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gitweb: Highlight interesting parts of diff 

Reading diff output is sometimes very hard, even if it's colored,
especially if lines differ only in few characters.  This is often true
when a commit fixes a typo or renames some variables or functions.

This commit teaches gitweb to highlight characters that are different
between old and new line with a light green/red background.  This should
work in the similar manner as in Trac or GitHub.

The algorithm that compares lines is based on contrib/diff-highlight.
Basically, it works by determining common prefix/suffix of corresponding
lines and highlightning only the middle part of lines.  For more
information, see contrib/diff-highlight/README.

Combined diffs are not supported but a following commit will change it.

Since we need to pass esc_html()'ed or esc_html_hl_regions()'ed lines to
format_diff_lines(), so it was taught to accept preformatted lines
passed as a reference.

Signed-off-by: Michał Kiedrowicz <michal.kiedrowicz@gmail.com>
Acked-by: Jakub Narębski <jnareb@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Michał Kiedrowicz 2012-04-11 23:18:43 +02:00 committed by Junio C Hamano
parent f4a8102650
commit 5fb6ddf67a
2 changed files with 103 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

107
gitweb/gitweb.perl
View File

@ -2430,19 +2430,25 @@ sub format_cc_diff_chunk_header {
}
# process patch (diff) line (not to be used for diff headers),
# returning HTML-formatted (but not wrapped) line
# returning HTML-formatted (but not wrapped) line.
# If the line is passed as a reference, it is treated as HTML and not
# esc_html()'ed.
sub format_diff_line {
my ($line, $diff_class, $from, $to) = @_;
chomp $line;
$line = untabify($line);
if ($from && $to && $line =~ m/^\@{2} /) {
$line = format_unidiff_chunk_header($line, $from, $to);
} elsif ($from && $to && $line =~ m/^\@{3}/) {
$line = format_cc_diff_chunk_header($line, $from, $to);
if (ref($line)) {
$line = $$line;
} else {
$line = esc_html($line, -nbsp=>1);
chomp $line;
$line = untabify($line);
if ($from && $to && $line =~ m/^\@{2} /) {
$line = format_unidiff_chunk_header($line, $from, $to);
} elsif ($from && $to && $line =~ m/^\@{3}/) {
$line = format_cc_diff_chunk_header($line, $from, $to);
} else {
$line = esc_html($line, -nbsp=>1);
}
}
my $diff_classes = "diff";
@ -5055,10 +5061,89 @@ sub print_inline_diff_lines {
print @$ctx, @$rem, @$add;
}
# Format removed and added line, mark changed part and HTML-format them.
# Implementation is based on contrib/diff-highlight
sub format_rem_add_lines_pair {
my ($rem, $add) = @_;
# We need to untabify lines before split()'ing them;
# otherwise offsets would be invalid.
chomp $rem;
chomp $add;
$rem = untabify($rem);
$add = untabify($add);
my @rem = split(//, $rem);
my @add = split(//, $add);
my ($esc_rem, $esc_add);
# Ignore +/- character, thus $prefix_len is set to 1.
my ($prefix_len, $suffix_len) = (1, 0);
my ($prefix_has_nonspace, $suffix_has_nonspace);
my $shorter = (@rem < @add) ? @rem : @add;
while ($prefix_len < $shorter) {
last if ($rem[$prefix_len] ne $add[$prefix_len]);
$prefix_has_nonspace = 1 if ($rem[$prefix_len] !~ /\s/);
$prefix_len++;
}
while ($prefix_len + $suffix_len < $shorter) {
last if ($rem[-1 - $suffix_len] ne $add[-1 - $suffix_len]);
$suffix_has_nonspace = 1 if ($rem[-1 - $suffix_len] !~ /\s/);
$suffix_len++;
}
# Mark lines that are different from each other, but have some common
# part that isn't whitespace. If lines are completely different, don't
# mark them because that would make output unreadable, especially if
# diff consists of multiple lines.
if ($prefix_has_nonspace || $suffix_has_nonspace) {
$esc_rem = esc_html_hl_regions($rem, 'marked',
[$prefix_len, @rem - $suffix_len], -nbsp=>1);
$esc_add = esc_html_hl_regions($add, 'marked',
[$prefix_len, @add - $suffix_len], -nbsp=>1);
} else {
$esc_rem = esc_html($rem, -nbsp=>1);
$esc_add = esc_html($add, -nbsp=>1);
}
return format_diff_line(\$esc_rem, 'rem'),
format_diff_line(\$esc_add, 'add');
}
# HTML-format diff context, removed and added lines.
sub format_ctx_rem_add_lines {
my ($ctx, $rem, $add, $is_combined) = @_;
my (@new_ctx, @new_rem, @new_add);
# Highlight if every removed line has a corresponding added line.
# Combined diffs are not supported at this moment.
if (!$is_combined && @$add > 0 && @$add == @$rem) {
for (my $i = 0; $i < @$add; $i++) {
my ($line_rem, $line_add) = format_rem_add_lines_pair(
$rem->[$i], $add->[$i]);
push @new_rem, $line_rem;
push @new_add, $line_add;
}
} else {
@new_rem = map { format_diff_line($_, 'rem') } @$rem;
@new_add = map { format_diff_line($_, 'add') } @$add;
}
@new_ctx = map { format_diff_line($_, 'ctx') } @$ctx;
return (\@new_ctx, \@new_rem, \@new_add);
}
# Print context lines and then rem/add lines.
sub print_diff_lines {
my ($ctx, $rem, $add, $diff_style, $is_combined) = @_;
($ctx, $rem, $add) = format_ctx_rem_add_lines($ctx, $rem, $add,
$is_combined);
if ($diff_style eq 'sidebyside' && !$is_combined) {
print_sidebyside_diff_lines($ctx, $rem, $add);
} else {
@ -5090,11 +5175,9 @@ sub print_diff_chunk {
foreach my $line_info (@chunk) {
my ($class, $line) = @$line_info;
$line = format_diff_line($line, $class, $from, $to);
# print chunk headers
if ($class && $class eq 'chunk_header') {
print $line;
print format_diff_line($line, $class, $from, $to);
next;
}

8
gitweb/static/gitweb.css
View File

@ -438,6 +438,10 @@ div.diff.add {
color: #008800;
}
div.diff.add span.marked {
background-color: #aaffaa;
}
div.diff.from_file a.path,
div.diff.from_file {
color: #aa0000;
@ -447,6 +451,10 @@ div.diff.rem {
color: #cc0000;
}
div.diff.rem span.marked {
background-color: #ffaaaa;
}
div.diff.chunk_header a,
div.diff.chunk_header {
color: #990099;