Do you absolutely need to solve it with a regex? Couldn’t you try pattern matching instead and then split accordingly?

OFF-TOPIC:

I am willing to bet $50 that within 24 hours somebody is going to post this to Reddit or 9GAG.

I really was not prepared to burst out laughing on the first post I see on ElixirForum today.

That works great! I tested it on some of the cities with long names and special characters and it broke it up into correct parts. You’re right in that some parts are empty strings, but I just Enum.filter those out.

One of my previous regex expressions was doing exactly what you described in the second bug. It was breaking the string into a part for every letter. Your suggestion works perfectly. Thank you so much!

AI: 0 Human: 1
Not that I’m keeping score.

Here is the final code for anyone else trying to bold just part of a string based on user input. Please see “Solution” above by @al2o3cr for explanation of the regular expression.

defp matches?(search_result, input) do
    String.contains?(String.downcase(search_result), String.downcase(input))
  end

  defp format_search_result(display_string, input) do
    if matches?(display_string, input) do
        Regex.run(~r/^(.*)(#{Regex.escape(input)})(.*)$/i, display_string, capture: :all_but_first)
        |> Enum.filter(&(&1 != ""))
        |> Enum.map(fn part ->
              if String.match?(part, ~r/#{Regex.escape(input)}/i ) do
                "<strong>#{part}</strong>"
              else part end
           end)
        |> Enum.join()
    else
      display_string
    end
  end