refs: introduce an iterator

This allows us to get a list of reference names in a loop instead of callbacks.

3 files changed, 64 insertions, 0 deletions

diff --git a/include/git2/refs.h b/include/git2/refs.h
index e1d425352..48ecc96e0 100644
--- a/include/git2/refs.h
+++ b/include/git2/refs.h
@@ -347,6 +347,31 @@ GIT_EXTERN(void) git_reference_free(git_reference *ref);
 GIT_EXTERN(int) git_reference_cmp(git_reference *ref1, git_reference *ref2);
 
 /**
+ * Create an iterator for the repo's references
+ *
+ * @param out pointer in which to store the iterator
+ * @param repo the repository
+ * @return 0 or an error code
+ */
+GIT_EXTERN(int) git_reference_iterator_new(git_reference_iterator **out, git_repository *repo);
+
+/**
+ * Get the next reference name
+ *
+ * @param out pointer in which to store the string
+ * @param iter the iterator
+ * @param 0, GIT_ITEROVER if there are no more; or an error code
+ */
+GIT_EXTERN(int) git_reference_next(const char **out, git_reference_iterator *iter);
+
+/**
+ * Free the iterator and its associated resources
+ *
+ * @param iter the iterator to free
+ */
+GIT_EXTERN(void) git_reference_iterator_free(git_reference_iterator *iter);
+
+/**
  * Perform a callback on each reference in the repository whose name
  * matches the given pattern.
  *
diff --git a/include/git2/sys/refdb_backend.h b/include/git2/sys/refdb_backend.h
index d5f599fec..4c882b5cd 100644
--- a/include/git2/sys/refdb_backend.h
+++ b/include/git2/sys/refdb_backend.h
@@ -20,6 +20,22 @@
  */
 GIT_BEGIN_DECL
 
+
+/**
+ * Every backend's iterator must have a pointer to itself as the first
+ * element, so the API can talk to it. You'd define your iterator as
+ *
+ *     struct my_iterator {
+ *             git_reference_iterator parent;
+ *             ...
+ *     }
+ *
+ * and assing `iter->parent.backend` to your `git_refdb_backend`.
+ */
+struct git_reference_iterator {
+	git_refdb_backend *backend;
+};
+
 /** An instance for a custom backend */
 struct git_refdb_backend {
     unsigned int version;
@@ -66,6 +82,25 @@ struct git_refdb_backend {
 		void *payload);
 
 	/**
+	 * Allocate an iterator object for the backend
+	 */
+	int (*iterator)(
+		git_reference_iterator **iter,
+		struct git_refdb_backend *backend);
+
+	/**
+	 * Return the current value and advance the iterator.
+	 */
+	int (*next)(
+		const char **name,
+		git_reference_iterator *iter);
+
+	/**
+	 * Free the iterator
+	 */
+	void (*iterator_free)(
+		git_reference_iterator *iter);
+	/*
 	 * Writes the given reference to the refdb.  A refdb implementation
 	 * must provide this function.
 	 */
diff --git a/include/git2/types.h b/include/git2/types.h
index aca9ed927..43751d3b0 100644
--- a/include/git2/types.h
+++ b/include/git2/types.h
@@ -165,6 +165,10 @@ typedef struct git_signature {
 /** In-memory representation of a reference. */
 typedef struct git_reference git_reference;
 
+/** Iterator for references */
+typedef struct git_reference_iterator  git_reference_iterator;
+
+
 /** Basic type of any Git reference. */
 typedef enum {
 	GIT_REF_INVALID = 0, /** Invalid reference */