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use crate::common::{ConstructRawHandled, ConvertCasing, IsRaw, LIFETIME_TICK_PREFIX};
use convert_case::Case;
use syn::Ident;
#[cfg(feature = "syn")]
use syn::Lifetime;
/// Types convertible to the letter casing corresponding to names of
/// [lifetimes](https://doc.rust-lang.org/rust-by-example/scope/lifetime.html).
pub trait ToLifetimeName {
/// The resulting type, coming out of the conversion.
type Output;
/// Converts self to the letter casing of
/// [lifetime](https://doc.rust-lang.org/rust-by-example/scope/lifetime.html) names
/// (`'snake_case`). Adheres to the
/// [general conversion rules](crate#general-rules-for-conversions).
///
/// # Examples
///
/// Usage with [`syn::Ident`]:
///
/// ```
/// # use caseidae::ToLifetimeName;
/// # use syn::Ident;
/// # use proc_macro2::Span;
/// let enum_name = Ident::new("HeroAbility", Span::call_site());
/// let lifetime = enum_name.to_lifetime_name();
/// assert_eq!(lifetime.to_string(), "'hero_ability");
/// ```
///
/// Note that the output of the conversion (here the `lifetime` variable) is of type
/// [`syn::Lifetime`].
///
/// Usage with strings:
///
/// ```
/// # use caseidae::ToLifetimeName;
/// assert_eq!("PIZZA_DIAMETER".to_lifetime_name(), "'pizza_diameter");
/// assert_eq!(String::from("AlexAndDerMurder").to_lifetime_name(), "'alex_and_der_murder");
/// assert_eq!(String::from("'already_a_lifetime").to_lifetime_name(), "'already_a_lifetime");
/// ```
///
/// # Panics
///
/// Whether this method panics depends on the implementator, see their documentation for that.
/// However, implementations from this crate never panic.
///
/// # Warning
///
/// The implementation on [`syn::Ident`] currently comes with a small caveat, see the
/// [documentation there](trait.ToLifetimeName.html#warning-1).
fn to_lifetime_name(&self) -> Self::Output;
}
impl ToLifetimeName for str {
type Output = <Self as ToOwned>::Owned;
fn to_lifetime_name(&self) -> Self::Output {
format!("{LIFETIME_TICK_PREFIX}{}", self.convert_casing(Case::Snake))
}
}
#[cfg(feature = "syn")]
impl ToLifetimeName for Ident {
type Output = Lifetime;
/// See the [trait method documentation](ToLifetimeName::to_lifetime_name).
///
/// The resulting [`Lifetime`] has the same span as self.
///
/// # Warning
///
/// May return a [`Lifetime`] which has an [`Ident`] that would not actually be accepted as
/// valid by [`Lifetime::new`]. This happens when the input [`Ident`] is
/// [raw](https://doc.rust-lang.org/rust-by-example/compatibility/raw_identifiers.html). `syn`
/// currently doesn't support creating [raw
/// lifetimes](https://doc.rust-lang.org/edition-guide/rust-2021/raw-lifetimes.html) through
/// [`Lifetime::new`], so the [`Lifetime`] is constructed with a stripped [`Ident`] at first and
/// then the `r#` prefix is artificially prepended, so that the original rawness is preserved.
/// This warning will hopefully be removed in the future, when the feature gets implemented in
/// `syn`. See the [related issue](https://codeberg.org/matous-volf/caseidae/issues/2).
fn to_lifetime_name(&self) -> Self::Output {
let lifetime_name = self.to_string().to_lifetime_name();
let is_raw = lifetime_name.is_raw_lifetime();
let lifetime_name_unrawed = if is_raw {
format!("{LIFETIME_TICK_PREFIX}{}", &lifetime_name[3..])
} else {
lifetime_name.clone()
};
let lifetime = Lifetime::new(lifetime_name_unrawed.as_str(), self.span());
if is_raw {
// See the warning in the docs.
Lifetime {
ident: Self::new_raw_handled(&lifetime_name[1..], self.span()),
..lifetime
}
} else {
lifetime
}
}
}