DifferentialChangesetParser.php
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Created: Sat, May 11, 15:24

DifferentialChangesetParser.php
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	<?php

	final class DifferentialChangesetParser extends Phobject {

	const HIGHLIGHT_BYTE_LIMIT = 262144;

	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;
	private $characterEncoding;
	private $highlightAs;
	private $highlightingDisabled;
	private $showEditAndReplyLinks = true;
	private $canMarkDone;
	private $objectOwnerPHID;
	private $offsetMode;

	private $rangeStart;
	private $rangeEnd;
	private $mask;

	private $highlightEngine;

	public function setRange($start, $end) {
	$this->rangeStart = $start;
	$this->rangeEnd = $end;
	return $this;
	}

	public function setMask(array $mask) {
	$this->mask = $mask;
	return $this;
	}

	public function renderChangeset() {
	return $this->render($this->rangeStart, $this->rangeEnd, $this->mask);
	}

	public function setShowEditAndReplyLinks($bool) {
	$this->showEditAndReplyLinks = $bool;
	return $this;
	}

	public function getShowEditAndReplyLinks() {
	return $this->showEditAndReplyLinks;
	}

	public function setHighlightAs($highlight_as) {
	$this->highlightAs = $highlight_as;
	return $this;
	}

	public function getHighlightAs() {
	return $this->highlightAs;
	}

	public function setCharacterEncoding($character_encoding) {
	$this->characterEncoding = $character_encoding;
	return $this;
	}

	public function getCharacterEncoding() {
	return $this->characterEncoding;
	}

	public function setRenderer(DifferentialChangesetRenderer $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;
	}

	public function setCanMarkDone($can_mark_done) {
	$this->canMarkDone = $can_mark_done;
	return $this;
	}

	public function getCanMarkDone() {
	return $this->canMarkDone;
	}

	public function setObjectOwnerPHID($phid) {
	$this->objectOwnerPHID = $phid;
	return $this;
	}

	public function getObjectOwnerPHID() {
	return $this->objectOwnerPHID;
	}

	public function setOffsetMode($offset_mode) {
	$this->offsetMode = $offset_mode;
	return $this;
	}

	public function getOffsetMode() {
	return $this->offsetMode;
	}

	public static function getDefaultRendererForViewer(PhabricatorUser $viewer) {
	$prefs = $viewer->loadPreferences();
	$pref_unified = PhabricatorUserPreferences::PREFERENCE_DIFF_UNIFIED;
	if ($prefs->getPreference($pref_unified) == 'unified') {
	return '1up';
	}
	return null;
	}

	public function readParametersFromRequest(AphrontRequest $request) {
	$this->setWhitespaceMode($request->getStr('whitespace'));
	$this->setCharacterEncoding($request->getStr('encoding'));
	$this->setHighlightAs($request->getStr('highlight'));

	$renderer = null;

	// If the viewer prefers unified diffs, always set the renderer to unified.
	// Otherwise, we leave it unspecified and the client will choose a
	// renderer based on the screen size.

	if ($request->getStr('renderer')) {
	$renderer = $request->getStr('renderer');
	} else {
	$renderer = self::getDefaultRendererForViewer($request->getViewer());
	}

	switch ($renderer) {
	case '1up':
	$this->setRenderer(new DifferentialChangesetOneUpRenderer());
	break;
	default:
	$this->setRenderer(new DifferentialChangesetTwoUpRenderer());
	break;
	}

	return $this;
	}

	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 ATTR_MOVEAWAY = 'attr:moveaway';

	const LINES_CONTEXT = 8;

	const WHITESPACE_SHOW_ALL = 'show-all';
	const WHITESPACE_IGNORE_TRAILING = 'ignore-trailing';
	const WHITESPACE_IGNORE_MOST = 'ignore-most';
	const WHITESPACE_IGNORE_ALL = 'ignore-all';

	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;
	return $this;
	}

	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 getUser() {
	return $this->user;
	}

	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',
	'highlightingDisabled',
	);
	}

	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;
	}

	$changeset = new DifferentialChangeset();
	$conn_w = $changeset->establishConnection('w');

	$unguarded = AphrontWriteGuard::beginScopedUnguardedWrites();
	try {
	queryfx(
	$conn_w,
	'INSERT INTO %T (id, cache, dateCreated) VALUES (%d, %B, %d)
	ON DUPLICATE KEY UPDATE cache = VALUES(cache)',
	DifferentialChangeset::TABLE_CACHE,
	$render_cache_key,
	$cache,
	time());
	} catch (AphrontQueryException $ex) {
	// Ignore these exceptions. A common cause is that the cache is
	// larger than 'max_allowed_packet', in which case we're better off
	// not writing it.

	// TODO: It would be nice to tailor this more narrowly.
	}
	unset($unguarded);
	}

	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);
	}

	public function isMoveAway() {
	return idx($this->specialAttributes, self::ATTR_MOVEAWAY, 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) {
	$language = $this->highlightAs;

	if (!$language) {
	$language = $this->highlightEngine->getLanguageFromFilename(
	$this->filename);

	if (($language != 'txt') &&
	(strlen($corpus) > self::HIGHLIGHT_BYTE_LIMIT)) {
	$this->highlightingDisabled = true;
	$language = 'txt';
	}
	}

	return $this->highlightEngine->getHighlightFuture(
	$language,
	$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_ALL:
	break;
	default:
	$whitespace_mode = self::WHITESPACE_IGNORE_MOST;
	break;
	}

	$skip_cache = ($whitespace_mode != self::WHITESPACE_IGNORE_MOST);
	if ($this->disableCache) {
	$skip_cache = true;
	}

	if ($this->characterEncoding) {
	$skip_cache = true;
	}

	if ($this->highlightAs) {
	$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_MOST) \|\|
	($whitespace_mode == self::WHITESPACE_IGNORE_ALL));

	$force_ignore = ($whitespace_mode == self::WHITESPACE_IGNORE_ALL);

	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;
	}
	}

	$moveaway = false;
	$changetype = $this->changeset->getChangeType();
	if ($changetype == DifferentialChangeType::TYPE_MOVE_AWAY) {
	$moveaway = true;
	}

	$this->setSpecialAttributes(array(
	self::ATTR_UNCHANGED => $unchanged,
	self::ATTR_DELETED => $hunk_parser->getIsDeleted(),
	self::ATTR_WHITELINES => !$hunk_parser->getHasTextChanges(),
	self::ATTR_MOVEAWAY => $moveaway,
	));

	$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,
	);

	$this->highlightErrors = false;
	foreach (new FutureIterator($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;
	}

	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();

	$encoding = null;
	if ($this->characterEncoding) {
	// We are forcing this changeset to be interpreted with a specific
	// character encoding, so force all the hunks into that encoding and
	// propagate it to the renderer.
	$encoding = $this->characterEncoding;
	foreach ($this->changeset->getHunks() as $hunk) {
	$hunk->forceEncoding($this->characterEncoding);
	}
	} else {
	// We're just using the default, so tell the renderer what that is
	// (by reading the encoding from the first hunk).
	foreach ($this->changeset->getHunks() as $hunk) {
	$encoding = $hunk->getDataEncoding();
	break;
	}
	}

	$this->tryCacheStuff();

	// If we're rendering in an offset mode, treat the range numbers as line
	// numbers instead of rendering offsets.
	$offset_mode = $this->getOffsetMode();
	if ($offset_mode) {
	if ($offset_mode == 'new') {
	$offset_map = $this->new;
	} else {
	$offset_map = $this->old;
	}

	$range_end = $this->getOffset($offset_map, $range_start + $range_len);
	$range_start = $this->getOffset($offset_map, $range_start);
	$range_len = ($range_end - $range_start);
	}

	$render_pch = $this->shouldRenderPropertyChangeHeader($this->changeset);

	$rows = max(
	count($this->old),
	count($this->new));

	$renderer = $this->getRenderer()
	->setUser($this->getUser())
	->setChangeset($this->changeset)
	->setRenderPropertyChangeHeader($render_pch)
	->setIsTopLevel($this->isTopLevel)
	->setOldRender($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)
	->setOriginalCharacterEncoding($encoding)
	->setShowEditAndReplyLinks($this->getShowEditAndReplyLinks())
	->setCanMarkDone($this->getCanMarkDone())
	->setObjectOwnerPHID($this->getObjectOwnerPHID())
	->setHighlightingDisabled($this->highlightingDisabled);

	$shield = null;
	if ($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->isMoveAway()) {
	// We put an empty shield on these files. Normally, they do not have
	// any diff content anyway. However, if they come through `arc`, they
	// may have content. We don't want to show it (it's not useful) and
	// we bailed out of fully processing it earlier anyway.

	// We could show a message like "this file was moved", but we show
	// that as a change header anyway, so it would be redundant. Instead,
	// just render an empty shield to skip rendering the diff body.
	$shield = '';
	} else if ($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';
	}

	$type_add = DifferentialChangeType::TYPE_ADD;
	if ($this->changeset->getChangeType() == $type_add) {
	// Although the generic message is sort of accurate in a technical
	// sense, this more-tailored message is less confusing.
	$shield = $renderer->renderShield(
	pht('This is an empty file.'),
	$type);
	} else {
	$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) {
	$shield = $renderer->renderShield(
	pht(
	'This file has a very large number of changes (%s lines).',
	new PhutilNumber($this->changeset->getAffectedLineCount())));
	}
	}

	if ($shield !== null) {
	return $renderer->renderChangesetTable($shield);
	}

	// This request should render the "undershield" headers if it's a top-level
	// request which made it this far (indicating the changeset has no shield)
	// or it's a request with no mask information (indicating it's the request
	// that removes the rendering shield). Possibly, this second class of
	// request might need to be made more explicit.
	$is_undershield = (empty($mask_force) \|\| $this->isTopLevel);
	$renderer->setIsUndershield($is_undershield);

	$old_comments = array();
	$new_comments = array();
	$old_mask = array();
	$new_mask = array();
	$feedback_mask = array();

	if ($this->comments) {
	// If there are any comments which appear in sections of the file which
	// we don't have, we're going to move them backwards to the closest
	// earlier line. Two cases where this may happen are:
	//
	// - Porting ghost comments forward into a file which was mostly
	// deleted.
	// - Porting ghost comments forward from a full-context diff to a
	// partial-context diff.

	list($old_backmap, $new_backmap) = $this->buildLineBackmaps();

	foreach ($this->comments as $comment) {
	$new_side = $this->isCommentOnRightSideWhenDisplayed($comment);

	$line = $comment->getLineNumber();
	if ($new_side) {
	$back_line = $new_backmap[$line];
	} else {
	$back_line = $old_backmap[$line];
	}

	if ($back_line != $line) {
	// TODO: This should probably be cleaner, but just be simple and
	// obvious for now.
	$ghost = $comment->getIsGhost();
	if ($ghost) {
	$moved = pht(
	'This comment originally appeared on line %s, but that line '.
	'does not exist in this version of the diff. It has been '.
	'moved backward to the nearest line.',
	new PhutilNumber($line));
	$ghost['reason'] = $ghost['reason']."\n\n".$moved;
	$comment->setIsGhost($ghost);
	}

	$comment->setLineNumber($back_line);
	$comment->setLineLength(0);

	}

	$start = max($comment->getLineNumber() - self::LINES_CONTEXT, 0);
	$end = $comment->getLineNumber() +
	$comment->getLineLength() +
	self::LINES_CONTEXT;
	for ($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 = $this->reorderAndThreadComments($this->comments);

	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);
	$old_phid = null;
	$new_phid = null;

	// TODO: This is spooky, see D6851
	if ($vs_changeset) {
	$vs_metadata = $vs_changeset->getMetadata();
	$old_phid = idx($vs_metadata, 'new:binary-phid');
	}

	$changeset = id(new DifferentialChangeset())->load($id);
	if ($changeset) {
	$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;
	}

	$files = id(new PhabricatorFileQuery())
	->setViewer($this->getUser())
	->withPHIDs($file_phids)
	->execute();
	foreach ($files as $file) {
	if (empty($file)) {
	continue;
	}
	if ($file->getPHID() == $old_phid) {
	$old = $file;
	} else if ($file->getPHID() == $new_phid) {
	$new = $file;
	}
	}
	}

	$renderer->attachOldFile($old);
	$renderer->attachNewFile($new);

	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;
	// 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(pht('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) {
	$lines = $hunk->getStructuredOldFile();
	foreach ($lines as $line => $info) {
	$type = $info['type'];
	if ($type == '\\') {
	continue;
	}
	$types[$file][$line] = $type;

	$text = $info['text'];
	$text = trim($text);
	$files[$file][$line] = $text;

	if (strlen($text) >= $min_width) {
	$map[$text][] = array($file, $line);
	}
	}
	}
	}

	foreach ($changesets as $changeset) {
	$copies = array();
	foreach ($changeset->getHunks() as $hunk) {
	$added = $hunk->getStructuredNewFile();
	$atype = array();

	foreach ($added as $line => $info) {
	$atype[$line] = $info['type'];
	$added[$line] = trim($info['text']);
	}

	$skip_lines = 0;
	foreach ($added as $line => $code) {
	if ($skip_lines) {
	// We're skipping lines that we already processed because we
	// extended a block above them downward to include them.
	$skip_lines--;
	continue;
	}

	if ($atype[$line] !== '+') {
	// This line hasn't been changed in the new file, so don't try
	// to figure out where it came from.
	continue;
	}

	if (empty($map[$code])) {
	// This line was too short to trigger copy/move detection.
	continue;
	}

	if (count($map[$code]) > 16) {
	// If there are a large number of identical lines in this diff,
	// don't try to figure out where this block came from: the analysis
	// is O(N^2), since we need to compare every line against every
	// other line. Even if we arrive at a result, it is unlikely to be
	// meaningful. See T5041.
	continue;
	}

	$best_length = 0;

	// Explore all candidates.
	foreach ($map[$code] as $val) {
	list($file, $orig_line) = $val;
	$length = 1;

	// Search backward and forward to find all of the adjacent lines
	// which match.
	foreach (array(-1, 1) as $direction) {
	$offset = $direction;
	while (true) {
	if (isset($copies[$line + $offset])) {
	// If we run into a block above us which we've already
	// attributed to a move or copy from elsewhere, stop
	// looking.
	break;
	}

	if (!isset($added[$line + $offset])) {
	// If we've run off the beginning or end of the new file,
	// stop looking.
	break;
	}

	if (!isset($files[$file][$orig_line + $offset])) {
	// If we've run off the beginning or end of the original
	// file, we also stop looking.
	break;
	}

	$old = $files[$file][$orig_line + $offset];
	$new = $added[$line + $offset];
	if ($old !== $new) {
	// If the old line doesn't match the new line, stop
	// looking.
	break;
	}

	$length++;
	$offset += $direction;
	}
	}

	if ($length < $best_length) {
	// If we already know of a better source (more matching lines)
	// for this move/copy, stick with that one. We prefer long
	// copies/moves which match a lot of context over short ones.
	continue;
	}

	if ($length == $best_length) {
	if (idx($types[$file], $orig_line) != '-') {
	// If we already know of an equally good source (same number
	// of matching lines) and this isn't a move, stick with the
	// other one. We prefer moves over copies.
	continue;
	}
	}

	$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));
	}

	$skip_lines = $best_offset;
	}
	}

	$copies = array_filter($copies);
	if ($copies) {
	$metadata = $changeset->getMetadata();
	$metadata['copy:lines'] = $copies;
	$changeset->setMetadata($metadata);
	}
	}
	return $changesets;
	}

	/**
	* Build maps from lines comments appear on to actual lines.
	*/
	private function buildLineBackmaps() {
	$old_back = array();
	$new_back = array();
	foreach ($this->old as $ii => $old) {
	$old_back[$old['line']] = $old['line'];
	}
	foreach ($this->new as $ii => $new) {
	$new_back[$new['line']] = $new['line'];
	}

	$max_old_line = 0;
	$max_new_line = 0;
	foreach ($this->comments as $comment) {
	if ($this->isCommentOnRightSideWhenDisplayed($comment)) {
	$max_new_line = max($max_new_line, $comment->getLineNumber());
	} else {
	$max_old_line = max($max_old_line, $comment->getLineNumber());
	}
	}

	$cursor = 1;
	for ($ii = 1; $ii <= $max_old_line; $ii++) {
	if (empty($old_back[$ii])) {
	$old_back[$ii] = $cursor;
	} else {
	$cursor = $old_back[$ii];
	}
	}

	$cursor = 1;
	for ($ii = 1; $ii <= $max_new_line; $ii++) {
	if (empty($new_back[$ii])) {
	$new_back[$ii] = $cursor;
	} else {
	$cursor = $new_back[$ii];
	}
	}

	return array($old_back, $new_back);
	}

	private function reorderAndThreadComments(array $comments) {
	$comments = msort($comments, 'getID');

	// Build an empty map of all the comments we actually have. If a comment
	// is a reply but the parent has gone missing, we don't want it to vanish
	// completely.
	$comment_phids = mpull($comments, 'getPHID');
	$replies = array_fill_keys($comment_phids, array());

	// Now, remove all comments which are replies, leaving only the top-level
	// comments.
	foreach ($comments as $key => $comment) {
	$reply_phid = $comment->getReplyToCommentPHID();
	if (isset($replies[$reply_phid])) {
	$replies[$reply_phid][] = $comment;
	unset($comments[$key]);
	}
	}

	// For each top level comment, add the comment, then add any replies
	// to it. Do this recursively so threads are shown in threaded order.
	$results = array();
	foreach ($comments as $comment) {
	$results[] = $comment;
	$phid = $comment->getPHID();
	$descendants = $this->getInlineReplies($replies, $phid, 1);
	foreach ($descendants as $descendant) {
	$results[] = $descendant;
	}
	}

	// If we have anything left, they were cyclic references. Just dump
	// them in a the end. This should be impossible, but users are very
	// creative.
	foreach ($replies as $phid => $comments) {
	foreach ($comments as $comment) {
	$results[] = $comment;
	}
	}

	return $results;
	}

	private function getInlineReplies(array &$replies, $phid, $depth) {
	$comments = idx($replies, $phid, array());
	unset($replies[$phid]);

	$results = array();
	foreach ($comments as $comment) {
	$results[] = $comment;
	$descendants = $this->getInlineReplies(
	$replies,
	$comment->getPHID(),
	$depth + 1);
	foreach ($descendants as $descendant) {
	$results[] = $descendant;
	}
	}

	return $results;
	}

	private function getOffset(array $map, $line) {
	if (!$map) {
	return null;
	}

	$line = (int)$line;
	foreach ($map as $key => $spec) {
	if ($spec && isset($spec['line'])) {
	if ((int)$spec['line'] >= $line) {
	return $key;
	}
	}
	}

	return $key;
	}

	}

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