completion: add --skip for cherry-pick and revert
[git/git.git] / contrib / diff-highlight / DiffHighlight.pm
1 package DiffHighlight;
2
3 use 5.008;
4 use warnings FATAL => 'all';
5 use strict;
6
7 # Use the correct value for both UNIX and Windows (/dev/null vs nul)
8 use File::Spec;
9
10 my $NULL = File::Spec->devnull();
11
12 # Highlight by reversing foreground and background. You could do
13 # other things like bold or underline if you prefer.
14 my @OLD_HIGHLIGHT = (
15 color_config('color.diff-highlight.oldnormal'),
16 color_config('color.diff-highlight.oldhighlight', "\x1b[7m"),
17 color_config('color.diff-highlight.oldreset', "\x1b[27m")
18 );
19 my @NEW_HIGHLIGHT = (
20 color_config('color.diff-highlight.newnormal', $OLD_HIGHLIGHT[0]),
21 color_config('color.diff-highlight.newhighlight', $OLD_HIGHLIGHT[1]),
22 color_config('color.diff-highlight.newreset', $OLD_HIGHLIGHT[2])
23 );
24
25 my $RESET = "\x1b[m";
26 my $COLOR = qr/\x1b\[[0-9;]*m/;
27 my $BORING = qr/$COLOR|\s/;
28
29 my @removed;
30 my @added;
31 my $in_hunk;
32 my $graph_indent = 0;
33
34 our $line_cb = sub { print @_ };
35 our $flush_cb = sub { local $| = 1 };
36
37 # Count the visible width of a string, excluding any terminal color sequences.
38 sub visible_width {
39 local $_ = shift;
40 my $ret = 0;
41 while (length) {
42 if (s/^$COLOR//) {
43 # skip colors
44 } elsif (s/^.//) {
45 $ret++;
46 }
47 }
48 return $ret;
49 }
50
51 # Return a substring of $str, omitting $len visible characters from the
52 # beginning, where terminal color sequences do not count as visible.
53 sub visible_substr {
54 my ($str, $len) = @_;
55 while ($len > 0) {
56 if ($str =~ s/^$COLOR//) {
57 next
58 }
59 $str =~ s/^.//;
60 $len--;
61 }
62 return $str;
63 }
64
65 sub handle_line {
66 my $orig = shift;
67 local $_ = $orig;
68
69 # match a graph line that begins a commit
70 if (/^(?:$COLOR?\|$COLOR?[ ])* # zero or more leading "|" with space
71 $COLOR?\*$COLOR?[ ] # a "*" with its trailing space
72 (?:$COLOR?\|$COLOR?[ ])* # zero or more trailing "|"
73 [ ]* # trailing whitespace for merges
74 /x) {
75 my $graph_prefix = $&;
76
77 # We must flush before setting graph indent, since the
78 # new commit may be indented differently from what we
79 # queued.
80 flush();
81 $graph_indent = visible_width($graph_prefix);
82
83 } elsif ($graph_indent) {
84 if (length($_) < $graph_indent) {
85 $graph_indent = 0;
86 } else {
87 $_ = visible_substr($_, $graph_indent);
88 }
89 }
90
91 if (!$in_hunk) {
92 $line_cb->($orig);
93 $in_hunk = /^$COLOR*\@\@ /;
94 }
95 elsif (/^$COLOR*-/) {
96 push @removed, $orig;
97 }
98 elsif (/^$COLOR*\+/) {
99 push @added, $orig;
100 }
101 else {
102 flush();
103 $line_cb->($orig);
104 $in_hunk = /^$COLOR*[\@ ]/;
105 }
106
107 # Most of the time there is enough output to keep things streaming,
108 # but for something like "git log -Sfoo", you can get one early
109 # commit and then many seconds of nothing. We want to show
110 # that one commit as soon as possible.
111 #
112 # Since we can receive arbitrary input, there's no optimal
113 # place to flush. Flushing on a blank line is a heuristic that
114 # happens to match git-log output.
115 if (!length) {
116 $flush_cb->();
117 }
118 }
119
120 sub flush {
121 # Flush any queued hunk (this can happen when there is no trailing
122 # context in the final diff of the input).
123 show_hunk(\@removed, \@added);
124 @removed = ();
125 @added = ();
126 }
127
128 sub highlight_stdin {
129 while (<STDIN>) {
130 handle_line($_);
131 }
132 flush();
133 }
134
135 # Ideally we would feed the default as a human-readable color to
136 # git-config as the fallback value. But diff-highlight does
137 # not otherwise depend on git at all, and there are reports
138 # of it being used in other settings. Let's handle our own
139 # fallback, which means we will work even if git can't be run.
140 sub color_config {
141 my ($key, $default) = @_;
142 my $s = `git config --get-color $key 2>$NULL`;
143 return length($s) ? $s : $default;
144 }
145
146 sub show_hunk {
147 my ($a, $b) = @_;
148
149 # If one side is empty, then there is nothing to compare or highlight.
150 if (!@$a || !@$b) {
151 $line_cb->(@$a, @$b);
152 return;
153 }
154
155 # If we have mismatched numbers of lines on each side, we could try to
156 # be clever and match up similar lines. But for now we are simple and
157 # stupid, and only handle multi-line hunks that remove and add the same
158 # number of lines.
159 if (@$a != @$b) {
160 $line_cb->(@$a, @$b);
161 return;
162 }
163
164 my @queue;
165 for (my $i = 0; $i < @$a; $i++) {
166 my ($rm, $add) = highlight_pair($a->[$i], $b->[$i]);
167 $line_cb->($rm);
168 push @queue, $add;
169 }
170 $line_cb->(@queue);
171 }
172
173 sub highlight_pair {
174 my @a = split_line(shift);
175 my @b = split_line(shift);
176
177 # Find common prefix, taking care to skip any ansi
178 # color codes.
179 my $seen_plusminus;
180 my ($pa, $pb) = (0, 0);
181 while ($pa < @a && $pb < @b) {
182 if ($a[$pa] =~ /$COLOR/) {
183 $pa++;
184 }
185 elsif ($b[$pb] =~ /$COLOR/) {
186 $pb++;
187 }
188 elsif ($a[$pa] eq $b[$pb]) {
189 $pa++;
190 $pb++;
191 }
192 elsif (!$seen_plusminus && $a[$pa] eq '-' && $b[$pb] eq '+') {
193 $seen_plusminus = 1;
194 $pa++;
195 $pb++;
196 }
197 else {
198 last;
199 }
200 }
201
202 # Find common suffix, ignoring colors.
203 my ($sa, $sb) = ($#a, $#b);
204 while ($sa >= $pa && $sb >= $pb) {
205 if ($a[$sa] =~ /$COLOR/) {
206 $sa--;
207 }
208 elsif ($b[$sb] =~ /$COLOR/) {
209 $sb--;
210 }
211 elsif ($a[$sa] eq $b[$sb]) {
212 $sa--;
213 $sb--;
214 }
215 else {
216 last;
217 }
218 }
219
220 if (is_pair_interesting(\@a, $pa, $sa, \@b, $pb, $sb)) {
221 return highlight_line(\@a, $pa, $sa, \@OLD_HIGHLIGHT),
222 highlight_line(\@b, $pb, $sb, \@NEW_HIGHLIGHT);
223 }
224 else {
225 return join('', @a),
226 join('', @b);
227 }
228 }
229
230 # we split either by $COLOR or by character. This has the side effect of
231 # leaving in graph cruft. It works because the graph cruft does not contain "-"
232 # or "+"
233 sub split_line {
234 local $_ = shift;
235 return utf8::decode($_) ?
236 map { utf8::encode($_); $_ }
237 map { /$COLOR/ ? $_ : (split //) }
238 split /($COLOR+)/ :
239 map { /$COLOR/ ? $_ : (split //) }
240 split /($COLOR+)/;
241 }
242
243 sub highlight_line {
244 my ($line, $prefix, $suffix, $theme) = @_;
245
246 my $start = join('', @{$line}[0..($prefix-1)]);
247 my $mid = join('', @{$line}[$prefix..$suffix]);
248 my $end = join('', @{$line}[($suffix+1)..$#$line]);
249
250 # If we have a "normal" color specified, then take over the whole line.
251 # Otherwise, we try to just manipulate the highlighted bits.
252 if (defined $theme->[0]) {
253 s/$COLOR//g for ($start, $mid, $end);
254 chomp $end;
255 return join('',
256 $theme->[0], $start, $RESET,
257 $theme->[1], $mid, $RESET,
258 $theme->[0], $end, $RESET,
259 "\n"
260 );
261 } else {
262 return join('',
263 $start,
264 $theme->[1], $mid, $theme->[2],
265 $end
266 );
267 }
268 }
269
270 # Pairs are interesting to highlight only if we are going to end up
271 # highlighting a subset (i.e., not the whole line). Otherwise, the highlighting
272 # is just useless noise. We can detect this by finding either a matching prefix
273 # or suffix (disregarding boring bits like whitespace and colorization).
274 sub is_pair_interesting {
275 my ($a, $pa, $sa, $b, $pb, $sb) = @_;
276 my $prefix_a = join('', @$a[0..($pa-1)]);
277 my $prefix_b = join('', @$b[0..($pb-1)]);
278 my $suffix_a = join('', @$a[($sa+1)..$#$a]);
279 my $suffix_b = join('', @$b[($sb+1)..$#$b]);
280
281 return visible_substr($prefix_a, $graph_indent) !~ /^$COLOR*-$BORING*$/ ||
282 visible_substr($prefix_b, $graph_indent) !~ /^$COLOR*\+$BORING*$/ ||
283 $suffix_a !~ /^$BORING*$/ ||
284 $suffix_b !~ /^$BORING*$/;
285 }