String balance check whether for brackets

string_balance_check.rb

require 'pry'
PAIRS = {
  '{' => '}',
  '[' => ']',
  '(' => ')'
}.freeze

def balanced?(string)
  return false if string.length.odd?
  return false if string =~ /[^\[\]\(\)\{\}]/

  stack = []

  push_and_pop string, stack
  stack.empty?
end

def push_and_pop string, stack
  string.chars do |bracket|
    if expectation = PAIRS[bracket]
      stack << expectation
    else
      return false unless stack.pop == bracket
    end
  end
end