A compiled RE2 regex.

Compile a regex pattern, throw InvalidRegexPattern in case of illegal patterns.

RE2 Regex options.

The options are (defaultRegexOpts in parentheses):

  posix_syntax     (false) restrict regexps to POSIX egrep syntax
  longest_match    (false) search for longest match, not first match
  log_errors       (true)  log syntax and execution errors to ERROR
  max_mem          (8<<20)  approx. max memory footprint of RE2
  literal          (false) interpret string as literal, not regexp
  never_nl         (false) never match \n, even if it is in regexp
  dot_nl           (false) dot matches everything including new line
  never_capture    (false) parse all parens as non-capturing
  case_sensitive   (true)  match is case-sensitive (regexp can override
                             with (?i) unless in posix_syntax mode)

The following options are only consulted when posix_syntax == true. When posix_syntax == false, these features are always enabled and cannot be turned off; to perform multi-line matching in that case, begin the regexp with (?m).

  perl_classes     (false) allow Perl's \d \s \w \D \S \W
  word_boundary    (false) allow Perl's \b \B (word boundary and not)
  one_line         (false) ^ and $ only match beginning and end of text

Default regex options, see RegexOpts.

Compile a regex pattern withOptions, throw InvalidRegexPattern in case of illegal patterns.

Escape a piece of text literal so that it can be safely used in regex pattern.

>>> escape "(\\d+)"
>>> "\\(\\\\d\\+\\)"

capturing group number(including \0)

Get back regex's pattern.

Exception thrown when using regex.

Check if text matched regex pattern.

Check if text matched regex pattern, if so return matched part, all capturing groups(from \1) and the text after matched part.

Nothing indicate a non-matching capturing group, e.g.

>>> match (regex "(foo)|(bar)baz") "barbazbla"
>>> ("barbaz",[Nothing,Just "bar"], "bla")

Replace matched part in input with a rewrite pattern. If no matched part found, return the original input.

>>> replace (regex "red") False "A red fox with red fur" "yellow"
>>> "A yellow fox with red fur"
>>> replace (regex "red") True  "A red fox with red fur" "yellow"
>>> "A yellow fox with yellow fur"

Extract capturing group to an extract pattern. If no matched capturing group found, return an empty string.

>>> extract (regex "(\\d{4})-(\\d{2})-(\\d{2})") "Today is 2020-12-15" "month: \\2, date: \\3"
>>> "month: 12, date: 15"