1use std::fmt;
2
3use crate::{lowercase, transform};
4
5/// This trait defines a snake case conversion.
6///
7/// In snake_case, word boundaries are indicated by underscores.
8///
9/// ## Example:
10///
11/// ```rust
12/// use heck::ToSnakeCase;
13///
14/// let sentence = "We carry a new world here, in our hearts.";
15/// assert_eq!(sentence.to_snake_case(), "we_carry_a_new_world_here_in_our_hearts");
16/// ```
17pub trait ToSnakeCase: ToOwned {
18 /// Convert this type to snake case.
19 fn to_snake_case(&self) -> Self::Owned;
20}
21
22/// Oh heck, SnekCase is an alias for ToSnakeCase. See ToSnakeCase for
23/// more documentation.
24pub trait ToSnekCase: ToOwned {
25 /// Convert this type to snek case.
26 fn to_snek_case(&self) -> Self::Owned;
27}
28
29impl<T: ?Sized + ToSnakeCase> ToSnekCase for T {
30 fn to_snek_case(&self) -> Self::Owned {
31 self.to_snake_case()
32 }
33}
34
35impl ToSnakeCase for str {
36 fn to_snake_case(&self) -> String {
37 AsSnakeCase(self).to_string()
38 }
39}
40
41/// This wrapper performs a snake case conversion in [`fmt::Display`].
42///
43/// ## Example:
44///
45/// ```
46/// use heck::AsSnakeCase;
47///
48/// let sentence = "We carry a new world here, in our hearts.";
49/// assert_eq!(format!("{}", AsSnakeCase(sentence)), "we_carry_a_new_world_here_in_our_hearts");
50/// ```
51pub struct AsSnakeCase<T: AsRef<str>>(pub T);
52
53impl<T: AsRef<str>> fmt::Display for AsSnakeCase<T> {
54 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
55 transform(self.0.as_ref(), with_word:lowercase, |f: &mut Formatter<'_>| write!(f, "_"), f)
56 }
57}
58
59#[cfg(test)]
60mod tests {
61 use super::ToSnakeCase;
62
63 macro_rules! t {
64 ($t:ident : $s1:expr => $s2:expr) => {
65 #[test]
66 fn $t() {
67 assert_eq!($s1.to_snake_case(), $s2)
68 }
69 };
70 }
71
72 t!(test1: "CamelCase" => "camel_case");
73 t!(test2: "This is Human case." => "this_is_human_case");
74 t!(test3: "MixedUP CamelCase, with some Spaces" => "mixed_up_camel_case_with_some_spaces");
75 t!(test4: "mixed_up_ snake_case with some _spaces" => "mixed_up_snake_case_with_some_spaces");
76 t!(test5: "kebab-case" => "kebab_case");
77 t!(test6: "SHOUTY_SNAKE_CASE" => "shouty_snake_case");
78 t!(test7: "snake_case" => "snake_case");
79 t!(test8: "this-contains_ ALLKinds OfWord_Boundaries" => "this_contains_all_kinds_of_word_boundaries");
80 #[cfg(feature = "unicode")]
81 t!(test9: "XΣXΣ baffle" => "xσxς_baffle");
82 t!(test10: "XMLHttpRequest" => "xml_http_request");
83 t!(test11: "FIELD_NAME11" => "field_name11");
84 t!(test12: "99BOTTLES" => "99bottles");
85 t!(test13: "FieldNamE11" => "field_nam_e11");
86
87 t!(test14: "abc123def456" => "abc123def456");
88 t!(test16: "abc123DEF456" => "abc123_def456");
89 t!(test17: "abc123Def456" => "abc123_def456");
90 t!(test18: "abc123DEf456" => "abc123_d_ef456");
91 t!(test19: "ABC123def456" => "abc123def456");
92 t!(test20: "ABC123DEF456" => "abc123def456");
93 t!(test21: "ABC123Def456" => "abc123_def456");
94 t!(test22: "ABC123DEf456" => "abc123d_ef456");
95 t!(test23: "ABC123dEEf456FOO" => "abc123d_e_ef456_foo");
96 t!(test24: "abcDEF" => "abc_def");
97 t!(test25: "ABcDE" => "a_bc_de");
98}
99