Initial Drupal 11 with DDEV setup

web/core/lib/Drupal/Component/Diff/Diff.php

@@ -0,0 +1,50 @@
+<?php
+
+namespace Drupal\Component\Diff;
+
+use SebastianBergmann\Diff\Differ;
+
+/**
+ * Class representing a 'diff' between two sequences of strings.
+ *
+ * Component code originally taken from https://www.drupal.org/project/diff
+ * which was itself based on the PHP diff engine for phpwiki. The original code
+ * in phpwiki was copyright (C) 2000, 2001 Geoffrey T. Dairiki
+ * <dairiki@dairiki.org> and licensed under GPL.
+ */
+class Diff {
+
+  /**
+   * The list of differences as an array of diff operations.
+   *
+   * @var \Drupal\Component\Diff\Engine\DiffOp[]
+   */
+  protected $edits;
+
+  /**
+   * Constructor.
+   * Computes diff between sequences of strings.
+   *
+   * @param array $from_lines
+   *   An array of strings.
+   *   (Typically these are lines from a file.)
+   * @param array $to_lines
+   *   An array of strings.
+   */
+  public function __construct($from_lines, $to_lines) {
+    $diffOpBuilder = new DiffOpOutputBuilder();
+    $differ = new Differ($diffOpBuilder);
+    $this->edits = $diffOpBuilder->toOpsArray($differ->diffToArray($from_lines, $to_lines));
+  }
+
+  /**
+   * Gets the list of differences as an array of diff operations.
+   *
+   * @return \Drupal\Component\Diff\Engine\DiffOp[]
+   *   The list of differences as an array of diff operations.
+   */
+  public function getEdits() {
+    return $this->edits;
+  }
+
+}

web/core/lib/Drupal/Component/Diff/DiffFormatter.php

@@ -0,0 +1,197 @@
+<?php
+
+namespace Drupal\Component\Diff;
+
+use Drupal\Component\Diff\Engine\DiffOpCopy;
+
+/**
+ * A class to format Diffs
+ *
+ * This class formats the diff in classic diff format.
+ * It is intended that this class be customized via inheritance,
+ * to obtain fancier outputs.
+ * @todo document
+ * @private
+ * @subpackage DifferenceEngine
+ */
+class DiffFormatter {
+  /**
+   * Should a block header be shown?
+   */
+  public $show_header = TRUE;
+
+  /**
+   * Number of leading context "lines" to preserve.
+   *
+   * This should be left at zero for this class, but subclasses
+   * may want to set this to other values.
+   */
+  public $leading_context_lines = 0;
+
+  /**
+   * Number of trailing context "lines" to preserve.
+   *
+   * This should be left at zero for this class, but subclasses
+   * may want to set this to other values.
+   */
+  public $trailing_context_lines = 0;
+
+  /**
+   * The line stats.
+   *
+   * @var array
+   */
+  protected $line_stats = [
+    'counter' => ['x' => 0, 'y' => 0],
+    'offset' => ['x' => 0, 'y' => 0],
+  ];
+
+  /**
+   * Format a diff.
+   *
+   * @param \Drupal\Component\Diff\Diff $diff
+   *   A Diff object.
+   *
+   * @return string
+   *   The formatted output.
+   */
+  public function format(Diff $diff) {
+    $xi = $yi = 1;
+    $block = FALSE;
+    $context = [];
+
+    $nlead = $this->leading_context_lines;
+    $ntrail = $this->trailing_context_lines;
+
+    $this->_start_diff();
+
+    foreach ($diff->getEdits() as $edit) {
+      if ($edit->type == 'copy') {
+        if (is_array($block)) {
+          if (sizeof($edit->orig) <= $nlead + $ntrail) {
+            $block[] = $edit;
+          }
+          else {
+            if ($ntrail) {
+              $context = array_slice($edit->orig, 0, $ntrail);
+              $block[] = new DiffOpCopy($context);
+            }
+            $this->_block($x0, $ntrail + $xi - $x0, $y0, $ntrail + $yi - $y0, $block);
+            $block = FALSE;
+          }
+        }
+        $context = $edit->orig;
+      }
+      else {
+        if (!is_array($block)) {
+          $context = array_slice($context, sizeof($context) - $nlead);
+          $x0 = $xi - sizeof($context);
+          $y0 = $yi - sizeof($context);
+          $block = [];
+          if ($context) {
+            $block[] = new DiffOpCopy($context);
+          }
+        }
+        $block[] = $edit;
+      }
+
+      if ($edit->orig) {
+        $xi += sizeof($edit->orig);
+      }
+      if ($edit->closing) {
+        $yi += sizeof($edit->closing);
+      }
+    }
+
+    if (is_array($block)) {
+      $this->_block($x0, $xi - $x0, $y0, $yi - $y0, $block);
+    }
+    $end = $this->_end_diff();
+
+    if (!empty($xi)) {
+      $this->line_stats['counter']['x'] += $xi;
+    }
+    if (!empty($yi)) {
+      $this->line_stats['counter']['y'] += $yi;
+    }
+
+    return $end;
+  }
+
+  protected function _block($xbeg, $xlen, $ybeg, $ylen, &$edits) {
+    $this->_start_block($this->_block_header($xbeg, $xlen, $ybeg, $ylen));
+    foreach ($edits as $edit) {
+      if ($edit->type == 'copy') {
+        $this->_context($edit->orig);
+      }
+      elseif ($edit->type == 'add') {
+        $this->_added($edit->closing);
+      }
+      elseif ($edit->type == 'delete') {
+        $this->_deleted($edit->orig);
+      }
+      elseif ($edit->type == 'change') {
+        $this->_changed($edit->orig, $edit->closing);
+      }
+      else {
+        trigger_error('Unknown edit type', E_USER_WARNING);
+      }
+    }
+    $this->_end_block();
+  }
+
+  protected function _start_diff() {
+    ob_start();
+  }
+
+  protected function _end_diff() {
+    $val = ob_get_contents();
+    ob_end_clean();
+    return $val;
+  }
+
+  protected function _block_header($xbeg, $xlen, $ybeg, $ylen) {
+    if ($xlen > 1) {
+      $xbeg .= "," . ($xbeg + $xlen - 1);
+    }
+    if ($ylen > 1) {
+      $ybeg .= "," . ($ybeg + $ylen - 1);
+    }
+
+    return $xbeg . ($xlen ? ($ylen ? 'c' : 'd') : 'a') . $ybeg;
+  }
+
+  protected function _start_block($header) {
+    if ($this->show_header) {
+      echo $header . "\n";
+    }
+  }
+
+  protected function _end_block() {
+  }
+
+  protected function _lines($lines, $prefix = ' ') {
+    foreach ($lines as $line) {
+      echo "$prefix $line\n";
+    }
+  }
+
+  protected function _context($lines) {
+    $this->_lines($lines);
+  }
+
+  protected function _added($lines) {
+    $this->_lines($lines, '>');
+  }
+
+  protected function _deleted($lines) {
+    $this->_lines($lines, '<');
+  }
+
+  protected function _changed($orig, $closing) {
+    $this->_deleted($orig);
+    echo "---\n";
+    $this->_added($closing);
+  }
+
+}

web/core/lib/Drupal/Component/Diff/DiffOpOutputBuilder.php

@@ -0,0 +1,130 @@
+<?php declare(strict_types=1);
+
+namespace Drupal\Component\Diff;
+
+use Drupal\Component\Diff\Engine\DiffOp;
+use Drupal\Component\Diff\Engine\DiffOpAdd;
+use Drupal\Component\Diff\Engine\DiffOpChange;
+use Drupal\Component\Diff\Engine\DiffOpCopy;
+use Drupal\Component\Diff\Engine\DiffOpDelete;
+use SebastianBergmann\Diff\Differ;
+use SebastianBergmann\Diff\Output\DiffOutputBuilderInterface;
+
+/**
+ * Returns a diff as an array of DiffOp operations.
+ */
+final class DiffOpOutputBuilder implements DiffOutputBuilderInterface {
+
+  /**
+   * A constant to manage removal+addition as a single operation.
+   */
+  private const CHANGED = 999;
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getDiff(array $diff): string {
+    return serialize($this->toOpsArray($diff));
+  }
+
+  /**
+   * Converts the output of Differ to an array of DiffOp* value objects.
+   *
+   * @param array $diff
+   *   The array output of Differ::diffToArray().
+   *
+   * @return \Drupal\Component\Diff\Engine\DiffOp[]
+   *   An array of DiffOp* value objects.
+   */
+  public function toOpsArray(array $diff): array {
+    $ops = [];
+    $hunkMode = NULL;
+    $hunkSource = [];
+    $hunkTarget = [];
+
+    for ($i = 0; $i < count($diff); $i++) {
+
+      // Handle a sequence of removals + additions as a sequence of changes, and
+      // manages the tail if required.
+      if ($diff[$i][1] === Differ::REMOVED) {
+        if ($hunkMode !== NULL) {
+          $ops[] = $this->hunkOp($hunkMode, $hunkSource, $hunkTarget);
+          $hunkSource = [];
+          $hunkTarget = [];
+        }
+        for ($n = $i; $n < count($diff) && $diff[$n][1] === Differ::REMOVED; $n++) {
+          $hunkSource[] = $diff[$n][0];
+        }
+        for (; $n < count($diff) && $diff[$n][1] === Differ::ADDED; $n++) {
+          $hunkTarget[] = $diff[$n][0];
+        }
+        if (count($hunkTarget) === 0) {
+          $ops[] = $this->hunkOp(Differ::REMOVED, $hunkSource, $hunkTarget);
+        }
+        else {
+          $ops[] = $this->hunkOp(self::CHANGED, $hunkSource, $hunkTarget);
+        }
+        $hunkMode = NULL;
+        $hunkSource = [];
+        $hunkTarget = [];
+        $i = $n - 1;
+        continue;
+      }
+
+      // When here, we are adding or copying the item. Removing or changing is
+      // managed above.
+      if ($hunkMode === NULL) {
+        $hunkMode = $diff[$i][1];
+      }
+      elseif ($hunkMode !== $diff[$i][1]) {
+        $ops[] = $this->hunkOp($hunkMode, $hunkSource, $hunkTarget);
+        $hunkMode = $diff[$i][1];
+        $hunkSource = [];
+        $hunkTarget = [];
+      }
+
+      $hunkSource[] = $diff[$i][0];
+    }
+
+    if ($hunkMode !== NULL) {
+      $ops[] = $this->hunkOp($hunkMode, $hunkSource, $hunkTarget);
+    }
+
+    return $ops;
+  }
+
+  /**
+   * Returns the proper DiffOp object based on the hunk mode.
+   *
+   * @param int $mode
+   *   A Differ constant or self::CHANGED.
+   * @param string[] $source
+   *   An array of strings to be changed/added/removed/copied.
+   * @param string[] $source
+   *   The array of strings to be changed to when self::CHANGED is specified.
+   *
+   * @return \Drupal\Component\Diff\Engine\DiffOp
+   *   A DiffOp* value object.
+   *
+   * @throw \InvalidArgumentException
+   *   When $mode is not valid.
+   */
+  private function hunkOp(int $mode, array $source, array $target): DiffOp {
+    switch ($mode) {
+      case Differ::OLD:
+        return new DiffOpCopy($source);
+
+      case self::CHANGED:
+        return new DiffOpChange($source, $target);
+
+      case Differ::ADDED:
+        return new DiffOpAdd($source);
+
+      case Differ::REMOVED:
+        return new DiffOpDelete($source);
+
+    }
+    throw new \InvalidArgumentException("Invalid \$mode {$mode} specified");
+  }
+
+}

web/core/lib/Drupal/Component/Diff/Engine/DiffOp.php

@@ -0,0 +1,14 @@
+<?php
+
+namespace Drupal\Component\Diff\Engine;
+
+/**
+ * @todo document
+ * @private
+ * @subpackage DifferenceEngine
+ */
+class DiffOp {
+  public $type;
+  public $orig;
+  public $closing;
+}

web/core/lib/Drupal/Component/Diff/Engine/DiffOpAdd.php

@@ -0,0 +1,18 @@
+<?php
+
+namespace Drupal\Component\Diff\Engine;
+
+/**
+ * @todo document
+ * @private
+ * @subpackage DifferenceEngine
+ */
+class DiffOpAdd extends DiffOp {
+  public $type = 'add';
+
+  public function __construct($lines) {
+    $this->closing = $lines;
+    $this->orig = FALSE;
+  }
+
+}

web/core/lib/Drupal/Component/Diff/Engine/DiffOpChange.php

@@ -0,0 +1,18 @@
+<?php
+
+namespace Drupal\Component\Diff\Engine;
+
+/**
+ * @todo document
+ * @private
+ * @subpackage DifferenceEngine
+ */
+class DiffOpChange extends DiffOp {
+  public $type = 'change';
+
+  public function __construct($orig, $closing) {
+    $this->orig = $orig;
+    $this->closing = $closing;
+  }
+
+}

web/core/lib/Drupal/Component/Diff/Engine/DiffOpCopy.php

@@ -0,0 +1,21 @@
+<?php
+
+namespace Drupal\Component\Diff\Engine;
+
+/**
+ * @todo document
+ * @private
+ * @subpackage DifferenceEngine
+ */
+class DiffOpCopy extends DiffOp {
+  public $type = 'copy';
+
+  public function __construct($orig, $closing = FALSE) {
+    if (!is_array($closing)) {
+      $closing = $orig;
+    }
+    $this->orig = $orig;
+    $this->closing = $closing;
+  }
+
+}

web/core/lib/Drupal/Component/Diff/Engine/DiffOpDelete.php

@@ -0,0 +1,18 @@
+<?php
+
+namespace Drupal\Component\Diff\Engine;
+
+/**
+ * @todo document
+ * @private
+ * @subpackage DifferenceEngine
+ */
+class DiffOpDelete extends DiffOp {
+  public $type = 'delete';
+
+  public function __construct($lines) {
+    $this->orig = $lines;
+    $this->closing = FALSE;
+  }
+
+}

web/core/lib/Drupal/Component/Diff/Engine/HWLDFWordAccumulator.php

@@ -0,0 +1,77 @@
+<?php
+
+namespace Drupal\Component\Diff\Engine;
+
+/**
+ * Additions by Axel Boldt follow, partly taken from diff.php, phpwiki-1.3.3
+ */
+
+/**
+ * @todo document
+ * @private
+ * @subpackage DifferenceEngine
+ */
+class HWLDFWordAccumulator {
+
+  /**
+   * An iso-8859-x non-breaking space.
+   */
+  const NBSP = '&#160;';
+
+  protected $lines = [];
+
+  protected $line = '';
+
+  protected $group = '';
+
+  protected $tag = '';
+
+  protected function _flushGroup($new_tag) {
+    if ($this->group !== '') {
+      if ($this->tag == 'mark') {
+        $this->line = $this->line . '<span class="diffchange">' . $this->group . '</span>';
+      }
+      else {
+        $this->line = $this->line . $this->group;
+      }
+    }
+    $this->group = '';
+    $this->tag = $new_tag;
+  }
+
+  protected function _flushLine($new_tag) {
+    $this->_flushGroup($new_tag);
+    if ($this->line != '') {
+      array_push($this->lines, $this->line);
+    }
+    else {
+      // make empty lines visible by inserting an NBSP
+      array_push($this->lines, $this::NBSP);
+    }
+    $this->line = '';
+  }
+
+  public function addWords($words, $tag = '') {
+    if ($tag != $this->tag) {
+      $this->_flushGroup($tag);
+    }
+    foreach ($words as $word) {
+      // new-line should only come as first char of word.
+      if ($word == '') {
+        continue;
+      }
+      if ($word[0] == "\n") {
+        $this->_flushLine($tag);
+        $word = mb_substr($word, 1);
+      }
+      assert(!str_contains($word, "\n"));
+      $this->group .= $word;
+    }
+  }
+
+  public function getLines() {
+    $this->_flushLine('~done');
+    return $this->lines;
+  }
+
+}

web/core/lib/Drupal/Component/Diff/LICENSE.txt

@@ -0,0 +1,339 @@
+        GNU GENERAL PUBLIC LICENSE
+           Version 2, June 1991
+
+ Copyright (C) 1989, 1991 Free Software Foundation, Inc.,
+ 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+          Preamble
+
+  The licenses for most software are designed to take away your
+freedom to share and change it.  By contrast, the GNU General Public
+License is intended to guarantee your freedom to share and change free
+software--to make sure the software is free for all its users.  This
+General Public License applies to most of the Free Software
+Foundation's software and to any other program whose authors commit to
+using it.  (Some other Free Software Foundation software is covered by
+the GNU Lesser General Public License instead.)  You can apply it to
+your programs, too.
+
+  When we speak of free software, we are referring to freedom, not
+price.  Our General Public Licenses are designed to make sure that you
+have the freedom to distribute copies of free software (and charge for
+this service if you wish), that you receive source code or can get it
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+  To protect your rights, we need to make restrictions that forbid
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+These restrictions translate to certain responsibilities for you if you
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+
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+   TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
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+  6. Each time you redistribute the Program (or any work based on the
+Program), the recipient automatically receives a license from the
+original licensor to copy, distribute or modify the Program subject to
+these terms and conditions.  You may not impose any further
+restrictions on the recipients' exercise of the rights granted herein.
+You are not responsible for enforcing compliance by third parties to
+this License.
+
+  7. If, as a consequence of a court judgment or allegation of patent
+infringement or for any other reason (not limited to patent issues),
+conditions are imposed on you (whether by court order, agreement or
+otherwise) that contradict the conditions of this License, they do not
+excuse you from the conditions of this License.  If you cannot
+distribute so as to satisfy simultaneously your obligations under this
+License and any other pertinent obligations, then as a consequence you
+may not distribute the Program at all.  For example, if a patent
+license would not permit royalty-free redistribution of the Program by
+all those who receive copies directly or indirectly through you, then
+the only way you could satisfy both it and this License would be to
+refrain entirely from distribution of the Program.
+
+If any portion of this section is held invalid or unenforceable under
+any particular circumstance, the balance of the section is intended to
+apply and the section as a whole is intended to apply in other
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+
+It is not the purpose of this section to induce you to infringe any
+patents or other property right claims or to contest validity of any
+such claims; this section has the sole purpose of protecting the
+integrity of the free software distribution system, which is
+implemented by public license practices.  Many people have made
+generous contributions to the wide range of software distributed
+through that system in reliance on consistent application of that
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+to distribute software through any other system and a licensee cannot
+impose that choice.
+
+This section is intended to make thoroughly clear what is believed to
+be a consequence of the rest of this License.
+
+  8. If the distribution and/or use of the Program is restricted in
+certain countries either by patents or by copyrighted interfaces, the
+original copyright holder who places the Program under this License
+may add an explicit geographical distribution limitation excluding
+those countries, so that distribution is permitted only in or among
+countries not thus excluded.  In such case, this License incorporates
+the limitation as if written in the body of this License.
+
+  9. The Free Software Foundation may publish revised and/or new versions
+of the General Public License from time to time.  Such new versions will
+be similar in spirit to the present version, but may differ in detail to
+address new problems or concerns.
+
+Each version is given a distinguishing version number.  If the Program
+specifies a version number of this License which applies to it and "any
+later version", you have the option of following the terms and conditions
+either of that version or of any later version published by the Free
+Software Foundation.  If the Program does not specify a version number of
+this License, you may choose any version ever published by the Free Software
+Foundation.
+
+  10. If you wish to incorporate parts of the Program into other free
+programs whose distribution conditions are different, write to the author
+to ask for permission.  For software which is copyrighted by the Free
+Software Foundation, write to the Free Software Foundation; we sometimes
+make exceptions for this.  Our decision will be guided by the two goals
+of preserving the free status of all derivatives of our free software and
+of promoting the sharing and reuse of software generally.
+
+          NO WARRANTY
+
+  11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
+FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW.  EXCEPT WHEN
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+TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU.  SHOULD THE
+PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING,
+REPAIR OR CORRECTION.
+
+  12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
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+REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES,
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+YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER
+PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE
+POSSIBILITY OF SUCH DAMAGES.
+
+         END OF TERMS AND CONDITIONS
+
+      How to Apply These Terms to Your New Programs
+
+  If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+  To do so, attach the following notices to the program.  It is safest
+to attach them to the start of each source file to most effectively
+convey the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+    <one line to give the program's name and a brief idea of what it does.>
+    Copyright (C) <year>  <name of author>
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License along
+    with this program; if not, write to the Free Software Foundation, Inc.,
+    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+
+Also add information on how to contact you by electronic and paper mail.
+
+If the program is interactive, make it output a short notice like this
+when it starts in an interactive mode:
+
+    Gnomovision version 69, Copyright (C) year name of author
+    Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
+    This is free software, and you are welcome to redistribute it
+    under certain conditions; type `show c' for details.
+
+The hypothetical commands `show w' and `show c' should show the appropriate
+parts of the General Public License.  Of course, the commands you use may
+be called something other than `show w' and `show c'; they could even be
+mouse-clicks or menu items--whatever suits your program.
+
+You should also get your employer (if you work as a programmer) or your
+school, if any, to sign a "copyright disclaimer" for the program, if
+necessary.  Here is a sample; alter the names:
+
+  Yoyodyne, Inc., hereby disclaims all copyright interest in the program
+  `Gnomovision' (which makes passes at compilers) written by James Hacker.
+
+  <signature of Ty Coon>, 1 April 1989
+  Ty Coon, President of Vice
+
+This General Public License does not permit incorporating your program into
+proprietary programs.  If your program is a subroutine library, you may
+consider it more useful to permit linking proprietary applications with the
+library.  If this is what you want to do, use the GNU Lesser General
+Public License instead of this License.

web/core/lib/Drupal/Component/Diff/MappedDiff.php

@@ -0,0 +1,57 @@
+<?php
+
+namespace Drupal\Component\Diff;
+
+/**
+ * FIXME: bad name.
+ * @todo document
+ * @private
+ * @subpackage DifferenceEngine
+ */
+class MappedDiff extends Diff {
+
+  /**
+   * Constructor.
+   *
+   * Computes diff between sequences of strings.
+   *
+   * This can be used to compute things like
+   * case-insensitive diffs, or diffs which ignore
+   * changes in white-space.
+   *
+   * @param array $from_lines
+   *   An array of strings.
+   *   (Typically these are lines from a file.)
+   * @param array $to_lines
+   *   An array of strings.
+   * @param array $mapped_from_lines
+   *   This array should have the same size number of elements as $from_lines.
+   *   The elements in $mapped_from_lines and $mapped_to_lines are what is
+   *   actually compared when computing the diff.
+   * @param array $mapped_to_lines
+   *   This array should have the same number of elements as $to_lines.
+   */
+  public function __construct($from_lines, $to_lines, $mapped_from_lines, $mapped_to_lines) {
+
+    assert(sizeof($from_lines) == sizeof($mapped_from_lines));
+    assert(sizeof($to_lines) == sizeof($mapped_to_lines));
+
+    parent::__construct($mapped_from_lines, $mapped_to_lines);
+
+    $xi = $yi = 0;
+    for ($i = 0; $i < sizeof($this->edits); $i++) {
+      $orig = &$this->edits[$i]->orig;
+      if (is_array($orig)) {
+        $orig = array_slice($from_lines, $xi, sizeof($orig));
+        $xi += sizeof($orig);
+      }
+
+      $closing = &$this->edits[$i]->closing;
+      if (is_array($closing)) {
+        $closing = array_slice($to_lines, $yi, sizeof($closing));
+        $yi += sizeof($closing);
+      }
+    }
+  }
+
+}

web/core/lib/Drupal/Component/Diff/README.txt

@@ -0,0 +1,12 @@
+The Drupal Diff Component
+
+Thanks for using this Drupal component.
+
+You can participate in its development on Drupal.org, through our issue system:
+https://www.drupal.org/project/issues/drupal
+
+You can get the full Drupal repo here:
+https://www.drupal.org/project/drupal/git-instructions
+
+You can browse the full Drupal repo here:
+https://git.drupalcode.org/project/drupal

web/core/lib/Drupal/Component/Diff/TESTING.txt

@@ -0,0 +1,18 @@
+HOW-TO: Test this Drupal component
+
+In order to test this component, you'll need to get the entire Drupal repo and
+run the tests there.
+
+You'll find the tests under core/tests/Drupal/Tests/Component.
+
+You can get the full Drupal repo here:
+https://www.drupal.org/project/drupal/git-instructions
+
+You can find more information about running PHPUnit tests with Drupal here:
+https://www.drupal.org/node/2116263
+
+Each component in the Drupal\Component namespace has its own annotated test
+group. You can use this group to run only the tests for this component. Like
+this:
+
+$ ./vendor/bin/phpunit -c core --group Diff

web/core/lib/Drupal/Component/Diff/WordLevelDiff.php

@@ -0,0 +1,81 @@
+<?php
+
+namespace Drupal\Component\Diff;
+
+use Drupal\Component\Diff\Engine\HWLDFWordAccumulator;
+
+/**
+ * @todo document
+ * @private
+ * @subpackage DifferenceEngine
+ */
+class WordLevelDiff extends MappedDiff {
+
+  const MAX_LINE_LENGTH = 10000;
+
+  public function __construct($orig_lines, $closing_lines) {
+    [$orig_words, $orig_stripped] = $this->_split($orig_lines);
+    [$closing_words, $closing_stripped] = $this->_split($closing_lines);
+
+    parent::__construct($orig_words, $closing_words, $orig_stripped, $closing_stripped);
+  }
+
+  protected function _split($lines) {
+    $words = [];
+    $stripped = [];
+    $first = TRUE;
+    foreach ($lines as $line) {
+      // If the line is too long, just pretend the entire line is one big word
+      // This prevents resource exhaustion problems
+      if ( $first ) {
+        $first = FALSE;
+      }
+      else {
+        $words[] = "\n";
+        $stripped[] = "\n";
+      }
+      if (mb_strlen($line) > $this::MAX_LINE_LENGTH) {
+        $words[] = $line;
+        $stripped[] = $line;
+      }
+      else {
+        if (preg_match_all('/ ( [^\S\n]+ | [0-9_A-Za-z\x80-\xff]+ | . ) (?: (?!< \n) [^\S\n])? /xs', $line, $m)) {
+          $words = array_merge($words, $m[0]);
+          $stripped = array_merge($stripped, $m[1]);
+        }
+      }
+    }
+    return [$words, $stripped];
+  }
+
+  public function orig() {
+    $orig = new HWLDFWordAccumulator();
+
+    foreach ($this->edits as $edit) {
+      if ($edit->type == 'copy') {
+        $orig->addWords($edit->orig);
+      }
+      elseif ($edit->orig) {
+        $orig->addWords($edit->orig, 'mark');
+      }
+    }
+    $lines = $orig->getLines();
+    return $lines;
+  }
+
+  public function closing() {
+    $closing = new HWLDFWordAccumulator();
+
+    foreach ($this->edits as $edit) {
+      if ($edit->type == 'copy') {
+        $closing->addWords($edit->closing);
+      }
+      elseif ($edit->closing) {
+        $closing->addWords($edit->closing, 'mark');
+      }
+    }
+    $lines = $closing->getLines();
+    return $lines;
+  }
+
+}

web/core/lib/Drupal/Component/Diff/composer.json

@@ -0,0 +1,23 @@
+{
+    "name": "drupal/core-diff",
+    "description": "Diff.",
+    "keywords": [
+        "drupal"
+    ],
+    "homepage": "https://www.drupal.org/project/drupal",
+    "license": "GPL-2.0-or-later",
+    "require": {
+        "php": ">=8.3.0",
+        "sebastian/diff": "^4 || ^5 || ^6 || ^7"
+    },
+    "autoload": {
+        "psr-4": {
+            "Drupal\\Component\\Diff\\": ""
+        }
+    },
+    "extra": {
+        "_readme": [
+            "This file was partially generated automatically. See: https://www.drupal.org/node/3293830"
+        ]
+    }
+}