Add git_commit_amend API

This adds an API to amend an existing commit, basically a shorthand
for creating a new commit filling in missing parameters from the
values of an existing commit.  As part of this, I also added a new
"sys" API to create a commit using a callback to get the parents.
This allowed me to rewrite all the other commit creation APIs so
that temporary allocations are no longer needed.

1 files changed, 37 insertions, 3 deletions

diff --git a/include/git2/sys/commit.h b/include/git2/sys/commit.h
index c8ed56b66..627d3ae2e 100644
--- a/include/git2/sys/commit.h
+++ b/include/git2/sys/commit.h
@@ -21,16 +21,18 @@
 GIT_BEGIN_DECL
 
 /**
- * Create new commit in the repository from a list of `git_oid` values
+ * Create new commit in the repository from a list of `git_oid` values.
  *
  * See documentation for `git_commit_create()` for information about the
  * parameters, as the meaning is identical excepting that `tree` and
  * `parents` now take `git_oid`.  This is a dangerous API in that nor
  * the `tree`, neither the `parents` list of `git_oid`s are checked for
  * validity.
+ *
+ * @see git_commit_create
  */
 GIT_EXTERN(int) git_commit_create_from_ids(
-	git_oid *oid,
+	git_oid *id,
 	git_repository *repo,
 	const char *update_ref,
 	const git_signature *author,
@@ -38,9 +40,41 @@ GIT_EXTERN(int) git_commit_create_from_ids(
 	const char *message_encoding,
 	const char *message,
 	const git_oid *tree,
-	int parent_count,
+	size_t parent_count,
 	const git_oid *parents[]);
 
+/**
+ * Callback function to return parents for commit.
+ *
+ * This is invoked with the count of the number of parents processed so far
+ * along with the user supplied payload.  This should return a git_oid of
+ * the next parent or NULL if all parents have been provided.
+ */
+typedef const git_oid *(*git_commit_parent_callback)(size_t idx, void *payload);
+
+/**
+ * Create a new commit in the repository with an callback to supply parents.
+ *
+ * See documentation for `git_commit_create()` for information about the
+ * parameters, as the meaning is identical excepting that `tree` takes a
+ * `git_oid` and doesn't check for validity, and `parent_cb` is invoked
+ * with `parent_payload` and should return `git_oid` values or NULL to
+ * indicate that all parents are accounted for.
+ *
+ * @see git_commit_create
+ */
+GIT_EXTERN(int) git_commit_create_from_callback(
+	git_oid *id,
+	git_repository *repo,
+	const char *update_ref,
+	const git_signature *author,
+	const git_signature *committer,
+	const char *message_encoding,
+	const char *message,
+	const git_oid *tree,
+	git_commit_parent_callback parent_cb,
+	void *parent_payload);
+
 /** @} */
 GIT_END_DECL
 #endif