[TopGit PATCH 01/10] cat_file: take -i/-w parameters

[Bert Wesarg <bert.wesarg@googlemail.com>]

This changes the way how cat_file selects the source of the file. It
accepts an optional parameter which is either -i or -w and will react on this
instead of the branch name. tg-patch is updated accordingly and can now
accepts the current branch name as argument with -i or -w given.

cat_file was also broken for the worktree case when we are not in the top level.

Also, tg-patch allowed to be on the top-base branch, but -i and -w doesn't
make sense there too.

Signed-off-by: Bert Wesarg <bert.wesarg@googlemail.com>

---

I will probably never understand why TopGit accepts to be on a top-base branch.
I will probably never understand why TopGit not changes the cwd to the top level.
I will probably never understand why TopGit does not use the git-sh-setup.sh.
---
 tg-patch.sh |   25 ++++++++++++++-----------
 tg.sh       |   27 +++++++++++++++------------
 2 files changed, 29 insertions(+), 23 deletions(-)

diff --git a/tg-patch.sh b/tg-patch.sh
index 7bafdfe..5b7386a 100644 tg-patch.sh
--- a/tg-patch.sh
+++ b/tg-patch.sh
@@ -5,7 +5,7 @@
 
 name=
 
-topic=
+head_from=
 diff_opts=
 diff_committed_only=yes	# will be unset for index/worktree
 
@@ -16,11 +16,13 @@ while [ -n "$1" ]; do
 	arg="$1"; shift
 	case "$arg" in
 	-i)
-		topic='(i)'
+		[ -z "$head_from" ] || die "-i and -w are mutually exclusive"
+		head_from=-i
 		diff_opts="$diff_opts --cached";
 		diff_committed_only=;;
 	-w)
-		topic='(w)'
+		[ -z "$head_from" ] || die "-i and -w are mutually exclusive"
+		head_from=-w
 		diff_committed_only=;;
 	-*)
 		echo "Usage: tg [...] patch [-i | -w] [NAME]" >&2
@@ -31,22 +33,23 @@ while [ -n "$1" ]; do
 	esac
 done
 
+head="$(git symbolic-ref HEAD)"
+head="${head#refs/heads/}"
 
-[ -n "$name"  -a  -z "$diff_committed_only" ]  &&
-	die "-i/-w are mutually exclusive with NAME"
-
-[ -n "$name" ] || name="$(git symbolic-ref HEAD | sed 's#^refs/\(heads\|top-bases\)/##')"
+[ -n "$name" ] ||
+	name="$head"
 base_rev="$(git rev-parse --short --verify "refs/top-bases/$name" 2>/dev/null)" ||
 	die "not a TopGit-controlled branch"
 
-# if not index/worktree, topic is current branch
-[ -z "$topic" ] && topic="$name"
+if [ -n "$head_from" ] && [ "$name" != "$head" ]; then
+	die "$head_from makes only sense for the current branch"
+fi
 
 
 
 setup_pager
 
-cat_file "$topic:.topmsg"
+cat_file "$name:.topmsg" $head_from
 echo
 [ -n "$(git grep $diff_opts '^[-]--' ${diff_committed_only:+"$name"} -- ".topmsg")" ] || echo '---'
 
@@ -64,7 +67,7 @@ fi
 rm "$git_is_stupid"
 
 echo '-- '
-echo "tg: ($base_rev..) $name (depends on: $(cat_file "$topic:.topdeps" | paste -s -d' '))"
+echo "tg: ($base_rev..) $name (depends on: $(cat_file "$name:.topdeps" $head_from | paste -s -d' '))"
 branch_contains "$name" "$base_rev" ||
 	echo "tg: The patch is out-of-date wrt. the base! Run \`$tg update\`."
 
diff --git a/tg.sh b/tg.sh
index 3718702..4d7d4ef 100644 tg.sh
--- a/tg.sh
+++ b/tg.sh
@@ -18,24 +18,27 @@ die()
 	exit 1
 }
 
-# cat_file "topic:file"
-# Like `git cat-file blob $1`, but topics '(i)' and '(w)' means index and worktree
+# cat_file TOPIC:PATH FROM
+# cat the file PATH from branch TOPIC when FROM is empty.
+# FROM can be -i or -w, than the file will be from the index or worktree,
+# respectively. The caller should than ensure that HEAD is TOPIC, to make sense.
 cat_file()
 {
-	arg="$1"
-	case "$arg" in
-	'(w):'*)
-		arg=$(echo "$arg" | tail --bytes=+5)
-		cat "$arg"
-		return
+	path="$1"
+	case "${2-}" in
+	-w)
+		cat "$root_dir/${path#*:}"
 		;;
-	'(i):'*)
+	-i)
 		# ':file' means cat from index
-		arg=$(echo "$arg" | tail --bytes=+5)
-		git cat-file blob ":$arg"
+		git cat-file blob ":${path#*:}"
+		;;
+	'')
+		git cat-file blob "$path"
 		;;
 	*)
-		git cat-file blob "$arg"
+		die "Wrong argument to cat_file: '$2'"
+		;;
 	esac
 }
 
-- 
1.7.1.1067.g5aeb7