Merge #2592

2592: Add ImportObject::get_namespace_exports r=syrusakbary a=Amanieu

This allows the contents of an existing namespace to be added to by
extracting an `Exports` from it, adding to that `Exports` and then
replacing the existing namespace with the modified `Exports`.

Co-authored-by: Amanieu d'Antras <[email protected]>
Co-authored-by: Syrus Akbary <[email protected]>

lib/api/src/sys/exports.rs

@@ -290,6 +290,10 @@ impl LikeNamespace for Exports {
             .map(|(k, v)| (k.clone(), v.to_export()))
             .collect()
     }
+
+    fn as_exports(&self) -> Option<Exports> {
+        Some(self.clone())
+    }
 }
 
 /// This trait is used to mark types as gettable from an [`Instance`].

lib/api/src/sys/import_object.rs

@@ -1,6 +1,7 @@
 //! The import module contains the implementation data structures and helper functions used to
 //! manipulate and access a wasm module's imports including memories, tables, globals, and
 //! functions.
+use crate::Exports;
 use std::borrow::{Borrow, BorrowMut};
 use std::collections::VecDeque;
 use std::collections::{hash_map::Entry, HashMap};
@@ -16,6 +17,12 @@ pub trait LikeNamespace {
     fn get_namespace_export(&self, name: &str) -> Option<Export>;
     /// Gets all exports in the namespace.
     fn get_namespace_exports(&self) -> Vec<(String, Export)>;
+    /// Returns the contents of this namespace as an `Exports`.
+    ///
+    /// This is used by `ImportObject::get_namespace_exports`.
+    fn as_exports(&self) -> Option<Exports> {
+        None
+    }
 }
 
 /// All of the import data used when instantiating.
@@ -101,6 +108,15 @@ impl ImportObject {
         }
     }
 
+    /// Returns the contents of a namespace as an `Exports`.
+    ///
+    /// Returns `None` if the namespace doesn't exist or doesn't implement the
+    /// `as_exports` method.
+    pub fn get_namespace_exports(&self, name: &str) -> Option<Exports> {
+        let map = self.map.lock().unwrap();
+        map.get(name).and_then(|ns| ns.as_exports())
+    }
+
     fn get_objects(&self) -> VecDeque<((String, String), Export)> {
         let mut out = VecDeque::new();
         let guard = self.map.lock().unwrap();