1use alloc::{
2 borrow::ToOwned,
3 fmt,
4 string::{String, ToString},
5};
6
7use crate::{lowercase, transform};
8
9/// This trait defines a snake case conversion.
10///
11/// In snake_case, word boundaries are indicated by underscores.
12///
13/// ## Example:
14///
15/// ```rust
16/// use heck::ToSnakeCase;
17///
18/// let sentence = "We carry a new world here, in our hearts.";
19/// assert_eq!(sentence.to_snake_case(), "we_carry_a_new_world_here_in_our_hearts");
20/// ```
21pub trait ToSnakeCase: ToOwned {
22 /// Convert this type to snake case.
23 fn to_snake_case(&self) -> Self::Owned;
24}
25
26/// Oh heck, `SnekCase` is an alias for [`ToSnakeCase`]. See ToSnakeCase for
27/// more documentation.
28pub trait ToSnekCase: ToOwned {
29 /// Convert this type to snek case.
30 fn to_snek_case(&self) -> Self::Owned;
31}
32
33impl<T: ?Sized + ToSnakeCase> ToSnekCase for T {
34 fn to_snek_case(&self) -> Self::Owned {
35 self.to_snake_case()
36 }
37}
38
39impl ToSnakeCase for str {
40 fn to_snake_case(&self) -> String {
41 AsSnakeCase(self).to_string()
42 }
43}
44
45/// This wrapper performs a snake case conversion in [`fmt::Display`].
46///
47/// ## Example:
48///
49/// ```
50/// use heck::AsSnakeCase;
51///
52/// let sentence = "We carry a new world here, in our hearts.";
53/// assert_eq!(format!("{}", AsSnakeCase(sentence)), "we_carry_a_new_world_here_in_our_hearts");
54/// ```
55pub struct AsSnakeCase<T: AsRef<str>>(pub T);
56
57impl<T: AsRef<str>> fmt::Display for AsSnakeCase<T> {
58 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
59 transform(self.0.as_ref(), with_word:lowercase, |f: &mut Formatter<'_>| write!(f, "_"), f)
60 }
61}
62
63#[cfg(test)]
64mod tests {
65 use super::ToSnakeCase;
66
67 macro_rules! t {
68 ($t:ident : $s1:expr => $s2:expr) => {
69 #[test]
70 fn $t() {
71 assert_eq!($s1.to_snake_case(), $s2)
72 }
73 };
74 }
75
76 t!(test1: "CamelCase" => "camel_case");
77 t!(test2: "This is Human case." => "this_is_human_case");
78 t!(test3: "MixedUP CamelCase, with some Spaces" => "mixed_up_camel_case_with_some_spaces");
79 t!(test4: "mixed_up_ snake_case with some _spaces" => "mixed_up_snake_case_with_some_spaces");
80 t!(test5: "kebab-case" => "kebab_case");
81 t!(test6: "SHOUTY_SNAKE_CASE" => "shouty_snake_case");
82 t!(test7: "snake_case" => "snake_case");
83 t!(test8: "this-contains_ ALLKinds OfWord_Boundaries" => "this_contains_all_kinds_of_word_boundaries");
84 t!(test9: "XΣXΣ baffle" => "xσxς_baffle");
85 t!(test10: "XMLHttpRequest" => "xml_http_request");
86 t!(test11: "FIELD_NAME11" => "field_name11");
87 t!(test12: "99BOTTLES" => "99bottles");
88 t!(test13: "FieldNamE11" => "field_nam_e11");
89 t!(test14: "abc123def456" => "abc123def456");
90 t!(test16: "abc123DEF456" => "abc123_def456");
91 t!(test17: "abc123Def456" => "abc123_def456");
92 t!(test18: "abc123DEf456" => "abc123_d_ef456");
93 t!(test19: "ABC123def456" => "abc123def456");
94 t!(test20: "ABC123DEF456" => "abc123def456");
95 t!(test21: "ABC123Def456" => "abc123_def456");
96 t!(test22: "ABC123DEf456" => "abc123d_ef456");
97 t!(test23: "ABC123dEEf456FOO" => "abc123d_e_ef456_foo");
98 t!(test24: "abcDEF" => "abc_def");
99 t!(test25: "ABcDE" => "a_bc_de");
100}
101

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