Rewrite constant to a method

ConstToMethodRewriter.rb

require 'pry'
require 'parser'
require 'parser/current'

class ConstToMethodRewriter < ::Parser::Rewriter
  def on_casgn(node)
    _, const_name, *args = node.children
    replace_range = node.location.expression
    const_value = args.first.location.expression.source

    case const_name
    when :LABEL
      replace(replace_range, "def self.label\n    #{const_value}\n  end")
    end
  end
end


Dir.glob("app/models/package/*.rb").each do |filename|
  source   = File.read(filename)
  parser   = Parser::CurrentRuby.new
  rewriter = ConstToMethodRewriter.new
  buffer   = Parser::Source::Buffer.new(filename)
  buffer.source = source

  new = rewriter.rewrite(buffer, parser.parse(buffer))
  File.open(filename, "w"){|f| f.write(new) }
end

Effect:

-  LABEL = 'Something (xlsx)'
+  def self.label
+    'Something (xlsx)'
+  end