# **heck** is a case conversion library
!["I specifically requested the opposite of this."](https://github.com/withoutboats/heck/blob/master/no_step_on_snek.png)
This library exists to provide case conversion between common cases like
CamelCase and snake_case. It is intended to be unicode aware, internally
consistent, and reasonably well performing.
## Definition of a word boundary
Word boundaries are defined as the "unicode words" defined in the
`unicode_segmentation` library, as well as within those words in this manner:
1. All underscore characters are considered word boundaries.
2. If an uppercase character is followed by lowercase letters, a word boundary
is considered to be just prior to that uppercase character.
3. If multiple uppercase characters are consecutive, they are considered to be
within a single word, except that the last will be part of the next word if it
is followed by lowercase characters (see rule 2).
That is, "HelloWorld" is segmented `Hello|World` whereas "XMLHttpRequest" is
Characters not within words (such as spaces, punctuations, and underscores)
are not included in the output string except as they are a part of the case
being converted to. Multiple adjacent word boundaries (such as a series of
underscores) are folded into one. ("hello__world" in snake case is therefore
"hello_world", not the exact same string). Leading or trailing word boundary
indicators are dropped, except insofar as CamelCase capitalizes the first word.
### Cases contained in this library:
6. Title Case
PRs of additional well-established cases welcome.
This library is a little bit opinionated (dropping punctuation, for example).
If that doesn't fit your use case, I hope there is another crate that does. I
would prefer **not** to receive PRs to make this behavior more configurable.
Bug reports & fixes always welcome. :-)
heck is distributed under the terms of both the MIT license and the
Apache License (Version 2.0).
See LICENSE-APACHE and LICENSE-MIT for details.