Differential D7726 Diff 17470 src/applications/phragment/util/PhragmentPatchUtil.php

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				<?php

				final class PhragmentPatchUtil extends Phobject {

				const EMPTY_HASH = "0000000000000000000000000000000000000000";

				/**
				* Calculate the DiffMatchPatch patch between two Phabricator files.
				*
				* @phutil-external-symbol class diff_match_patch
				*/
				public 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);
				}

				}