77 lines
1.8 KiB
Rust
77 lines
1.8 KiB
Rust
use std::{sync::{OnceLock, Arc, Mutex}, collections::HashMap};
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#[derive(Default)]
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struct SymbolTable {
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names: Vec<Arc<str>>,
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values: HashMap<Arc<str>, Symbol>
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}
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static SYM_TABLE: OnceLock<Mutex<SymbolTable>> = OnceLock::new();
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const MAX_SYMBOL: usize = 0xff_ffff;
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#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Debug, Hash)]
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pub struct Symbol(u32);
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fn get_table() -> &'static Mutex<SymbolTable> {
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SYM_TABLE.get_or_init(|| Mutex::new(SymbolTable::default()))
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}
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impl Symbol {
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/// # Panics
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/// If the mutex storing the symbol table is poisoned
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pub fn try_get(name: &str) -> Option<Self> {
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let table = get_table().lock().expect("couldn't lock symbol table");
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table.values.get(name).copied()
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}
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/// # Panics
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/// If the mutex storing the symbol table is poisoned
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pub fn get(name: &str) -> Self {
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let mut table = get_table().lock().expect("couldn't lock symbol table");
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if let Some(sym) = table.values.get(name) {
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return *sym
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}
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let symno = table.names.len();
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assert!(symno <= MAX_SYMBOL, "too many symbols");
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let sym = Symbol(symno as u32);
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let name: Arc<str> = name.into();
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table.names.push(name.clone());
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table.values.insert(name, sym);
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sym
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}
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/// # Panics
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/// If the mutex storing the symbol table is poisoned
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pub fn from_id(id: u32) -> Option<Self> {
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let table = get_table().lock().expect("couldn't lock symbol table");
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if id as usize <= table.names.len() {
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Some(Self(id))
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} else {
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None
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}
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}
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/// # Safety
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/// Safe if argument is a valid symbol ID
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pub unsafe fn from_id_unchecked(id: u32) -> Self {
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Self(id)
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}
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pub fn id(self) -> u32 {
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self.0
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}
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/// # Panics
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/// If the mutex storing the symbol table is poisoned
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pub fn name(self) -> Arc<str> {
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let table = get_table().lock().expect("couldn't lock symbol table");
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table.names.get(self.0 as usize).cloned().expect("symbol does not exist")
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}
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}
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