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//! Symbol interner for proc-macro-srv
use std::{cell::RefCell, collections::HashMap};
use tt::SmolStr;
thread_local! {
static SYMBOL_INTERNER: RefCell<SymbolInterner> = Default::default();
}
// ID for an interned symbol.
#[derive(Hash, Eq, PartialEq, Copy, Clone)]
pub struct Symbol(u32);
impl Symbol {
pub fn intern(data: &str) -> Symbol {
SYMBOL_INTERNER.with(|i| i.borrow_mut().intern(data))
}
pub fn text(&self) -> SmolStr {
SYMBOL_INTERNER.with(|i| i.borrow().get(self).clone())
}
}
#[derive(Default)]
struct SymbolInterner {
idents: HashMap<SmolStr, u32>,
ident_data: Vec<SmolStr>,
}
impl SymbolInterner {
fn intern(&mut self, data: &str) -> Symbol {
if let Some(index) = self.idents.get(data) {
return Symbol(*index);
}
let index = self.idents.len() as u32;
let data = SmolStr::from(data);
self.ident_data.push(data.clone());
self.idents.insert(data, index);
Symbol(index)
}
fn get(&self, sym: &Symbol) -> &SmolStr {
&self.ident_data[sym.0 as usize]
}
}
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