viewdiff: make $UNSAFE a variable

There's no sense in using a constant here since it
gets copied into the uri_escape_utf8 function anyways.
Furthermore, inlined constants still leave behind a
subroutine and subs cost several KB of memory.

Finally, add a comment as to why it's different than the default
escape, since I just spent a minute wondering that.

1 files changed, 4 insertions, 5 deletions

diff --git a/lib/PublicInbox/ViewDiff.pm b/lib/PublicInbox/ViewDiff.pm
index d2c5fabe..05acc242 100644
--- a/lib/PublicInbox/ViewDiff.pm
+++ b/lib/PublicInbox/ViewDiff.pm
@@ -15,8 +15,7 @@ use URI::Escape qw(uri_escape_utf8);
 use PublicInbox::Hval qw(ascii_html to_attr);
 use PublicInbox::Git qw(git_unquote);
 
-sub UNSAFE () { "^A-Za-z0-9\-\._~/" }
-
+my $UNSAFE = "^A-Za-z0-9\-\._~/"; # '/' + $URI::Escape::Unsafe{RFC3986}
 my $OID_NULL = '0{7,}';
 my $OID_BLOB = '[a-f0-9]{7,}';
 my $LF = qr!\n!;
@@ -124,14 +123,14 @@ sub diff_header ($$$) {
         $pa = (split(m'/', git_unquote($pa), 2))[1] if $pa ne '/dev/null';
         $pb = (split(m'/', git_unquote($pb), 2))[1] if $pb ne '/dev/null';
         if ($pa eq $pb && $pb ne '/dev/null') {
-                $dctx->{Q} = "?b=".uri_escape_utf8($pb, UNSAFE);
+                $dctx->{Q} = "?b=".uri_escape_utf8($pb, $UNSAFE);
         } else {
                 my @q;
                 if ($pb ne '/dev/null') {
-                        push @q, 'b='.uri_escape_utf8($pb, UNSAFE);
+                        push @q, 'b='.uri_escape_utf8($pb, $UNSAFE);
                 }
                 if ($pa ne '/dev/null') {
-                        push @q, 'a='.uri_escape_utf8($pa, UNSAFE);
+                        push @q, 'a='.uri_escape_utf8($pa, $UNSAFE);
                 }
                 $dctx->{Q} = '?'.join('&', @q);
         }