oidmap: introduce high-level getter for values

The current way of looking up an entry from a map is tightly coupled with the
map implementation, as one first has to look up the index of the key and then
retrieve the associated value by using the index. As a caller, you usually do
not care about any indices at all, though, so this is more complicated than
really necessary. Furthermore, it invites for errors to happen if the correct
error checking sequence is not being followed.

Introduce a new high-level function `git_oidmap_get` that takes a map and a key
and returns a pointer to the associated value if such a key exists. Otherwise,
a `NULL` pointer is returned. Adjust all callers that can trivially be
converted.

1 files changed, 3 insertions, 10 deletions

diff --git a/src/pack-objects.c b/src/pack-objects.c
index 4ccc84d4b..094317a80 100644
--- a/src/pack-objects.c
+++ b/src/pack-objects.c
@@ -512,15 +512,12 @@ static int cb_tag_foreach(const char *name, git_oid *oid, void *data)
 {
 	git_packbuilder *pb = data;
 	git_pobject *po;
-	size_t pos;
 
 	GIT_UNUSED(name);
 
-	pos = git_oidmap_lookup_index(pb->object_ix, oid);
-	if (!git_oidmap_valid_index(pb->object_ix, pos))
+	if ((po = git_oidmap_get(pb->object_ix, oid)) == NULL)
 		return 0;
 
-	po = git_oidmap_value_at(pb->object_ix, pos);
 	po->tagged = 1;
 
 	/* TODO: peel objects */
@@ -1537,14 +1534,10 @@ static int lookup_walk_object(struct walk_object **out, git_packbuilder *pb, con
 
 static int retrieve_object(struct walk_object **out, git_packbuilder *pb, const git_oid *id)
 {
-	int error;
-	size_t pos;
 	struct walk_object *obj;
+	int error;
 
-	pos = git_oidmap_lookup_index(pb->walk_objects, id);
-	if (git_oidmap_valid_index(pb->walk_objects, pos)) {
-		obj = git_oidmap_value_at(pb->walk_objects, pos);
-	} else {
+	if ((obj = git_oidmap_get(pb->walk_objects, id)) == NULL) {
 		if ((error = lookup_walk_object(&obj, pb, id)) < 0)
 			return error;