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|
use proc_macro2::{Ident, Span};
use std::fmt;
/// Specialized formatting trait used by `format_ident!`.
///
/// [`Ident`] arguments formatted using this trait will have their `r#` prefix
/// stripped, if present.
///
/// See [`format_ident!`] for more information.
pub trait IdentFragment {
/// Format this value as an identifier fragment.
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result;
/// Span associated with this `IdentFragment`.
///
/// If non-`None`, may be inherited by formatted identifiers.
fn span(&self) -> Option<Span> {
None
}
}
impl<'a, T: IdentFragment + ?Sized> IdentFragment for &'a T {
fn span(&self) -> Option<Span> {
<T as IdentFragment>::span(*self)
}
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
IdentFragment::fmt(*self, f)
}
}
impl<'a, T: IdentFragment + ?Sized> IdentFragment for &'a mut T {
fn span(&self) -> Option<Span> {
<T as IdentFragment>::span(*self)
}
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
IdentFragment::fmt(*self, f)
}
}
impl IdentFragment for Ident {
fn span(&self) -> Option<Span> {
Some(self.span())
}
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
let id = self.to_string();
if id.starts_with("r#") {
fmt::Display::fmt(&id[2..], f)
} else {
fmt::Display::fmt(&id[..], f)
}
}
}
// Limited set of types which this is implemented for, as we want to avoid types
// which will often include non-identifier characters in their `Display` impl.
macro_rules! ident_fragment_display {
($($T:ty),*) => {
$(
impl IdentFragment for $T {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
fmt::Display::fmt(self, f)
}
}
)*
}
}
ident_fragment_display!(bool, str, String);
ident_fragment_display!(u8, u16, u32, u64, u128, usize);
|
