Websites/bugs.webkit.org/PrettyPatch/PrettyPatch.rb

   1 require 'cgi'
   2 require 'diff'
   3 require 'open3'
   4 require 'pp'
   5 require 'set'
   6 require 'tempfile'
   7
   8 module PrettyPatch
   9
  10 public
  11
  12     GIT_PATH = "git"
  13
  14     def self.prettify(string)
  15         fileDiffs = FileDiff.parse(string)
  16
  17         str = HEADER + "\n"
  18
  19         # Just look at the first line to see if it is an SVN revision number as added
  20         # by webkit-patch for git checkouts.
  21         string.each_line do |line|
  22             match = /^Subversion\ Revision: (\d*)$/.match(line)
  23             unless match.nil?
  24               str += "<span class='revision'>" + match[1] + "</span>\n"
  25             end
  26             break
  27         end
  28
  29         str += fileDiffs.collect{ |diff| diff.to_html }.join
  30     end
  31
  32     def self.filename_from_diff_header(line)
  33         DIFF_HEADER_FORMATS.each do |format|
  34             match = format.match(line)
  35             return match[1] unless match.nil?
  36         end
  37         nil
  38     end
  39
  40     def self.diff_header?(line)
  41         RELAXED_DIFF_HEADER_FORMATS.any? { |format| line =~ format }
  42     end
  43
  44 private
  45     DIFF_HEADER_FORMATS = [
  46         /^Index: (.*)\r?$/,
  47         /^diff --git "?a\/.+"? "?b\/(.+)"?\r?$/,
  48         /^\+\+\+ ([^\t]+)(\t.*)?\r?$/
  49     ]
  50
  51     RELAXED_DIFF_HEADER_FORMATS = [
  52         /^Index:/,
  53         /^diff/
  54     ]
  55
  56     BINARY_FILE_MARKER_FORMAT = /^Cannot display: file marked as a binary type.$/
  57
  58     IMAGE_FILE_MARKER_FORMAT = /^svn:mime-type = image\/png$/
  59
  60     GIT_INDEX_MARKER_FORMAT = /^index ([0-9a-f]{40})\.\.([0-9a-f]{40})/
  61
  62     GIT_BINARY_FILE_MARKER_FORMAT = /^GIT binary patch$/
  63
  64     GIT_LITERAL_FORMAT = /^literal \d+$/
  65
  66     START_OF_BINARY_DATA_FORMAT = /^[0-9a-zA-Z\+\/=]{20,}/ # Assume 20 chars without a space is base64 binary data.
  67
  68     START_OF_SECTION_FORMAT = /^@@ -(\d+)(?:,\d+)? \+(\d+)(?:,\d+)? @@\s*(.*)/
  69
  70     START_OF_EXTENT_STRING = "%c" % 0
  71     END_OF_EXTENT_STRING = "%c" % 1
  72
  73     SMALLEST_EQUAL_OPERATION = 3
  74
  75     OPENSOURCE_TRAC_URL = "http://trac.webkit.org/"
  76
  77     OPENSOURCE_DIRS = Set.new %w[
  78         Examples
  79         LayoutTests
  80         PerformanceTests
  81         Source
  82         Tools
  83         WebKit
  84         WebKitLibraries
  85         Websites
  86     ]
  87
  88     def self.find_url_and_path(file_path)
  89         # Search file_path from the bottom up, at each level checking whether
  90         # we've found a directory we know exists in the source tree.
  91
  92         dirname, basename = File.split(file_path)
  93         dirname.split(/\//).reverse.inject(basename) do |path, directory|
  94             path = directory + "/" + path
  95
  96             return [OPENSOURCE_TRAC_URL, path] if OPENSOURCE_DIRS.include?(directory)
  97
  98             path
  99         end
 100
 101         [nil, file_path]
 102     end
 103
 104     def self.linkifyFilename(filename)
 105         url, pathBeneathTrunk = find_url_and_path(filename)
 106
 107         url.nil? ? filename : "<a href='#{url}browser/trunk/#{pathBeneathTrunk}'>#{filename}</a>"
 108     end
 109
 110
 111     HEADER =<<EOF
 112 <style>
 113 :link, :visited {
 114     text-decoration: none;
 115     border-bottom: 1px dotted;
 116 }
 117
 118 :link {
 119     color: #039;
 120 }
 121
 122 .FileDiff {
 123     background-color: #f8f8f8;
 124     border: 1px solid #ddd;
 125     font-family: monospace;
 126     margin: 1em 0;
 127 }
 128
 129 h1 {
 130     color: #333;
 131     font-family: sans-serif;
 132     font-size: 1em;
 133     margin-left: 0.5em;
 134     display: table-cell;
 135     width: 100%;
 136     padding: 0.5em;
 137 }
 138
 139 h1 :link, h1 :visited {
 140     color: inherit;
 141 }
 142
 143 h1 :hover {
 144     color: #555;
 145     background-color: #eee;
 146 }
 147
 148 .DiffLinks {
 149     float: right;
 150 }
 151
 152 .FileDiffLinkContainer {
 153     opacity: 0;
 154     display: table-cell;
 155     padding-right: 0.5em;
 156     white-space: nowrap;
 157 }
 158
 159 .DiffSection {
 160     background-color: white;
 161     border: solid #ddd;
 162     border-width: 1px 0px;
 163 }
 164
 165 .ExpansionLine, .LineContainer {
 166     white-space: nowrap;
 167 }
 168
 169 .sidebyside .DiffBlockPart.add:first-child {
 170     float: right;
 171 }
 172
 173 .LineSide:last-child {
 174     float: right;
 175 }
 176
 177 .LineSide,
 178 .sidebyside .DiffBlockPart.remove,
 179 .sidebyside .DiffBlockPart.add {
 180     display:inline-block;
 181     width:50%;
 182     vertical-align: top;
 183 }
 184
 185 .sidebyside .DiffBlockPart.remove .to,
 186 .sidebyside .DiffBlockPart.add .from {
 187     display: none;
 188 }
 189
 190 .lineNumber, .expansionLineNumber {
 191     border-bottom: 1px solid #998;
 192     border-right: 1px solid #ddd;
 193     color: #444;
 194     display: inline-block;
 195     padding: 1px 5px 0px 0px;
 196     text-align: right;
 197     vertical-align: bottom;
 198     width: 3em;
 199 }
 200
 201 .lineNumber {
 202   background-color: #eed;
 203 }
 204
 205 .expansionLineNumber {
 206   background-color: #eee;
 207 }
 208
 209 .text {
 210     padding-left: 5px;
 211     white-space: pre-wrap;
 212     word-wrap: break-word;
 213 }
 214
 215 .image {
 216     border: 2px solid black;
 217 }
 218
 219 .context, .context .lineNumber {
 220     color: #849;
 221     background-color: #fef;
 222 }
 223
 224 .Line.add {
 225     background-color: #dfd;
 226 }
 227
 228 .Line.add ins {
 229     background-color: #9e9;
 230     text-decoration: none;
 231 }
 232
 233 .Line.remove {
 234     background-color: #fdd;
 235 }
 236
 237 .Line.remove del {
 238     background-color: #e99;
 239     text-decoration: none;
 240 }
 241
 242 /* Support for inline comments */
 243
 244 .author {
 245   font-style: italic;
 246 }
 247
 248 .comment {
 249   position: relative;
 250 }
 251
 252 .comment textarea {
 253   height: 6em;
 254 }
 255
 256 .overallComments textarea {
 257   height: 2em;
 258 }
 259
 260 .comment textarea, .overallComments textarea {
 261   display: block;
 262   width: 100%;
 263 }
 264
 265 .overallComments .open {
 266   -webkit-transition: height .2s;
 267   height: 4em;
 268 }
 269
 270 #statusBubbleContainer.wrap {
 271   display: block;
 272 }
 273
 274 body {
 275   margin-bottom: 40px;
 276 }
 277
 278 #toolbar {
 279   display: -webkit-box;
 280   display: -moz-box;
 281   padding: 3px;
 282   left: 0;
 283   right: 0;
 284   border: 1px solid #ddd;
 285   background-color: #eee;
 286   font-family: sans-serif;
 287   position: fixed;
 288 }
 289
 290 #toolbar.anchored {
 291   bottom: 0;
 292 }
 293
 294 #toolbar .actions {
 295   float: right;
 296 }
 297
 298 .winter {
 299   position: fixed;
 300   z-index: 5;
 301   left: 0;
 302   right: 0;
 303   top: 0;
 304   bottom: 0;
 305   background-color: black;
 306   opacity: 0.8;
 307 }
 308
 309 .inactive {
 310   display: none;
 311 }
 312
 313 .lightbox {
 314   position: fixed;
 315   z-index: 6;
 316   left: 10%;
 317   right: 10%;
 318   top: 10%;
 319   bottom: 10%;
 320   background: white;
 321 }
 322
 323 .lightbox iframe {
 324   width: 100%;
 325   height: 100%;
 326 }
 327
 328 .commentContext .lineNumber {
 329   background-color: yellow;
 330 }
 331
 332 .selected .lineNumber {
 333   background-color: #69F;
 334   border-bottom-color: #69F;
 335   border-right-color: #69F;
 336 }
 337
 338 .ExpandLinkContainer {
 339   opacity: 0;
 340   border-top: 1px solid #ddd;
 341   border-bottom: 1px solid #ddd;
 342 }
 343
 344 .ExpandArea {
 345   margin: 0;
 346 }
 347
 348 .ExpandText {
 349   margin-left: 0.67em;
 350 }
 351
 352 .LinkContainer {
 353   font-family: sans-serif;
 354   font-size: small;
 355   font-style: normal;
 356   -webkit-transition: opacity 0.5s;
 357 }
 358
 359 .LinkContainer a {
 360   border: 0;
 361 }
 362
 363 .LinkContainer a:after {
 364   content: " | ";
 365   color: black;
 366 }
 367
 368 .LinkContainer a:last-of-type:after {
 369   content: "";
 370 }
 371
 372 .help {
 373  color: gray;
 374  font-style: italic;
 375 }
 376
 377 #message {
 378   font-size: small;
 379   font-family: sans-serif;
 380 }
 381
 382 .commentStatus {
 383   font-style: italic;
 384 }
 385
 386 .comment, .previousComment, .frozenComment {
 387   background-color: #ffd;
 388 }
 389
 390 .overallComments {
 391   -webkit-box-flex: 1;
 392   -moz-box-flex: 1;
 393   margin-right: 3px;
 394 }
 395
 396 .previousComment, .frozenComment {
 397   border: inset 1px;
 398   padding: 5px;
 399   white-space: pre-wrap;
 400 }
 401
 402 .comment button {
 403   width: 6em;
 404 }
 405
 406 div:focus {
 407   outline: 1px solid blue;
 408   outline-offset: -1px;
 409 }
 410
 411 .statusBubble {
 412   /* The width/height get set to the bubble contents via postMessage on browsers that support it. */
 413   width: 450px;
 414   height: 20px;
 415   margin: 2px 2px 0 0;
 416   border: none;
 417   vertical-align: middle;
 418 }
 419
 420 .pseudo_resize_event_iframe {
 421   height: 10%;
 422   width: 10%;
 423   position: absolute;
 424   top: -11%;
 425 }
 426
 427 .revision {
 428   display: none;
 429 }
 430
 431 .autosave-state {
 432   position: absolute;
 433   right: 0;
 434   top: -1.3em;
 435   padding: 0 3px;
 436   outline: 1px solid #DDD;
 437   color: #8FDF5F;
 438   font-size: small;
 439   background-color: #EEE;
 440 }
 441
 442 .autosave-state:empty {
 443   outline: 0px;
 444 }
 445 .autosave-state.saving {
 446   color: #E98080;
 447 }
 448
 449 .clear_float {
 450     clear: both;
 451 }
 452 </style>
 453 <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js"></script>
 454 <script src="code-review.js?version=36"></script>
 455 EOF
 456
 457     def self.revisionOrDescription(string)
 458         case string
 459         when /\(revision \d+\)/
 460             /\(revision (\d+)\)/.match(string)[1]
 461         when /\(.*\)/
 462             /\((.*)\)/.match(string)[1]
 463         end
 464     end
 465
 466     def self.has_image_suffix(filename)
 467         filename =~ /\.(png|jpg|gif)$/
 468     end
 469
 470     class FileDiff
 471         def initialize(lines)
 472             @filename = PrettyPatch.filename_from_diff_header(lines[0].chomp)
 473             startOfSections = 1
 474             for i in 0...lines.length
 475                 case lines[i]
 476                 when /^--- /
 477                     @from = PrettyPatch.revisionOrDescription(lines[i])
 478                 when /^\+\+\+ /
 479                     @filename = PrettyPatch.filename_from_diff_header(lines[i].chomp) if @filename.nil?
 480                     @to = PrettyPatch.revisionOrDescription(lines[i])
 481                     startOfSections = i + 1
 482                     break
 483                 when BINARY_FILE_MARKER_FORMAT
 484                     @binary = true
 485                     if (IMAGE_FILE_MARKER_FORMAT.match(lines[i + 1]) or PrettyPatch.has_image_suffix(@filename)) then
 486                         @image = true
 487                         startOfSections = i + 2
 488                         for x in startOfSections...lines.length
 489                             # Binary diffs often have property changes listed before the actual binary data.  Skip them.
 490                             if START_OF_BINARY_DATA_FORMAT.match(lines[x]) then
 491                                 startOfSections = x
 492                                 break
 493                             end
 494                         end
 495                     end
 496                     break
 497                 when GIT_INDEX_MARKER_FORMAT
 498                     @git_indexes = [$1, $2]
 499                 when GIT_BINARY_FILE_MARKER_FORMAT
 500                     @binary = true
 501                     if (GIT_LITERAL_FORMAT.match(lines[i + 1]) and PrettyPatch.has_image_suffix(@filename)) then
 502                         @git_image = true
 503                         startOfSections = i + 1
 504                     end
 505                     break
 506                 end
 507             end
 508             lines_with_contents = lines[startOfSections...lines.length]
 509             @sections = DiffSection.parse(lines_with_contents) unless @binary
 510             if @image
 511                 @image_url = "data:image/png;base64," + lines_with_contents.join
 512             elsif @git_image
 513                 begin
 514                     raise "index line is missing" unless @git_indexes
 515
 516                     chunks = nil
 517                     for i in 0...lines_with_contents.length
 518                         if lines_with_contents[i] =~ /^$/
 519                             chunks = [lines_with_contents[i + 1 .. -1], lines_with_contents[0 .. i]]
 520                             break
 521                         end
 522                     end
 523
 524                     raise "no binary chunks" unless chunks
 525
 526                     @image_urls = chunks.zip(@git_indexes).collect do |chunk, git_index|
 527                         FileDiff.extract_contents_from_git_binary_chunk(chunk, git_index)
 528                     end
 529                 rescue
 530                     @image_error = "Exception raised during decoding git binary patch:<pre>#{CGI.escapeHTML($!.to_s + "\n" + $!.backtrace.join("\n"))}</pre>"
 531                 end
 532             end
 533             nil
 534         end
 535
 536         def to_html
 537             str = "<div class='FileDiff'>\n"
 538             str += "<h1>#{PrettyPatch.linkifyFilename(@filename)}</h1>\n"
 539             if @image then
 540                 str += "<img class='image' src='" + @image_url + "' />"
 541             elsif @git_image then
 542                 if @image_error
 543                     str += @image_error
 544                 else
 545                     for i in (0...2)
 546                         image_url = @image_urls[i]
 547                         style = ["remove", "add"][i]
 548                         str += "<p class=\"#{style}\">"
 549                         if image_url
 550                             str += "<img class='image' src='" + image_url + "' />"
 551                         else
 552                             str += ["Added", "Removed"][i]
 553                         end
 554                     end
 555                 end
 556             elsif @binary then
 557                 str += "<span class='text'>Binary file, nothing to see here</span>"
 558             else
 559                 str += @sections.collect{ |section| section.to_html }.join("<br>\n") unless @sections.nil?
 560             end
 561
 562             if @from then
 563                 str += "<span class='revision'>" + @from + "</span>"
 564             end
 565
 566             str += "</div>\n"
 567         end
 568
 569         def self.parse(string)
 570             haveSeenDiffHeader = false
 571             linesForDiffs = []
 572             string.each_line do |line|
 573                 if (PrettyPatch.diff_header?(line))
 574                     linesForDiffs << []
 575                     haveSeenDiffHeader = true
 576                 elsif (!haveSeenDiffHeader && line =~ /^--- /)
 577                     linesForDiffs << []
 578                     haveSeenDiffHeader = false
 579                 end
 580                 linesForDiffs.last << line unless linesForDiffs.last.nil?
 581             end
 582
 583             linesForDiffs.collect { |lines| FileDiff.new(lines) }
 584         end
 585
 586         def self.git_new_file_binary_patch(filename, encoded_chunk, git_index)
 587             return <<END
 588 diff --git a/#{filename} b/#{filename}
 589 new file mode 100644
 590 index 0000000000000000000000000000000000000000..#{git_index}
 591 GIT binary patch
 592 #{encoded_chunk.join("")}literal 0
 593 HcmV?d00001
 594
 595 END
 596         end
 597
 598         def self.extract_contents_from_git_binary_chunk(encoded_chunk, git_index)
 599             # We use Tempfile we need a unique file among processes.
 600             tempfile = Tempfile.new("PrettyPatch")
 601             # We need a filename which doesn't exist to apply a patch
 602             # which creates a new file. Append a suffix so filename
 603             # doesn't exist.
 604             filepath = tempfile.path + '.bin'
 605             filename = File.basename(filepath)
 606
 607             patch = FileDiff.git_new_file_binary_patch(filename, encoded_chunk, git_index)
 608
 609             # Apply the git binary patch using git-apply.
 610             cmd = GIT_PATH + " apply --directory=" + File.dirname(filepath)
 611             stdin, stdout, stderr = *Open3.popen3(cmd)
 612             begin
 613                 stdin.puts(patch)
 614                 stdin.close
 615
 616                 error = stderr.read
 617                 raise error if error != ""
 618
 619                 contents = File.read(filepath)
 620             ensure
 621                 stdin.close unless stdin.closed?
 622                 stdout.close
 623                 stderr.close
 624                 File.unlink(filename) if File.exists?(filename)
 625             end
 626
 627             return nil if contents.empty?
 628             return "data:image/png;base64," + [contents].pack("m")
 629         end
 630     end
 631
 632     class DiffBlock
 633         attr_accessor :parts
 634
 635         def initialize(container)
 636             @parts = []
 637             container << self
 638         end
 639
 640         def to_html
 641             str = "<div class='DiffBlock'>\n"
 642             str += @parts.collect{ |part| part.to_html }.join
 643             str += "<div class='clear_float'></div></div>\n"
 644         end
 645     end
 646
 647     class DiffBlockPart
 648         attr_reader :className
 649         attr :lines
 650
 651         def initialize(className, container)
 652             @className = className
 653             @lines = []
 654             container.parts << self
 655         end
 656
 657         def to_html
 658             str = "<div class='DiffBlockPart %s'>\n" % @className
 659             str += @lines.collect{ |line| line.to_html }.join
 660             # Don't put white-space after this so adjacent inline-block DiffBlockParts will not wrap.
 661             str += "</div>"
 662         end
 663     end
 664
 665     class DiffSection
 666         def initialize(lines)
 667             lines.length >= 1 or raise "DiffSection.parse only received %d lines" % lines.length
 668
 669             matches = START_OF_SECTION_FORMAT.match(lines[0])
 670             from, to = [matches[1].to_i, matches[2].to_i] unless matches.nil?
 671
 672             @blocks = []
 673             diff_block = nil
 674             diff_block_part = nil
 675
 676             for line in lines[1...lines.length]
 677                 startOfLine = line =~ /^[-\+ ]/ ? 1 : 0
 678                 text = line[startOfLine...line.length].chomp
 679                 case line[0]
 680                 when ?-
 681                     if (diff_block_part.nil? or diff_block_part.className != 'remove')
 682                         diff_block = DiffBlock.new(@blocks)
 683                         diff_block_part = DiffBlockPart.new('remove', diff_block)
 684                     end
 685
 686                     diff_block_part.lines << CodeLine.new(from, nil, text)
 687                     from += 1 unless from.nil?
 688                 when ?+
 689                     if (diff_block_part.nil? or diff_block_part.className != 'add')
 690                         # Put add lines that immediately follow remove lines into the same DiffBlock.
 691                         if (diff_block.nil? or diff_block_part.className != 'remove')
 692                             diff_block = DiffBlock.new(@blocks)
 693                         end
 694
 695                         diff_block_part = DiffBlockPart.new('add', diff_block)
 696                     end
 697
 698                     diff_block_part.lines << CodeLine.new(nil, to, text)
 699                     to += 1 unless to.nil?
 700                 else
 701                     if (diff_block_part.nil? or diff_block_part.className != 'shared')
 702                         diff_block = DiffBlock.new(@blocks)
 703                         diff_block_part = DiffBlockPart.new('shared', diff_block)
 704                     end
 705
 706                     diff_block_part.lines << CodeLine.new(from, to, text)
 707                     from += 1 unless from.nil?
 708                     to += 1 unless to.nil?
 709                 end
 710             end
 711
 712             changes = [ [ [], [] ] ]
 713             for block in @blocks
 714                 for block_part in block.parts
 715                     for line in block_part.lines
 716                         if (!line.fromLineNumber.nil? and !line.toLineNumber.nil?) then
 717                             changes << [ [], [] ]
 718                             next
 719                         end
 720                         changes.last.first << line if line.toLineNumber.nil?
 721                         changes.last.last << line if line.fromLineNumber.nil?
 722                     end
 723                 end
 724             end
 725
 726             for change in changes
 727                 next unless change.first.length == change.last.length
 728                 for i in (0...change.first.length)
 729                     raw_operations = HTMLDiff::DiffBuilder.new(change.first[i].text, change.last[i].text).operations
 730                     operations = []
 731                     back = 0
 732                     raw_operations.each_with_index do |operation, j|
 733                         if operation.action == :equal and j < raw_operations.length - 1
 734                            length = operation.end_in_new - operation.start_in_new
 735                            if length < SMALLEST_EQUAL_OPERATION
 736                                back = length
 737                                next
 738                            end
 739                         end
 740                         operation.start_in_old -= back
 741                         operation.start_in_new -= back
 742                         back = 0
 743                         operations << operation
 744                     end
 745                     change.first[i].operations = operations
 746                     change.last[i].operations = operations
 747                 end
 748             end
 749
 750             @blocks.unshift(ContextLine.new(matches[3])) unless matches.nil? || matches[3].empty?
 751         end
 752
 753         def to_html
 754             str = "<div class='DiffSection'>\n"
 755             str += @blocks.collect{ |block| block.to_html }.join
 756             str += "</div>\n"
 757         end
 758
 759         def self.parse(lines)
 760             linesForSections = lines.inject([[]]) do |sections, line|
 761                 sections << [] if line =~ /^@@/
 762                 sections.last << line
 763                 sections
 764             end
 765
 766             linesForSections.delete_if { |lines| lines.nil? or lines.empty? }
 767             linesForSections.collect { |lines| DiffSection.new(lines) }
 768         end
 769     end
 770
 771     class Line
 772         attr_reader :fromLineNumber
 773         attr_reader :toLineNumber
 774         attr_reader :text
 775
 776         def initialize(from, to, text)
 777             @fromLineNumber = from
 778             @toLineNumber = to
 779             @text = text
 780         end
 781
 782         def text_as_html
 783             CGI.escapeHTML(text)
 784         end
 785
 786         def classes
 787             lineClasses = ["Line", "LineContainer"]
 788             lineClasses << ["add"] unless @toLineNumber.nil? or !@fromLineNumber.nil?
 789             lineClasses << ["remove"] unless @fromLineNumber.nil? or !@toLineNumber.nil?
 790             lineClasses
 791         end
 792
 793         def to_html
 794             markedUpText = self.text_as_html
 795             str = "<div class='%s'>\n" % self.classes.join(' ')
 796             str += "<span class='from lineNumber'>%s</span><span class='to lineNumber'>%s</span>" %
 797                    [@fromLineNumber.nil? ? '&nbsp;' : @fromLineNumber,
 798                     @toLineNumber.nil? ? '&nbsp;' : @toLineNumber] unless @fromLineNumber.nil? and @toLineNumber.nil?
 799             str += "<span class='text'>%s</span>\n" % markedUpText
 800             str += "</div>\n"
 801         end
 802     end
 803
 804     class CodeLine < Line
 805         attr :operations, true
 806
 807         def text_as_html
 808             html = []
 809             tag = @fromLineNumber.nil? ? "ins" : "del"
 810             if @operations.nil? or @operations.empty?
 811                 return CGI.escapeHTML(@text)
 812             end
 813             @operations.each do |operation|
 814                 start = @fromLineNumber.nil? ? operation.start_in_new : operation.start_in_old
 815                 eend = @fromLineNumber.nil? ? operation.end_in_new : operation.end_in_old
 816                 escaped_text = CGI.escapeHTML(@text[start...eend])
 817                 if eend - start === 0 or operation.action === :equal
 818                     html << escaped_text
 819                 else
 820                     html << "<#{tag}>#{escaped_text}</#{tag}>"
 821                 end
 822             end
 823             html.join
 824         end
 825     end
 826
 827     class ContextLine < Line
 828         def initialize(context)
 829             super("@", "@", context)
 830         end
 831
 832         def classes
 833             super << "context"
 834         end
 835     end
 836 end