The compare-cooking.perl script is meant to help viewing the differences

between periodical "What's cooking" messages, and can be used as an

external diff driver by:

$ git config diff.whatscooking.command ./compare-cooking.perl

to produce this section in your .git/config

[diff "whatscooking"]

command = ./compare-cooking.perl

You can use e.g.

$ git log -p --ext-diff whats-cooking.txt

$ git show --ext-diff whats-cooking.txt

to review the history.

my ($old, $new);

if (@ARGV == 7) {

# called as GIT_EXTERNAL_DIFF script

$old = parse_cooking($ARGV[1]);

$new = parse_cooking($ARGV[4]);

} else {

# called with old and new

$old = parse_cooking($ARGV[0]);

$new = parse_cooking($ARGV[1]);

}

compare_cooking($old, $new);

use File::Temp qw(tempfile);

sub compare_them {

local($_);

my ($a, $b, $force, $soft) = @_;

if ($soft) {

$plus = $minus = ' ';

} else {

$plus = '+';

$minus = '-';

}

if (!defined $a->[0]) {

return map { "$plus$_\n" } map { split(/\n/) } @{$b};

} elsif (!defined $b->[0]) {

return map { "$minus$_\n" } map { split(/\n/) } @{$a};

} elsif (join('', @$a) eq join('', @$b)) {

if ($force) {

return map { " $_\n" } map { split(/\n/) } @{$a};

} else {

return ();

}

}

my ($ah, $aname) = tempfile();

my ($bh, $bname) = tempfile();

my $cnt = 0;

my @result = ();

for (@$a) {

print $ah $_;

$cnt += tr/\n/\n/;

}

for (@$b) {

print $bh $_;

$cnt += tr/\n/\n/;

}

close $ah;

close $bh;

open(my $fh, "-|", 'diff', "-U$cnt", $aname, $bname);

$cnt = 0;

while (<$fh>) {

next if ($cnt++ < 3);

push @result, $_;

}

close $fh;

unlink ($aname, $bname);

return @result;

}

sub flush_topic {

my ($cooking, $name, $desc) = @_;

my $section = $cooking->{SECTIONS}[-1];

return if (!defined $name);

$desc =~ s/\s+\Z/\n/s;

$desc =~ s/\A\s+//s;

my $topic = +{

IN_SECTION => $section,

NAME => $name,

DESC => $desc,

};

$cooking->{TOPICS}{$name} = $topic;

push @{$cooking->{TOPIC_ORDER}}, $name;

}

sub parse_section {

my ($cooking, @line) = @_;

while (@line && $line[-1] =~ /^\s*$/) {

pop @line;

}

return if (!@line);

if (!exists $cooking->{SECTIONS}) {

$cooking->{SECTIONS} = [];

$cooking->{TOPICS} = {};

$cooking->{TOPIC_ORDER} = [];

}

if (!exists $cooking->{HEADER}) {

my $line = join('', @line);

$line =~ s/\A.*?\n\n//s;

$cooking->{HEADER} = $line;

return;

}

if (!exists $cooking->{GREETING}) {

$cooking->{GREETING} = join('', @line);

return;

}

my ($section_name, $topic_name, $topic_desc);

for (@line) {

if (!defined $section_name && /^\[(.*)\]$/) {

$section_name = $1;

push @{$cooking->{SECTIONS}}, $section_name;

next;

}

if (/^\* (\S+) /) {

my $next_name = $1;

flush_topic($cooking, $topic_name, $topic_desc);

$topic_name = $next_name;

$topic_desc = '';

}

$topic_desc .= $_;

}

flush_topic($cooking, $topic_name, $topic_desc);

}

sub dump_cooking {

my ($cooking) = @_;

print $cooking->{HEADER};

print "-" x 50, "\n";

print $cooking->{GREETING};

for my $section_name (@{$cooking->{SECTIONS}}) {

print "\n", "-" x 50, "\n";

print "[$section_name]\n";

for my $topic_name (@{$cooking->{TOPIC_ORDER}}) {

$topic = $cooking->{TOPICS}{$topic_name};

next if ($topic->{IN_SECTION} ne $section_name);

print "\n", $topic->{DESC};

}

}

}

sub parse_cooking {

my ($filename) = @_;

my (%cooking, @current, $fh);

open $fh, "<", $filename

or die "cannot open $filename: $!";

while (<$fh>) {

if (/^-{30,}$/) {

parse_section(\%cooking, @current);

@current = ();

next;

}

push @current, $_;

}

close $fh;

parse_section(\%cooking, @current);

return \%cooking;

}

sub compare_topics {

my ($a, $b) = @_;

if (!@$a || !@$b) {

print compare_them($a, $b, 1, 1);

return;

}

# otherwise they both have title.

$a = [map { "$_\n" } split(/\n/, join('', @$a))];

$b = [map { "$_\n" } split(/\n/, join('', @$b))];

my $atitle = shift @$a;

my $btitle = shift @$b;

print compare_them([$atitle], [$btitle], 1);

my (@atail, @btail);

while (@$a && $a->[-1] !~ /^\s/) {

unshift @atail, pop @$a;

}

while (@$b && $b->[-1] !~ /^\s/) {

unshift @btail, pop @$b;

}

print compare_them($a, $b);

print compare_them(\@atail, \@btail);

}

sub compare_class {

my ($fromto, $names, $topics) = @_;

my (@where, %where);

for my $name (@$names) {

my $t = $topics->{$name};

my ($a, $b, $in, $force);

if ($t->{OLD} && $t->{NEW}) {

$a = [$t->{OLD}{DESC}];

$b = [$t->{NEW}{DESC}];

if ($t->{OLD}{IN_SECTION} ne $t->{NEW}{IN_SECTION}) {

$force = 1;

$in = '';

} else {

$in = "[$t->{NEW}{IN_SECTION}]";

}

} elsif ($t->{OLD}) {

$a = [$t->{OLD}{DESC}];

$b = [];

$in = "Was in [$t->{OLD}{IN_SECTION}]";

} else {

$a = [];

$b = [$t->{NEW}{DESC}];

$in = "[$t->{NEW}{IN_SECTION}]";

}

next if (defined $a->[0] &&

defined $b->[0] &&

$a->[0] eq $b->[0] && !$force);

if (!exists $where{$in}) {

push @where, $in;

$where{$in} = [];

}

push @{$where{$in}}, [$a, $b];

}

return if (!@where);

for my $in (@where) {

my @bag = @{$where{$in}};

if (defined $fromto && $fromto ne '') {

print "\n", '-' x 50, "\n$fromto\n";

$fromto = undef;

}

print "\n$in\n" if ($in ne '');

for (@bag) {

my ($a, $b) = @{$_};

print "\n";

compare_topics($a, $b);

}

}

}

sub compare_cooking {

my ($old, $new) = @_;

print compare_them([$old->{HEADER}], [$new->{HEADER}]);

print compare_them([$old->{GREETING}], [$new->{GREETING}]);

my (@sections, %sections, @topics, %topics, @fromto, %fromto);

for my $section_name (@{$old->{SECTIONS}}, @{$new->{SECTIONS}}) {

next if (exists $sections{$section_name});

$sections{$section_name} = scalar @sections;

push @sections, $section_name;

}

my $gone_class = "Gone topics";

my $born_class = "Born topics";

my $stay_class = "Other topics";

push @fromto, $born_class;

for my $topic_name (@{$old->{TOPIC_ORDER}}, @{$new->{TOPIC_ORDER}}) {

next if (exists $topics{$topic_name});

push @topics, $topic_name;

my $oldtopic = $old->{TOPICS}{$topic_name};

my $newtopic = $new->{TOPICS}{$topic_name};

$topics{$topic_name} = +{

OLD => $oldtopic,

NEW => $newtopic,

};

my $oldsec = $oldtopic->{IN_SECTION};

my $newsec = $newtopic->{IN_SECTION};

if (defined $oldsec && defined $newsec) {

if ($oldsec ne $newsec) {

my $fromto =

"Moved from [$oldsec] to [$newsec]";

if (!exists $fromto{$fromto}) {

$fromto{$fromto} = [];

push @fromto, $fromto;

}

push @{$fromto{$fromto}}, $topic_name;

} else {

push @{$fromto{$stay_class}}, $topic_name;

}

} elsif (defined $oldsec) {

push @{$fromto{$gone_class}}, $topic_name;

} else {

push @{$fromto{$born_class}}, $topic_name;

}

}

push @fromto, $stay_class;

push @fromto, $gone_class;

for my $fromto (@fromto) {

compare_class($fromto, $fromto{$fromto}, \%topics);

}

}