pycases

A case conversion library for Python.

Features

• Automatic case detection, no need to specify the input case
• Extremely fast, written in Rust ✨
• Support for Unicode characters
• Support for providing acronyms in title case

Supported cases

Function	Output
cases.to_camel(s)	camelCase
cases.to_pascal(s)	PascalCase
cases.to_snake(s)	snake_case
cases.to_screaming_snake(s)	SCREAMING_SNAKE_CASE
cases.to_kebab(s)	kebab-case
cases.to_screaming_kebab(s)	SCREAMING-KEBAB-CASE
cases.to_train(s)	Train-Case
cases.to_lower(s)	lower case
cases.to_title(s)	Title Case
cases.to_upper(s)	UPPER CASE

Getting started

Install using

pip install pycases

Now convert a string using the relevant function.

import cases

cases.to_snake("XMLHttpRequest") # returns "xml_http_request"

Details

Each of the provided functions using the same underlying implementation which does the following:

• Divide the input string into words
• Convert each word as required
• Join the words back together optionally with a separator

Word boundaries are defined as follows:

• A set of consecutive Unicode non-letter and non-number characters.

  For example: 'foo _bar' is two words (foo and bar)

• A transition from a lowercase letter to an uppercase letter.

  For example: fooBar is two words (foo and Bar)

• A transition from multiple uppercase letters to a single uppercase letter followed by lowercase letters.

  For example: FOOBar is two words (FOO and Bar)

Functions where the transform is "title" accept an optional acronyms argument, which is a mapping of lowercase words to their output. For example:

>>> cases.to_pascal("xml_http_request", acronyms={"xml": "XML"})
'XMLHttpRequest'
>>> cases.to_pascal("xml_http_request", acronyms={"xml": "XML", "http": "HTTP"})
'XMLHTTPRequest'

Benchmarks

A simple benchmark against various other libraries is provided in ./benches. The following table shows the results when run on my Macbook M2 Max.

Library	Min (µs)	Max (µs)	Mean (µs)
cases	26.666	176.834	30.909
pyheck	51.000	131.416	53.565
pure python	63.583	108.125	65.075
re	81.916	171.000	87.856
stringcase	99.250	222.292	102.197
pydantic.alias_generators	182.000	304.458	189.063
inflection	229.750	360.792	239.153
caseconversion	1,430.042	1,838.375	1,559.019

License

This project is licensed under the terms of the MIT license. See LICENSE for more details.