rebase -i: rearrange fixup/squash lines using the rebase--helper
commitc44a4c650c66eb7b8d50c57fd4e1bff1add7bf77
authorJohannes Schindelin <johannes.schindelin@gmx.de>
Fri, 14 Jul 2017 14:45:31 +0000 (14 16:45 +0200)
committerJunio C Hamano <gitster@pobox.com>
Thu, 27 Jul 2017 22:35:06 +0000 (27 15:35 -0700)
tree117981093dba638b85433c00c123d48bd2085f06
parentb174ae7df2aa196beefca605f2df778ad15b6ad7
rebase -i: rearrange fixup/squash lines using the rebase--helper

This operation has quadratic complexity, which is especially painful
on Windows, where shell scripts are *already* slow (mainly due to the
overhead of the POSIX emulation layer).

Let's reimplement this with linear complexity (using a hash map to
match the commits' subject lines) for the common case; Sadly, the
fixup/squash feature's design neglected performance considerations,
allowing arbitrary prefixes (read: `fixup! hell` will match the
commit subject `hello world`), which means that we are stuck with
quadratic performance in the worst case.

The reimplemented logic also happens to fix a bug where commented-out
lines (representing empty patches) were dropped by the previous code.

While at it, clarify how the fixup/squash feature works in `git rebase
-i`'s man page.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Documentation/git-rebase.txt
builtin/rebase--helper.c
git-rebase--interactive.sh
sequencer.c
sequencer.h
t/t3415-rebase-autosquash.sh