git/git-merge.sh
Junio C Hamano 64da9e604e Add 'ours' merge strategy.
This adds the coolest merge strategy ever, "ours".  It can take
arbitrary number of foreign heads and merge them into the
current branch, with the resulting tree always taken from our
branch head, hence its name.

What this means is that you can declare that the current branch
supersedes the development histories of other branches using
this merge strategy.

Signed-off-by: Junio C Hamano <junkio@cox.net>
2005-11-03 14:55:10 -08:00

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#!/bin/sh
#
# Copyright (c) 2005 Junio C Hamano
#
. git-sh-setup || die "Not a git archive"
LF='
'
usage () {
die "git-merge [-n] [--no-commit] [-s <strategy>]... <merge-message> <head> <remote>+"
}
# all_strategies='resolve recursive stupid octopus'
all_strategies='recursive octopus resolve stupid ours'
default_strategies='resolve octopus'
use_strategies=
dropsave() {
rm -f -- "$GIT_DIR/MERGE_HEAD" "$GIT_DIR/MERGE_MSG" \
"$GIT_DIR/MERGE_SAVE" || exit 1
}
savestate() {
# Stash away any local modifications.
git-diff-index -z --name-only $head |
cpio -0 -o >"$GIT_DIR/MERGE_SAVE"
}
restorestate() {
if test -f "$GIT_DIR/MERGE_SAVE"
then
git reset --hard $head
cpio -iuv <"$GIT_DIR/MERGE_SAVE"
git-update-index --refresh >/dev/null
fi
}
finish () {
test '' = "$2" || echo "$2"
case "$merge_msg" in
'')
echo "No merge message -- not updating HEAD"
;;
*)
git-update-ref HEAD "$1" "$head" || exit 1
;;
esac
case "$no_summary" in
'')
git-diff-tree -p -M "$head" "$1" |
git-apply --stat --summary
;;
esac
}
while case "$#" in 0) break ;; esac
do
case "$1" in
-n|--n|--no|--no-|--no-s|--no-su|--no-sum|--no-summ|\
--no-summa|--no-summar|--no-summary)
no_summary=t ;;
--no-c|--no-co|--no-com|--no-comm|--no-commi|--no-commit)
no_commit=t ;;
-s=*|--s=*|--st=*|--str=*|--stra=*|--strat=*|--strate=*|\
--strateg=*|--strategy=*|\
-s|--s|--st|--str|--stra|--strat|--strate|--strateg|--strategy)
case "$#,$1" in
*,*=*)
strategy=`expr "$1" : '-[^=]*=\(.*\)'` ;;
1,*)
usage ;;
*)
strategy="$2"
shift ;;
esac
case " $all_strategies " in
*" $strategy "*)
use_strategies="$use_strategies$strategy " ;;
*)
die "available strategies are: $all_strategies" ;;
esac
;;
-*) usage ;;
*) break ;;
esac
shift
done
case "$use_strategies" in
'')
use_strategies=$default_strategies
;;
esac
test "$#" -le 2 && usage ;# we need at least two heads.
merge_msg="$1"
shift
head_arg="$1"
head=$(git-rev-parse --verify "$1"^0) || usage
shift
# All the rest are remote heads
for remote
do
git-rev-parse --verify "$remote"^0 >/dev/null ||
die "$remote - not something we can merge"
done
common=$(git-show-branch --merge-base $head "$@")
echo "$head" >"$GIT_DIR/ORIG_HEAD"
case "$#,$common,$no_commit" in
*,'',*)
# No common ancestors found. We need a real merge.
;;
1,"$1",*)
# If head can reach all the merge then we are up to date.
# but first the most common case of merging one remote
echo "Already up-to-date."
dropsave
exit 0
;;
1,"$head",*)
# Again the most common case of merging one remote.
echo "Updating from $head to $1."
git-update-index --refresh 2>/dev/null
new_head=$(git-rev-parse --verify "$1^0") &&
git-read-tree -u -m $head "$new_head" &&
finish "$new_head" "Fast forward"
dropsave
exit 0
;;
1,?*"$LF"?*,*)
# We are not doing octopus and not fast forward. Need a
# real merge.
;;
1,*,)
# We are not doing octopus, not fast forward, and have only
# one common. See if it is really trivial.
echo "Trying really trivial in-index merge..."
git-update-index --refresh 2>/dev/null
if git-read-tree --trivial -m -u $common $head "$1" &&
result_tree=$(git-write-tree)
then
echo "Wonderful."
result_commit=$(
echo "$merge_msg" |
git-commit-tree $result_tree -p HEAD -p "$1"
) || exit
finish "$result_commit" "In-index merge"
dropsave
exit 0
fi
echo "Nope."
;;
*)
# An octopus. If we can reach all the remote we are up to date.
up_to_date=t
for remote
do
common_one=$(git-merge-base $head $remote)
if test "$common_one" != "$remote"
then
up_to_date=f
break
fi
done
if test "$up_to_date" = t
then
echo "Already up-to-date. Yeeah!"
dropsave
exit 0
fi
;;
esac
# At this point, we need a real merge. No matter what strategy
# we use, it would operate on the index, possibly affecting the
# working tree, and when resolved cleanly, have the desired tree
# in the index -- this means that the index must be in sync with
# the $head commit. The strategies are responsible to ensure this.
case "$use_strategies" in
?*' '?*)
# Stash away the local changes so that we can try more than one.
savestate
single_strategy=no
;;
*)
rm -f "$GIT_DIR/MERGE_SAVE"
single_strategy=yes
;;
esac
result_tree= best_cnt=-1 best_strategy= wt_strategy=
for strategy in $use_strategies
do
test "$wt_strategy" = '' || {
echo "Rewinding the tree to pristine..."
restorestate
}
case "$single_strategy" in
no)
echo "Trying merge strategy $strategy..."
;;
esac
# Remember which strategy left the state in the working tree
wt_strategy=$strategy
git-merge-$strategy $common -- "$head_arg" "$@"
exit=$?
if test "$no_commit" = t && test "$exit" = 0
then
exit=1 ;# pretend it left conflicts.
fi
test "$exit" = 0 || {
# The backend exits with 1 when conflicts are left to be resolved,
# with 2 when it does not handle the given merge at all.
if test "$exit" -eq 1
then
cnt=`{
git-diff-files --name-only
git-ls-files --unmerged
} | wc -l`
if test $best_cnt -le 0 -o $cnt -le $best_cnt
then
best_strategy=$strategy
best_cnt=$cnt
fi
fi
continue
}
# Automerge succeeded.
result_tree=$(git-write-tree) && break
done
# If we have a resulting tree, that means the strategy module
# auto resolved the merge cleanly.
if test '' != "$result_tree"
then
parents="-p $head"
for remote
do
parents="$parents -p $remote"
done
result_commit=$(echo "$merge_msg" | git-commit-tree $result_tree $parents) || exit
finish "$result_commit" "Merge $result_commit, made by $wt_strategy."
dropsave
exit 0
fi
# Pick the result from the best strategy and have the user fix it up.
case "$best_strategy" in
'')
restorestate
die "No merge strategy handled the merge."
;;
"$wt_strategy")
# We already have its result in the working tree.
;;
*)
echo "Rewinding the tree to pristine..."
restorestate
echo "Using the $best_strategy to prepare resolving by hand."
git-merge-$best_strategy $common -- "$head_arg" "$@"
;;
esac
for remote
do
echo $remote
done >"$GIT_DIR/MERGE_HEAD"
echo $merge_msg >"$GIT_DIR/MERGE_MSG"
die "Automatic merge failed/prevented; fix up by hand"