Concurrently counts how many files reference a certain word at least once in the sub folders of the Rails app folder

count.exs

#!/usr/local/bin/elixir
import IO.ANSI, only: [yellow: 0, light_magenta: 0, light_cyan: 0]

defmodule Counter do
  use GenServer

  @cmd "rg"

  def start do
    GenServer.start(__MODULE__, [])
  end

  def count_and_format(pid, dir, word) do
    GenServer.cast(pid, {:count_and_format, dir, word})
  end

  def handle_cast({:count_and_format, dir, word}, _state) do
    IO.puts "#{light_magenta()}#{dir}: #{light_cyan()}#{count(dir, word)}"
    {:stop, :done, []}
  end

  defp count(dir, word) when is_binary(dir) do
    @cmd
    |> System.cmd(["-l", word, dir])
    |> get_str()
    |> String.split("\n")
    |> Enum.count
  end

  def get_str({str, _}), do: str
end

defmodule Count do
  @dirs [
    "app/assets",
    "app/controllers",
    "app/datatubes",
    "app/helpers",
    "app/mailers",
    "app/models",
    "app/presenters",
    "app/services",
    "app/views",
    "app/workers"
  ]

  def refs(word) when is_binary(word) do
    IO.puts """

    #{yellow()}Number of files with references to "#{word}"
    --------------------------------------------
    """

    @dirs
    |> Enum.map(fn dir ->
      {:ok, pid} = Counter.start
      Counter.count_and_format(pid, dir, word)
      pid
    end)
    |> wait
  end

  defp wait([]), do: []
  defp wait(pids) do
    pids
    |> Enum.map(&({Process.alive?(&1), &1}))
    |> Enum.filter(fn {alive, _pid} -> alive == true end)
    |> Enum.map(fn {_bool, pid} -> pid end)
    |> wait
  end
end

[word | _] = System.argv()

Count.refs word

Rust + Elixir in action

This uses ripgrep to do the file searching.

usage:

$ chmod +x count.exs
$ ./count.exs `word_to_search`