[PATCH] Add some functions for commit lists

This adds a function for inserting an item in a commit list, a function
for sorting a commit list by date, and a function for progressively
scanning a commit history from most recent to least recent.

Signed-Off-By: Daniel Barkalow <barkalow@iabervon.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 61 insertions, 6 deletions

diff --git a/commit.c b/commit.c
index 9f0668eb68..911f6435a7 100644
--- a/commit.c
+++ b/commit.c
@@ -63,12 +63,9 @@ int parse_commit(struct commit *item)
 	bufptr += 46; /* "tree " + "hex sha1" + "\n" */
 	while (!memcmp(bufptr, "parent ", 7) &&
 	       !get_sha1_hex(bufptr + 7, parent)) {
-		struct commit_list *new_parent = 
-			malloc(sizeof(struct commit_list));
-		new_parent->next = item->parents;
-		new_parent->item = lookup_commit(parent);
-		add_ref(&item->object, &new_parent->item->object);
-		item->parents = new_parent;
+		struct commit *new_parent = lookup_commit(parent);
+		commit_list_insert(new_parent, &item->parents);
+		add_ref(&item->object, &new_parent->object);
 		bufptr += 48;
 	}
 	item->date = parse_commit_date(bufptr);
@@ -76,6 +73,14 @@ int parse_commit(struct commit *item)
 	return 0;
 }
 
+void commit_list_insert(struct commit *item, struct commit_list **list_p)
+{
+	struct commit_list *new_list = malloc(sizeof(struct commit_list));
+	new_list->item = item;
+	new_list->next = *list_p;
+	*list_p = new_list;
+}
+
 void free_commit_list(struct commit_list *list)
 {
 	while (list) {
@@ -84,3 +89,44 @@ void free_commit_list(struct commit_list *list)
 		free(temp);
 	}
 }
+
+static void insert_by_date(struct commit_list **list, struct commit *item)
+{
+	struct commit_list **pp = list;
+	struct commit_list *p;
+	while ((p = *pp) != NULL) {
+		if (p->item->date < item->date) {
+			break;
+		}
+		pp = &p->next;
+	}
+	commit_list_insert(item, pp);
+}
+
+	
+void sort_by_date(struct commit_list **list)
+{
+	struct commit_list *ret = NULL;
+	while (*list) {
+		insert_by_date(&ret, (*list)->item);
+		*list = (*list)->next;
+	}
+	*list = ret;
+}
+
+struct commit *pop_most_recent_commit(struct commit_list **list)
+{
+	struct commit *ret = (*list)->item;
+	struct commit_list *parents = ret->parents;
+	struct commit_list *old = *list;
+
+	*list = (*list)->next;
+	free(old);
+
+	while (parents) {
+		parse_commit(parents->item);
+		insert_by_date(list, parents->item);
+		parents = parents->next;
+	}
+	return ret;
+}
diff --git a/commit.h b/commit.h
index 4afd27b109..c8684d1cd0 100644
--- a/commit.h
+++ b/commit.h
@@ -22,6 +22,15 @@ struct commit *lookup_commit(unsigned char *sha1);
 
 int parse_commit(struct commit *item);
 
+void commit_list_insert(struct commit *item, struct commit_list **list_p);
+
 void free_commit_list(struct commit_list *list);
 
+void sort_by_date(struct commit_list **list);
+
+/** Removes the first commit from a list sorted by date, and adds all
+ * of its parents.
+ **/
+struct commit *pop_most_recent_commit(struct commit_list **list);
+
 #endif /* COMMIT_H */