Dbg is a life-saver for text parsing

Theres also nimble parsec GitHub - dashbitco/nimble_parsec: A simple and fast library for text-based parser combinators · GitHub I found incredibly powerful

I’m getting really expressive and simple pipelines from these two helper functions I wrote. The basic idea is to make the String the first param; and just return the matches.

defmodule Crawlers.String do
  @moduledoc """
  Extensions to String.
  """

  @spec capture(binary, Regex.t()) :: binary | nil
  def capture(string, regex) do
    captures(string, regex) |> Enum.at(0)
  end

  @spec captures(binary, Regex.t()) :: [binary] | nil
  def captures(string, regex) do
    Regex.run(regex, string, capture: :all_but_first)
  end
end

An example from my client code:

  #
  # Extract the chapter range numbers from a Volume heading like this:
  #   "Volume : 01 - Courts, Oregon Rules of Civil Procedure - Chapters 1-55 (48)"
  #
  # to:
  #   ["1", "55"]
  #
  defp extract_chapter_range(raw_string) do
    raw_string
    |> captures(~r/Chapters (\w+)-(\w+)/u)
  end

I haven’t yet bought into combinators yet — I don’t find them very expressive. They seem very procedural.

FYI I think this is a fantastic idea — modular, expressive components. It’s like a parser language. GitHub - manoss96/pregex: PRegEx - Programmable Regular Expressions · GitHub

Here’s a screenshot showing how dbg immediately helped me see why my Regex was failing:

dbg-example1200×780 68.5 KB