From 8692e89b0ae94d9ff8350a66b7c8907dc759edff Mon Sep 17 00:00:00 2001
From: Armin Ronacher <armin.ronacher@active-4.com>
Date: Sat, 23 Jan 2021 22:29:10 +0100
Subject: [PATCH] Add utility methods to diff that capture

---
 src/algorithms/capture.rs |  9 ++++++---
 src/algorithms/mod.rs     | 32 ++++++++++++++++++++++++++++++++
 2 files changed, 38 insertions(+), 3 deletions(-)

diff --git a/src/algorithms/capture.rs b/src/algorithms/capture.rs
index 7c0a154..183f54c 100644
--- a/src/algorithms/capture.rs
+++ b/src/algorithms/capture.rs
@@ -123,8 +123,7 @@ impl Capture {
 
     /// Isolate change clusters by eliminating ranges with no changes.
     ///
-    /// This will leave holes behind in long periods of equal ranges so that
-    /// you can build things like unified diffs.
+    /// This is equivalent to calling [`group_diff_ops`] on [`Capture::into_ops`].
     pub fn into_grouped_ops(self, n: usize) -> Vec<Vec<DiffOp>> {
         group_diff_ops(self.into_ops(), n)
     }
@@ -135,7 +134,11 @@ impl Capture {
     }
 }
 
-fn group_diff_ops(mut ops: Vec<DiffOp>, n: usize) -> Vec<Vec<DiffOp>> {
+/// Isolate change clusters by eliminating ranges with no changes.
+///
+/// This will leave holes behind in long periods of equal ranges so that
+/// you can build things like unified diffs.
+pub fn group_diff_ops(mut ops: Vec<DiffOp>, n: usize) -> Vec<Vec<DiffOp>> {
     if ops.is_empty() {
         return vec![];
     }
diff --git a/src/algorithms/mod.rs b/src/algorithms/mod.rs
index beac4de..339e3b5 100644
--- a/src/algorithms/mod.rs
+++ b/src/algorithms/mod.rs
@@ -77,3 +77,35 @@ where
 {
     diff(alg, d, old, 0..old.len(), new, 0..new.len())
 }
+
+/// Creates a diff between old and new with the given algorithm capturing the ops.
+///
+/// This is like [`diff`] but instead of using an arbitrary hook this will
+/// always use [`Replace`] + [`Capture`] and return the captured [`DiffOp`]s.
+pub fn capture_diff<Old, New>(
+    alg: Algorithm,
+    old: &Old,
+    old_range: Range<usize>,
+    new: &New,
+    new_range: Range<usize>,
+) -> Vec<DiffOp>
+where
+    Old: Index<usize> + ?Sized,
+    New: Index<usize> + ?Sized,
+    Old::Output: Hash + Eq + Ord,
+    New::Output: PartialEq<Old::Output> + Hash + Eq + Ord,
+{
+    let mut d = Replace::new(Capture::new());
+    diff(alg, &mut d, old, old_range, new, new_range).unwrap();
+    d.into_inner().into_ops()
+}
+
+/// Creates a diff between old and new with the given algorithm capturing the ops.
+pub fn capture_diff_slices<D, T>(alg: Algorithm, old: &[T], new: &[T]) -> Vec<DiffOp>
+where
+    T: Eq + Hash + Ord,
+{
+    let mut d = Replace::new(Capture::new());
+    diff_slices(alg, &mut d, old, new).unwrap();
+    d.into_inner().into_ops()
+}