Make "git checkout" know about different branches

Now "git checkout xyzzy" will check out branch "xyzzy" and
switch the HEAD to it.

diff --git a/git-checkout-script b/git-checkout-script
index dc1cffd..a3bfae7 100755 (executable)
--- a/git-checkout-script
+++ b/git-checkout-script
@@ -1,27 +1,35 @@
 #!/bin/sh
 : ${GIT_DIR=.git}
 old=$(git-rev-parse HEAD)
-new=$(git-rev-parse --revs-only "$@")
-new=${new:-$old}
-args=($(git-rev-parse --no-revs "$@"))
-
-i=0
+new=
 force=
-update=
-while [ $i -lt ${#args} ]; do
-    case "${args[$i]}" in
+branch=
+while [ "$#" != "0" ]; do
+    arg="$1"
+    shift
+    case "$arg" in
        "-f")
-               force=1;;
-       "-u")
-               update=1;;
-       "")
+               force=1
                ;;
        *)
-               echo "unknown flag ${args[$i]}"
-               exit 1;;
+               rev=$(git-rev-parse "$arg")
+               if [ -z "$rev" ]; then
+                       echo "unknown flag $arg"
+                       exit 1
+               fi
+               if [ "$new" ]; then
+                       echo "Multiple revisions?"
+                       exit 1
+               fi
+               new="$rev"
+               if [ -f "$GIT_DIR/revs/heads/$arg" ]; then
+                       branch="$arg"
+               fi
+               ;;
     esac
     i=$(($i+1))
 done
+: ${new=$old}
 
 if [ "$force" ]
 then
@@ -29,5 +37,4 @@ then
        git-checkout-cache -q -f -u -a
 else
     git-read-tree -m -u $old $new
-fi && [ "$update" ] && echo $new > "$GIT_DIR/HEAD"
-
+fi && [ "$branch" ] && ln -sf "refs/heads/$branch" "$GIT_DIR/HEAD"