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//! Converts to and from various cases.
//!
//! # Command Line Utility `ccase`
//!
//! Since version "0.3.0" this crate is just a case conversion _library_. The command line utility
//! that uses the tools in this library has been moved to the `ccase` crate. You can read about it
//! at the [github repository](https://github.com/rutrum/convert-case/tree/master/ccase).
//!
//! # Rust Library
//!
//! Provides a [`Case`](enum.Case.html) enum which defines a variety of cases to convert into.
//! A `Case` can be used with an item that implements the [`Casing`](trait.Casing.html) trait,
//! which allows the item to be converted to a given case.
//!
//! You can convert a string or string slice into a case using the `to_case` method.
//! ```
//! use convert_case::{Case, Casing};
//!
//! assert_eq!("Ronnie James Dio", "ronnie james dio".to_case(Case::Title));
//! assert_eq!("ronnieJamesDio", "Ronnie_James_dio".to_case(Case::Camel));
//! assert_eq!("Ronnie-James-Dio", "RONNIE_JAMES_DIO".to_case(Case::Train));
//! ```
//!
//! By default, `to_case` will split along all word boundaries, that is
//! * space characters ` `,
//! * underscores `_`,
//! * hyphens `-`,
//! * and changes in capitalization `aA`.
//!
//! For more accuracy, the `from_case` method splits based on the word boundaries
//! of a particular case. For example, splitting from snake case will only treat
//! underscores as word boundaries.
//! ```
//! use convert_case::{Case, Casing};
//!
//! assert_eq!(
//! "2020 04 16 My Cat Cali",
//! "2020-04-16_my_cat_cali".to_case(Case::Title)
//! );
//! assert_eq!(
//! "2020-04-16 My Cat Cali",
//! "2020-04-16_my_cat_cali".from_case(Case::Snake).to_case(Case::Title)
//! );
//! ```
//!
//! By default (and when converting from camel case or similar cases) `convert_case`
//! will detect acronyms. It also ignores any leading, trailing, or deplicate delimeters.
//! ```
//! use convert_case::{Case, Casing};
//!
//! assert_eq!("io_stream", "IOStream".to_case(Case::Snake));
//! assert_eq!("my_json_parser", "myJSONParser".to_case(Case::Snake));
//!
//! assert_eq!("weird_var_name", "__weird--var _name-".to_case(Case::Snake));
//! ```
//!
//! It also works non-ascii characters. However, no inferences on the language itself is made.
//! For instance, the diagraph `ij` in dutch will not be capitalized, because it is represented
//! as two distinct unicode characters. However, `æ` would be capitalized.
//! ```
//! use convert_case::{Case, Casing};
//!
//! assert_eq!("granat-äpfel", "GranatÄpfel".to_case(Case::Kebab));
//!
//! // The example from str::to_lowercase documentation
//! let odysseus = "ὈΔΥΣΣΕΎΣ";
//! assert_eq!("ὀδυσσεύς", odysseus.to_case(Case::Lower));
//! ```
//!
//! For the purposes of case conversion, characters followed by numerics and vice-versa are
//! considered word boundaries. In addition, any special ascii characters (besides `_` and `-`)
//! are ignored.
//! ```
//! use convert_case::{Case, Casing};
//!
//! assert_eq!("e_5150", "E5150".to_case(Case::Snake));
//! assert_eq!("10,000_days", "10,000Days".to_case(Case::Snake));
//! assert_eq!("HELLO, WORLD!", "Hello, world!".to_case(Case::Upper));
//! assert_eq!("One\ntwo\nthree", "ONE\nTWO\nTHREE".to_case(Case::Title));
//! ```
//!
//! # Note on Accuracy
//!
//! The `Casing` methods `from_case` and `to_case` do not fail. Conversion to a case will always
//! succeed. However, the results can still be unexpected. Failure to detect any word boundaries
//! for a particular case means the entire string will be considered a single word.
//! ```
//! use convert_case::{Case, Casing};
//!
//! // Mistakenly parsing using Case::Snake
//! assert_eq!("My-kebab-var", "my-kebab-var".from_case(Case::Snake).to_case(Case::Title));
//!
//! // Converts using an unexpected method
//! assert_eq!("my_kebab_like_variable", "myKebab-like-variable".to_case(Case::Snake));
//! ```
//!
//! # Random Feature
//!
//! To ensure this library had zero dependencies, randomness was moved to the _random_ feature,
//! which requires the `rand` crate. You can enable this feature by including the
//! following in your `Cargo.toml`.
//! ```{toml}
//! [dependencies]
//! convert_case = { version = "^0.3, features = ["random"] }
//! ```
//! This will add two additional cases: Random and PseudoRandom. You can read about their
//! construction in the [Case enum](enum.Case.html).
mod case;
mod words;
pub use case::Case;
use words::Words;
/// Describes items that can be converted into a case.
///
/// Implemented for string slices `&str` and owned strings `String`.
pub trait Casing {
/// References `self` and converts to the given case.
fn to_case(&self, case: Case) -> String;
/// Creates a `FromCasing` struct, which saves information about
/// how to parse `self` before converting to a case.
fn from_case(&self, case: Case) -> FromCasing;
}
impl Casing for str {
fn to_case(&self, case: Case) -> String {
Words::new(self).into_case(case)
}
fn from_case(&self, case: Case) -> FromCasing {
FromCasing::new(self.to_string(), case)
}
}
impl Casing for String {
fn to_case(&self, case: Case) -> String {
Words::new(self).into_case(case)
}
fn from_case(&self, case: Case) -> FromCasing {
FromCasing::new(self.to_string(), case)
}
}
/// Holds information about parsing before converting into a case.
///
/// This struct is used when invoking the `from_case` method on
/// `Casing`. `FromCasing` also implements `Casing`.
/// ```
/// use convert_case::{Case, Casing};
///
/// let title = "ninety-nine_problems".from_case(Case::Snake).to_case(Case::Title);
/// assert_eq!("Ninety-nine Problems", title);
/// ```
pub struct FromCasing {
name: String,
case: Case,
}
impl FromCasing {
const fn new(name: String, case: Case) -> Self {
Self { name, case }
}
}
impl Casing for FromCasing {
fn to_case(&self, case: Case) -> String {
Words::from_casing(&self.name, self.case).into_case(case)
}
fn from_case(&self, case: Case) -> Self {
Self::new(self.name.to_string(), case)
}
}
#[cfg(test)]
mod test {
use super::*;
use strum::IntoEnumIterator;
#[test]
fn lossless_against_lossless() {
let examples = vec![
(Case::Lower, "my variable 22 name"),
(Case::Upper, "MY VARIABLE 22 NAME"),
(Case::Title, "My Variable 22 Name"),
(Case::Camel, "myVariable22Name"),
(Case::Pascal, "MyVariable22Name"),
(Case::Snake, "my_variable_22_name"),
(Case::ScreamingSnake, "MY_VARIABLE_22_NAME"),
(Case::Kebab, "my-variable-22-name"),
(Case::Cobol, "MY-VARIABLE-22-NAME"),
(Case::Toggle, "mY vARIABLE 22 nAME"),
(Case::Train, "My-Variable-22-Name"),
(Case::Alternating, "mY vArIaBlE 22 nAmE"),
];
for (case_a, str_a) in examples.iter() {
for (case_b, str_b) in examples.iter() {
assert_eq!(*str_a, str_b.from_case(*case_b).to_case(*case_a))
}
}
}
#[test]
fn obvious_default_parsing() {
let examples = vec![
"SuperMario64Game",
"super-mario64-game",
"superMario64 game",
"Super Mario 64_game",
"SUPERMario 64-game",
"super_mario-64 game",
];
for example in examples {
assert_eq!("super_mario_64_game", example.to_case(Case::Snake));
}
}
#[test]
fn multiline_strings() {
assert_eq!(
"One\ntwo\nthree",
"one\ntwo\nthree".to_case(Case::Title)
);
}
#[test]
fn camel_case_acroynms() {
assert_eq!(
"xml_http_request",
"XMLHttpRequest".from_case(Case::Camel).to_case(Case::Snake)
);
assert_eq!(
"xml_http_request",
"XMLHttpRequest"
.from_case(Case::UpperCamel)
.to_case(Case::Snake)
);
assert_eq!(
"xml_http_request",
"XMLHttpRequest"
.from_case(Case::Pascal)
.to_case(Case::Snake)
);
}
#[test]
fn leading_tailing_delimeters() {
assert_eq!(
"leading_underscore",
"_leading_underscore"
.from_case(Case::Snake)
.to_case(Case::Snake)
);
assert_eq!(
"tailing_underscore",
"tailing_underscore_"
.from_case(Case::Snake)
.to_case(Case::Snake)
);
assert_eq!(
"leading_hyphen",
"-leading-hyphen"
.from_case(Case::Kebab)
.to_case(Case::Snake)
);
assert_eq!(
"tailing_hyphen",
"tailing-hyphen-"
.from_case(Case::Kebab)
.to_case(Case::Snake)
);
}
#[test]
fn double_delimeters() {
assert_eq!(
"many_underscores",
"many___underscores"
.from_case(Case::Snake)
.to_case(Case::Snake)
);
assert_eq!(
"many-underscores",
"many---underscores"
.from_case(Case::Kebab)
.to_case(Case::Kebab)
);
}
#[test]
fn early_word_boundaries() {
assert_eq!(
"a_bagel",
"aBagel".from_case(Case::Camel).to_case(Case::Snake)
);
}
#[test]
fn late_word_boundaries() {
assert_eq!(
"team_a",
"teamA".from_case(Case::Camel).to_case(Case::Snake)
);
}
#[test]
fn empty_string() {
for (case_a, case_b) in Case::iter().zip(Case::iter()) {
assert_eq!("", "".from_case(case_a).to_case(case_b));
}
}
#[test]
fn owned_string() {
assert_eq!(
"test_variable",
String::from("TestVariable").to_case(Case::Snake)
)
}
#[test]
fn default_all_boundaries() {
assert_eq!(
"abc_abc_abc_abc_abc_abc",
"ABC-abc_abcAbc ABCAbc".to_case(Case::Snake)
);
}
#[test]
fn alternating_ignore_symbols() {
assert_eq!("tHaT's", "that's".to_case(Case::Alternating));
}
}