--- /dev/null
+<?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 $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);
+ }
+ }
+ }
+
+}