/**
* Calculate the DiffMatchPatch patch between two Phabricator files.
*
* @phutil-external-symbol class diff_match_patch
*/
public static function calculatePatch(PhabricatorFile $old = null, PhabricatorFile $new = null)
{
$root = dirname(phutil_get_library_root('phabricator'));
require_once $root . '/externals/diff_match_patch/diff_match_patch.php';
$old_hash = self::EMPTY_HASH;
$new_hash = self::EMPTY_HASH;
if ($old !== null) {
$old_hash = $old->getContentHash();
}
if ($new !== null) {
$new_hash = $new->getContentHash();
}
$old_content = '';
$new_content = '';
if ($old_hash === $new_hash) {
return null;
}
if ($old_hash !== self::EMPTY_HASH) {
$old_content = $old->loadFileData();
} else {
$old_content = '';
}
if ($new_hash !== self::EMPTY_HASH) {
$new_content = $new->loadFileData();
} else {
$new_content = '';
}
$dmp = new diff_match_patch();
$dmp_patches = $dmp->patch_make($old_content, $new_content);
return $dmp->patch_toText($dmp_patches);
}
