Hello, I need to find the position of a match using Regex.run on a text with unicode characters. This is an example: iex> Regex.run(~r/x/u, "áéíóúx", return: :index) [{10, 1}] When te expected output should be: [{5, 1}] Shouldn’t the unicode modificator take care of this? how could I get the ri…

how could I get the right result? For exactly this example iex(1)> [before, _after] = :binary.split("áéíóúx", "x") ["áéíóú", ""] iex(2)> String.length(before) 5 seems to work.

The index returned is the byte index, and this is perfect for further processing it in parallel to the original input, eg, when cutting the matched substring, as indexing per byte is O(1), per character/glyph is O(n).

iex(1)> byte_size("áéíóúx") 11 Looks correct to me. :slight_smile: It returns byte positions, not character positions, UTF-8 is multibyte. :slight_smile:

Or maybe defmodule Test do @spec find_index(String.t, String.t) :: non_neg_integer | nil def find_index(target, <<char::utf8>>) do find_index(target, char, 0) end @spec find_index(String.t, pos_integer, non_neg_integer) :: non_neg_integer | nil defp find_index(<<target::utf8, _rest:…

Thank you all for your answers. @idi527 , your solution looks very good to me, I finally did something inspired on that, but simpler for my usecase. I needed to replace a tag in the text, so i had to find the tag name, and replace it with the new value. Kind of a template engine where I can substitu…

Have you considered using GitHub - dashbitco/nimble_parsec: A simple and fast library for text-based parser combinators · GitHub ?

Elixir Programming Language Forum

Regex and unicode returning wrong indexes

Questions & Help Questions

adrian July 11, 2018, 2:19pm 8

I didn’t know that existed! it’s the way to go probably