Split TypeCompletion to a gem

[tompng]

Description

TypeCompletion requires Prism and RBS. Since IRB is a default gem and IRB supports ruby>=2.7.0, we can't write Prism dependency(ruby>=3.0) to gemspec.

Splitting to gem allows to simplify the version checks and other. (Other problems are described in #734 (comment))

API of repl_type_completor

https://github.com/ruby/repl_type_completor/blob/main/sig/repl_type_completor.rbs

module ReplTypeCompletor
  VERSION: String

  class Result
    def completion_candidates: () -> Array[String]
    def doc_namespace: (String) -> String?
  end

  def self.analyze: (String, binding: Binding, ?filename: String?) -> Result?

  def self.rbs_load_error: () -> Exception?
  def self.last_completion_error: () -> Exception?

  def self.rbs_load_started?: () -> bool
  def self.rbs_loaded?: () -> bool
  def self.load_rbs: () -> void
  def self.preload_rbs: () -> void
  def self.info: () -> String
end

Future extending plans

The completion_candidates and doc_namespace is insufficient when we want to

• Show a hint in completion dialog (example: abort (method) alias (keyword) and (keyword) at_exit (method) a_local_var (lvar))
• Show something in document dialog (example: RBS signature) when there is no document
• Add another dialog to show something (example: possible types of receiver in method call)

We can add a method to ReplCompletion::Result to extend.

# These are just an idea

result.categorized_candidates
#=>
[
  { type: :lvar, candidates: ['abc, 'abcde'] },
  { type: :keyword, candidates: ['and', 'alias'] },
  { type: :call, candidates: ['abort', 'at_exit'], receiver: Kernel },
  { type: :call, candidates: ['aaa', 'aab'], receiver: main.singleton_class },
]

result.match_info(matched)
# =>
{
  type: :lvar,
  value_classes: [Array, Hash],
  value_type_inspect: 'Array[String] | Hash[Symbol, String | Integer]',
  other_useful_information: something
}

Duplicate implementation with IRB

Gem repl_type_completor has a reimplementation of IRB::InputCompletor#retrieve_files_to_require_from_load_path and IRB::InputCompletor#retrieve_files_to_require_relative_from_current_dir.
It is duplicated but I think it should be calculated in the separated gem.

Also IRB can't delete these methods until dropping RegexpCompletor.

filename: option

We need source file path to correctly complete require_relative paths.
require_relative will load relative path from __dir__, not from Dir.pwd.
IRB.CurrentContext.irb_path is passed to eval(string, binding, filename, lineno) and completor needs this value.

# Using binding.source_locaiton[0] as a filename is not sufficient because:
irb(main):001> IRB.CurrentContext.workspace.binding.source_location[0]
=> "/path/to/irb/lib/irb/workspace.rb" # wrong base path for require_relative
irb(main):002> __FILE__
=> "(irb)" # In this case, looks like `Dir.pwd` is used instead

[st0012]

Does this mean in the entire IRB session, user only gets the completion targeting one source file? For example, if I put a binding.irb under app/models/user.rb, will it run all analysis only around user.rb?

[tompng]

Nice catch. Actually, this initialization (build_type_completor and also IRB::Irb.new) will be called in each binding.irb.
But I found that @irb_path is not fully initialized yet when build_completor is called and context.irb_path is overwritten after IRB::Irb initialization.

# In irb.rb:1050
binding_irb = IRB::Irb.new(workspace)
binding_irb.context.irb_path = irb_path
binding_irb.run(IRB.conf)

I will change to IRB::TypeCompletor.new(context) and call ReplTypeCompletor.analyze(preposing + target, binding: bind, filename: context.irb_path) on completion phase.

[st0012]

Yeah I think that's better because with irb:rdbg, irb_path could be updated if user moves around with the debugger. If we store it as a state in InputMethod, it won't be synced correctly.

[st0012]

Ah I forgot to change this in #794 🤦‍♂️