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Regex Builder

A simple regex builder python interface, making describing complicated regular expressions slightly easier to understand Licensed under BSD License, see LICENSE.txt for details.

Features

  • Chaining API
  • Easy to use

API

method builders

These can be imported from the library as functions, and chained as normal. They return a RegexBuilder object, so do to_string if you want to feed it into the re module

from regex_builder import *
regex = str(repeats(literal('a'),2,3))
assertEquals('a{2,3}', regex)
  • literal(string) returns a literal string to be used in the regex. Be careful of backslash characters
  • range(string) takes a literal, and turns it into a character range, i.e. abc => [abc]
  • inverted_range(string) takes a literal and turns it into an inverted chaarcter range, i.e. abc => [^abc]
  • repeats(regex) takes another regex and either fixed number of repeats, or a minimum and maximum
  • group(regex) takes another regex, and creates a matching group. use non_capture=True for non-capturing groups
  • one_or_more(regex) takes a regex and adds the '+' repeat token
  • zero_or_more(regex) takes a regex and adds the '*' repeat token
  • optional(regex) makes the passed regex optional
  • append(regex) takes a regex and appends it to your regex.

Shortcuts

There are a few shortcuts that are handy.

  • Any method that takes a regex can also take a string, for example one_or_more('ab') returns '(?:ab)+'
  • The Builder objects are immutable, so you can store them and reuse them, for example, ab= literal('ab'); 'abc' == ab.literal('c'); 'abd' == ab.literal('d')

Examples

There are some examples in the unit testing framework, but here are some extra from regex_builder import * number = optional(range('1-2')).optional(range('0-9')).range('0-9') dotted_number = number.literal('\.') ip_addr = repeats(dotted_number, 3).append(dotted_number)