//! Various [`String`] and [`str`] extensions
use std::borrow::Cow;
/// The trait responsible for adding methods to [`str`].
pub trait StrExtensions {
/// Works like [`str::to_ascii_lowercase`], but returns a [`Cow::Borrowed`] when the original
/// already is ASCII and lowercase.
fn to_ascii_lowercase_cow(&self) -> Cow<'_, str>;
/// Returns whether or not this [`str`] is already ASCII lowercase.
fn is_ascii_lowercase(&self) -> bool;
}
impl StrExtensions for str {
fn to_ascii_lowercase_cow(&self) -> Cow<'_, str> {
if self.is_ascii_lowercase() {
Cow::Borrowed(self)
} else {
Cow::Owned(self.to_ascii_lowercase())
}
}
fn is_ascii_lowercase(&self) -> bool {
let bytes = self.as_bytes();
bytes.is_ascii()
&& bytes
.iter()
.all(|b| !b.is_ascii_alphabetic() || b.is_ascii_lowercase())
}
}