revision: add --maximal-only option

When inspecting a range of commits from some set of starting references, it
is sometimes useful to learn which commits are not reachable from any other
commits in the selected range.

One such application is in the creation of a sequence of bundles for the
bundle URI feature. Creating a stack of bundles representing different
slices of time includes defining which references to include. If all
references are used, then this may be overwhelming or redundant. Instead,
selecting commits that are maximal to the range could help defining a
smaller reference set to use in the bundle header.

Add a new '--maximal-only' option to restrict the output of a revision range
to be only the commits that are not reachable from any other commit in the
range, based on the reachability definition of the walk.

This is accomplished by adding a new 28th bit flag, CHILD_VISITED, that is
set as we walk. This does extend the bit range in object.h, but using an
earlier bit may collide with another feature.

The tests demonstrate the behavior of the feature with a positive-only
range, ranges with negative references, and walk-modifying flags like
--first-parent and --exclude-first-parent-only.

Since the --boundary option would not increase any results when used with
the --maximal-only option, mark them as incompatible.

Signed-off-by: Derrick Stolee <stolee@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

0 files changed, 0 insertions, 0 deletions