use std::any::type_name;
use std::collections::hash_map::Entry;
use std::collections::HashMap;
use std::error::Error;
use std::fmt;
pub trait RegistryEntry {
fn get_name(&self) -> &str;
}
pub struct Registry<'l, E: RegistryEntry + fmt::Debug + 'static> {
by_name: HashMap<&'l str, &'l E>,
}
impl<'l, E: RegistryEntry + fmt::Debug + 'static> Default for Registry<'l, E> {
fn default() -> Self {
Self {
by_name: HashMap::new(),
}
}
}
impl<'l, E: RegistryEntry + fmt::Debug + 'static> Registry<'l, E> {
pub fn register(&mut self, val: &'l E) -> Result<&'l E, RegisterError<'l, E>> {
match self.by_name.entry(val.get_name()) {
Entry::Occupied(e) => Err(RegisterError(e.get())),
Entry::Vacant(e) => Ok(e.insert(val)),
}
}
#[must_use]
pub fn get(&self, name: &str) -> Option<&'l E> {
self.by_name.get(name).copied()
}
}
#[derive(Clone, Copy, Debug)]
pub struct RegisterError<'l, E: RegistryEntry + fmt::Debug + 'static>(pub &'l E);
impl<'l, E: RegistryEntry + fmt::Debug + 'static> fmt::Display for RegisterError<'l, E> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(
f,
"{} {:?} already exists",
type_name::<E>(),
self.0.get_name()
)
}
}
impl<'l, E: RegistryEntry + fmt::Debug + 'static> Error for RegisterError<'l, E> {}