fix(organize): copy annotation actions with one shared reference map

Fixing up copied annotations cloned the whole source-to-destination map for
every non-GoTo action and dropped the copies it made, so many annotations
cost quadratic memory and time and an object shared by their actions was
copied once per action. The copier now lends its map to the action copy and
takes it back with the new entries.

crates/organize/src/import.rs

@@ -154,8 +154,8 @@ impl<'a> Copier<'a> {
     }
 
     /// Rewrite `/P`, `/Dest` and GoTo actions on copied annotations.
-    fn fix_annotations(&self, dst: &mut Document, annot_pages: &HashMap<ObjRef, ObjRef>) -> Result<(), OrganizeError> {
-        for &a in &self.annots {
+    fn fix_annotations(&mut self, dst: &mut Document, annot_pages: &HashMap<ObjRef, ObjRef>) -> Result<(), OrganizeError> {
+        for &a in &std::mem::take(&mut self.annots) {
             let src_dict = dst.get(a).as_dict().cloned();
             let Some(d) = src_dict else { continue };
             let mut d = d;
@@ -188,10 +188,13 @@ impl<'a> Copier<'a> {
                             }
                         }
                     } else {
-                        // Other actions (URI, Launch, JavaScript…) carry no page references.
-                        let mut c = Copier::new(self.src, self.map.clone(), HashMap::new());
-                        let copied = c.copy_value(dst, &Object::Dict(ad.clone()), None)?;
-                        d.set(b"A".to_vec(), copied);
+                        // Other actions (URI, Launch, JavaScript…) carry no page references. The
+                        // copier lends its map out and takes it back with the new copies in it,
+                        // so actions sharing an object share its one copy.
+                        let mut c = Copier::new(self.src, std::mem::take(&mut self.map), HashMap::new());
+                        let copied = c.copy_value(dst, &Object::Dict(ad.clone()), None);
+                        self.map = c.map;
+                        d.set(b"A".to_vec(), copied?);
                     }
                 }
             }

crates/organize/src/tests.rs

@@ -3175,3 +3175,19 @@ fn renaming_many_same_named_fields_resumes_the_suffix_search() {
     assert_eq!(renames.first(), Some(&("x".to_string(), "x-1".to_string())));
     assert_eq!(renames.last(), Some(&("x".to_string(), format!("x-{}", n - 1))));
 }
+
+#[test]
+fn annotation_actions_share_the_objects_they_copy() {
+    // Fifty links whose URI actions all point at one string object.
+    let n = 50;
+    let links: Vec<String> =
+        (0..n).map(|_| format!("<< /Type /Annot /Subtype /Link /Rect [0 0 10 10] /A << /S /URI /URI {} 0 R >> >>", n + 5)).collect();
+    let src = page_with_annots(&links, &["(https://example.com/shared)".into()], "");
+    let out = extract_pages(&src, &[0]).unwrap();
+    let copies = out
+        .object_numbers()
+        .into_iter()
+        .filter(|&o| out.get(ObjRef::new(o, out.generation(o))).as_string().is_some_and(|s| s.bytes == b"https://example.com/shared"))
+        .count();
+    assert_eq!(copies, 1, "the shared URI is copied once, not once per action");
+}