1use std::fmt;
2
3use crate::{capitalize, lowercase, transform};
4
5/// This trait defines a lower camel case conversion.
6///
7/// In lowerCamelCase, word boundaries are indicated by capital letters,
8/// excepting the first word.
9///
10/// ## Example:
11///
12/// ```rust
13/// use heck::ToLowerCamelCase;
14///
15/// let sentence = "It is we who built these palaces and cities.";
16/// assert_eq!(sentence.to_lower_camel_case(), "itIsWeWhoBuiltThesePalacesAndCities");
17/// ```
18pub trait ToLowerCamelCase: ToOwned {
19 /// Convert this type to lower camel case.
20 fn to_lower_camel_case(&self) -> Self::Owned;
21}
22
23impl ToLowerCamelCase for str {
24 fn to_lower_camel_case(&self) -> String {
25 AsLowerCamelCase(self).to_string()
26 }
27}
28
29/// This wrapper performs a lower camel case conversion in [`fmt::Display`].
30///
31/// ## Example:
32///
33/// ```
34/// use heck::AsLowerCamelCase;
35///
36/// let sentence = "It is we who built these palaces and cities.";
37/// assert_eq!(format!("{}", AsLowerCamelCase(sentence)), "itIsWeWhoBuiltThesePalacesAndCities");
38/// ```
39pub struct AsLowerCamelCase<T: AsRef<str>>(pub T);
40
41impl<T: AsRef<str>> fmt::Display for AsLowerCamelCase<T> {
42 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
43 let mut first: bool = true;
44 transform(
45 self.0.as_ref(),
46 |s, f| {
47 if first {
48 first = false;
49 lowercase(s, f)
50 } else {
51 capitalize(s, f)
52 }
53 },
54 |_| Ok(()),
55 f,
56 )
57 }
58}
59
60#[cfg(test)]
61mod tests {
62 use super::ToLowerCamelCase;
63
64 macro_rules! t {
65 ($t:ident : $s1:expr => $s2:expr) => {
66 #[test]
67 fn $t() {
68 assert_eq!($s1.to_lower_camel_case(), $s2)
69 }
70 };
71 }
72
73 t!(test1: "CamelCase" => "camelCase");
74 t!(test2: "This is Human case." => "thisIsHumanCase");
75 t!(test3: "MixedUP CamelCase, with some Spaces" => "mixedUpCamelCaseWithSomeSpaces");
76 t!(test4: "mixed_up_ snake_case, with some _spaces" => "mixedUpSnakeCaseWithSomeSpaces");
77 t!(test5: "kebab-case" => "kebabCase");
78 t!(test6: "SHOUTY_SNAKE_CASE" => "shoutySnakeCase");
79 t!(test7: "snake_case" => "snakeCase");
80 t!(test8: "this-contains_ ALLKinds OfWord_Boundaries" => "thisContainsAllKindsOfWordBoundaries");
81 #[cfg(feature = "unicode")]
82 t!(test9: "XΣXΣ baffle" => "xσxςBaffle");
83 t!(test10: "XMLHttpRequest" => "xmlHttpRequest");
84 // TODO unicode tests
85}
86