Clarify the role of each function and in particular mention that there
is no need for the backend or stream to worry about the object's id,
as it will be given when `finalize_write` is called.
The frontend is in charge of calculating the id of the objects. Thus
the backends should treat it as a read-only value. The positioning in
the function signature made it seem as though it was an output
parameter.
Make the id const and move it from the front to behind the subject
(backend or stream).
new functions in struct git_config_backend:
* iterator_new(...)
* iterator_free(...)
* next(...)
The old callback based foreach style can still be used with `git_config_backend_foreach_match`
The GIT_CONFIG_LEVEL constants actually work well as an enum
because they are mutually exclusive, so this adds a typedef to
the enum and uses that everywhere that one of these constants are
expected, instead of the old code that typically used an unsigned
int.
Nobody should ever be using anything other than ALL at this level, so
remove the option altogether.
As part of this, git_reference_foreach_glob is now implemented in the
frontend using an iterator. Backends will later regain the ability of
doing the glob filtering in the backend.
This moves most of the refdb stuff over to the include/git2/sys
directory, with some minor shifts in function organization.
While I was making the necessary updates, I also removed the
trailing whitespace in a few files that I modified just because I
was there and it was bugging me.
Actually this renames git_commit_create_oid to
git_commit_create_from_oids and moves the API declaration to
include/git2/sys/commit.h since it is a dangerous API for general
use (because it doesn't check that the OID list items actually
refer to real objects).
This moves some of the odb_backend stuff that is related to the
internals of an odb_backend implementation into include/git2/sys.
Some of the stuff related to streaming I left in include/git2
because it seemed like it would be reasonably needed by a normal
user who wanted to stream objects into and out of the ODB.
Also, I added APIs for traversing the list of backends so that
some of the tests would not need to access ODB internals.
