+## Quilt driver
+
+quilt()
+{
+ if [ -z "$_dep_is_tgish" ]; then
+ # This dep is not for rewrite
+ return
+ fi
+
+ if "$flatten"; then
+ bn="$(echo "$_dep.diff" | sed -e 's#_#__#g' -e 's#/#_#g')";
+ dn="";
+ else
+ bn="$(basename "$_dep.diff")";
+ dn="$(dirname "$_dep.diff")/";
+ if [ "x$dn" = "x./" ]; then
+ dn="";
+ fi;
+ fi;
+
+ if [ -e "$playground/$_dep" ]; then
+ # We've already seen this dep
+ return
+ fi
+
+ mkdir -p "$playground/$(dirname "$_dep")";
+ touch "$playground/$_dep";
+
+ if branch_empty "$_dep"; then
+ echo "Skip empty patch $_dep";
+ else
+ if "$numbered"; then
+ number="$(printf "%04u" $(($(cat "$playground/^number" 2>/dev/null) + 1)))";
+ bn="$number-$bn";
+ echo "$number" >"$playground/^number";
+ fi;
+
+ echo "Exporting $_dep"
+ mkdir -p "$output/$dn";
+ $tg patch "$_dep" >"$output/$dn$bn"
+ echo "$dn$bn -p1" >>"$output/series"
+ fi
+}
+
+
+## Machinery
+
+if [ "$driver" = "collapse" ]; then
+ [ -n "$output" ] ||
+ die "no target branch specified"
+ ! ref_exists "$output" ||
+ die "target branch '$output' already exists; first run: git branch -D $output"
+
+elif [ "$driver" = "quilt" ]; then
+ [ -n "$output" ] ||
+ die "no target directory specified"
+ [ ! -e "$output" ] ||
+ die "target directory already exists: $output"
+
+ mkdir -p "$output"
+fi
+
+
+driver()
+{
+ case $_dep in refs/remotes/*) return;; esac
+ branch_needs_update >/dev/null
+ [ "$_ret" -eq 0 ] ||
+ die "cancelling export of $_dep (-> $_name): branch not up-to-date"
+
+ $driver
+}
+
+# Call driver on all the branches - this will happen
+# in topological order.
+if [ -z "$branches" ]; then
+ recurse_deps driver "$name"
+ (_ret=0; _dep="$name"; _name=""; _dep_is_tgish=1; driver)
+else
+ echo "$branches" | tr ',' '\n' | while read _dep; do
+ _dep_is_tgish=1
+ $driver
+ done
+ name="$(echo "$branches" | sed 's/.*,//')"
+fi
+
+
+if [ "$driver" = "collapse" ]; then
+ git update-ref "refs/heads/$output" "$(cat "$playground/$name")" ""
+
+ depcount="$(cat "$playground/^ticker" | wc -l)"
+ echo "Exported topic branch $name (total $depcount topics) to branch $output"
+
+elif [ "$driver" = "quilt" ]; then
+ depcount="$(cat "$output/series" | wc -l)"
+ echo "Exported topic branch $name (total $depcount topics) to directory $output"
+fi