diff options
Diffstat (limited to 'contrib/diff-highlight/diff-highlight')
| -rwxr-xr-x | contrib/diff-highlight/diff-highlight | 218 |
1 files changed, 218 insertions, 0 deletions
diff --git a/contrib/diff-highlight/diff-highlight b/contrib/diff-highlight/diff-highlight new file mode 100755 index 0000000..ffefc31 --- /dev/null +++ b/contrib/diff-highlight/diff-highlight @@ -0,0 +1,218 @@ +#!/usr/bin/perl + +use 5.008; +use warnings FATAL => 'all'; +use strict; + +# 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 $in_hunk; + +# Some scripts may not realize that SIGPIPE is being ignored when launching the +# pager--for instance scripts written in Python. +$SIG{PIPE} = 'DEFAULT'; + +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*[\@ ]/; + } + + # 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 (!length) { + local $| = 1; + } +} + +# Flush any queued hunk (this can happen when there is no trailing context in +# the final diff of the input). +show_hunk(\@removed, \@added); + +exit 0; + +# Ideally we would feed the default as a human-readable color to +# git-config as the fallback value. But diff-highlight does +# not otherwise depend on git at all, and there are reports +# of it being used in other settings. Let's handle our own +# fallback, which means we will work even if git can't be run. +sub color_config { + my ($key, $default) = @_; + my $s = `git config --get-color $key 2>/dev/null`; + return length($s) ? $s : $default; +} + +sub show_hunk { + my ($a, $b) = @_; + + # If one side is empty, then there is nothing to compare or highlight. + if (!@$a || !@$b) { + print @$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 != @$b) { + print @$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); + + # 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); + } +} + +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 $prefix_a !~ /^$COLOR*-$BORING*$/ || + $prefix_b !~ /^$COLOR*\+$BORING*$/ || + $suffix_a !~ /^$BORING*$/ || + $suffix_b !~ /^$BORING*$/; +} |