Class: RubyLsp::Requests::SignatureHelp

Inherits:
Listener
  • Object
show all
Extended by:
T::Generic, T::Sig
Defined in:
lib/ruby_lsp/requests/signature_help.rb

Overview

Signature help demo

The signature help request displays information about the parameters of a method as you type an invocation.

Currently only supports methods invoked directly on self without taking inheritance into account.

Example

class Foo
 def bar(a, b, c)
 end

 def baz
   bar( # -> Signature help will show the parameters of `bar`
 end

Constant Summary collapse

ResponseType = 
type_member { { fixed: T.nilable(T.any(Interface::SignatureHelp, T::Hash[Symbol, T.untyped])) } }

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods inherited from Listener

#response

Methods included from RubyLsp::Requests::Support::Common

#create_code_lens, #defined_in_gem?, #markdown_from_index_entries, #range_from_location, #range_from_node, #self_receiver?, #visible?

Constructor Details

#initialize(context, nesting, index, dispatcher) ⇒ SignatureHelp

Returns a new instance of SignatureHelp.



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# File 'lib/ruby_lsp/requests/signature_help.rb', line 42

def initialize(context, nesting, index, dispatcher)
  @context = context
  @nesting = nesting
  @index = index
  @_response = T.let(nil, ResponseType)

  super(dispatcher)
  dispatcher.register(self, :on_call_node_enter)
end

Instance Attribute Details

#_response ⇒ Object (readonly)

Returns the value of attribute _response.



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# File 'lib/ruby_lsp/requests/signature_help.rb', line 32

def _response
  @_response
end

Instance Method Details

#on_call_node_enter(node) ⇒ Object 



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# File 'lib/ruby_lsp/requests/signature_help.rb', line 53

def on_call_node_enter(node)
  return if DependencyDetector.instance.typechecker
  return unless self_receiver?(node)

  message = node.message
  return unless message

  target_method = @index.resolve_method(message, @nesting.join("::"))
  return unless target_method

  parameters = target_method.parameters
  name = target_method.name

  # If the method doesn't have any parameters, there's no need to show signature help
  return if parameters.empty?

  label = "#{name}(#{parameters.map(&:decorated_name).join(", ")})"

  arguments_node = node.arguments
  arguments = arguments_node&.arguments || []
  active_parameter = (arguments.length - 1).clamp(0, parameters.length - 1)

  # If there are arguments, then we need to check if there's a trailing comma after the end of the last argument
  # to advance the active parameter to the next one
  if arguments_node &&
      node.slice.byteslice(arguments_node.location.end_offset - node.location.start_offset) == ","
    active_parameter += 1
  end

  @_response = Interface::SignatureHelp.new(
    signatures: [
      Interface::SignatureInformation.new(
        label: label,
        parameters: parameters.map { |param| Interface::ParameterInformation.new(label: param.name) },
        documentation: markdown_from_index_entries("", target_method),
      ),
    ],
    active_parameter: active_parameter,
  )
end