xref: /third_party/rust/crates/heck/src/snake.rs (revision 6fccd0a4) 
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(), lowercase, |f| 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