diff --git a/src/applications/differential/parser/DifferentialChangesetParser.php b/src/applications/differential/parser/DifferentialChangesetParser.php
index 101bf2a3f5..f92b2c27e2 100644
--- a/src/applications/differential/parser/DifferentialChangesetParser.php
+++ b/src/applications/differential/parser/DifferentialChangesetParser.php
@@ -1,1221 +1,1221 @@
 <?php
 
 final class DifferentialChangesetParser {
 
   protected $visible      = array();
   protected $new          = array();
   protected $old          = array();
   protected $intra        = array();
   protected $newRender    = null;
   protected $oldRender    = null;
 
   protected $filename     = null;
   protected $hunkStartLines = array();
 
   protected $comments     = array();
   protected $specialAttributes = array();
 
   protected $changeset;
   protected $whitespaceMode = null;
 
   protected $renderCacheKey = null;
 
   private $handles = array();
   private $user;
 
   private $leftSideChangesetID;
   private $leftSideAttachesToNewFile;
 
   private $rightSideChangesetID;
   private $rightSideAttachesToNewFile;
 
   private $originalLeft;
   private $originalRight;
 
   private $renderingReference;
   private $isSubparser;
 
   private $isTopLevel;
   private $coverage;
   private $markupEngine;
   private $highlightErrors;
   private $disableCache;
   private $renderer;
 
   public function setRenderer($renderer) {
     $this->renderer = $renderer;
     return $this;
   }
 
   public function getRenderer() {
     if (!$this->renderer) {
       return new DifferentialChangesetTwoUpRenderer();
     }
     return $this->renderer;
   }
 
   public function setDisableCache($disable_cache) {
     $this->disableCache = $disable_cache;
     return $this;
   }
 
   public function getDisableCache() {
     return $this->disableCache;
   }
 
   const CACHE_VERSION = 11;
   const CACHE_MAX_SIZE = 8e6;
 
   const ATTR_GENERATED  = 'attr:generated';
   const ATTR_DELETED    = 'attr:deleted';
   const ATTR_UNCHANGED  = 'attr:unchanged';
   const ATTR_WHITELINES = 'attr:white';
 
   const LINES_CONTEXT = 8;
 
   const WHITESPACE_SHOW_ALL         = 'show-all';
   const WHITESPACE_IGNORE_TRAILING  = 'ignore-trailing';
 
   // TODO: This is now "Ignore Most" in the UI.
   const WHITESPACE_IGNORE_ALL       = 'ignore-all';
 
   const WHITESPACE_IGNORE_FORCE     = 'ignore-force';
 
   public function setOldLines(array $lines) {
     $this->old = $lines;
     return $this;
   }
 
   public function setNewLines(array $lines) {
     $this->new = $lines;
     return $this;
   }
 
   public function setSpecialAttributes(array $attributes) {
     $this->specialAttributes = $attributes;
     return $this;
   }
 
   public function setIntraLineDiffs(array $diffs) {
     $this->intra = $diffs;
     return $this;
   }
 
   public function setVisibileLinesMask(array $mask) {
     $this->visible = $mask;
     return $this;
   }
 
   /**
    * Configure which Changeset comments added to the right side of the visible
    * diff will be attached to. The ID must be the ID of a real Differential
    * Changeset.
    *
    * The complexity here is that we may show an arbitrary side of an arbitrary
    * changeset as either the left or right part of a diff. This method allows
    * the left and right halves of the displayed diff to be correctly mapped to
    * storage changesets.
    *
    * @param id    The Differential Changeset ID that comments added to the right
    *              side of the visible diff should be attached to.
    * @param bool  If true, attach new comments to the right side of the storage
    *              changeset. Note that this may be false, if the left side of
    *              some storage changeset is being shown as the right side of
    *              a display diff.
    * @return this
    */
   public function setRightSideCommentMapping($id, $is_new) {
     $this->rightSideChangesetID = $id;
     $this->rightSideAttachesToNewFile = $is_new;
     return $this;
   }
 
   /**
    * See setRightSideCommentMapping(), but this sets information for the left
    * side of the display diff.
    */
   public function setLeftSideCommentMapping($id, $is_new) {
     $this->leftSideChangesetID = $id;
     $this->leftSideAttachesToNewFile = $is_new;
     return $this;
   }
 
   public function setOriginals(
     DifferentialChangeset $left,
     DifferentialChangeset $right) {
 
     $this->originalLeft = $left;
     $this->originalRight = $right;
   }
 
   public function diffOriginals() {
     $engine = new PhabricatorDifferenceEngine();
     $changeset = $engine->generateChangesetFromFileContent(
       implode('', mpull($this->originalLeft->getHunks(), 'getChanges')),
       implode('', mpull($this->originalRight->getHunks(), 'getChanges')));
 
     $parser = new DifferentialHunkParser();
 
     return $parser->parseHunksForHighlightMasks(
       $changeset->getHunks(),
       $this->originalLeft->getHunks(),
       $this->originalRight->getHunks());
   }
 
   /**
    * Set a key for identifying this changeset in the render cache. If set, the
    * parser will attempt to use the changeset render cache, which can improve
    * performance for frequently-viewed changesets.
    *
    * By default, there is no render cache key and parsers do not use the cache.
    * This is appropriate for rarely-viewed changesets.
    *
    * NOTE: Currently, this key must be a valid Differential Changeset ID.
    *
    * @param   string  Key for identifying this changeset in the render cache.
    * @return  this
    */
   public function setRenderCacheKey($key) {
     $this->renderCacheKey = $key;
     return $this;
   }
 
   private function getRenderCacheKey() {
     return $this->renderCacheKey;
   }
 
   public function setChangeset(DifferentialChangeset $changeset) {
     $this->changeset = $changeset;
 
     $this->setFilename($changeset->getFilename());
 
     return $this;
   }
 
   public function setWhitespaceMode($whitespace_mode) {
     $this->whitespaceMode = $whitespace_mode;
     return $this;
   }
 
   public function setRenderingReference($ref) {
     $this->renderingReference = $ref;
     return $this;
   }
 
   private function getRenderingReference() {
     return $this->renderingReference;
   }
 
   public function getChangeset() {
     return $this->changeset;
   }
 
   public function setFilename($filename) {
     $this->filename = $filename;
     return $this;
   }
 
   public function setHandles(array $handles) {
     assert_instances_of($handles, 'PhabricatorObjectHandle');
     $this->handles = $handles;
     return $this;
   }
 
   public function setMarkupEngine(PhabricatorMarkupEngine $engine) {
     $this->markupEngine = $engine;
     return $this;
   }
 
   public function setUser(PhabricatorUser $user) {
     $this->user = $user;
     return $this;
   }
 
   public function setCoverage($coverage) {
     $this->coverage = $coverage;
     return $this;
   }
   private function getCoverage() {
     return $this->coverage;
   }
 
   public function parseInlineComment(
     PhabricatorInlineCommentInterface $comment) {
 
     // Parse only comments which are actually visible.
     if ($this->isCommentVisibleOnRenderedDiff($comment)) {
       $this->comments[] = $comment;
     }
     return $this;
   }
 
   private function loadCache() {
     $render_cache_key = $this->getRenderCacheKey();
     if (!$render_cache_key) {
       return false;
     }
 
     $data = null;
 
     $changeset = new DifferentialChangeset();
     $conn_r = $changeset->establishConnection('r');
     $data = queryfx_one(
       $conn_r,
       'SELECT * FROM %T WHERE id = %d',
       $changeset->getTableName().'_parse_cache',
       $render_cache_key);
 
     if (!$data) {
       return false;
     }
 
     if ($data['cache'][0] == '{') {
       // This is likely an old-style JSON cache which we will not be able to
       // deserialize.
       return false;
     }
 
     $data = unserialize($data['cache']);
     if (!is_array($data) || !$data) {
       return false;
     }
 
     foreach (self::getCacheableProperties() as $cache_key) {
       if (!array_key_exists($cache_key, $data)) {
         // If we're missing a cache key, assume we're looking at an old cache
         // and ignore it.
         return false;
       }
     }
 
     if ($data['cacheVersion'] !== self::CACHE_VERSION) {
       return false;
     }
 
     // Someone displays contents of a partially cached shielded file.
     if (!isset($data['newRender']) && (!$this->isTopLevel || $this->comments)) {
       return false;
     }
 
     unset($data['cacheVersion'], $data['cacheHost']);
     $cache_prop = array_select_keys($data, self::getCacheableProperties());
     foreach ($cache_prop as $cache_key => $v) {
       $this->$cache_key = $v;
     }
 
     return true;
   }
 
   protected static function getCacheableProperties() {
     return array(
       'visible',
       'new',
       'old',
       'intra',
       'newRender',
       'oldRender',
       'specialAttributes',
       'hunkStartLines',
       'cacheVersion',
       'cacheHost',
     );
   }
 
   public function saveCache() {
     if ($this->highlightErrors) {
       return false;
     }
 
     $render_cache_key = $this->getRenderCacheKey();
     if (!$render_cache_key) {
       return false;
     }
 
     $cache = array();
     foreach (self::getCacheableProperties() as $cache_key) {
       switch ($cache_key) {
         case 'cacheVersion':
           $cache[$cache_key] = self::CACHE_VERSION;
           break;
         case 'cacheHost':
           $cache[$cache_key] = php_uname('n');
           break;
         default:
           $cache[$cache_key] = $this->$cache_key;
           break;
       }
     }
     $cache = serialize($cache);
 
     // We don't want to waste too much space by a single changeset.
     if (strlen($cache) > self::CACHE_MAX_SIZE) {
       return;
     }
 
     try {
       $changeset = new DifferentialChangeset();
       $conn_w = $changeset->establishConnection('w');
 
       $unguarded = AphrontWriteGuard::beginScopedUnguardedWrites();
       queryfx(
         $conn_w,
         'INSERT INTO %T (id, cache, dateCreated) VALUES (%d, %s, %d)
           ON DUPLICATE KEY UPDATE cache = VALUES(cache)',
         DifferentialChangeset::TABLE_CACHE,
         $render_cache_key,
         $cache,
         time());
     } catch (AphrontQueryException $ex) {
       // TODO: uhoh
     }
   }
 
   private function markGenerated($new_corpus_block = '') {
     $generated_guess = (strpos($new_corpus_block, '@'.'generated') !== false);
 
     if (!$generated_guess) {
       $generated_path_regexps = PhabricatorEnv::getEnvConfig(
         'differential.generated-paths');
       foreach ($generated_path_regexps as $regexp) {
         if (preg_match($regexp, $this->changeset->getFilename())) {
           $generated_guess = true;
           break;
         }
       }
     }
 
     $event = new PhabricatorEvent(
       PhabricatorEventType::TYPE_DIFFERENTIAL_WILLMARKGENERATED,
       array(
         'corpus' => $new_corpus_block,
         'is_generated' => $generated_guess,
       )
     );
     PhutilEventEngine::dispatchEvent($event);
 
     $generated = $event->getValue('is_generated');
     $this->specialAttributes[self::ATTR_GENERATED] = $generated;
   }
 
   public function isGenerated() {
     return idx($this->specialAttributes, self::ATTR_GENERATED, false);
   }
 
   public function isDeleted() {
     return idx($this->specialAttributes, self::ATTR_DELETED, false);
   }
 
   public function isUnchanged() {
     return idx($this->specialAttributes, self::ATTR_UNCHANGED, false);
   }
 
   public function isWhitespaceOnly() {
     return idx($this->specialAttributes, self::ATTR_WHITELINES, false);
   }
 
   private function applyIntraline(&$render, $intra, $corpus) {
 
     foreach ($render as $key => $text) {
       if (isset($intra[$key])) {
         $render[$key] = ArcanistDiffUtils::applyIntralineDiff(
           $text,
           $intra[$key]);
       }
     }
   }
 
   private function getHighlightFuture($corpus) {
     return $this->highlightEngine->getHighlightFuture(
       $this->highlightEngine->getLanguageFromFilename($this->filename),
       $corpus);
   }
 
   protected function processHighlightedSource($data, $result) {
 
     $result_lines = phutil_split_lines($result);
     foreach ($data as $key => $info) {
       if (!$info) {
         unset($result_lines[$key]);
       }
     }
     return $result_lines;
   }
 
   private function tryCacheStuff() {
     $whitespace_mode = $this->whitespaceMode;
     switch ($whitespace_mode) {
       case self::WHITESPACE_SHOW_ALL:
       case self::WHITESPACE_IGNORE_TRAILING:
       case self::WHITESPACE_IGNORE_FORCE:
         break;
       default:
         $whitespace_mode = self::WHITESPACE_IGNORE_ALL;
         break;
     }
 
     $skip_cache = ($whitespace_mode != self::WHITESPACE_IGNORE_ALL);
     if ($this->disableCache) {
       $skip_cache = true;
     }
 
     $this->whitespaceMode = $whitespace_mode;
 
     $changeset = $this->changeset;
 
     if ($changeset->getFileType() != DifferentialChangeType::FILE_TEXT &&
         $changeset->getFileType() != DifferentialChangeType::FILE_SYMLINK) {
 
       $this->markGenerated();
 
     } else {
       if ($skip_cache || !$this->loadCache()) {
         $this->process();
         if (!$skip_cache) {
           $this->saveCache();
         }
       }
     }
   }
 
   private function process() {
     $whitespace_mode = $this->whitespaceMode;
     $changeset = $this->changeset;
 
     $ignore_all = (($whitespace_mode == self::WHITESPACE_IGNORE_ALL) ||
                   ($whitespace_mode == self::WHITESPACE_IGNORE_FORCE));
 
     $force_ignore = ($whitespace_mode == self::WHITESPACE_IGNORE_FORCE);
 
     if (!$force_ignore) {
       if ($ignore_all && $changeset->getWhitespaceMatters()) {
         $ignore_all = false;
       }
     }
 
     // The "ignore all whitespace" algorithm depends on rediffing the
     // files, and we currently need complete representations of both
     // files to do anything reasonable. If we only have parts of the files,
     // don't use the "ignore all" algorithm.
     if ($ignore_all) {
       $hunks = $changeset->getHunks();
       if (count($hunks) !== 1) {
         $ignore_all = false;
       } else {
         $first_hunk = reset($hunks);
         if ($first_hunk->getOldOffset() != 1 ||
             $first_hunk->getNewOffset() != 1) {
             $ignore_all = false;
         }
       }
     }
 
     if ($ignore_all) {
       $old_file = $changeset->makeOldFile();
       $new_file = $changeset->makeNewFile();
       if ($old_file == $new_file) {
         // If the old and new files are exactly identical, the synthetic
         // diff below will give us nonsense and whitespace modes are
         // irrelevant anyway. This occurs when you, e.g., copy a file onto
         // itself in Subversion (see T271).
         $ignore_all = false;
       }
     }
 
     $hunk_parser = new DifferentialHunkParser();
     $hunk_parser->setWhitespaceMode($whitespace_mode);
     $hunk_parser->parseHunksForLineData($changeset->getHunks());
 
     // Depending on the whitespace mode, we may need to compute a different
     // set of changes than the set of changes in the hunk data (specificaly,
     // we might want to consider changed lines which have only whitespace
     // changes as unchanged).
     if ($ignore_all) {
       $engine = new PhabricatorDifferenceEngine();
       $engine->setIgnoreWhitespace(true);
       $no_whitespace_changeset = $engine->generateChangesetFromFileContent(
         $old_file,
         $new_file);
 
       $type_parser = new DifferentialHunkParser();
       $type_parser->parseHunksForLineData($no_whitespace_changeset->getHunks());
 
       $hunk_parser->setOldLineTypeMap($type_parser->getOldLineTypeMap());
       $hunk_parser->setNewLineTypeMap($type_parser->getNewLineTypeMap());
     }
 
     $hunk_parser->reparseHunksForSpecialAttributes();
 
     $unchanged = false;
     if (!$hunk_parser->getHasAnyChanges()) {
       $filetype = $this->changeset->getFileType();
       if ($filetype == DifferentialChangeType::FILE_TEXT ||
           $filetype == DifferentialChangeType::FILE_SYMLINK) {
         $unchanged = true;
       }
     }
 
     $changetype = $this->changeset->getChangeType();
     if ($changetype == DifferentialChangeType::TYPE_MOVE_AWAY) {
       // sometimes we show moved files as unchanged, sometimes deleted,
       // and sometimes inconsistent with what actually happened at the
       // destination of the move.  Rather than make a false claim,
       // omit the 'not changed' notice if this is the source of a move
       $unchanged = false;
     }
 
     $this->setSpecialAttributes(array(
       self::ATTR_UNCHANGED  => $unchanged,
       self::ATTR_DELETED    => $hunk_parser->getIsDeleted(),
       self::ATTR_WHITELINES => !$hunk_parser->getHasTextChanges(),
     ));
 
     $hunk_parser->generateIntraLineDiffs();
     $hunk_parser->generateVisibileLinesMask();
 
     $this->setOldLines($hunk_parser->getOldLines());
     $this->setNewLines($hunk_parser->getNewLines());
     $this->setIntraLineDiffs($hunk_parser->getIntraLineDiffs());
     $this->setVisibileLinesMask($hunk_parser->getVisibleLinesMask());
     $this->hunkStartLines = $hunk_parser->getHunkStartLines(
       $changeset->getHunks());
 
     $new_corpus = $hunk_parser->getNewCorpus();
     $new_corpus_block = implode('', $new_corpus);
     $this->markGenerated($new_corpus_block);
 
     if ($this->isTopLevel &&
         !$this->comments &&
           ($this->isGenerated() ||
            $this->isUnchanged() ||
            $this->isDeleted())) {
       return;
     }
 
     $old_corpus = $hunk_parser->getOldCorpus();
     $old_corpus_block = implode('', $old_corpus);
     $old_future = $this->getHighlightFuture($old_corpus_block);
     $new_future = $this->getHighlightFuture($new_corpus_block);
     $futures = array(
       'old' => $old_future,
       'new' => $new_future,
     );
     $corpus_blocks = array(
       'old' => $old_corpus_block,
       'new' => $new_corpus_block,
     );
 
     $this->highlightErrors = false;
     foreach (Futures($futures) as $key => $future) {
       try {
         try {
           $highlighted = $future->resolve();
         } catch (PhutilSyntaxHighlighterException $ex) {
           $this->highlightErrors = true;
           $highlighted = id(new PhutilDefaultSyntaxHighlighter())
             ->getHighlightFuture($corpus_blocks[$key])
             ->resolve();
         }
         switch ($key) {
         case 'old':
           $this->oldRender = $this->processHighlightedSource(
             $this->old,
             $highlighted);
           break;
         case 'new':
           $this->newRender = $this->processHighlightedSource(
             $this->new,
             $highlighted);
           break;
         }
       } catch (Exception $ex) {
         phlog($ex);
         throw $ex;
       }
     }
 
     $this->applyIntraline(
       $this->oldRender,
       ipull($this->intra, 0),
       $old_corpus);
     $this->applyIntraline(
       $this->newRender,
       ipull($this->intra, 1),
       $new_corpus);
   }
 
   private function shouldRenderPropertyChangeHeader($changeset) {
     if (!$this->isTopLevel) {
       // We render properties only at top level; otherwise we get multiple
       // copies of them when a user clicks "Show More".
       return false;
     }
 
     $old = $changeset->getOldProperties();
     $new = $changeset->getNewProperties();
 
     if ($old === $new) {
       return false;
     }
 
     if ($changeset->getChangeType() == DifferentialChangeType::TYPE_ADD &&
         $new == array('unix:filemode' => '100644')) {
       return false;
     }
 
     if ($changeset->getChangeType() == DifferentialChangeType::TYPE_DELETE &&
         $old == array('unix:filemode' => '100644')) {
       return false;
      }
 
     return true;
   }
 
   public function render(
     $range_start  = null,
     $range_len    = null,
     $mask_force   = array()) {
 
     // "Top level" renders are initial requests for the whole file, versus
     // requests for a specific range generated by clicking "show more". We
     // generate property changes and "shield" UI elements only for toplevel
     // requests.
     $this->isTopLevel = (($range_start === null) && ($range_len === null));
     $this->highlightEngine = PhabricatorSyntaxHighlighter::newEngine();
     $this->tryCacheStuff();
     $render_pch = $this->shouldRenderPropertyChangeHeader($this->changeset);
 
     $rows = max(
       count($this->old),
       count($this->new));
 
     $renderer = $this->getRenderer()
       ->setChangeset($this->changeset)
       ->setRenderPropertyChangeHeader($render_pch)
       ->setOldRender($this->oldRender)
       ->setNewRender($this->newRender)
       ->setHunkStartLines($this->hunkStartLines)
       ->setOldChangesetID($this->leftSideChangesetID)
       ->setNewChangesetID($this->rightSideChangesetID)
       ->setOldAttachesToNewFile($this->leftSideAttachesToNewFile)
       ->setNewAttachesToNewFile($this->rightSideAttachesToNewFile)
       ->setCodeCoverage($this->getCoverage())
       ->setRenderingReference($this->getRenderingReference())
       ->setMarkupEngine($this->markupEngine)
       ->setHandles($this->handles)
       ->setOldLines($this->old)
       ->setNewLines($this->new);
 
     if ($this->user) {
       $renderer->setUser($this->user);
     }
 
     $shield = null;
     if ($this->isTopLevel && !$this->comments) {
       if ($this->isGenerated()) {
         $shield = $renderer->renderShield(
           pht(
             'This file contains generated code, which does not normally '.
             'need to be reviewed.'));
       } else if ($this->isUnchanged()) {
         $type = 'text';
         if (!$rows) {
           // NOTE: Normally, diffs which don't change files do not include
           // file content (for example, if you "chmod +x" a file and then
           // run "git show", the file content is not available). Similarly,
           // if you move a file from A to B without changing it, diffs normally
           // do not show the file content. In some cases `arc` is able to
           // synthetically generate content for these diffs, but for raw diffs
           // we'll never have it so we need to be prepared to not render a link.
           $type = 'none';
         }
         $shield = $renderer->renderShield(
           pht('The contents of this file were not changed.'),
           $type);
       } else if ($this->isWhitespaceOnly()) {
         $shield = $renderer->renderShield(
           pht('This file was changed only by adding or removing whitespace.'),
           'whitespace');
       } else if ($this->isDeleted()) {
         $shield = $renderer->renderShield(
           pht('This file was completely deleted.'));
       } else if ($this->changeset->getAffectedLineCount() > 2500) {
         $lines = number_format($this->changeset->getAffectedLineCount());
         $shield = $renderer->renderShield(
           pht(
             'This file has a very large number of changes (%s lines).',
             $lines));
       }
     }
 
     if ($shield) {
       return $renderer->renderChangesetTable($shield);
     }
 
     $old_comments = array();
     $new_comments = array();
     $old_mask = array();
     $new_mask = array();
     $feedback_mask = array();
 
     if ($this->comments) {
       foreach ($this->comments as $comment) {
         $start = max($comment->getLineNumber() - self::LINES_CONTEXT, 0);
         $end = $comment->getLineNumber() +
           $comment->getLineLength() +
           self::LINES_CONTEXT;
         $new_side = $this->isCommentOnRightSideWhenDisplayed($comment);
         for ($ii = $start; $ii <= $end; $ii++) {
           if ($new_side) {
             $new_mask[$ii] = true;
           } else {
             $old_mask[$ii] = true;
           }
         }
       }
 
       foreach ($this->old as $ii => $old) {
         if (isset($old['line']) && isset($old_mask[$old['line']])) {
           $feedback_mask[$ii] = true;
         }
       }
 
       foreach ($this->new as $ii => $new) {
         if (isset($new['line']) && isset($new_mask[$new['line']])) {
           $feedback_mask[$ii] = true;
         }
       }
       $this->comments = msort($this->comments, 'getID');
       foreach ($this->comments as $comment) {
         $final = $comment->getLineNumber() +
           $comment->getLineLength();
         $final = max(1, $final);
         if ($this->isCommentOnRightSideWhenDisplayed($comment)) {
           $new_comments[$final][] = $comment;
         } else {
           $old_comments[$final][] = $comment;
         }
       }
     }
     $renderer
       ->setOldComments($old_comments)
       ->setNewComments($new_comments);
 
     switch ($this->changeset->getFileType()) {
       case DifferentialChangeType::FILE_IMAGE:
         $old = null;
         $new = null;
         // TODO: Improve the architectural issue as discussed in D955
         // https://secure.phabricator.com/D955
         $reference = $this->getRenderingReference();
         $parts = explode('/', $reference);
         if (count($parts) == 2) {
           list($id, $vs) = $parts;
         } else {
           $id = $parts[0];
           $vs = 0;
         }
         $id = (int)$id;
         $vs = (int)$vs;
 
         if (!$vs) {
           $metadata = $this->changeset->getMetadata();
           $data = idx($metadata, 'attachment-data');
 
           $old_phid = idx($metadata, 'old:binary-phid');
           $new_phid = idx($metadata, 'new:binary-phid');
         } else {
           $vs_changeset = id(new DifferentialChangeset())->load($vs);
           $vs_metadata = $vs_changeset->getMetadata();
           $old_phid = idx($vs_metadata, 'new:binary-phid');
 
           $changeset = id(new DifferentialChangeset())->load($id);
           $metadata = $changeset->getMetadata();
           $new_phid = idx($metadata, 'new:binary-phid');
         }
 
         if ($old_phid || $new_phid) {
           // grab the files, (micro) optimization for 1 query not 2
           $file_phids = array();
           if ($old_phid) {
             $file_phids[] = $old_phid;
           }
           if ($new_phid) {
             $file_phids[] = $new_phid;
           }
 
           $files = id(new PhabricatorFile())->loadAllWhere(
             'phid IN (%Ls)',
             $file_phids);
           foreach ($files as $file) {
             if (empty($file)) {
               continue;
             }
             if ($file->getPHID() == $old_phid) {
               $old = $file;
             } else if ($file->getPHID() == $new_phid) {
               $new = $file;
             }
           }
         }
 
         return $renderer->renderFileChange($old, $new, $id, $vs);
       case DifferentialChangeType::FILE_DIRECTORY:
       case DifferentialChangeType::FILE_BINARY:
         $output = $renderer->renderChangesetTable(null);
         return $output;
     }
 
     if ($this->originalLeft && $this->originalRight) {
       list($highlight_old, $highlight_new) = $this->diffOriginals();
       $highlight_old = array_flip($highlight_old);
       $highlight_new = array_flip($highlight_new);
       $renderer
         ->setHighlightOld($highlight_old)
         ->setHighlightNew($highlight_new);
     }
     $renderer
       ->setOriginalOld($this->originalLeft)
       ->setOriginalNew($this->originalRight);
 
     if ($range_start === null) {
       $range_start = 0;
     }
     if ($range_len === null) {
       $range_len = $rows;
     }
     $range_len = min($range_len, $rows - $range_start);
 
     list($gaps, $mask, $depths) = $this->calculateGapsMaskAndDepths(
       $mask_force,
       $feedback_mask,
       $range_start,
       $range_len);
 
     $renderer
       ->setGaps($gaps)
       ->setMask($mask)
       ->setDepths($depths);
 
     $html = $renderer->renderTextChange(
       $range_start,
       $range_len,
       $rows);
 
     return $renderer->renderChangesetTable($html);
   }
 
   /**
    * This function calculates a lot of stuff we need to know to display
    * the diff:
    *
    * Gaps - compute gaps in the visible display diff, where we will render
    * "Show more context" spacers. If a gap is smaller than the context size,
    * we just display it. Otherwise, we record it into $gaps and will render a
    * "show more context" element instead of diff text below. A given $gap
    * is a tuple of $gap_line_number_start and $gap_length.
    *
    * Mask - compute the actual lines that need to be shown (because they
    * are near changes lines, near inline comments, or the request has
    * explicitly asked for them, i.e. resulting from the user clicking
    * "show more"). The $mask returned is a sparesely populated dictionary
    * of $visible_line_number => true.
    *
    * Depths - compute how indented any given line is. The $depths returned
    * is a sparesely populated dictionary of $visible_line_number => $depth.
    *
    * This function also has the side effect of modifying member variable
    * new such that tabs are normalized to spaces for each line of the diff.
    *
    * @return array($gaps, $mask, $depths)
    */
   private function calculateGapsMaskAndDepths($mask_force,
                                               $feedback_mask,
                                               $range_start,
                                               $range_len) {
 
     // Calculate gaps and mask first
     $gaps = array();
     $gap_start = 0;
     $in_gap = false;
     $base_mask = $this->visible + $mask_force + $feedback_mask;
     $base_mask[$range_start + $range_len] = true;
     for ($ii = $range_start; $ii <= $range_start + $range_len; $ii++) {
       if (isset($base_mask[$ii])) {
         if ($in_gap) {
           $gap_length = $ii - $gap_start;
           if ($gap_length <= self::LINES_CONTEXT) {
             for ($jj = $gap_start; $jj <= $gap_start + $gap_length; $jj++) {
               $base_mask[$jj] = true;
             }
           } else {
             $gaps[] = array($gap_start, $gap_length);
           }
           $in_gap = false;
         }
       } else {
         if (!$in_gap) {
           $gap_start = $ii;
           $in_gap = true;
         }
       }
     }
     $gaps = array_reverse($gaps);
     $mask = $base_mask;
 
     // Time to calculate depth.
     // We need to go backwards to properly indent whitespace in this code:
     //
     //   0: class C {
     //   1:
     //   1:   function f() {
     //   2:
     //   2:     return;
-    //   3:
-    //   3:   }
-    //   4:
-    //   4: }
+    //   1:
+    //   1:   }
+    //   0:
+    //   0: }
     //
     $depths = array();
     $last_depth = 0;
     $range_end = $range_start + $range_len;
     if (!isset($this->new[$range_end])) {
       $range_end--;
     }
     for ($ii = $range_end; $ii >= $range_start; $ii--) {
       // We need to expand tabs to process mixed indenting and to round
       // correctly later.
       $line = str_replace("\t", "  ", $this->new[$ii]['text']);
       $trimmed = ltrim($line);
       if ($trimmed != '') {
         // We round down to flatten "/**" and " *".
         $last_depth = floor((strlen($line) - strlen($trimmed)) / 2);
       }
       $depths[$ii] = $last_depth;
     }
 
     return array($gaps, $mask, $depths);
   }
 
   /**
    * Determine if an inline comment will appear on the rendered diff,
    * taking into consideration which halves of which changesets will actually
    * be shown.
    *
    * @param PhabricatorInlineCommentInterface Comment to test for visibility.
    * @return bool True if the comment is visible on the rendered diff.
    */
   private function isCommentVisibleOnRenderedDiff(
     PhabricatorInlineCommentInterface $comment) {
 
       $changeset_id = $comment->getChangesetID();
       $is_new = $comment->getIsNewFile();
 
       if ($changeset_id == $this->rightSideChangesetID &&
         $is_new == $this->rightSideAttachesToNewFile) {
           return true;
         }
 
       if ($changeset_id == $this->leftSideChangesetID &&
         $is_new == $this->leftSideAttachesToNewFile) {
           return true;
         }
 
     return false;
   }
 
 
   /**
    * Determine if a comment will appear on the right side of the display diff.
    * Note that the comment must appear somewhere on the rendered changeset, as
    * per isCommentVisibleOnRenderedDiff().
    *
    * @param PhabricatorInlineCommentInterface Comment to test for display
    *              location.
    * @return bool True for right, false for left.
    */
   private function isCommentOnRightSideWhenDisplayed(
     PhabricatorInlineCommentInterface $comment) {
 
     if (!$this->isCommentVisibleOnRenderedDiff($comment)) {
       throw new Exception("Comment is not visible on changeset!");
     }
 
     $changeset_id = $comment->getChangesetID();
     $is_new = $comment->getIsNewFile();
 
     if ($changeset_id == $this->rightSideChangesetID &&
         $is_new == $this->rightSideAttachesToNewFile) {
       return true;
     }
 
     return false;
   }
 
   /**
    * Parse the 'range' specification that this class and the client-side JS
    * emit to indicate that a user clicked "Show more..." on a diff. Generally,
    * use is something like this:
    *
    *   $spec = $request->getStr('range');
    *   $parsed = DifferentialChangesetParser::parseRangeSpecification($spec);
    *   list($start, $end, $mask) = $parsed;
    *   $parser->render($start, $end, $mask);
    *
    * @param string Range specification, indicating the range of the diff that
    *               should be rendered.
    * @return tuple List of <start, end, mask> suitable for passing to
    *               @{method:render}.
    */
   public static function parseRangeSpecification($spec) {
     $range_s = null;
     $range_e = null;
     $mask = array();
 
     if ($spec) {
       $match = null;
       if (preg_match('@^(\d+)-(\d+)(?:/(\d+)-(\d+))?$@', $spec, $match)) {
         $range_s = (int)$match[1];
         $range_e = (int)$match[2];
         if (count($match) > 3) {
           $start = (int)$match[3];
           $len = (int)$match[4];
           for ($ii = $start; $ii < $start + $len; $ii++) {
             $mask[$ii] = true;
           }
         }
       }
     }
 
     return array($range_s, $range_e, $mask);
   }
 
   /**
    * Render "modified coverage" information; test coverage on modified lines.
    * This synthesizes diff information with unit test information into a useful
    * indicator of how well tested a change is.
    */
   public function renderModifiedCoverage() {
     $na = phutil_tag('em', array(), '-');
 
     $coverage = $this->getCoverage();
     if (!$coverage) {
       return $na;
     }
 
     $covered = 0;
     $not_covered = 0;
 
     foreach ($this->new as $k => $new) {
       if (!$new['line']) {
         continue;
       }
 
       if (!$new['type']) {
         continue;
       }
 
       if (empty($coverage[$new['line'] - 1])) {
         continue;
       }
 
       switch ($coverage[$new['line'] - 1]) {
         case 'C':
           $covered++;
           break;
         case 'U':
           $not_covered++;
           break;
       }
     }
 
     if (!$covered && !$not_covered) {
       return $na;
     }
 
     return sprintf('%d%%', 100 * ($covered / ($covered + $not_covered)));
   }
 
   public function detectCopiedCode(
     array $changesets,
     $min_width = 30,
     $min_lines = 3) {
 
     assert_instances_of($changesets, 'DifferentialChangeset');
 
     $map = array();
     $files = array();
     $types = array();
     foreach ($changesets as $changeset) {
       $file = $changeset->getFilename();
       foreach ($changeset->getHunks() as $hunk) {
         $line = $hunk->getOldOffset();
         foreach (explode("\n", $hunk->getChanges()) as $code) {
           $type = (isset($code[0]) ? $code[0] : '');
           if ($type == '-' || $type == ' ') {
             $code = trim(substr($code, 1));
             $files[$file][$line] = $code;
             $types[$file][$line] = $type;
             if (strlen($code) >= $min_width) {
               $map[$code][] = array($file, $line);
             }
             $line++;
           }
         }
       }
     }
 
     foreach ($changesets as $changeset) {
       $copies = array();
       foreach ($changeset->getHunks() as $hunk) {
         $added = array_map('trim', $hunk->getAddedLines());
         for (reset($added); list($line, $code) = each($added); ) {
           if (isset($map[$code])) { // We found a long matching line.
             $best_length = 0;
             foreach ($map[$code] as $val) { // Explore all candidates.
               list($file, $orig_line) = $val;
               $length = 1;
               // Search also backwards for short lines.
               foreach (array(-1, 1) as $direction) {
                 $offset = $direction;
                 while (!isset($copies[$line + $offset]) &&
                     isset($added[$line + $offset]) &&
                     idx($files[$file], $orig_line + $offset) ===
                       $added[$line + $offset]) {
                   $length++;
                   $offset += $direction;
                 }
               }
               if ($length > $best_length ||
                   ($length == $best_length && // Prefer moves.
                    idx($types[$file], $orig_line) == '-')) {
                 $best_length = $length;
                 // ($offset - 1) contains number of forward matching lines.
                 $best_offset = $offset - 1;
                 $best_file = $file;
                 $best_line = $orig_line;
               }
             }
             $file = ($best_file == $changeset->getFilename() ? '' : $best_file);
             for ($i = $best_length; $i--; ) {
               $type = idx($types[$best_file], $best_line + $best_offset - $i);
               $copies[$line + $best_offset - $i] = ($best_length < $min_lines
                 ? array() // Ignore short blocks.
                 : array($file, $best_line + $best_offset - $i, $type));
             }
             for ($i = 0; $i < $best_offset; $i++) {
               next($added);
             }
           }
         }
       }
       $copies = array_filter($copies);
       if ($copies) {
         $metadata = $changeset->getMetadata();
         $metadata['copy:lines'] = $copies;
         $changeset->setMetadata($metadata);
       }
     }
     return $changesets;
   }
 
 }