🐟 My personal dotfiles
User diff-highlight
Signed-off-by: Stephen Celis <stephen@stephencelis.com>
authored by
Stephen Celis
and committed by
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gitconfig
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gitconfig
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local/bin/diff-highlight
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local/bin/diff-highlight
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#!/usr/bin/perl
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# https://raw.github.com/git/git/master/contrib/diff-highlight/diff-highlight
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use warnings FATAL => 'all';
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use strict;
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# Highlight by reversing foreground and background. You could do
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# other things like bold or underline if you prefer.
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my $HIGHLIGHT = "\x1b[7m";
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my $UNHIGHLIGHT = "\x1b[27m";
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my $COLOR = qr/\x1b\[[0-9;]*m/;
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my $BORING = qr/$COLOR|\s/;
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my @removed;
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my @added;
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my $in_hunk;
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while (<>) {
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if (!$in_hunk) {
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print;
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$in_hunk = /^$COLOR*\@/;
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}
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elsif (/^$COLOR*-/) {
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push @removed, $_;
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}
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elsif (/^$COLOR*\+/) {
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push @added, $_;
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}
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else {
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show_hunk(\@removed, \@added);
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@removed = ();
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@added = ();
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print;
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$in_hunk = /^$COLOR*[\@ ]/;
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}
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# Most of the time there is enough output to keep things streaming,
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# but for something like "git log -Sfoo", you can get one early
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# commit and then many seconds of nothing. We want to show
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# that one commit as soon as possible.
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#
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# Since we can receive arbitrary input, there's no optimal
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# place to flush. Flushing on a blank line is a heuristic that
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# happens to match git-log output.
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if (!length) {
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local $| = 1;
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}
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}
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# Flush any queued hunk (this can happen when there is no trailing context in
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# the final diff of the input).
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show_hunk(\@removed, \@added);
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exit 0;
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sub show_hunk {
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my ($a, $b) = @_;
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# If one side is empty, then there is nothing to compare or highlight.
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if (!@$a || !@$b) {
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print @$a, @$b;
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return;
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}
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# If we have mismatched numbers of lines on each side, we could try to
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# be clever and match up similar lines. But for now we are simple and
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# stupid, and only handle multi-line hunks that remove and add the same
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# number of lines.
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if (@$a != @$b) {
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print @$a, @$b;
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return;
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}
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my @queue;
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for (my $i = 0; $i < @$a; $i++) {
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my ($rm, $add) = highlight_pair($a->[$i], $b->[$i]);
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print $rm;
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push @queue, $add;
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}
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print @queue;
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}
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sub highlight_pair {
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my @a = split_line(shift);
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my @b = split_line(shift);
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# Find common prefix, taking care to skip any ansi
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# color codes.
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my $seen_plusminus;
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my ($pa, $pb) = (0, 0);
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while ($pa < @a && $pb < @b) {
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if ($a[$pa] =~ /$COLOR/) {
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$pa++;
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}
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elsif ($b[$pb] =~ /$COLOR/) {
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$pb++;
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}
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elsif ($a[$pa] eq $b[$pb]) {
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$pa++;
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$pb++;
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}
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elsif (!$seen_plusminus && $a[$pa] eq '-' && $b[$pb] eq '+') {
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$seen_plusminus = 1;
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$pa++;
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$pb++;
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}
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else {
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last;
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}
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}
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# Find common suffix, ignoring colors.
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my ($sa, $sb) = ($#a, $#b);
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while ($sa >= $pa && $sb >= $pb) {
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if ($a[$sa] =~ /$COLOR/) {
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$sa--;
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}
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elsif ($b[$sb] =~ /$COLOR/) {
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$sb--;
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}
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elsif ($a[$sa] eq $b[$sb]) {
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$sa--;
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$sb--;
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}
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else {
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last;
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}
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}
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if (is_pair_interesting(\@a, $pa, $sa, \@b, $pb, $sb)) {
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return highlight_line(\@a, $pa, $sa),
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highlight_line(\@b, $pb, $sb);
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}
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else {
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return join('', @a),
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join('', @b);
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}
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}
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sub split_line {
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local $_ = shift;
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return map { /$COLOR/ ? $_ : (split //) }
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split /($COLOR*)/;
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}
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sub highlight_line {
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my ($line, $prefix, $suffix) = @_;
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return join('',
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@{$line}[0..($prefix-1)],
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$HIGHLIGHT,
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@{$line}[$prefix..$suffix],
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$UNHIGHLIGHT,
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@{$line}[($suffix+1)..$#$line]
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);
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}
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# Pairs are interesting to highlight only if we are going to end up
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# highlighting a subset (i.e., not the whole line). Otherwise, the highlighting
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# is just useless noise. We can detect this by finding either a matching prefix
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# or suffix (disregarding boring bits like whitespace and colorization).
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sub is_pair_interesting {
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my ($a, $pa, $sa, $b, $pb, $sb) = @_;
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my $prefix_a = join('', @$a[0..($pa-1)]);
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my $prefix_b = join('', @$b[0..($pb-1)]);
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my $suffix_a = join('', @$a[($sa+1)..$#$a]);
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my $suffix_b = join('', @$b[($sb+1)..$#$b]);
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return $prefix_a !~ /^$COLOR*-$BORING*$/ ||
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$prefix_b !~ /^$COLOR*\+$BORING*$/ ||
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$suffix_a !~ /^$BORING*$/ ||
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$suffix_b !~ /^$BORING*$/;
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}