From f6e6dea5399a6b3aea85aaf1ddb00440c5b3973f Mon Sep 17 00:00:00 2001
From: Steve Hancock <perltidy@users.sourceforge.net>
Date: Wed, 9 Oct 2024 08:30:57 -0700
Subject: [PATCH] simplify sub compare_string_buffers

---
 lib/Perl/Tidy.pm | 80 ++++++++++++++++++++++++++++--------------------
 1 file changed, 46 insertions(+), 34 deletions(-)

diff --git a/lib/Perl/Tidy.pm b/lib/Perl/Tidy.pm
index daec260c..94251a56 100644
--- a/lib/Perl/Tidy.pm
+++ b/lib/Perl/Tidy.pm
@@ -3226,17 +3226,24 @@ sub compare_string_buffers {
 
     # Compare input and output string buffers and return a brief text
     # description of the first difference.
-
-    my $leni = defined($rbufi) ? length( ${$rbufi} ) : 0;
-    my $leno = defined($rbufo) ? length( ${$rbufo} ) : 0;
-    my $msg =
-      "Input  file length is $leni chars\nOutput file length is $leno chars\n";
+    my ( @aryi, @aryo );
+    my ( $leni, $leno ) = ( 0, 0 );
+    if ( defined($rbufi) ) {
+        $leni = length( ${$rbufi} );
+        @aryi = split /^/, ${$rbufi};
+    }
+    if ( defined($rbufo) ) {
+        $leno = length( ${$rbufo} );
+        @aryo = split /^/, ${$rbufo};
+    }
+    my $nlines_i = @aryi;
+    my $nlines_o = @aryo;
+    my $msg      = <<EOM;
+Input   file length has $leni chars in $nlines_i lines
+Output  file length has $leno chars in $nlines_o lines
+EOM
     return $msg unless ( $leni && $leno );
-    my @aryi = split /^/, ${$rbufi};
-    my @aryo = split /^/, ${$rbufo};
-    my ( $linei,  $lineo );
-    my ( $counti, $counto )                          = ( 0, 0 );
-    my ( $last_nonblank_line, $last_nonblank_count ) = ( EMPTY_STRING, 0 );
+
     my $truncate = sub {
         my ( $str, $lenmax ) = @_;
         if ( length($str) > $lenmax ) {
@@ -3245,28 +3252,31 @@ sub compare_string_buffers {
         return $str;
     }; ## end $truncate = sub
 
+    my $last_nonblank_line  = EMPTY_STRING;
+    my $last_nonblank_count = 0;
+
     # loop over lines until we find a difference
-    while ( @aryi || @aryo ) {
-        if ($linei) {
-            $last_nonblank_line  = $linei;
-            $last_nonblank_count = $counti;
+    my $count = 0;
+    while ( @aryi && @aryo ) {
+        $count++;
+        my $linei = shift @aryi;
+        my $lineo = shift @aryo;
+        chomp $linei;
+        chomp $lineo;
+        if ( $linei eq $lineo ) {
+            if ( length($linei) ) {
+                $last_nonblank_line  = $linei;
+                $last_nonblank_count = $count;
+            }
+            next;
         }
-        $linei = shift @aryi;
-        $lineo = shift @aryo;
-
-        # compare chomp'ed lines
-        if ( defined($linei) ) { $counti++; chomp $linei }
-        if ( defined($lineo) ) { $counto++; chomp $lineo }
-
-        # all done if one or both are out of lines
-        last unless ( defined($linei) && defined($lineo) );
-
-        next if ( $linei eq $lineo );
 
-        # lines differ ...
+        #---------------------------
+        # lines differ ... finish up
+        #---------------------------
         my ( $line_diff, $pos1 ) = line_diff( $linei, $lineo );
         my $ch1    = $pos1 + 1;
-        my $reason = "Files first differ at character $ch1 of line $counti";
+        my $reason = "Files first differ at character $ch1 of line $count";
 
         my ( $leading_ws_i, $leading_ws_o ) = ( EMPTY_STRING, EMPTY_STRING );
         if ( $linei =~ /^(\s+)/ ) { $leading_ws_i = $1; }
@@ -3304,22 +3314,24 @@ sub compare_string_buffers {
  $last_nonblank_count:$last_nonblank_line
 EOM
         }
-        $line_diff = SPACE x ( 2 + length($counto) ) . $line_diff;
+        $line_diff = SPACE x ( 2 + length($count) ) . $line_diff;
         $msg .= <<EOM;
-<$counti:$linei
->$counto:$lineo
+<$count:$linei
+>$count:$lineo
 $line_diff
 EOM
         return $msg;
-    } ## end while ( @aryi || @aryo )
+    } ## end while ( @aryi && @aryo )
 
-    # no line differences found, but one file may have fewer lines
-    if ( $counti > $counto ) {
+    #------------------------------------------------------
+    # no differences found, see if one file has fewer lines
+    #------------------------------------------------------
+    if ( $nlines_i > $nlines_o ) {
         $msg .= <<EOM;
 Files initially match file but output file has fewer lines
 EOM
     }
-    elsif ( $counti < $counto ) {
+    elsif ( $nlines_i < $nlines_o ) {
         $msg .= <<EOM;
 Files initially match file but input file has fewer lines
 EOM
-- 
2.39.5