Files
wasmtime/crates/wasi-c2/src/table.rs
2020-12-01 18:26:45 -08:00

60 lines
1.6 KiB
Rust

use crate::Error;
use std::any::Any;
use std::cell::{RefCell, RefMut};
use std::collections::HashMap;
pub struct Table {
map: HashMap<u32, RefCell<Box<dyn Any>>>,
next_key: u32,
}
impl Table {
pub fn new() -> Self {
Table {
map: HashMap::new(),
next_key: 0,
}
}
pub fn insert_at(&mut self, key: u32, a: impl Any + Sized) {
self.map.insert(key, RefCell::new(Box::new(a)));
}
pub fn push(&mut self, a: impl Any + Sized) -> u32 {
loop {
let key = self.next_key;
self.next_key += 1;
if self.map.contains_key(&key) {
continue;
}
self.map.insert(key, RefCell::new(Box::new(a)));
return key;
}
}
pub fn contains_key(&self, key: u32) -> bool {
self.map.contains_key(&key)
}
// Todo: we can refine these errors and translate them to Exist at abi
pub fn get<T: Any + Sized>(&self, key: u32) -> Result<RefMut<T>, Error> {
if let Some(refcell) = self.map.get(&key) {
if let Ok(refmut) = refcell.try_borrow_mut() {
if refmut.is::<T>() {
Ok(RefMut::map(refmut, |r| r.downcast_mut::<T>().unwrap()))
} else {
Err(Error::Exist) // Exists at another type
}
} else {
Err(Error::Exist) // Does exist, but borrowed
}
} else {
Err(Error::Exist) // Does not exist
}
}
pub fn delete(&mut self, key: u32) -> Option<Box<dyn Any>> {
self.map.remove(&key).map(|rc| RefCell::into_inner(rc))
}
}