matching_brackets

elixir/matching-brackets/lib/matching_brackets.ex

@@ -0,0 +1,28 @@
+defmodule MatchingBrackets do
+  require Logger
+
+  @opening_brackets ~w"[ { ("
+  @closing_brackets ~w"] } )"
+  @bracket_pairs Enum.zip(@closing_brackets, @opening_brackets)
+
+  @doc """
+  Checks that all the brackets and braces in the string are matched correctly, and nested correctly
+  """
+  @spec check_brackets(String.t()) :: boolean
+  def check_brackets(str), do: do_check_brackets(str, [])
+
+  defguardp is_opening_bracket(char) when char in @opening_brackets
+  defguardp is_closing_bracket(char) when char in @closing_brackets
+  defguardp is_pair(closing, opening) when {closing, opening} in @bracket_pairs
+
+  # Base cases
+  defp do_check_brackets("", []), do: true
+  defp do_check_brackets("", _any), do: false
+  # Opening bracket
+  defp do_check_brackets(<<opening::binary-size(1), str::binary>>, acc) when is_opening_bracket(opening), do: do_check_brackets(str, [opening | acc])
+  # Closing bracket
+  defp do_check_brackets(<<closing::binary-size(1), str::binary>>, [opening | tail]) when is_pair(closing, opening), do: do_check_brackets(str, tail)
+  defp do_check_brackets(<<closing::binary-size(1), _str::binary>>, _acc) when is_closing_bracket(closing), do: false
+  # Not a bracket
+  defp do_check_brackets(<<_char::binary-size(1), str::binary>>, acc), do: do_check_brackets(str, acc)
+end