index: delete IndexRef, use Index trait

I don't know why I didn't create a trait to begin with. Maybe I had
trouble with lifetimes or object-safety.

lib/src/index.rs

@@ -44,7 +44,6 @@ pub struct IndexPosition(u32);
 impl IndexPosition {
     pub const MAX: Self = IndexPosition(u32::MAX);
 }
-
 pub trait Index {
     fn num_commits(&self) -> u32;
 
@@ -73,110 +72,6 @@ pub trait Index {
     fn topo_order(&self, input: &mut dyn Iterator<Item = &CommitId>) -> Vec<IndexEntry>;
 }
 
-#[derive(Clone, Copy)]
-pub enum IndexRef<'a> {
-    Readonly(&'a ReadonlyIndex),
-    Mutable(&'a MutableIndex),
-}
-
-impl<'a> From<&'a ReadonlyIndex> for IndexRef<'a> {
-    fn from(index: &'a ReadonlyIndex) -> Self {
-        IndexRef::Readonly(index)
-    }
-}
-
-impl<'a> From<&'a MutableIndex> for IndexRef<'a> {
-    fn from(index: &'a MutableIndex) -> Self {
-        IndexRef::Mutable(index)
-    }
-}
-
-impl<'a> IndexRef<'a> {
-    pub fn num_commits(&self) -> u32 {
-        match self {
-            IndexRef::Readonly(index) => index.num_commits(),
-            IndexRef::Mutable(index) => index.num_commits(),
-        }
-    }
-
-    pub fn stats(&self) -> IndexStats {
-        match self {
-            IndexRef::Readonly(index) => index.stats(),
-            IndexRef::Mutable(index) => index.stats(),
-        }
-    }
-
-    pub fn commit_id_to_pos(&self, commit_id: &CommitId) -> Option<IndexPosition> {
-        match self {
-            IndexRef::Readonly(index) => index.commit_id_to_pos(commit_id),
-            IndexRef::Mutable(index) => index.commit_id_to_pos(commit_id),
-        }
-    }
-
-    pub fn shortest_unique_commit_id_prefix_len(&self, commit_id: &CommitId) -> usize {
-        match self {
-            IndexRef::Readonly(index) => index.shortest_unique_commit_id_prefix_len(commit_id),
-            IndexRef::Mutable(index) => index.shortest_unique_commit_id_prefix_len(commit_id),
-        }
-    }
-
-    pub fn resolve_prefix(&self, prefix: &HexPrefix) -> PrefixResolution<CommitId> {
-        match self {
-            IndexRef::Readonly(index) => index.resolve_prefix(prefix),
-            IndexRef::Mutable(index) => index.resolve_prefix(prefix),
-        }
-    }
-
-    pub fn entry_by_id(&self, commit_id: &CommitId) -> Option<IndexEntry<'a>> {
-        match self {
-            IndexRef::Readonly(index) => index.entry_by_id(commit_id),
-            IndexRef::Mutable(index) => index.entry_by_id(commit_id),
-        }
-    }
-
-    pub fn entry_by_pos(&self, pos: IndexPosition) -> IndexEntry<'a> {
-        match self {
-            IndexRef::Readonly(index) => index.entry_by_pos(pos),
-            IndexRef::Mutable(index) => index.entry_by_pos(pos),
-        }
-    }
-
-    pub fn has_id(&self, commit_id: &CommitId) -> bool {
-        match self {
-            IndexRef::Readonly(index) => index.has_id(commit_id),
-            IndexRef::Mutable(index) => index.has_id(commit_id),
-        }
-    }
-
-    pub fn is_ancestor(&self, ancestor_id: &CommitId, descendant_id: &CommitId) -> bool {
-        match self {
-            IndexRef::Readonly(index) => index.is_ancestor(ancestor_id, descendant_id),
-            IndexRef::Mutable(index) => index.is_ancestor(ancestor_id, descendant_id),
-        }
-    }
-
-    pub fn common_ancestors(&self, set1: &[CommitId], set2: &[CommitId]) -> Vec<CommitId> {
-        match self {
-            IndexRef::Readonly(index) => index.common_ancestors(set1, set2),
-            IndexRef::Mutable(index) => index.common_ancestors(set1, set2),
-        }
-    }
-
-    pub fn walk_revs(&self, wanted: &[CommitId], unwanted: &[CommitId]) -> RevWalk<'a> {
-        match self {
-            IndexRef::Readonly(index) => index.walk_revs(wanted, unwanted),
-            IndexRef::Mutable(index) => index.walk_revs(wanted, unwanted),
-        }
-    }
-
-    pub fn heads(&self, candidates: &mut dyn Iterator<Item = &CommitId>) -> Vec<CommitId> {
-        match self {
-            IndexRef::Readonly(index) => index.heads(candidates),
-            IndexRef::Mutable(index) => index.heads(candidates),
-        }
-    }
-}
-
 struct CommitGraphEntry<'a> {
     data: &'a [u8],
     commit_id_length: usize,
@@ -431,10 +326,6 @@ impl MutableIndex {
         }
     }
 
-    pub fn as_index_ref(&self) -> IndexRef {
-        IndexRef::Mutable(self)
-    }
-
     pub fn add_commit(&mut self, commit: &Commit) {
         self.add_commit_data(
             commit.id().clone(),
@@ -1624,10 +1515,6 @@ impl ReadonlyIndex {
         }))
     }
 
-    pub fn as_index_ref(self: &ReadonlyIndex) -> IndexRef {
-        IndexRef::Readonly(self)
-    }
-
     pub fn name(&self) -> &str {
         &self.name
     }

lib/src/refs.rs

@@ -13,11 +13,11 @@
 // limitations under the License.
 
 use crate::backend::CommitId;
-use crate::index::IndexRef;
+use crate::index::Index;
 use crate::op_store::{BranchTarget, RefTarget};
 
 pub fn merge_ref_targets(
-    index: IndexRef,
+    index: &dyn Index,
     left: Option<&RefTarget>,
     base: Option<&RefTarget>,
     right: Option<&RefTarget>,
@@ -63,7 +63,7 @@ pub fn merge_ref_targets(
 }
 
 fn find_pair_to_remove(
-    index: IndexRef,
+    index: &dyn Index,
     adds: &[CommitId],
     removes: &[CommitId],
 ) -> Option<(Option<usize>, usize)> {

lib/src/repo.rs

@@ -30,8 +30,7 @@ use crate::commit_builder::CommitBuilder;
 use crate::dag_walk::topo_order_reverse;
 use crate::git_backend::GitBackend;
 use crate::index::{
-    HexPrefix, Index, IndexEntry, IndexPosition, IndexRef, MutableIndex, PrefixResolution,
-    ReadonlyIndex,
+    HexPrefix, Index, IndexEntry, IndexPosition, MutableIndex, PrefixResolution, ReadonlyIndex,
 };
 use crate::index_store::IndexStore;
 use crate::local_backend::LocalBackend;
@@ -80,10 +79,10 @@ impl<'a> RepoRef<'a> {
         }
     }
 
-    pub fn index(&self) -> IndexRef<'a> {
+    pub fn index(&self) -> &'a dyn Index {
         match self {
-            RepoRef::Readonly(repo) => IndexRef::Readonly(repo.index()),
-            RepoRef::Mutable(repo) => IndexRef::Mutable(repo.index()),
+            RepoRef::Readonly(repo) => repo.index().as_ref(),
+            RepoRef::Mutable(repo) => repo.index(),
         }
     }
 
@@ -1080,7 +1079,7 @@ impl MutableRepo {
             let base_target = base.get_ref(&ref_name);
             let other_target = other.get_ref(&ref_name);
             self.view.get_mut().merge_single_ref(
-                self.index.as_index_ref(),
+                &self.index,
                 &ref_name,
                 base_target.as_ref(),
                 other_target.as_ref(),
@@ -1088,7 +1087,7 @@ impl MutableRepo {
         }
 
         if let Some(new_git_head) = merge_ref_targets(
-            self.index.as_index_ref(),
+            &self.index,
             self.view().git_head(),
             base.git_head(),
             other.git_head(),
@@ -1148,12 +1147,9 @@ impl MutableRepo {
         base_target: Option<&RefTarget>,
         other_target: Option<&RefTarget>,
     ) {
-        self.view.get_mut().merge_single_ref(
-            self.index.as_index_ref(),
-            ref_name,
-            base_target,
-            other_target,
-        );
+        self.view
+            .get_mut()
+            .merge_single_ref(&self.index, ref_name, base_target, other_target);
     }
 }
 

lib/src/view.rs

@@ -17,7 +17,7 @@ use std::collections::{BTreeMap, HashMap, HashSet};
 use itertools::Itertools;
 
 use crate::backend::CommitId;
-use crate::index::IndexRef;
+use crate::index::Index;
 use crate::op_store;
 use crate::op_store::{BranchTarget, RefTarget, WorkspaceId};
 use crate::refs::merge_ref_targets;
@@ -266,7 +266,7 @@ impl View {
 
     pub fn merge_single_ref(
         &mut self,
-        index: IndexRef,
+        index: &dyn Index,
         ref_name: &RefName,
         base_target: Option<&RefTarget>,
         other_target: Option<&RefTarget>,

lib/tests/test_refs.rs

@@ -50,7 +50,7 @@ fn test_merge_ref_targets() {
     let _target7 = RefTarget::Normal(commit7.id().clone());
 
     let index = repo.index();
-    let index_ref = index.as_index_ref();
+    let index_ref = index.as_ref();
 
     // Left moved forward
     assert_eq!(