wasi-c2: rewrite wasi-common in terms of system-interface

crates/wasi-c2/src/table.rs

@@ -0,0 +1,46 @@
+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(&mut self, a: impl Any + Sized) -> u32 {
+        let key = self.next_key;
+        self.next_key += 1;
+        self.map.insert(key, RefCell::new(Box::new(a)));
+        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))
+    }
+}