feat!: Provide more source information when emitting rewrites.

Previously, the source was entirely missing, now it's also made available.
Further, all the cloning of these resources is now left to the user,
which should safe time.

Author: Byron

Cargo.lock

@@ -83,7 +83,7 @@ pub mod visit {
 
     /// The source of a rewrite, rename or copy.
     #[derive(Debug, Clone, PartialEq, PartialOrd)]
-    pub struct Source<'a> {
+    pub struct Source<'a, T> {
         /// The kind of entry.
         pub entry_mode: EntryMode,
         /// The hash of the state of the source as seen in the object database.
@@ -92,6 +92,8 @@ pub mod visit {
         pub kind: SourceKind,
         /// The repository-relative location of this entry.
         pub location: &'a BStr,
+        /// The change that was registered as source.
+        pub change: &'a T,
         /// If this is a rewrite, indicate how many lines would need to change to turn this source into the destination.
         pub diff: Option<DiffLineStats>,
     }
@@ -193,7 +195,7 @@ impl<T: Change> Tracker<T> {
     /// will panic if `change` is not a modification, and it's valid to not call `push` at all.
     pub fn emit<PushSourceTreeFn, E>(
         &mut self,
-        mut cb: impl FnMut(visit::Destination<'_, T>, Option<visit::Source<'_>>) -> crate::tree::visit::Action,
+        mut cb: impl FnMut(visit::Destination<'_, T>, Option<visit::Source<'_, T>>) -> crate::tree::visit::Action,
         diff_cache: &mut crate::blob::Platform,
         objects: &impl gix_object::FindObjectOrHeader,
         mut push_source_tree: PushSourceTreeFn,
@@ -283,7 +285,7 @@ impl<T: Change> Tracker<T> {
     fn match_pairs_of_kind(
         &mut self,
         kind: visit::SourceKind,
-        cb: &mut impl FnMut(visit::Destination<'_, T>, Option<visit::Source<'_>>) -> crate::tree::visit::Action,
+        cb: &mut impl FnMut(visit::Destination<'_, T>, Option<visit::Source<'_, T>>) -> crate::tree::visit::Action,
         percentage: Option<f32>,
         out: &mut Outcome,
         diff_cache: &mut crate::blob::Platform,
@@ -326,7 +328,7 @@ impl<T: Change> Tracker<T> {
 
     fn match_pairs(
         &mut self,
-        cb: &mut impl FnMut(visit::Destination<'_, T>, Option<visit::Source<'_>>) -> crate::tree::visit::Action,
+        cb: &mut impl FnMut(visit::Destination<'_, T>, Option<visit::Source<'_, T>>) -> crate::tree::visit::Action,
         percentage: Option<f32>,
         kind: visit::SourceKind,
         stats: &mut Outcome,
@@ -360,6 +362,7 @@ impl<T: Change> Tracker<T> {
                         id,
                         kind,
                         location,
+                        change: &src.change,
                         diff,
                     },
                     src_idx,
@@ -371,11 +374,15 @@ impl<T: Change> Tracker<T> {
             let location = dest.location(&self.path_backing);
             let change = dest.change.clone();
             let dest = visit::Destination { change, location };
+            let src_idx = src.as_ref().map(|t| t.1);
+            let res = cb(dest, src.map(|t| t.0));
+
             self.items[dest_idx].emitted = true;
-            if let Some(src_idx) = src.as_ref().map(|t| t.1) {
+            if let Some(src_idx) = src_idx {
                 self.items[src_idx].emitted = true;
             }
-            if cb(dest, src.map(|t| t.0)) == crate::tree::visit::Action::Cancel {
+
+            if res == crate::tree::visit::Action::Cancel {
                 return Ok(crate::tree::visit::Action::Cancel);
             }
         }

gix-diff/src/rewrites/tracker.rs

@@ -25,3 +25,4 @@ gix-filter = { path = "../../gix-filter" }
 gix-traverse = { path = "../../gix-traverse" }
 gix-testtools = { path = "../../tests/tools" }
 shell-words = "1"
+pretty_assertions = "1.4.0"

gix-diff/tests/Cargo.toml

@@ -4,7 +4,7 @@ use gix_object::tree::{EntryKind, EntryMode};
 
 mod tracker;
 
-#[derive(Clone)]
+#[derive(Debug, Clone, PartialEq, Eq)]
 pub struct Change {
     id: ObjectId,
     kind: ChangeKind,

gix-diff/tests/fixtures/generated-archives/make_diff_repo.tar.xz

@@ -12,6 +12,7 @@ use gix_diff::{
     Rewrites,
 };
 use gix_object::tree::EntryKind;
+use pretty_assertions::assert_eq;
 
 use crate::{
     hex_to_id,
@@ -51,6 +52,7 @@ fn rename_by_id() -> crate::Result {
                     id: NULL_ID,
                     kind: SourceKind::Rename,
                     location: "b".into(),
+                    change: &Change::deletion(),
                     diff: None,
                 }
             );
@@ -146,11 +148,16 @@ fn copy_by_id() -> crate::Result {
         let out = util::assert_emit_with_objects(
             &mut track,
             |dst, src| {
+                let id = hex_to_id("2e65efe2a145dda7ee51d1741299f848e5bf752e");
                 let source_a = Source {
                     entry_mode: EntryKind::Blob.into(),
-                    id: hex_to_id("2e65efe2a145dda7ee51d1741299f848e5bf752e"),
+                    id: id,
                     kind: SourceKind::Copy,
                     location: "a".into(),
+                    change: &Change {
+                        id,
+                        ..Change::modification()
+                    },
                     diff: None,
                 };
                 match calls {
@@ -219,6 +226,10 @@ fn copy_by_id_search_in_all_sources() -> crate::Result {
                     id: content_id,
                     kind: SourceKind::Copy,
                     location: "a-src".into(),
+                    change: &Change {
+                        id: content_id,
+                        ..Change::modification()
+                    },
                     diff: None,
                 };
                 match calls {
@@ -289,11 +300,16 @@ fn copy_by_50_percent_similarity() -> crate::Result {
     let out = util::assert_emit_with_objects(
         &mut track,
         |dst, src| {
+            let id = hex_to_id("78981922613b2afb6025042ff6bd878ac1994e85");
             let source_a = Source {
                 entry_mode: EntryKind::Blob.into(),
-                id: hex_to_id("78981922613b2afb6025042ff6bd878ac1994e85"),
+                id: id,
                 kind: SourceKind::Copy,
                 location: "a".into(),
+                change: &Change {
+                    id,
+                    ..Change::modification()
+                },
                 diff: Some(DiffLineStats {
                     removals: 0,
                     insertions: 1,
@@ -459,13 +475,18 @@ fn rename_by_50_percent_similarity() -> crate::Result {
         |dst, src| {
             match calls {
                 0 => {
+                    let id = hex_to_id("66a52ee7a1d803dc57859c3e95ac9dcdc87c0164");
                     assert_eq!(
                         src.unwrap(),
                         Source {
                             entry_mode: EntryKind::Blob.into(),
-                            id: hex_to_id("66a52ee7a1d803dc57859c3e95ac9dcdc87c0164"),
+                            id: id,
                             kind: SourceKind::Rename,
                             location: "a".into(),
+                            change: &Change {
+                                id,
+                                ..Change::deletion()
+                            },
                             diff: Some(DiffLineStats {
                                 removals: 1,
                                 insertions: 1,
@@ -532,7 +553,7 @@ fn add_only() -> crate::Result {
     let out = util::assert_emit(&mut track, |dst, src| {
         assert!(!called);
         called = true;
-        assert_eq!(src, None, "there is just a single deletion, no pair");
+        assert!(src.is_none(), "there is just a single deletion, no pair");
         assert_eq!(dst.location, "a");
         assert_eq!(dst.change.kind, ChangeKind::Addition);
         Action::Continue
@@ -569,22 +590,22 @@ mod util {
 
     pub fn assert_emit(
         tracker: &mut rewrites::Tracker<Change>,
-        cb: impl FnMut(Destination<'_, Change>, Option<Source<'_>>) -> Action,
+        cb: impl FnMut(Destination<'_, Change>, Option<Source<'_, Change>>) -> Action,
     ) -> rewrites::Outcome {
         assert_emit_with_objects(tracker, cb, gix_object::find::Never)
     }
 
     pub fn assert_emit_with_objects(
         tracker: &mut rewrites::Tracker<Change>,
-        cb: impl FnMut(Destination<'_, Change>, Option<Source<'_>>) -> Action,
+        cb: impl FnMut(Destination<'_, Change>, Option<Source<'_, Change>>) -> Action,
         objects: impl gix_object::FindObjectOrHeader,
     ) -> rewrites::Outcome {
         assert_emit_with_objects_and_sources(tracker, cb, objects, None)
     }
 
     pub fn assert_emit_with_objects_and_sources<'a>(
         tracker: &mut rewrites::Tracker<Change>,
-        cb: impl FnMut(Destination<'_, Change>, Option<Source<'_>>) -> Action,
+        cb: impl FnMut(Destination<'_, Change>, Option<Source<'_, Change>>) -> Action,
         objects: impl gix_object::FindObjectOrHeader,
         sources: impl IntoIterator<Item = (Change, &'a str)>,
     ) -> rewrites::Outcome {