Phone Number Parsing

Mix.install([
  {:jason, "~> 1.4"},
  {:kino, "~> 0.8.0", override: true},
  {:youtube, github: "brooklinjazz/youtube"},
  {:hidden_cell, github: "brooklinjazz/hidden_cell"}
])

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Phone Number Parsing

You have been provided a large string of phone numbers. The problem is, each phone number does not follow a standard format.

You have been asked to convert them from the non standardized format into a standard format.

Phone numbers will be given in the following formats:

• 1231231234
• 123 123 1234
• (123)-123-1234
• (123) 123 1234
• (123)123-1234

You need to convert them into the format 123-123-1234.

text = """
1231231234
123 123 1234
(123)-123-1234
(123) 123 1234
(123)123-1234
"""
PhoneNumber.parse(text)
"""
123-123-1234
123-123-1234
123-123-1234
123-123-1234
123-123-1234
"""

Hint

Consider using regular expressions with digits and capture groups to replace phone number expressions in the string.

You can replace expressions one at a time, rather than all at once.

Example Solution

defmodule PhoneNumber
  def parse(string) do
    replacement = "\\1-\\2-\\3"

    string
    |> String.replace(~r/(\d{3})(\d{3})(\d{4})/, replacement)
    |> String.replace(~r/(\d{3}) (\d{3}) (\d{4})/, replacement)
    |> String.replace(~r/\((\d{3})\)-(\d{3})-(\d{4})/, replacement)
    |> String.replace(~r/\((\d{3})\) (\d{3}) (\d{4})/, replacement)
    |> String.replace(~r/\((\d{3})\)(\d{3})-(\d{4})/, replacement)
  end
end

Implement the PhoneNumber module as documented below.

defmodule PhoneNumber do
  @moduledoc """
  Documentation for `PhoneNumber`
  """

  @doc """
  Parse phone numbers and convert them to XXX-XXX-XXXX format.

  ## Examples

    iex> PhoneNumber.parse("1231231234")
    "123-123-1234"

    iex> PhoneNumber.parse("123 123 1234")
    "123-123-1234"

    iex> PhoneNumber.parse("(123)-123-1234")
    "123-123-1234"

    iex> PhoneNumber.parse("(123) 123 1234")
    "123-123-1234"

    iex> PhoneNumber.parse("(123)123-1234")
    "123-123-1234"

    iex> PhoneNumber.parse("1231231234 4564564567")
    "123-123-1234 456-456-4567"
  """
  def parse(string) do
  end
end

Mark As Completed

file_name = Path.basename(Regex.replace(~r/#.+/, __ENV__.file, ""), ".livemd")

save_name =
  case Path.basename(__DIR__) do
    "reading" -> "phone_number_parsing_reading"
    "exercises" -> "phone_number_parsing_exercise"
  end

progress_path = __DIR__ <> "/../progress.json"
existing_progress = File.read!(progress_path) |> Jason.decode!()

default = Map.get(existing_progress, save_name, false)

form =
  Kino.Control.form(
    [
      completed: input = Kino.Input.checkbox("Mark As Completed", default: default)
    ],
    report_changes: true
  )

Task.async(fn ->
  for %{data: %{completed: completed}} <- Kino.Control.stream(form) do
    File.write!(
      progress_path,
      Jason.encode!(Map.put(existing_progress, save_name, completed), pretty: true)
    )
  end
end)

form

Commit Your Progress

Run the following in your command line from the curriculum folder to track and save your progress in a Git commit. Ensure that you do not already have undesired or unrelated changes by running git status or by checking the source control tab in Visual Studio Code.

$ git checkout -b phone-number-parsing-exercise
$ git add .
$ git commit -m "finish phone number parsing exercise"
$ git push origin phone-number-parsing-exercise

Create a pull request from your phone-number-parsing-exercise branch to your solutions branch. Please do not create a pull request to the DockYard Academy repository as this will spam our PR tracker.

DockYard Academy Students Only:

Notify your teacher by including @BrooklinJazz in your PR description to get feedback. You (or your teacher) may merge your PR into your solutions branch after review.

If you are interested in joining the next academy cohort, sign up here to receive more news when it is available.

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