How to fix broken UTF-8 string in ruby 2

Question

I have as an input string tat thinks is UTF-8 but is not and need to fix it. The code is in ruby 2 so iconv is no more and encode or force_encode are not working as intended:

[5] pry(main)> a='zg\u0142oszeniem'
=> "zg\\u0142oszeniem"
[6] pry(main)> a.encode("UTF-8", :invalid => :replace, :undef => :replace, :replace => "?")
=> "zg\\u0142oszeniem"
[8] pry(main)> a.encode!(Encoding::UTF_8, :invalid => :replace, :undef => :replace, :replace => "?")
=> "zg\\u0142oszeniem"
[10] pry(main)> a.force_encoding(Encoding::UTF_8)
=> "zg\\u0142oszeniem"

How can I fix it?

Answer 1

Here's solution using regex:

a.gsub(/\\\\u([0-9a-fA-F]{1,5}|10[0-9a-fA-F]{4})/) { $1.hex.chr(Encoding::UTF_8) } ¹

It should work for that particular string:

[1] pry(main)> before = 'zg\u0142oszeniem'
=> "zg\\u0142oszeniem"
[2] pry(main)> before.split('')
=> ["z", "g", "\\", "u", "0", "1", "4", "2", "o", "s", "z", "e", "n", "i", "e", "m"]
[3] pry(main)> after = before.gsub(/\\u([0-9a-fA-F]{1,5}|10[0-9a-fA-F]{4})/) { $1.hex.chr(Encoding::UTF_8) }
=> "zgłoszeniem"
[4] pry(main)> after.split('')
=> ["z", "g", "ł", "o", "s", "z", "e", "n", "i", "e", "m"]

---

[1] Unicode codepoints can range from 0 to 10FFFF ₁₆ ( definition D9 in Section 3.4, Characters and Encoding ), that should explains why above regex looks like that.