repath

Or something

A port of the node module path-to-regexp to Python.

Turn an Express-style path string such as /user/:name into a regular expression*.

(it is actually used to generate patterns which you can then compile using the re module, including appropriate regex flag(s))

Installation

repath is a single module, so installation can be as simple as copying the repath.py file to your project directory, but you can also cd to your cloned repository and:

• python setup.py install, or
• pip install ./

repath is not currently available on pypi.

Usage

import re
import repath

pattern = repath.path_to_pattern(path)
match = re.match(pattern, requested_url_path)

if match:
    params = match.groupdict()

• path A string in the express format, an array of strings, or a regular expression.
• options
  • strict When False the trailing slash is optional. (default: False)
  • end Attempt to match full paths (default: True)
    • /foo/bar with end=False will match /foo/bar or /foo/bar/baz
    • /foo/bar with end=True will only match /foo/bar

>>> path_to_pattern('/foo/:bar')
'^/foo/(?<bar>[^/]+?)/?$'

Parameters

The path has the ability to define parameters and automatically generate capture groups in the resulting regular expression pattern.

Named Parameters

Named parameters are defined by prefixing the parameter name with a colon (e.g. :foo). By default, this parameter will match up to the next path segment.

>>> regex = re.compile(path_to_pattern('/:foo/:bar'), re.I)
>>> match = regex.match('/test/route')
>>> match.groups()
('test', 'route',)
>>> match.groupdict()
{'foo': 'test', 'bar': 'route'}

Suffixed Parameters

Optional

Parameters can be suffixed with a question mark (?) to make the entire parameter optional. This will also make any prefixed path delimiter optional (/ or .).

>>> regex = re.compile(path_to_pattern('/:foo/:bar?'))
>>> regex.match('/test').groupdict()
{'foo': 'test', 'bar': None}

>>> regex.match('/test/route').groupdict()
{'foo': 'test', 'bar': 'route'}

Zero or more

Parameters can be suffixed with an asterisk (*) to denote a zero or more parameter match. The prefixed path delimiter is also taken into account for the match.

>>> regexp = re.compile(path_to_pattern('/:foo*'))
>>> regexp.match('/').groupdict()
{'foo': None}

>>> regexp.match('/bar/baz')
{'foo': 'bar/baz'}

One or more

Parameters can be suffixed with a plus sign (+) to denote a one or more parameters match. The prefixed path delimiter is included in the match.

>>> regexp = re.compile(path_to_pattern('/:foo+'))
>>> regexp.match('/')
None

>>> regexp.match('/bar/baz').groupdict()
{'foo': 'bar/baz'}

Custom Match Parameters

All parameters can be provided a custom matching regexp and override the default. Please note: Backslashes need to be escaped in strings.

>>> regexp = re.compile(path_to_pattern('/:foo(\\d+)'))
>>> regexp.match('/123').groupdict()
{'foo': '123'}

>>> regexp.match('/abc')
None

Unnamed Parameters

It is possible to write an unnamed parameter that is only a matching group. It works the same as a named parameter, except it must be retrieved by its group number.

>>> regexp = re.compile(path_to_pattern('/:foo/(.*)'))
>>> regexp.match('/test/route').groupdict()
{'foo': 'test'}
>>> regexp.match('/test/route').groups()
('test', 'route',)

Asterisk

An asterisk can be used for matching everything. It is equivalent to an unnamed matching group of (.*).

>>> regexp = re.compile(path_to_pattern('/fooo/*'))
>>> regexp.match('/foo/bar/baz').groups()
('bar/baz',)

Parse

The parse function is exposed via repath.parse. This will yield an array of strings and dictionary tokens.

>>> tokens = repath.parse('/route/:foo/(.*)')
>>> tokens[0]
'/route'
>>> tokens[1]
{'name': 'foo', 'prefix': '/', 'delimiter': '/', 'optional': False, 'repeat': False, 'pattern': '[^/]+?'}
>>> tokens[2]
{'name': '0', 'prefix': '/', 'delimiter': '/', 'optional': False, 'repeat': False, 'pattern': '.*'}

Note: This method only works with strings.

Compile ("Reverse" Path-To-RegExp)

Path-To-RegExp exposes a compile function for transforming an express path into valid path. Confusing enough? This example will straighten everything out for you.

>>> template = repath.compile('/user/:id')
>>> template({'id': 123})
'/user/123'

Note: The generated function will throw on any invalid input. It will execute all necessary checks to ensure the generated path is valid. This method only works with strings.

Working with Tokens

Path-To-RegExp exposes the two functions used internally that accept an array of tokens.

• repath.tokens_to_pattern(tokens, options) Transform an array of tokens into a matching regular expression pattern.
• repath.tokens_to_function(tokens) Transform an array of tokens into a path templating function.