regex.rb

def scan(regex, text)
  return match_found?(regex[1..-1], text) if regex[0] == '^'
  until  text[0].nil?
    match_found?(regex, text) ? (return true) : text = text[1..-1]
  end
  false
end

def match_found?(regex, text)
  if    regex[0] == nil then return true
  elsif regex[1] == '*' then return splat_match?(regex[0],regex[2..-1],text)
  elsif regex[0] == '$' && regex[1] == nil then return text[0].nil?
  elsif text[0]  != nil && (regex[0] == '.' || regex[0] == text[0])
    return match_found?(regex[1..-1], text[1..-1])
  end
  false
end

def splat_match?(current_regex, next_regex, text)
  until text[0].nil? && (text[0] == current_regex || current_regex == '.')
    match_found?(next_regex, text) ? (return true) : text = text[1..-1]
  end
  false
end

p scan('bc','abc')
p scan('disco','stu') == false
p scan('a*','abc')
p scan('^a','abc')
p scan('aster .*aster','master blaster')
p scan('a$','bca')
p scan('a$','abc') == false
p scan('.*','abc')
p scan('.*g','nathanielwroblewski@gmail.com')