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DifferentialLineAdjustmentMap.php
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Thu, Mar 6, 14:18

DifferentialLineAdjustmentMap.php
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<?php
/**
* Datastructure which follows lines of code across source changes.
*
* This map is used to update the positions of inline comments after diff
* updates. For example, if a inline comment appeared on line 30 of a diff
* but the next update adds 15 more lines above it, the comment should move
* down to line 45.
*
*/
final class DifferentialLineAdjustmentMap extends Phobject {
private $map;
private $nearestMap;
private $isInverse;
private $finalOffset;
private $nextMapInChain;
/**
* Get the raw adjustment map.
*/
public function getMap() {
return $this->map;
}
public function getNearestMap() {
if ($this->nearestMap === null) {
$this->buildNearestMap();
}
return $this->nearestMap;
}
public function getFinalOffset() {
// Make sure we've built this map already.
$this->getNearestMap();
return $this->finalOffset;
}
/**
* Add a map to the end of the chain.
*
* When a line is mapped with @{method:mapLine}, it is mapped through all
* maps in the chain.
*/
public function addMapToChain(DifferentialLineAdjustmentMap $map) {
if ($this->nextMapInChain) {
$this->nextMapInChain->addMapToChain($map);
} else {
$this->nextMapInChain = $map;
}
return $this;
}
/**
* Map a line across a change, or a series of changes.
*
* @param int Line to map
* @param bool True to map it as the end of a range.
* @return wild Spooky magic.
*/
public function mapLine($line, $is_end) {
$nmap = $this->getNearestMap();
$deleted = false;
$offset = false;
if (isset($nmap[$line])) {
$line_range = $nmap[$line];
if ($is_end) {
$to_line = end($line_range);
} else {
$to_line = reset($line_range);
}
if ($to_line <= 0) {
// If we're tracing the first line and this block is collapsing,
// compute the offset from the top of the block.
if (!$is_end && $this->isInverse) {
$offset = 0;
$cursor = $line - 1;
while (isset($nmap[$cursor])) {
$prev = $nmap[$cursor];
$prev = reset($prev);
if ($prev == $to_line) {
$offset++;
} else {
break;
}
$cursor--;
}
}
$to_line = -$to_line;
if (!$this->isInverse) {
$deleted = true;
}
}
$line = $to_line;
} else {
$line = $line + $this->finalOffset;
}
if ($this->nextMapInChain) {
$chain = $this->nextMapInChain->mapLine($line, $is_end);
list($chain_deleted, $chain_offset, $line) = $chain;
$deleted = ($deleted || $chain_deleted);
if ($chain_offset !== false) {
if ($offset === false) {
$offset = 0;
}
$offset += $chain_offset;
}
}
return array($deleted, $offset, $line);
}
/**
* Build a derived map which maps deleted lines to the nearest valid line.
*
* This computes a "nearest line" map and a final-line offset. These
* derived maps allow us to map deleted code to the previous (or next) line
* which actually exists.
*/
private function buildNearestMap() {
$map = $this->map;
$nmap = array();
$nearest = 0;
foreach ($map as $key => $value) {
if ($value) {
$nmap[$key] = $value;
$nearest = end($value);
} else {
$nmap[$key][0] = -$nearest;
}
}
if (isset($key)) {
$this->finalOffset = ($nearest - $key);
} else {
$this->finalOffset = 0;
}
foreach (array_reverse($map, true) as $key => $value) {
if ($value) {
$nearest = reset($value);
} else {
$nmap[$key][1] = -$nearest;
}
}
$this->nearestMap = $nmap;
return $this;
}
public static function newFromHunks(array $hunks) {
assert_instances_of($hunks, 'DifferentialHunk');
$map = array();
$o = 0;
$n = 0;
$hunks = msort($hunks, 'getOldOffset');
foreach ($hunks as $hunk) {
// If the hunks are disjoint, add the implied missing lines where
// nothing changed.
$min = ($hunk->getOldOffset() - 1);
while ($o < $min) {
$o++;
$n++;
$map[$o][] = $n;
}
$lines = $hunk->getStructuredLines();
foreach ($lines as $line) {
switch ($line['type']) {
case '-':
$o++;
$map[$o] = array();
break;
case '+':
$n++;
$map[$o][] = $n;
break;
case ' ':
$o++;
$n++;
$map[$o][] = $n;
break;
default:
break;
}
}
}
$map = self::reduceMapRanges($map);
return self::newFromMap($map);
}
public static function newFromMap(array $map) {
$obj = new DifferentialLineAdjustmentMap();
$obj->map = $map;
return $obj;
}
public static function newInverseMap(DifferentialLineAdjustmentMap $map) {
$old = $map->getMap();
$inv = array();
$last = 0;
foreach ($old as $k => $v) {
if (count($v) > 1) {
$v = range(reset($v), end($v));
}
if ($k == 0) {
foreach ($v as $line) {
$inv[$line] = array();
$last = $line;
}
} else if ($v) {
$first = true;
foreach ($v as $line) {
if ($first) {
$first = false;
$inv[$line][] = $k;
$last = $line;
} else {
$inv[$line] = array();
}
}
} else {
$inv[$last][] = $k;
}
}
$inv = self::reduceMapRanges($inv);
$obj = new DifferentialLineAdjustmentMap();
$obj->map = $inv;
$obj->isInverse = !$map->isInverse;
return $obj;
}
private static function reduceMapRanges(array $map) {
foreach ($map as $key => $values) {
if (count($values) > 2) {
$map[$key] = array(reset($values), end($values));
}
}
return $map;
}
public static function loadMaps(array $maps) {
$keys = array();
foreach ($maps as $map) {
list($u, $v) = $map;
$keys[self::getCacheKey($u, $v)] = $map;
}
$cache = new PhabricatorKeyValueDatabaseCache();
$cache = new PhutilKeyValueCacheProfiler($cache);
$cache->setProfiler(PhutilServiceProfiler::getInstance());
$results = array();
if ($keys) {
$caches = $cache->getKeys(array_keys($keys));
foreach ($caches as $key => $value) {
list($u, $v) = $keys[$key];
try {
$results[$u][$v] = self::newFromMap(
phutil_json_decode($value));
} catch (Exception $ex) {
// Ignore, rebuild below.
}
unset($keys[$key]);
}
}
if ($keys) {
$built = self::buildMaps($maps);
$write = array();
foreach ($built as $u => $list) {
foreach ($list as $v => $map) {
$write[self::getCacheKey($u, $v)] = json_encode($map->getMap());
$results[$u][$v] = $map;
}
}
$cache->setKeys($write);
}
return $results;
}
private static function buildMaps(array $maps) {
$need = array();
foreach ($maps as $map) {
list($u, $v) = $map;
$need[$u] = $u;
$need[$v] = $v;
}
if ($need) {
$changesets = id(new DifferentialChangesetQuery())
->setViewer(PhabricatorUser::getOmnipotentUser())
->withIDs($need)
->needHunks(true)
->execute();
$changesets = mpull($changesets, null, 'getID');
}
$results = array();
foreach ($maps as $map) {
list($u, $v) = $map;
$u_set = idx($changesets, $u);
$v_set = idx($changesets, $v);
if (!$u_set || !$v_set) {
continue;
}
// This is the simple case.
if ($u == $v) {
$results[$u][$v] = self::newFromHunks(
$u_set->getHunks());
continue;
}
$u_old = $u_set->makeOldFile();
$v_old = $v_set->makeOldFile();
// No difference between the two left sides.
if ($u_old == $v_old) {
$results[$u][$v] = self::newFromMap(
array());
continue;
}
// If we're missing context, this won't currently work. We can
// make this case work, but it's fairly rare.
$u_hunks = $u_set->getHunks();
$v_hunks = $v_set->getHunks();
if (count($u_hunks) != 1 ||
count($v_hunks) != 1 ||
head($u_hunks)->getOldOffset() != 1 ||
head($u_hunks)->getNewOffset() != 1 ||
head($v_hunks)->getOldOffset() != 1 ||
head($v_hunks)->getNewOffset() != 1) {
continue;
}
$changeset = id(new PhabricatorDifferenceEngine())
->setIgnoreWhitespace(true)
->generateChangesetFromFileContent($u_old, $v_old);
$results[$u][$v] = self::newFromHunks(
$changeset->getHunks());
}
return $results;
}
private static function getCacheKey($u, $v) {
return 'diffadjust.v1('.$u.','.$v.')';
}
}

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