use warnings FATAL => 'all';
use strict;
my $HIGHLIGHT = "\x1b[7m";
my $UNHIGHLIGHT = "\x1b[27m";
my $COLOR = qr/\x1b\[[0-9;]*m/;
my $BORING = qr/$COLOR|\s/;
my @removed;
my @added;
my $in_hunk;
while (<>) {
if (!$in_hunk) {
print;
$in_hunk = /^$COLOR*\@/;
}
elsif (/^$COLOR*-/) {
push @removed, $_;
}
elsif (/^$COLOR*\+/) {
push @added, $_;
}
else {
show_hunk(\@removed, \@added);
@removed = ();
@added = ();
print;
$in_hunk = /^$COLOR*[\@ ]/;
}
if (!length) {
local $| = 1;
}
}
show_hunk(\@removed, \@added);
exit 0;
sub show_hunk {
my ($a, $b) = @_;
if (!@$a || !@$b) {
print @$a, @$b;
return;
}
if (@$a != @$b) {
print @$a, @$b;
return;
}
my @queue;
for (my $i = 0; $i < @$a; $i++) {
my ($rm, $add) = highlight_pair($a->[$i], $b->[$i]);
print $rm;
push @queue, $add;
}
print @queue;
}
sub highlight_pair {
my @a = split_line(shift);
my @b = split_line(shift);
my $seen_plusminus;
my ($pa, $pb) = (0, 0);
while ($pa < @a && $pb < @b) {
if ($a[$pa] =~ /$COLOR/) {
$pa++;
}
elsif ($b[$pb] =~ /$COLOR/) {
$pb++;
}
elsif ($a[$pa] eq $b[$pb]) {
$pa++;
$pb++;
}
elsif (!$seen_plusminus && $a[$pa] eq '-' && $b[$pb] eq '+') {
$seen_plusminus = 1;
$pa++;
$pb++;
}
else {
last;
}
}
my ($sa, $sb) = ($#a, $#b);
while ($sa >= $pa && $sb >= $pb) {
if ($a[$sa] =~ /$COLOR/) {
$sa--;
}
elsif ($b[$sb] =~ /$COLOR/) {
$sb--;
}
elsif ($a[$sa] eq $b[$sb]) {
$sa--;
$sb--;
}
else {
last;
}
}
if (is_pair_interesting(\@a, $pa, $sa, \@b, $pb, $sb)) {
return highlight_line(\@a, $pa, $sa),
highlight_line(\@b, $pb, $sb);
}
else {
return join('', @a),
join('', @b);
}
}
sub split_line {
local $_ = shift;
return map { /$COLOR/ ? $_ : (split //) }
split /($COLOR*)/;
}
sub highlight_line {
my ($line, $prefix, $suffix) = @_;
return join('',
@{$line}[0..($prefix-1)],
$HIGHLIGHT,
@{$line}[$prefix..$suffix],
$UNHIGHLIGHT,
@{$line}[($suffix+1)..$ );
}
sub is_pair_interesting {
my ($a, $pa, $sa, $b, $pb, $sb) = @_;
my $prefix_a = join('', @$a[0..($pa-1)]);
my $prefix_b = join('', @$b[0..($pb-1)]);
my $suffix_a = join('', @$a[($sa+1)..$ my $suffix_b = join('', @$b[($sb+1)..$
return $prefix_a !~ /^$COLOR*-$BORING*$/ ||
$prefix_b !~ /^$COLOR*\+$BORING*$/ ||
$suffix_a !~ /^$BORING*$/ ||
$suffix_b !~ /^$BORING*$/;
}