Drupal 8.0.0 beta 12. More info: https://www.drupal.org/node/2514176

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

@@ -0,0 +1,64 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Component\Diff\MappedDiff.
+ */
+
+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 $from_lines array An array of strings.
+   *  (Typically these are lines from a file.)
+   *
+   * @param $to_lines array An array of strings.
+   *
+   * @param $mapped_from_lines array 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 $mapped_to_lines array 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);
+      }
+    }
+  }
+}
+