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PhabricatorDifferenceEngine.php
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Tue, Apr 22, 18:05

PhabricatorDifferenceEngine.php
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<?php
/*
* Copyright 2011 Facebook, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/**
* Utility class which encapsulates some shared behavior between different
* applications which render diffs.
*
* @task config Configuring the Engine
* @task diff Generating Diffs
*/
final class PhabricatorDifferenceEngine {
private $ignoreWhitespace;
/* -( Configuring the Engine )--------------------------------------------- */
/**
* If true, ignore whitespace when computing differences.
*
* @param bool Ignore whitespace?
* @return this
* @task config
*/
public function setIgnoreWhitespace($ignore_whitespace) {
$this->ignoreWhitespace = $ignore_whitespace;
return $this;
}
/* -( Generating Diffs )--------------------------------------------------- */
/**
* Generate an @{class:DifferentialChangeset} from two raw files. This is
* principally useful because you can feed the output to
* @{class:DifferentialChangesetParser} in order to render it.
*
* @param string Entire previous file content.
* @param string Entire current file content.
* @return @{class:DifferentialChangeset} Synthetic changeset.
* @task diff
*/
public function generateChangesetFromFileContent($old, $new) {
$options = array();
if ($this->ignoreWhitespace) {
$options[] = '-bw';
}
// Generate diffs with full context.
$options[] = '-U65535';
$old_tmp = new TempFile();
$new_tmp = new TempFile();
Filesystem::writeFile($old_tmp, $old);
Filesystem::writeFile($new_tmp, $new);
list($err, $diff) = exec_manual(
'/usr/bin/diff %Ls %s %s',
$options,
$old_tmp,
$new_tmp);
if (!strlen($diff)) {
// This indicates that the two files are the same (or, possibly, the
// same modulo whitespace differences, which is why we can't do this
// check trivially before running `diff`). Build a synthetic, changeless
// diff so that we can still render the raw, unchanged file instead of
// being forced to just say "this file didn't change" since we don't have
// the content.
$entire_file = explode("\n", $old);
foreach ($entire_file as $k => $line) {
$entire_file[$k] = ' '.$line;
}
$len = count($entire_file);
$entire_file = implode("\n", $entire_file);
// This is a bit hacky but the diff parser can handle it.
$diff = "--- ignored 9999-99-99\n".
"+++ ignored 9999-99-99\n".
"@@ -1,{$len} +1,{$len} @@\n".
$entire_file."\n";
}
$changes = id(new ArcanistDiffParser())->parseDiff($diff);
$diff = DifferentialDiff::newFromRawChanges($changes);
return head($diff->getChangesets());
}
}

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