stash: implement "stash create"

This subcommand creates a stash from the current state and writes out the
resulting commit object ID to the standard output, without updating the
stash ref nor resetting the tree.  It is intended to be used by scripts
to temporarily rewind the working tree to a clean state.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/git-stash.sh b/git-stash.sh
index 7ba61625baff8236f51d6c0babe9747c43664351..04af892531b400716aad3502a37c89e36c9bad51 100755 (executable)
--- a/git-stash.sh
+++ b/git-stash.sh
@@ -25,19 +25,13 @@ clear_stash () {
        fi
 }
 
-save_stash () {
+create_stash () {
        stash_msg="$1"
 
        if no_changes
        then
-               echo >&2 'No local changes to save'
                exit 0
        fi
-       test -f "$GIT_DIR/logs/$ref_stash" ||
-               clear_stash || die "Cannot initialize stash"
-
-       # Make sure the reflog for stash is kept.
-       : >>"$GIT_DIR/logs/$ref_stash"
 
        # state of the base commit
        if b_commit=$(git rev-parse --verify HEAD)
@@ -84,7 +78,20 @@ save_stash () {
        w_commit=$(printf '%s\n' "$stash_msg" |
                git commit-tree $w_tree -p $b_commit -p $i_commit) ||
                die "Cannot record working tree state"
+}
 
+save_stash () {
+       stash_msg="$1"
+
+       if no_changes
+       then
+               echo >&2 'No local changes to save'
+               exit 0
+       fi
+       test -f "$GIT_DIR/logs/$ref_stash" ||
+               clear_stash || die "Cannot initialize stash"
+
+       create_stash "$stash_msg"
        git update-ref -m "$stash_msg" $ref_stash $w_commit ||
                die "Cannot save the current status"
        printf >&2 'Saved "%s"\n' "$stash_msg"
@@ -202,6 +209,13 @@ apply)
 clear)
        clear_stash
        ;;
+create)
+       if test $# -gt 0 && test "$1" = create
+       then
+               shift
+       fi
+       create_stash "$*" && echo "$w_commit"
+       ;;
 help | usage)
        usage
        ;;