patches: Optimize the multiple files case

I didn't put too many thoughts when adding support for multiple files
to the "patches" command. The nested loop approach turns out to be
very inefficient for unapplied patches.

Get rid of the innermost loop by building a single pattern matching
all filenames at once. That way, performance no longer depends on the
number of files (as far as unapplied patches are concerned.)

2 files changed, 23 insertions, 13 deletions

diff --git a/quilt/patches.in b/quilt/patches.in
index 6ec5e01..89c5b86 100644
--- a/quilt/patches.in
+++ b/quilt/patches.in
@@ -88,7 +88,7 @@ scan_unapplied()
 {
 	local color=$1 prefix=$2 strip
 	shift 2
-	local patch file match
+	local patch file
 	local -a files_bre
 
 	# Quote each file name only once
@@ -97,23 +97,19 @@ scan_unapplied()
 		files_bre[${#files_bre[@]}]=$(quote_bre "$file")
 	done
 
+	# "Or" all files in a single pattern
+	file=\\\($(array_join \\\| "${files_bre[@]}")\\\)
+
 	for patch in "$@"
 	do
 		strip=$(patch_strip_level $patch)
 		[ "$strip" = ab ] && strip=1
 
-		match=
-		for file in "${files_bre[@]}"
-		do
-			if touched_by_patch $strip $patch \
-			   | grep -q "^$file\$"
-			then
-				match=1
-				break
-			fi
-		done
-
-		[ -z "$match" ] || echo "$color$prefix$(print_patch $patch)$color_clear"
+		if touched_by_patch $strip "$patch" \
+		   | grep -q "^$file\$"
+		then
+			echo "$color$prefix$(print_patch $patch)$color_clear"
+		fi
 	done
 }
 
diff --git a/quilt/scripts/patchfns.in b/quilt/scripts/patchfns.in
index 42e8de8..e00c819 100644
--- a/quilt/scripts/patchfns.in
+++ b/quilt/scripts/patchfns.in
@@ -76,6 +76,20 @@ trap run_exit_handlers EXIT
 
 # ========================================================
 
+# Join multiple stings using the given separator.
+array_join()
+{
+	local sep=$1 str=$2
+	shift 2
+
+	printf %s "$str"
+
+	for str in "$@"
+	do
+		printf %s%s "$sep" "$str"
+	done
+}
+
 # Quote a string for use in a basic regular expression.
 quote_bre()
 {