Convert Case

Convert between string cases with built-in case inference.

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Installing

Install the package from pypi:

pip install convert-case

To experiment with the source code locally, clone the repository:

git clone https://github.com/joellefkowitz/convert-case

To install linters, formatters and test runners:

pip install .[all]
npm install

Usage

from convert_case import camel_case

camel_case('camel case') # Inferred: lower -> camel
'camelCase'

camel_case('Camel Case') # Inferred: title -> camel
'camelCase'

camel_case('CamelCase') # Inferred: pascal -> camel
'camelCase'

Exports

def pascal_case(string: str) -> str:
    ...
def is_pascal_case(string: str) -> bool:
    ...

def camel_case(string: str) -> str:
    ...
def is_camel_case(string: str) -> bool:
    ...

def kebab_case(string: str) -> str:
    ...
def is_kebab_case(string: str) -> bool:
    ...

def sentence_case(string: str) -> str:
    ...
def is_sentence_case(string: str) -> bool:
    ...

def snake_case(string: str) -> str:
    ...
def is_snake_case(string: str) -> bool:
    ...

def title_case(string: str) -> str:
    ...
def is_title_case(string: str) -> bool:
    ...

def upper_case(string: str) -> str:
    ...
def is_upper_case(string: str) -> bool:
    ...

Definitions

LOWER = re.compile(r"^[a-z0-9\s]*$")
UPPER = re.compile(r"^[A-Z0-9\s]*$")

TITLE = re.compile(r"^(([A-Z0-9][a-z0-9]*)(\s[A-Z0-9][a-z0-9]*)*)?$")
SENTENCE = re.compile(r"^(([A-Z0-9][a-z0-9]*)(\s[a-z0-9]*)*)?$")

CAMEL = re.compile(r"^([a-z0-9][a-zA-Z0-9]*)?$")
PASCAL = re.compile(r"^([A-Z0-9]|([A-Z0-9][a-z0-9]+)*)?$")

SNAKE = re.compile(r"^([a-z0-9]+(_[a-z0-9]+)*)?$")
KEBAB = re.compile(r"^([a-z0-9]+(-[a-z0-9]+)*)?$")

Tests

To run unit tests:

grunt test

Test cases

test	lower	upper	sentence	title	camel	snake	kebab	pascal
a	a	A	A	A	a	a	a	A
A	a	A	A	A	a	a	a	A
abc	abc	ABC	Abc	Abc	abc	abc	abc	Abc
ab cd	ab cd	AB CD	Ab cd	Ab Cd	abCd	ab_cd	ab-cd	AbCd
Ab cd	ab cd	AB CD	Ab cd	Ab Cd	abCd	ab_cd	ab-cd	AbCd
Ab Cd	ab cd	AB CD	Ab cd	Ab Cd	abCd	ab_cd	ab-cd	AbCd
ab_cd	ab cd	AB CD	Ab cd	Ab Cd	abCd	ab_cd	ab-cd	AbCd
ab-cd	ab cd	AB CD	Ab cd	Ab Cd	abCd	ab_cd	ab-cd	AbCd
abCd	ab cd	AB CD	Ab cd	Ab Cd	abCd	ab_cd	ab-cd	AbCd
ABCD	abcd	ABCD	Abcd	Abcd	abcd	abcd	abcd	Abcd
AbCd	ab cd	AB CD	Ab cd	Ab Cd	abCd	ab_cd	ab-cd	AbCd
ab cd ef	ab cd ef	AB CD EF	Ab cd ef	Ab Cd Ef	abCdEf	ab_cd_ef	ab-cd-ef	AbCdEf
AbCdEf	ab cd ef	AB CD EF	Ab cd ef	Ab Cd Ef	abCdEf	ab_cd_ef	ab-cd-ef	AbCdEf
ab-cd-ef	ab cd ef	AB CD EF	Ab cd ef	Ab Cd Ef	abCdEf	ab_cd_ef	ab-cd-ef	AbCdEf
Ab cd ef	ab cd ef	AB CD EF	Ab cd ef	Ab Cd Ef	abCdEf	ab_cd_ef	ab-cd-ef	AbCdEf

Numbers

Numbers are treated as letters with no specific case.

test	lower	upper	sentence	title	camel	snake	kebab	pascal
1	1	1	1	1	1	1	1	1
1bc	1bc	1BC	1bc	1bc	1bc	1bc	1bc	1bc
a1c	a1c	A1C	A1c	A1c	a1c	a1c	a1c	A1c
ab1	ab1	AB1	Ab1	Ab1	ab1	ab1	ab1	Ab1
a1 c	a1 c	A1 C	A1 c	A1 C	a1C	a1_c	a1-c	A1C
a1-c	a1 c	A1 C	A1 c	A1 C	a1C	a1_c	a1-c	A1C

Advanced

A goal of this converter is that it is deterministic. If we consider the following examples we can see that this is not simple to achieve. How should we interpret the string 'ABC', is it in upper case or pascal case?

test	upper	pascal
abc	ABC	Abc
a b c	A B C	ABC

Our options are:

• To consider strings with consecutive capitals like 'ABC' not to be pascal case. If in this case 'a b c' is parsed to 'Abc' it would clash with parsing 'abc' into pascal case.

• To store some state that remembers the string's case before parsing. This would introduce too much complexity.

• To prioritize parsing the string as one case unless told otherwise. We choose to pick upper case as the inferred case. The caveat here is that we will no longer be performing 'round trip' conversion.

Round trip conversion:

kebab_case('a b c')
'a-b-c'

lower_case('a-b-c')
'a b c'

Not round trip conversion:

pascal_case('a b c')
'ABC'

lower_case('ABC')
'abc'

Documentation

This repository's documentation is hosted on readthedocs.

Tooling

To run linters:

grunt lint

To run formatters:

grunt format

Continuous integration

This repository uses github actions to lint and test each commit. Formatting tasks and writing/generating documentation must be done before committing new code.

Versioning

This repository adheres to semantic versioning standards. For more information on semantic versioning visit SemVer.

Bump2version is used to version and tag changes. For example:

bump2version patch

Changelog

Please read this repository's changelog for details on changes that have been made.

Contributing

Please read this repository's guidelines on contributing for details on the process for submitting pull requests. Moreover, our code of conduct declares our collaboration standards.

Contributors

• joellefkowitz - Initial work - joellefkowitz

Remarks

Lots of love to the open source community!