development/git
development/git
1
0
Fork 0
mirror of https://github.com/git/git synced 2024-10-28 19:25:47 +00:00
Code Issues Projects Releases Packages Wiki Activity
No description
15696 commits 6 branches 956 tags 485 MiB
C 50.3%
Shell 38.6%
Perl 5.2%
Tcl 3.3%
Python 0.8%
Other 1.6%
Find a file
Junio C Hamano 83133740d9 xmerge.c: "diff3 -m" style clips merge reduction level to EAGER or less 
When showing a conflicting merge result, and "--diff3 -m" style is asked
for, this patch makes sure that the merge reduction level does not exceed
XDL_MERGE_EAGER.  This is because "diff3 -m" style output would not make
sense for anything more aggressive than XDL_MERGE_EAGER, because of the
way how the merge reduction works.

"git merge-file" no longer has to force MERGE_EAGER when "--diff3" is
asked for because of this change.

Suppose a common ancestor (shared preimage) is modified to postimage #1
and #2 (each letter represents one line):

                     #####
    postimage#1: 1234ABCDE789
                    |    /
                    |   /
    preimage:    123456789
                    |   \
    postimage#2: 1234AXYE789
                     ####

XDL_MERGE_MINIMAL and XDL_MERGE_EAGER would:

 (1) find the s/56/ABCDE/ done on one side and s/56/AXYE/ done on the
     other side,

 (2) notice that they touch an overlapping area, and

 (3) mark it as a conflict, "ABCDE vs AXYE".

The difference between the two algorithms is that EAGER drops the hunk
altogether if the postimages match (i.e. both sides modified the same
way), while MINIMAL keeps it.  There is no other operation performed to
the hunk.  As the result, lines marked with "#" in the above picure will
be in the RCS merge style output like this (letters <, = and > represent
conflict marker lines):

    output:      1234<ABCDE=AXYE>789    ; with MINIMAL/EAGER

The part from the preimage that corresponds to these conflicting changes
is "56", which is what "diff3 -m" style output adds to it:

    output:      1234<ABCDE|56=AXYE>789 ; in "diff3 -m" style

Now, XDL_MERGE_ZEALOUS looks at the differences between the changes two
postimages made in order to reduce the number of lines in the conflicting
regions.  It notices that both sides start their new contents with "A",
and excludes it from the output (it also excludes "E" for the same
reason).  The conflict that used to be "ABCDE vs AXYE" is now "BCD vs XY":

    output:      1234A<BCD=XY>E789      ; with ZEALOUS

There could even be matching parts between two postimages in the middle.
Instead of one side rewriting the shared "56" to "ABCDE" and the other
side to "AXYE", imagine the case where the postimages are "ABCDE" and
"AXCYE", in which case instead of having one conflicted hunk "BCD vs XY",
you would have two conflicting hunks "B vs X" and "D vs Y".

In either case, once you reduce "ABCDE vs AXYE" to "BCD vs XY" (or "ABCDE
vs AXCYE" to "B vs X" and "D vs Y"), there is no part from the preimage
that corresponds to the conflicting change made in both postimages
anymore.  In other words, conflict reduced by ZEALOUS algorithm cannot be
expressed in "diff3 -m" style.  Representing the last illustration like
this is misleading to say the least:

    output:      1234A<BCD|56=XY>E789   ; broken "diff3 -m" style

because the preimage was not ...4A56E... to begin with.  "A" and "E" are
common only between the postimages.

Even worse, once a single conflicting hunk is split into multiple ones
(recall the example of breaking "ABCDE vs AXCYE" to "B vs X" and "D vs
Y"), there is no sane way to distribute the preimage text across split
conflicting hunks.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-08-30 19:41:43 -07:00
arm
compat
contrib
Documentation
git-gui
gitk-git
gitweb
mozilla-sha1
perl
ppc
t
templates
xdiff xmerge.c: "diff3 -m" style clips merge reduction level to EAGER or less 2008-08-30 19:41:43 -07:00
.gitattributes
.gitignore
.mailmap
abspath.c
alias.c
alloc.c
archive-tar.c
archive-zip.c
archive.c
archive.h
attr.c
attr.h
base85.c
blob.c
blob.h
branch.c
branch.h
builtin-add.c
builtin-annotate.c
builtin-apply.c
builtin-archive.c
builtin-blame.c
builtin-branch.c
builtin-bundle.c
builtin-cat-file.c
builtin-check-attr.c
builtin-check-ref-format.c
builtin-checkout-index.c
builtin-checkout.c
builtin-clean.c
builtin-clone.c
builtin-commit-tree.c
builtin-commit.c
builtin-config.c
builtin-count-objects.c
builtin-describe.c
builtin-diff-files.c
builtin-diff-index.c
builtin-diff-tree.c
builtin-diff.c
builtin-fast-export.c
builtin-fetch--tool.c
builtin-fetch-pack.c
builtin-fetch.c
builtin-fmt-merge-msg.c
builtin-for-each-ref.c
builtin-fsck.c
builtin-gc.c
builtin-grep.c
builtin-http-fetch.c
builtin-init-db.c
builtin-log.c
builtin-ls-files.c
builtin-ls-remote.c
builtin-ls-tree.c
builtin-mailinfo.c
builtin-mailsplit.c
builtin-merge-base.c
builtin-merge-file.c xmerge.c: "diff3 -m" style clips merge reduction level to EAGER or less 2008-08-30 19:41:43 -07:00
builtin-merge-ours.c
builtin-merge-recursive.c
builtin-merge.c
builtin-mv.c
builtin-name-rev.c
builtin-pack-objects.c
builtin-pack-refs.c
builtin-prune-packed.c
builtin-prune.c
builtin-push.c
builtin-read-tree.c
builtin-reflog.c
builtin-remote.c
builtin-rerere.c
builtin-reset.c
builtin-rev-list.c
builtin-rev-parse.c
builtin-revert.c
builtin-rm.c
builtin-send-pack.c
builtin-shortlog.c
builtin-show-branch.c
builtin-show-ref.c
builtin-stripspace.c
builtin-symbolic-ref.c
builtin-tag.c
builtin-tar-tree.c
builtin-unpack-objects.c
builtin-update-index.c
builtin-update-ref.c
builtin-upload-archive.c
builtin-verify-pack.c
builtin-verify-tag.c
builtin-write-tree.c
builtin.h
bundle.c
bundle.h
cache-tree.c
cache-tree.h
cache.h
check-builtins.sh
check-racy.c
check_bindir
color.c
color.h
combine-diff.c
command-list.txt
commit.c
commit.h
config.c
config.mak.in
configure.ac
connect.c
convert.c
copy.c
COPYING
csum-file.c
csum-file.h
ctype.c
daemon.c
date.c
decorate.c
decorate.h
delta.h
diff-delta.c
diff-lib.c
diff-no-index.c
diff.c
diff.h
diffcore-break.c
diffcore-delta.c
diffcore-order.c
diffcore-pickaxe.c
diffcore-rename.c
diffcore.h
dir.c
dir.h
dump-cache-tree.c
editor.c
entry.c
environment.c
exec_cmd.c
exec_cmd.h
fast-import.c
fetch-pack.h
fixup-builtins
fsck.c
fsck.h
generate-cmdlist.sh
git-add--interactive.perl
git-am.sh
git-archimport.perl
git-bisect.sh
git-compat-util.h
git-cvsexportcommit.perl
git-cvsimport.perl
git-cvsserver.perl
git-filter-branch.sh
git-instaweb.sh
git-lost-found.sh
git-merge-octopus.sh
git-merge-one-file.sh
git-merge-resolve.sh
git-mergetool.sh
git-parse-remote.sh
git-pull.sh
git-quiltimport.sh
git-rebase--interactive.sh
git-rebase.sh
git-relink.perl
git-repack.sh
git-request-pull.sh
git-send-email.perl
git-sh-setup.sh
git-stash.sh
git-submodule.sh
git-svn.perl
GIT-VERSION-GEN
git-web--browse.sh
git.c
git.spec.in
graph.c
graph.h
grep.c
grep.h
hash-object.c
hash.c
hash.h
help.c
http-push.c
http-walker.c
http.c
http.h
ident.c
imap-send.c
index-pack.c
INSTALL
interpolate.c
interpolate.h
list-objects.c
list-objects.h
ll-merge.c
ll-merge.h
lockfile.c
log-tree.c
log-tree.h
mailmap.c
mailmap.h
Makefile
match-trees.c
merge-file.c
merge-index.c
merge-recursive.h
merge-tree.c
mktag.c
mktree.c
name-hash.c
object.c
object.h
pack-check.c
pack-redundant.c
pack-refs.c
pack-refs.h
pack-revindex.c
pack-revindex.h
pack-write.c
pack.h
pager.c
parse-options.c
parse-options.h
patch-delta.c
patch-id.c
patch-ids.c
patch-ids.h
path.c
pkt-line.c
pkt-line.h
pretty.c
progress.c
progress.h
quote.c
quote.h
reachable.c
reachable.h
read-cache.c
README
receive-pack.c
reflog-walk.c
reflog-walk.h
refs.c
refs.h
RelNotes
remote.c
remote.h
rerere.c
rerere.h
revision.c
revision.h
run-command.c
run-command.h
send-pack.h
server-info.c
setup.c
sha1-lookup.c
sha1-lookup.h
sha1_file.c
sha1_name.c
shallow.c
shell.c
shortlog.h
show-index.c
sideband.c
sideband.h
strbuf.c
strbuf.h
string-list.c
string-list.h
symlinks.c
tag.c
tag.h
tar.h
test-chmtime.c
test-date.c
test-delta.c
test-genrandom.c
test-match-trees.c
test-parse-options.c
test-path-utils.c
test-sha1.c
test-sha1.sh
thread-utils.c
thread-utils.h
trace.c
transport.c
transport.h
tree-diff.c
tree-walk.c
tree-walk.h
tree.c
tree.h
unpack-file.c
unpack-trees.c
unpack-trees.h
update-server-info.c
upload-pack.c
usage.c
utf8.c
utf8.h
var.c
walker.c
walker.h
wrapper.c
write_or_die.c
ws.c
wt-status.c
wt-status.h
xdiff-interface.c
xdiff-interface.h

README 

////////////////////////////////////////////////////////////////

	GIT - the stupid content tracker

////////////////////////////////////////////////////////////////

"git" can mean anything, depending on your mood.

 - random three-letter combination that is pronounceable, and not
   actually used by any common UNIX command.  The fact that it is a
   mispronunciation of "get" may or may not be relevant.
 - stupid. contemptible and despicable. simple. Take your pick from the
   dictionary of slang.
 - "global information tracker": you're in a good mood, and it actually
   works for you. Angels sing, and a light suddenly fills the room.
 - "goddamn idiotic truckload of sh*t": when it breaks

Git is a fast, scalable, distributed revision control system with an
unusually rich command set that provides both high-level operations
and full access to internals.

Git is an Open Source project covered by the GNU General Public License.
It was originally written by Linus Torvalds with help of a group of
hackers around the net. It is currently maintained by Junio C Hamano.

Please read the file INSTALL for installation instructions.
See Documentation/tutorial.txt to get started, then see
Documentation/everyday.txt for a useful minimum set of commands,
and "man git-commandname" for documentation of each command.
CVS users may also want to read Documentation/cvs-migration.txt.

Many Git online resources are accessible from http://git.or.cz/
including full documentation and Git related tools.

The user discussion and development of Git take place on the Git
mailing list -- everyone is welcome to post bug reports, feature
requests, comments and patches to git@vger.kernel.org. To subscribe
to the list, send an email with just "subscribe git" in the body to
majordomo@vger.kernel.org. The mailing list archives are available at
http://marc.theaimsgroup.com/?l=git and other archival sites.

The messages titled "A note from the maintainer", "What's in
git.git (stable)" and "What's cooking in git.git (topics)" and
the discussion following them on the mailing list give a good
reference for project status, development direction and
remaining tasks.