1 files changed, 93 insertions, 0 deletions
diff --git a/src/graph.c b/src/graph.c
new file mode 100644
index 000000000..28026d4b4
--- /dev/null
+++ b/src/graph.c
@@ -0,0 +1,93 @@
+
+/*
+ * Copyright (C) 2009-2012 the libgit2 contributors
+ *
+ * This file is part of libgit2, distributed under the GNU GPL v2 with
+ * a Linking Exception. For full terms see the included COPYING file.
+ */
+
+#include "revwalk.h"
+#include "merge.h"
+#include "git2/graph.h"
+
+static int ahead_behind(git_commit_list_node *one, git_commit_list_node *two,
+	size_t *ahead, size_t *behind)
+{
+	git_commit_list_node *commit;
+	git_pqueue pq;
+	int i;
+	*ahead = 0;
+	*behind = 0;
+
+	if (git_pqueue_init(&pq, 2, git_commit_list_time_cmp) < 0)
+		return -1;
+	if (git_pqueue_insert(&pq, one) < 0)
+		return -1;
+	if (git_pqueue_insert(&pq, two) < 0)
+		return -1;
+
+	while ((commit = git_pqueue_pop(&pq)) != NULL) {
+		if (commit->flags & RESULT ||
+			(commit->flags & (PARENT1 | PARENT2)) == (PARENT1 | PARENT2))
+			continue;
+		else if (commit->flags & PARENT1)
+			(*behind)++;
+		else if (commit->flags & PARENT2)
+			(*ahead)++;
+
+		for (i = 0; i < commit->out_degree; i++) {
+			git_commit_list_node *p = commit->parents[i];
+			if (git_pqueue_insert(&pq, p) < 0)
+				return -1;
+		}
+		commit->flags |= RESULT;
+	}
+
+	return 0;
+}
+
+int git_graph_ahead_behind(size_t *ahead, size_t *behind, git_repository *repo,
+	const git_oid *one, const git_oid *two)
+{
+	git_revwalk *walk;
+	git_vector list;
+	struct git_commit_list *result = NULL;
+	git_commit_list_node *commit1, *commit2;
+	void *contents[1];
+
+	if (git_revwalk_new(&walk, repo) < 0)
+		return -1;
+
+	commit2 = git_revwalk__commit_lookup(walk, two);
+	if (commit2 == NULL)
+		goto on_error;
+
+	/* This is just one value, so we can do it on the stack */
+	memset(&list, 0x0, sizeof(git_vector));
+	contents[0] = commit2;
+	list.length = 1;
+	list.contents = contents;
+
+	commit1 = git_revwalk__commit_lookup(walk, one);
+	if (commit1 == NULL)
+		goto on_error;
+
+	if (git_merge__bases_many(&result, walk, commit1, &list) < 0)
+		goto on_error;
+	if (ahead_behind(commit1, commit2, ahead, behind) < 0)
+		goto on_error;
+
+	if (!result) {
+		git_revwalk_free(walk);
+		return GIT_ENOTFOUND;
+	}
+
+	git_commit_list_free(&result);
+	git_revwalk_free(walk);
+
+	return 0;
+
+on_error:
+	git_revwalk_free(walk);
+	return -1;
+}