Added -[GTRepository enumerateLocalCommitsInBranch:trackingBranch:error:].

Author: joshaber

ObjectiveGit/GTRepository.h

@@ -565,6 +565,20 @@ NS_ASSUME_NONNULL_BEGIN
 /// Returns whether `ahead` and `behind` were successfully calculated.
 - (BOOL)calculateAhead:(size_t *)ahead behind:(size_t *)behind ofOID:(GTOID *)headOID relativeToOID:(GTOID *)baseOID error:(NSError **)error;
 
+/// Creates an enumerator for walking the local commits in relative to the
+/// tracking branch.
+///
+/// Note that this will only be accurate iff `trackingBranch` truly is
+/// `localBranch`s tracking branch. If you need more general functionality, see
+/// -[GTBranch uniqueCommitsRelativeToBranch:error:].
+///
+/// localBranch    - The local branch.
+/// trackingBranch - `localBranch`s tracking branch.
+/// error          - The error if one occurred.
+///
+/// Returns the enumerator or nil if an error occurred.
+- (nullable GTEnumerator *)enumerateLocalCommitsInBranch:(GTBranch *)localBranch trackingBranch:(GTBranch *)trackingBranch error:(NSError **)error;
+
 @end
 
 NS_ASSUME_NONNULL_END

ObjectiveGit/GTRepository.m

@@ -912,4 +912,20 @@ - (BOOL)calculateAhead:(size_t *)ahead behind:(size_t *)behind ofOID:(GTOID *)he
 	return YES;
 }
 
+- (GTEnumerator *)enumerateLocalCommitsInBranch:(GTBranch *)localBranch trackingBranch:(GTBranch *)trackingBranch error:(NSError **)error {
+	NSParameterAssert(localBranch != nil);
+	NSParameterAssert(trackingBranch != nil);
+
+	GTEnumerator *enumerator = [[GTEnumerator alloc] initWithRepository:self error:error];
+	if (enumerator == nil) return nil;
+
+	BOOL success = [enumerator pushSHA:localBranch.OID.SHA error:error];
+	if (!success) return nil;
+
+	success = [enumerator hideSHA:trackingBranch.OID.SHA error:error];
+	if (!success) return nil;
+
+	return enumerator;
+}
+
 @end