viewdiff: favor `qr' to precompile regexps

We can also avoid `o' regexp modifier, since it isn't
recommended by Perl upstream, anymore (although we don't
have any bugs or unintended behavior because of it).

1 files changed, 26 insertions, 21 deletions

diff --git a/lib/PublicInbox/ViewDiff.pm b/lib/PublicInbox/ViewDiff.pm
index 57a1b5d6..d22c80b9 100644
--- a/lib/PublicInbox/ViewDiff.pm
+++ b/lib/PublicInbox/ViewDiff.pm
@@ -25,7 +25,23 @@ my $ANY = qr![^\n]!;
 my $FN = qr!(?:"?[^/\n]+/[^\n]+|/dev/null)!;
 
 # cf. git diff.c :: get_compact_summary
-my $DIFFSTAT_COMMENT = qr/\((?:new|gone|(?:(?:new|mode) [\+\-][lx]))\)/;
+my $DIFFSTAT_COMMENT =
+        qr/(?: *\((?:new|gone|(?:(?:new|mode) [\+\-][lx]))\))? *\z/s;
+my $NULL_TO_BLOB = qr/^(index $OID_NULL\.\.)($OID_BLOB)\b/ms;
+my $BLOB_TO_NULL = qr/^index ($OID_BLOB)(\.\.$OID_NULL)\b/ms;
+my $BLOB_TO_BLOB = qr/^index ($OID_BLOB)\.\.($OID_BLOB)/ms;
+my $EXTRACT_DIFFS = qr/(
+                (?:        # begin header stuff, don't capture filenames, here,
+                        # but instead wait for the --- and +++ lines.
+                        (?:^diff\x20--git\x20$FN\x20$FN$LF)
+
+                        # old mode || new mode || copy|rename|deleted|...
+                        (?:^[a-z]$ANY+$LF)*
+                )? # end of optional stuff, everything below is required
+                ^index\x20($OID_BLOB)\.\.($OID_BLOB)$ANY*$LF
+                ^---\x20($FN)$LF
+                ^\+{3}\x20($FN)$LF)/msx;
+my $IS_OID = qr/\A$OID_BLOB\z/s;
 
 # link to line numbers in blobs
 sub diff_hunk ($$$$) {
@@ -62,7 +78,7 @@ sub anchor0 ($$$$) {
         # So only do best-effort handling of renames for common cases;
         # which works well in practice. If projects put "=>", or trailing
         # spaces in filenames, oh well :P
-        $fn =~ s/(?: *$DIFFSTAT_COMMENT)? *\z//so;
+        $fn =~ s/$DIFFSTAT_COMMENT//;
         $fn =~ s/{(?:.+) => (.+)}/$1/ or $fn =~ s/.* => (.+)/$1/;
         $fn = git_unquote($fn);
 
@@ -132,18 +148,17 @@ sub diff_header ($$$$) {
 
         # no need to capture oid_a and oid_b on add/delete,
         # we just linkify OIDs directly via s///e in conditional
-        if (($$x =~ s/^(index $OID_NULL\.\.)($OID_BLOB)\b/
-                        $1 . oid($dctx, $spfx, $2)/emos) ||
-                ($$x =~ s/^index ($OID_BLOB)(\.\.$OID_NULL)\b/
-                        'index ' . oid($dctx, $spfx, $1) . $2/emos)) {
-        } elsif ($$x =~ /^index ($OID_BLOB)\.\.($OID_BLOB)/mos) {
+        if (($$x =~ s/$NULL_TO_BLOB/$1 . oid($dctx, $spfx, $2)/e) ||
+                ($$x =~ s/$BLOB_TO_NULL/
+                        'index ' . oid($dctx, $spfx, $1) . $2/e)) {
+        } elsif ($$x =~ $BLOB_TO_BLOB) {
                 # modification-only, not add/delete:
                 # linkify hunk headers later using oid_a and oid_b
                 @$dctx{qw(oid_a oid_b)} = ($1, $2);
         } else {
                 warn "BUG? <$$x> had no ^index line";
         }
-        $$x =~ s!^diff --git!anchor1($ctx, $pb) // 'diff --git'!emos;
+        $$x =~ s!^diff --git!anchor1($ctx, $pb) // 'diff --git'!ems;
         $$dst .= qq(<span\nclass="head">);
         $$dst .= $$x;
         $$dst .= '</span>';
@@ -174,17 +189,7 @@ sub diff_before_or_after ($$$) {
 sub flush_diff ($$$) {
         my ($dst, $ctx, $cur) = @_;
 
-        my @top = split(/(
-                (?:        # begin header stuff, don't capture filenames, here,
-                        # but instead wait for the --- and +++ lines.
-                        (?:^diff\x20--git\x20$FN\x20$FN$LF)
-
-                        # old mode || new mode || copy|rename|deleted|...
-                        (?:^[a-z]$ANY+$LF)*
-                )? # end of optional stuff, everything below is required
-                ^index\x20($OID_BLOB)\.\.($OID_BLOB)$ANY*$LF
-                ^---\x20($FN)$LF
-                ^\+{3}\x20($FN)$LF)/smxo, $$cur);
+        my @top = split($EXTRACT_DIFFS, $$cur);
         $$cur = undef;
 
         my $linkify = $ctx->{-linkify};
@@ -192,8 +197,8 @@ sub flush_diff ($$$) {
 
         while (defined(my $x = shift @top)) {
                 if (scalar(@top) >= 4 &&
-                                $top[1] =~ /\A$OID_BLOB\z/os &&
-                                $top[0] =~ /\A$OID_BLOB\z/os) {
+                                $top[1] =~ $IS_OID &&
+                                $top[0] =~ $IS_OID) {
                         $dctx = diff_header($dst, \$x, $ctx, \@top);
                 } elsif ($dctx) {
                         my $after = '';