From b0bacf791921a610d4acfe7466ffeef48d383b52 Mon Sep 17 00:00:00 2001
From: Steve Hancock <perltidy@users.sourceforge.net>
Date: Thu, 8 Oct 2020 19:18:39 -0700
Subject: [PATCH] replaced sub link_back with more efficient loop

---
 lib/Perl/Tidy/Formatter.pm | 23 ++++++++++++++++++++---
 1 file changed, 20 insertions(+), 3 deletions(-)

diff --git a/lib/Perl/Tidy/Formatter.pm b/lib/Perl/Tidy/Formatter.pm
index 5b989eb1..3edd23a5 100644
--- a/lib/Perl/Tidy/Formatter.pm
+++ b/lib/Perl/Tidy/Formatter.pm
@@ -4471,7 +4471,8 @@ sub respace_tokens {
         my $type_sequence = $item->[_TYPE_SEQUENCE_];
         if ($type_sequence) {
 
-            $link_back->( $KK_new, _KNEXT_SEQ_ITEM_ );
+            ## moved below, this was very slow
+            ##$link_back->( $KK_new, _KNEXT_SEQ_ITEM_ );
 
             my $token = $item->[_TOKEN_];
             if ( $is_opening_token{$token} ) {
@@ -4492,8 +4493,14 @@ sub respace_tokens {
                     $K_closing_ternary->{$type_sequence} = $KK_new;
                 }
                 else {
-                    # shouldn't happen
-                    Fault("Ugh: shouldn't happen");
+
+                    # We really shouldn't arrive here, just being cautious:
+		    # The only sequenced types output by the tokenizer are the
+		    # opening & closing containers and the ternary types.
+                    my $type = $item->[_TYPE_];
+                    Fault(
+"Unexpected token type with sequence number: type='$type', seqno='$type_sequence'"
+                    );
                 }
             }
         }
@@ -5273,6 +5280,16 @@ sub respace_tokens {
         }    # End token loop
     }    # End line loop
 
+    # Walk backwards through the tokens, making forward links to sequence items
+    # This replaces calls to sub link_back above, which was inefficient.
+    if ( @{$rLL_new} ) {
+        my $KNEXT;
+        for ( my $KK = @{$rLL_new} - 1 ; $KK >= 0 ; $KK-- ) {
+            $rLL_new->[$KK]->[_KNEXT_SEQ_ITEM_] = $KNEXT;
+            if ( $rLL_new->[$KK]->[_TYPE_SEQUENCE_] ) { $KNEXT = $KK }
+        }
+    }
+
     # Reset memory to be the new array
     $self->[_rLL_] = $rLL_new;
     $self->set_rLL_max_index();
-- 
2.39.5