1 use std::fmt; 2 3 use 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 /// ``` 17 pub trait ToSnakeCase: ToOwned { 18 /// Convert this type to snake case. to_snake_case(&self) -> Self::Owned19 fn to_snake_case(&self) -> Self::Owned; 20 } 21 22 /// Oh heck, SnekCase is an alias for ToSnakeCase. See ToSnakeCase for 23 /// more documentation. 24 pub trait ToSnekCase: ToOwned { 25 /// Convert this type to snek case. to_snek_case(&self) -> Self::Owned26 fn to_snek_case(&self) -> Self::Owned; 27 } 28 29 impl<T: ?Sized + ToSnakeCase> ToSnekCase for T { to_snek_case(&self) -> Self::Owned30 fn to_snek_case(&self) -> Self::Owned { 31 self.to_snake_case() 32 } 33 } 34 35 impl ToSnakeCase for str { to_snake_case(&self) -> String36 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 /// ``` 51 pub struct AsSnakeCase<T: AsRef<str>>(pub T); 52 53 impl<T: AsRef<str>> fmt::Display for AsSnakeCase<T> { fmt(&self, f: &mut fmt::Formatter) -> fmt::Result54 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)] 60 mod 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