Method>) —

  The parsed methods.

# File 'lib/parlour/type_parser.rb', line 535

def parse_sig_into_methods(path, is_within_eigenclass: false)
  sig_block_node = path.traverse(ast)

  # A :def node represents a definition like "def x; end"
  # A :defs node represents a definition like "def self.x; end"
  def_node = path.sibling(1).traverse(ast)
  if def_node.type == :send && [:def, :defs].include?(def_node.children.last.type)
    # bypass inline modifier (e.g. "private")
    def_node = def_node.children.last
  end
  case def_node.type
  when :def
    class_method = false
    def_names = [def_node.to_a[0].to_s]
    def_params = def_node.to_a[1].to_a
    kind = :def
  when :defs
    parse_err 'targeted definitions on a non-self target are not supported', def_node \
      unless def_node.to_a[0].type == :self
    class_method = true
    def_names = [def_node.to_a[1].to_s]
    def_params = def_node.to_a[2].to_a
    kind = :def
  when :send
    target, method_name, *parameters = *def_node

    parse_err 'node after a sig must be a method definition', def_node \
      unless [:attr_reader, :attr_writer, :attr_accessor].include?(method_name) \
        || target != nil

    parse_err 'typed attribute should have at least one name', def_node if parameters&.length == 0

    kind = :attr
    attr_direction = method_name.to_s.gsub('attr_', '').to_sym
    def_names = T.must(parameters).map { |param| param.to_a[0].to_s }
    class_method = false
  else
    parse_err 'node after a sig must be a method definition', def_node
  end

  if is_within_eigenclass
    parse_err 'cannot represent multiple levels of eigenclassing', def_node if class_method
    class_method = true
  end

  this_sig = parse_sig_into_sig(path)
  params = this_sig.params
  return_type = this_sig.return_type

  if kind == :def
    # Sorbet allows a trailing blockarg that's not in the sig
    if params &&
       def_params.length == params.length + 1 &&
       def_params[-1].type == :blockarg
      def_params = def_params[0...-1]
    end

    parse_err 'mismatching number of arguments in sig and def', sig_block_node \
      if params && def_params.length != params.length

    # sig_args will look like:
    #   [(pair (sym :x) <type>), (pair (sym :y) <type>), ...]
    # def_params will look like:
    #   [(arg :x), (arg :y), ...]
    parameters = params \
      ? zip_by(params, ->x{ x.to_a[0].to_a[0] }, def_params, ->x{ x.to_a[0] })
        .map do |sig_arg, def_param|

          arg_name = def_param.to_a[0]

          # TODO: anonymous restarg
          full_name = arg_name.to_s
          full_name = "*#{arg_name}"  if def_param.type == :restarg
          full_name = "**#{arg_name}" if def_param.type == :kwrestarg
          full_name = "#{arg_name}:"  if def_param.type == :kwarg || def_param.type == :kwoptarg
          full_name = "&#{arg_name}"  if def_param.type == :blockarg

          default = def_param.to_a[1] ? node_to_s(def_param.to_a[1]) : nil
          type = node_to_s(sig_arg.to_a[1])

          RbiGenerator::Parameter.new(full_name, type: type, default: default)
        end
      : []

    # There should only be one ever here, but future-proofing anyway
    def_names.map do |def_name|
      RbiGenerator::Method.new(
        generator,
        def_name,
        parameters,
        return_type,
        type_parameters: this_sig.type_parameters,
        override: this_sig.override,
        overridable: this_sig.overridable,
        abstract: this_sig.abstract,
        final: this_sig.final,
        class_method: class_method
      )
    end
  elsif kind == :attr
    case attr_direction
    when :reader, :accessor
      parse_err "attr_#{attr_direction} sig should have no parameters", sig_block_node \
        if params && params.length > 0

      parse_err "attr_#{attr_direction} sig should have non-void return", sig_block_node \
        unless return_type

      attr_type = return_type
    when :writer
      # These are special and can only have one name
      raise 'typed attr_writer can only have one name' if def_names.length > 1

      def_name = def_names[0]
      parse_err "attr_writer sig should take one argument with the property's name", sig_block_node \
        if !params || params.length != 1 || params[0].to_a[0].to_a[0].to_s != def_name

      parse_err "attr_writer sig should have non-void return", sig_block_node \
        if return_type.nil?

      attr_type = T.must(node_to_s(params[0].to_a[1]))
    else
      raise "unknown attribute direction #{attr_direction}"
    end

    def_names.map do |def_name|
      RbiGenerator::Attribute.new(
        generator,
        def_name,
        attr_direction,
        attr_type,
        class_attribute: class_method
      )
    end
  else
    raise "unknown definition kind #{kind}"
  end
end