copies-rust: yield both p1 and p2 copies in `ChangedFiles.actions()`

copies-rust: yield both p1 and p2 copies in `ChangedFiles.actions()`

Instead of filtering the relevant parent inside de ChangedFiles method, we now
yield all copies information and let the caller do the filtering. Soon, the
filtering will be replaced by dispatching.

Differential Revision: https://phab.mercurial-scm.org/D9649

--- a/rust/hg-core/src/copy_tracing.rs	Wed Dec 16 10:01:34 2020 +0100
+++ b/rust/hg-core/src/copy_tracing.rs	Mon Dec 21 10:24:16 2020 +0100
@@ -107,7 +107,8 @@
     Removed(&'a HgPath),
     /// The parent ? children edge introduce copy information between (dest,
     /// source)
-    Copied(&'a HgPath, &'a HgPath),
+    CopiedFromP1(&'a HgPath, &'a HgPath),
+    CopiedFromP2(&'a HgPath, &'a HgPath),
 }
 
 /// This express the possible "special" case we can get in a merge
@@ -246,10 +247,9 @@
     }
 
     /// Return an iterator over all the `Action` in this instance.
-    fn iter_actions(&self, parent: Parent) -> ActionsIterator {
+    fn iter_actions(&self) -> ActionsIterator {
         ActionsIterator {
             changes: &self,
-            parent: parent,
             current: 0,
         }
     }
@@ -283,7 +283,6 @@
 
 struct ActionsIterator<'a> {
     changes: &'a ChangedFiles<'a>,
-    parent: Parent,
     current: u32,
 }
 
@@ -291,10 +290,6 @@
     type Item = Action<'a>;
 
     fn next(&mut self) -> Option<Action<'a>> {
-        let copy_flag = match self.parent {
-            Parent::FirstParent => P1_COPY,
-            Parent::SecondParent => P2_COPY,
-        };
         while self.current < self.changes.nb_items {
             let (flags, file, source) = self.changes.entry(self.current);
             self.current += 1;
@@ -302,8 +297,10 @@
                 return Some(Action::Removed(file));
             }
             let copy = flags & COPY_MASK;
-            if copy == copy_flag {
-                return Some(Action::Copied(file, source));
+            if copy == P1_COPY {
+                return Some(Action::CopiedFromP1(file, source));
+            } else if copy == P2_COPY {
+                return Some(Action::CopiedFromP2(file, source));
             }
         }
         return None;
@@ -500,17 +497,33 @@
     current_rev: Revision,
 ) -> InternalPathCopies {
     let mut copies = base_copies.clone();
-    for action in changes.iter_actions(parent) {
+    for action in changes.iter_actions() {
         match action {
-            Action::Copied(path_dest, path_source) => {
-                add_one_copy(
-                    current_rev,
-                    &mut path_map,
-                    &mut copies,
-                    &base_copies,
-                    path_dest,
-                    path_source,
-                );
+            Action::CopiedFromP1(path_dest, path_source) => {
+                match parent {
+                    _ => (), // not the parent we are looking for
+                    Parent::FirstParent => add_one_copy(
+                        current_rev,
+                        path_map,
+                        &mut copies,
+                        &base_copies,
+                        path_dest,
+                        path_source,
+                    ),
+                };
+            }
+            Action::CopiedFromP2(path_dest, path_source) => {
+                match parent {
+                    _ => (), //not the parent we are looking for
+                    Parent::SecondParent => add_one_copy(
+                        current_rev,
+                        path_map,
+                        &mut copies,
+                        &base_copies,
+                        path_dest,
+                        path_source,
+                    ),
+                };
             }
             Action::Removed(deleted_path) => {
                 // We must drop copy information for removed file.