class IRB::SourceFinder

# File irb/source_finder.rb, line 15
def initialize(irb_context)
  @irb_context = irb_context
end

# File irb/source_finder.rb, line 19
def find_source(signature, super_level = 0)
  context_binding = @irb_context.workspace.binding
  case signature
  when /\A[A-Z]\w*(::[A-Z]\w*)*\z/ # Const::Name
    eval(signature, context_binding) # trigger autoload
    base = context_binding.receiver.yield_self { |r| r.is_a?(Module) ? r : Object }
    file, line = base.const_source_location(signature)
  when /\A(?<owner>[A-Z]\w*(::[A-Z]\w*)*)#(?<method>[^ :.]+)\z/ # Class#method
    owner = eval(Regexp.last_match[:owner], context_binding)
    method = Regexp.last_match[:method]
    return unless owner.respond_to?(:instance_method)
    file, line = method_target(owner, super_level, method, "owner")
  when /\A((?<receiver>.+)(\.|::))?(?<method>[^ :.]+)\z/ # method, receiver.method, receiver::method
    receiver = eval(Regexp.last_match[:receiver] || 'self', context_binding)
    method = Regexp.last_match[:method]
    return unless receiver.respond_to?(method, true)
    file, line = method_target(receiver, super_level, method, "receiver")
  end
  if file && line && File.exist?(file)
    Source.new(file: file, first_line: line, last_line: find_end(file, line))
  end
end

# File irb/source_finder.rb, line 44
def find_end(file, first_line)
  lex = RubyLex.new
  lines = File.read(file).lines[(first_line - 1)..-1]
  tokens = RubyLex.ripper_lex_without_warning(lines.join)
  prev_tokens = []

  # chunk with line number
  tokens.chunk { |tok| tok.pos[0] }.each do |lnum, chunk|
    code = lines[0..lnum].join
    prev_tokens.concat chunk
    continue = lex.should_continue?(prev_tokens)
    syntax = lex.check_code_syntax(code, local_variables: [])
    if !continue && syntax == :valid
      return first_line + lnum
    end
  end
  first_line
end

# File irb/source_finder.rb, line 63
def method_target(owner_receiver, super_level, method, type)
  case type
  when "owner"
    target_method = owner_receiver.instance_method(method)
  when "receiver"
    target_method = owner_receiver.method(method)
  end
  super_level.times do |s|
    target_method = target_method.super_method if target_method
  end
  target_method.nil? ? nil : target_method.source_location
rescue NameError
  nil
end