Add clone instances for arenas

stack-graphs/src/arena.rs

@@ -173,6 +173,20 @@ impl<T> Drop for Arena<T> {
     }
 }
 
+impl<T> Clone for Arena<T>
+where
+    T: Clone,
+{
+    fn clone(&self) -> Self {
+        let mut items = Vec::with_capacity(self.items.len());
+        items.extend((0..self.items.len()).map(|_| MaybeUninit::uninit()));
+        unsafe {
+            std::ptr::copy_nonoverlapping(self.items.as_ptr(), items.as_mut_ptr(), self.items.len())
+        };
+        Self { items }
+    }
+}
+
 impl<T> Arena<T> {
     /// Creates a new arena.
     pub fn new() -> Arena<T> {
@@ -271,6 +285,23 @@ impl<H, T> Drop for SupplementalArena<H, T> {
     }
 }
 
+impl<H, T> Clone for SupplementalArena<H, T>
+where
+    T: Clone,
+{
+    fn clone(&self) -> Self {
+        let mut items = Vec::with_capacity(self.items.len());
+        items.extend((0..self.items.len()).map(|_| MaybeUninit::uninit()));
+        unsafe {
+            std::ptr::copy_nonoverlapping(self.items.as_ptr(), items.as_mut_ptr(), self.items.len())
+        };
+        Self {
+            items,
+            _phantom: PhantomData::default(),
+        }
+    }
+}
+
 impl<H, T> SupplementalArena<H, T> {
     /// Creates a new, empty supplemental arena.
     pub fn new() -> SupplementalArena<H, T> {
@@ -374,6 +405,15 @@ pub struct HandleSet<T> {
     _phantom: PhantomData<T>,
 }
 
+impl<T> Clone for HandleSet<T> {
+    fn clone(&self) -> Self {
+        Self {
+            elements: self.elements.clone(),
+            _phantom: PhantomData::default(),
+        }
+    }
+}
+
 impl<T> HandleSet<T> {
     /// Creates a new, empty handle set.
     pub fn new() -> HandleSet<T> {
@@ -457,6 +497,7 @@ pub struct List<T> {
 
 #[doc(hidden)]
 #[repr(C)]
+#[derive(Clone)]
 pub struct ListCell<T> {
     head: T,
     // The value of this handle will be EMPTY_LIST_HANDLE if this is the last element of the list.
@@ -610,6 +651,7 @@ pub struct ReversibleList<T> {
 
 #[repr(C)]
 #[doc(hidden)]
+#[derive(Clone)]
 pub struct ReversibleListCell<T> {
     head: T,
     tail: Handle<ReversibleListCell<T>>,

stack-graphs/src/partial.rs

@@ -2610,6 +2610,7 @@ struct Join {
 
 /// Manages the state of a collection of partial paths built up as part of the partial-path-finding
 /// algorithm or path-stitching algorithm.
+#[derive(Clone)]
 pub struct PartialPaths {
     pub(crate) partial_symbol_stacks: DequeArena<PartialScopedSymbol>,
     pub(crate) partial_scope_stacks: DequeArena<Handle<Node>>,

stack-graphs/src/stitching.rs

@@ -227,6 +227,7 @@ impl Candidates<Edge> for GraphEdges {
 /// We've written the path-stitching algorithm so that you have a chance to only load in the
 /// partial paths that are actually needed, placing them into a `Database` instance as they're
 /// needed.
+#[derive(Clone)]
 pub struct Database {
     pub(crate) partial_paths: Arena<PartialPath>,
     pub(crate) local_nodes: HandleSet<Node>,