diff-highlight: match multi-line hunks

[git.git] / contrib / diff-highlight / diff-highlight

diff --git a/contrib/diff-highlight/diff-highlight b/contrib/diff-highlight/diff-highlight
index 279d21181e9e34a8b4295a7624d43533bd5dca3e..c4404d49c9968608510809309b26e2d08eec8810 100755 (executable)
--- a/contrib/diff-highlight/diff-highlight
+++ b/contrib/diff-highlight/diff-highlight
@@ -10,23 +10,28 @@ my $UNHIGHLIGHT = "\x1b[27m";
 my $COLOR = qr/\x1b\[[0-9;]*m/;
 my $BORING = qr/$COLOR|\s/;
 
-my @window;
+my @removed;
+my @added;
+my $in_hunk;
 
 while (<>) {
-       # We highlight only single-line changes, so we need
-       # a 4-line window to make a decision on whether
-       # to highlight.
-       push @window, $_;
-       next if @window < 4;
-       if ($window[0] =~ /^$COLOR*(\@| )/ &&
-           $window[1] =~ /^$COLOR*-/ &&
-           $window[2] =~ /^$COLOR*\+/ &&
-           $window[3] !~ /^$COLOR*\+/) {
-               print shift @window;
-               show_hunk(shift @window, shift @window);
+       if (!$in_hunk) {
+               print;
+               $in_hunk = /^$COLOR*\@/;
+       }
+       elsif (/^$COLOR*-/) {
+               push @removed, $_;
+       }
+       elsif (/^$COLOR*\+/) {
+               push @added, $_;
        }
        else {
-               print shift @window;
+               show_hunk(\@removed, \@added);
+               @removed = ();
+               @added = ();
+
+               print;
+               $in_hunk = /^$COLOR*[\@ ]/;
        }
 
        # Most of the time there is enough output to keep things streaming,
@@ -42,26 +47,37 @@ while (<>) {
        }
 }
 
-# Special case a single-line hunk at the end of file.
-if (@window == 3 &&
-    $window[0] =~ /^$COLOR*(\@| )/ &&
-    $window[1] =~ /^$COLOR*-/ &&
-    $window[2] =~ /^$COLOR*\+/) {
-       print shift @window;
-       show_hunk(shift @window, shift @window);
-}
-
-# And then flush any remaining lines.
-while (@window) {
-       print shift @window;
-}
+# 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;
 
 sub show_hunk {
        my ($a, $b) = @_;
 
-       print highlight_pair($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 {