Regex alternative

pattern source_code =
{
  lines = (any, ['\n'])|repeat =>

  tokens = any of
  (
    private whitespace = (any of ' \t\r')|repeat
    symbol = (any of '~`!@#$%^&*+-=;:\'",.?/\\|')|repeat
    brackets = any of '(){}[]<>'
    invalid = (any < 32 except whitespace)|repeat
    literal = any of
    (
        number = any of
        (
           decimal = any of
           (
               private nonnegative_int = (any of '0123456789')|repeat
               int = ['-'], nonnegative_int
               float = ([int], '.', [nonnegative_int]).mask > 0, ['e'|nocase, int]
           )
           hex = {
               int = ['-'], '0x', (any of '0123456789ABCDEF'|nocase)|repeat
           }
        )
        string = any of (
           single_quoted = '\'', any eat '\\\'', '\''
           double_quoted = '"', any eat '\\"', '"'
        )
    )

    word = any left
  )|repeat =>

  objects =
  (
    pattern class_path = [(word|lowercase, ['.', word|lowercase])|repeat]
    pattern class_name = word{0|uppercase}, any
    pattern full_class_name = [class_path, '.'], class_name
    pattern var_name = word
    pattern function_name = word
    pattern operator = symbol
    pattern type_name = class_name
    pattern arguments_list = (var_name, [':', type_name]), [',', arguments_list]
    pattern block = any of ((expression, ';'), '{', content == block|repeat, '}')

    pattern expression = any of
    (
      var_name
      literal
      '('
        content = expression
      ')'
    ), [operator, expression]

    package = 'package', [class_path], ';'
    imports = any of
    (
      import = 'import', class_path, ['.*'], ';'
      using = 'using', class_path, ';'
    )|repeat

    pattern class =
    (
      'class', name = class_name, ['extends', full_class_name], [('implements', full_class_name)|repeat]
      '{'
        content == any of
        (
          var = [any of ('public', 'private', 'static', 'inline')|repeat once], 'var', name = var_name, ['=', expression], ';'
          function =
          (
            attribs = [any of ('public', 'private', 'static', 'inline')|repeat once]
            'function'
            name = function_name
            args = '(', content == [arguments_list], ')'
            block = block
          )
        )|repeat
      '}'
    )

    definitions = (class)|repeat
  )
}