FM / diff-highlight

/snap/gh/640/usr/share/doc/git/contrib/diff-highlight/

/snap/gh/640/usr/share/doc/git/contrib/diff-highlight

Name	Size	Mode	Actions
t/	-	0755	rm
diff-highlight	7281	0644	edit dl rm
diff-highlight.perl	211	0644	edit dl rm
DiffHighlight.pm	7054	0644	edit dl rm
Makefile	395	0644	edit dl rm
README	8008	0644	edit dl rm
shebang.perl	16	0644	edit dl rm

Edit: /snap/gh/640/usr/share/doc/git/contrib/diff-highlight/DiffHighlight.pm (7054B)

package DiffHighlight;

use 5.008;
use warnings FATAL => 'all';
use strict;

# Use the correct value for both UNIX and Windows (/dev/null vs nul)
use File::Spec;

my $NULL = File::Spec->devnull();

# Highlight by reversing foreground and background. You could do
# other things like bold or underline if you prefer.
my @OLD_HIGHLIGHT = (
	color_config('color.diff-highlight.oldnormal'),
	color_config('color.diff-highlight.oldhighlight', "\x1b[7m"),
	color_config('color.diff-highlight.oldreset', "\x1b[27m")
);
my @NEW_HIGHLIGHT = (
	color_config('color.diff-highlight.newnormal', $OLD_HIGHLIGHT[0]),
	color_config('color.diff-highlight.newhighlight', $OLD_HIGHLIGHT[1]),
	color_config('color.diff-highlight.newreset', $OLD_HIGHLIGHT[2])
);

my $RESET = "\x1b[m";
my $COLOR = qr/\x1b\[[0-9;]*m/;
my $BORING = qr/$COLOR|\s/;

my @removed;
my @added;
my $in_hunk;
my $graph_indent = 0;

our $line_cb = sub { print @_ };
our $flush_cb = sub { local $| = 1 };

# Count the visible width of a string, excluding any terminal color sequences.
sub visible_width {
	local $_ = shift;
	my $ret = 0;
	while (length) {
		if (s/^$COLOR//) {
			# skip colors
		} elsif (s/^.//) {
			$ret++;
		}
	}
	return $ret;
}

# Return a substring of $str, omitting $len visible characters from the
# beginning, where terminal color sequences do not count as visible.
sub visible_substr {
	my ($str, $len) = @_;
	while ($len > 0) {
		if ($str =~ s/^$COLOR//) {
			next
		}
		$str =~ s/^.//;
		$len--;
	}
	return $str;
}

sub handle_line {
	my $orig = shift;
	local $_ = $orig;

# match a graph line that begins a commit
	if (/^(?:$COLOR?\|$COLOR?[ ])* # zero or more leading "|" with space
	         $COLOR?\*$COLOR?[ ]   # a "*" with its trailing space
	      (?:$COLOR?\|$COLOR?[ ])* # zero or more trailing "|"
	                         [ ]*  # trailing whitespace for merges
	    /x) {
		my $graph_prefix = $&;

# We must flush before setting graph indent, since the
		# new commit may be indented differently from what we
		# queued.
		flush();
		$graph_indent = visible_width($graph_prefix);

} elsif ($graph_indent) {
		if (length($_) < $graph_indent) {
			$graph_indent = 0;
		} else {
			$_ = visible_substr($_, $graph_indent);
		}
	}

if (!$in_hunk) {
		$line_cb->($orig);
		$in_hunk = /^$COLOR*\@\@ /;
	}
	elsif (/^$COLOR*-/) {
		push @removed, $orig;
	}
	elsif (/^$COLOR*\+/) {
		push @added, $orig;
	}
	else {
		flush();
		$line_cb->($orig);
		$in_hunk = /^$COLOR*[\@ ]/;
	}

# Most of the time there is enough output to keep things streaming,
	# but for something like "git log -Sfoo", you can get one early
	# commit and then many seconds of nothing. We want to show
	# that one commit as soon as possible.
	#
	# Since we can receive arbitrary input, there's no optimal
	# place to flush. Flushing on a blank line is a heuristic that
	# happens to match git-log output.
	if (/^$/) {
		$flush_cb->();
	}
}

sub flush {
	# Flush any queued hunk (this can happen when there is no trailing
	# context in the final diff of the input).
	show_hunk(\@removed, \@added);
	@removed = ();
	@added = ();
}

sub highlight_stdin {
	while (<STDIN>) {
		handle_line($_);
	}
	flush();
}

# Ideally we would feed the default as a human-readable color to
# git-config as the fallback value. But diff-highlight does
# not otherwise depend on git at all, and there are reports
# of it being used in other settings. Let's handle our own
# fallback, which means we will work even if git can't be run.
sub color_config {
	my ($key, $default) = @_;
	my $s = `git config --get-color $key 2>$NULL`;
	return length($s) ? $s : $default;
}

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

# If one side is empty, then there is nothing to compare or highlight.
	if (!@$a || !@$b) {
		$line_cb->(@$a, @$b);
		return;
	}

# If we have mismatched numbers of lines on each side, we could try to
	# be clever and match up similar lines. But for now we are simple and
	# stupid, and only handle multi-line hunks that remove and add the same
	# number of lines.
	if (@$a != @$b) {
		$line_cb->(@$a, @$b);
		return;
	}

my @queue;
	for (my $i = 0; $i < @$a; $i++) {
		my ($rm, $add) = highlight_pair($a->[$i], $b->[$i]);
		$line_cb->($rm);
		push @queue, $add;
	}
	$line_cb->(@queue);
}

sub highlight_pair {
	my @a = split_line(shift);
	my @b = split_line(shift);

# Find common prefix, taking care to skip any ansi
	# color codes.
	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;
		}
	}

# Find common suffix, ignoring colors.
	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, \@OLD_HIGHLIGHT),
		       highlight_line(\@b, $pb, $sb, \@NEW_HIGHLIGHT);
	}
	else {
		return join('', @a),
		       join('', @b);
	}
}

# we split either by $COLOR or by character. This has the side effect of
# leaving in graph cruft. It works because the graph cruft does not contain "-"
# or "+"
sub split_line {
	local $_ = shift;
	return utf8::decode($_) ?
		map { utf8::encode($_); $_ }
			map { /$COLOR/ ? $_ : (split //) }
			split /($COLOR+)/ :
		map { /$COLOR/ ? $_ : (split //) }
		split /($COLOR+)/;
}

sub highlight_line {
	my ($line, $prefix, $suffix, $theme) = @_;

my $start = join('', @{$line}[0..($prefix-1)]);
	my $mid = join('', @{$line}[$prefix..$suffix]);
	my $end = join('', @{$line}[($suffix+1)..$#$line]);

# If we have a "normal" color specified, then take over the whole line.
	# Otherwise, we try to just manipulate the highlighted bits.
	if (defined $theme->[0]) {
		s/$COLOR//g for ($start, $mid, $end);
		chomp $end;
		return join('',
			$theme->[0], $start, $RESET,
			$theme->[1], $mid, $RESET,
			$theme->[0], $end, $RESET,
			"\n"
		);
	} else {
		return join('',
			$start,
			$theme->[1], $mid, $theme->[2],
			$end
		);
	}
}

# Pairs are interesting to highlight only if we are going to end up
# highlighting a subset (i.e., not the whole line). Otherwise, the highlighting
# is just useless noise. We can detect this by finding either a matching prefix
# or suffix (disregarding boring bits like whitespace and colorization).
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[($sa+1)..$#$a]);
	my $suffix_b = join('', @$b[($sb+1)..$#$b]);

return visible_substr($prefix_a, $graph_indent) !~ /^$COLOR*-$BORING*$/ ||
	       visible_substr($prefix_b, $graph_indent) !~ /^$COLOR*\+$BORING*$/ ||
	       $suffix_a !~ /^$BORING*$/ ||
	       $suffix_b !~ /^$BORING*$/;
}

cmd: