Diff iterators

This refactors the diff output code so that an iterator object
can be used to traverse and generate the diffs, instead of just
the `foreach()` style with callbacks.  The code has been rearranged
so that the two styles can still share most functions.

This also replaces `GIT_REVWALKOVER` with `GIT_ITEROVER` and uses
that as a common error code for marking the end of iteration when
using a iterator style of object.

1 files changed, 10 insertions, 4 deletions

diff --git a/src/diff.c b/src/diff.c
index 430f52e0..f8a01086 100644
--- a/src/diff.c
+++ b/src/diff.c
@@ -316,6 +316,7 @@ static git_diff_list *git_diff_list_alloc(
 	if (diff == NULL)
 		return NULL;
 
+	GIT_REFCOUNT_INC(diff);
 	diff->repo = repo;
 
 	if (git_vector_init(&diff->deltas, 0, diff_delta__cmp) < 0 ||
@@ -391,15 +392,12 @@ fail:
 	return NULL;
 }
 
-void git_diff_list_free(git_diff_list *diff)
+static void diff_list_free(git_diff_list *diff)
 {
 	git_diff_delta *delta;
 	git_attr_fnmatch *match;
 	unsigned int i;
 
-	if (!diff)
-		return;
-
 	git_vector_foreach(&diff->deltas, i, delta) {
 		git__free(delta);
 		diff->deltas.contents[i] = NULL;
@@ -416,6 +414,14 @@ void git_diff_list_free(git_diff_list *diff)
 	git__free(diff);
 }
 
+void git_diff_list_free(git_diff_list *diff)
+{
+	if (!diff)
+		return;
+
+	GIT_REFCOUNT_DEC(diff, diff_list_free);
+}
+
 static int oid_for_workdir_item(
 	git_repository *repo,
 	const git_index_entry *item,