//! Checked strings containing Unicode identifiers according to the
//! [Unicode Standard Annex #31](
https://www.unicode.org/reports/tr31/).
//!
//! # Examples
//!
//! ```rust
//! use strck_ident::{IntoCk, unicode::UnicodeIdent};
//!
//! assert!("foo".ck::<UnicodeIdent>().is_ok());
//! assert!("struct".ck::<UnicodeIdent>().is_ok());
//! assert!("Москва".ck::<UnicodeIdent>().is_ok());
//! assert!("東京".ck::<UnicodeIdent>().is_ok());
//!
//! assert!("_identifier".ck::<UnicodeIdent>().is_err());
//! assert!("r#try".ck::<UnicodeIdent>().is_err());
//! assert!("��".ck::<UnicodeIdent>().is_err());
//! ```
//!
//! # Aliases
//!
//! This module exposes [`Ident`] and [`IdentBuf`], which alias `Ck<UnicodeIdent>`
//! and `Check<UnicodeIdent>` respectively. These aliases are preferred to keep
//! type signatures succinct.
//!
//! These are also exported under the root, and can be accessed as
//! `strck_ident::Ident` and `strck_ident::IdentBuf`.
use core::fmt;
use strck::{Check, Ck, Invariant};
/// An [`Invariant`] for unicode identifiers according to
/// [Unicode Standard Annex #31](
https://www.unicode.org/reports/tr31/).
///
/// # Invariants
///
/// * The string is nonempty.
/// * The first character is XID_Start.
/// * Any following characters are XID_Continue.
#[derive(Clone, Debug)]
pub struct UnicodeIdent;
/// Borrowed checked string containing a Unicode identifier.
///
/// See [`UnicodeIdent`] for more details.
pub type Ident = Ck<UnicodeIdent>;
/// Owned checked string containing a Unicode identifier.
///
/// See [`UnicodeIdent`] for more details.
pub type IdentBuf<B = String> = Check<UnicodeIdent, B>;
/// The error type returned from checking invariants of [`UnicodeIdent`].
#[derive(Debug, Copy, Clone, Hash, PartialEq, Eq, PartialOrd, Ord)]
pub enum Error {
/// Empty string.
Empty,
/// The first character isn't XID_Start.
Start(char),
/// A trailing character isn't XID_Continue.
Continue(char),
}
impl std::error::Error for Error {}
impl fmt::Display for Error {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
match self {
Error::Empty => f.pad("empty"),
Error::Start(ch) => write!(f, "invalid start '{ch}'"),
Error::Continue(ch) => write!(f, "invalid continue '{ch}'"),
}
}
}
impl Invariant for UnicodeIdent {
type Error = Error;
fn check(slice: &str) -> Result<(), Self::Error> {
let mut chars = slice.chars();
let start = chars.next().ok_or(Error::Empty)?;
if !unicode_ident::is_xid_start(start) {
return Err(Error::Start(start));
}
for ch in chars {
if !unicode_ident::is_xid_continue(ch) {
return Err(Error::Continue(ch));
}
}
Ok(())
}
}
#[cfg(test)]
mod tests {
use super::{Error, UnicodeIdent};
use strck::IntoCk;
#[test]
fn test_invalid() {
assert_eq!("".ck::<UnicodeIdent>().unwrap_err(), Error::Empty);
assert_eq!("12345".ck::<UnicodeIdent>().unwrap_err(), Error::Start('1'));
assert_eq!(
"��_foo".ck::<UnicodeIdent>().unwrap_err(),
Error::Start('��')
);
assert_eq!(
"foo_��".ck::<UnicodeIdent>().unwrap_err(),
Error::Continue('��')
);
assert_eq!(
"hello.there".ck::<UnicodeIdent>().unwrap_err(),
Error::Continue('.')
);
assert_eq!(
"\\as2mkf".ck::<UnicodeIdent>().unwrap_err(),
Error::Start('\\')
);
assert_eq!(
"the book".ck::<UnicodeIdent>().unwrap_err(),
Error::Continue(' ')
);
assert_eq!(" book".ck::<UnicodeIdent>().unwrap_err(), Error::Start(' '));
assert_eq!("\n".ck::<UnicodeIdent>().unwrap_err(), Error::Start('\n'));
assert_eq!(
"_underscore".ck::<UnicodeIdent>().unwrap_err(),
Error::Start('_')
);
assert_eq!(
"r#try".ck::<UnicodeIdent>().unwrap_err(),
Error::Continue('#')
);
}
#[test]
fn test_valid() {
assert!("a2345".ck::<UnicodeIdent>().is_ok());
assert!("foo".ck::<UnicodeIdent>().is_ok());
assert!("snake_case".ck::<UnicodeIdent>().is_ok());
assert!("impl".ck::<UnicodeIdent>().is_ok());
assert!("岡林".ck::<UnicodeIdent>().is_ok());
}
}
