class MappedDiff

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);
            }
        }
    }

}