TYPO3: clever HMENU browse next/prev

setup.typoscript

# This menu is considered to be 'clever' due to the fact that it's sliding accross the entire page tree:
#
# * Previous link: if there's no previous sibling page, we're linking to the parent page instead
# * Next link:
#   * if there's no child page, we're linking to the next sibling page
#   * if that's not available, we're linking to the next sibling page of the parent page
#   * if that's not available, we're linking to the next sibling page of the grandparent page

temp.browseMenuItem = HMENU
temp.browseMenuItem.special = browse
temp.browseMenuItem.includeNotInMenu = 0
temp.browseMenuItem.1 = TMENU
temp.browseMenuItem.1.NO = 1

page.10.variables {
            # Menu item for prev-link
            prevPage < temp.browseMenuItem
            prevPage {
                # Try prev sibling first
                special.items = prev

                # If not available -> use parent page instead
                stdWrap.ifEmpty.override.cObject < temp.browseMenuItem
                stdWrap.ifEmpty.override.cObject {
                    special.items = up
                }
            }

            # Menu item for next-link
            nextPage < temp.browseMenuItem
            nextPage {
                # Try first child first
                special = directory
                maxItems = 1

                # If not available -> use next sibling
                stdWrap.ifEmpty.override.cObject < temp.browseMenuItem
                stdWrap.ifEmpty.override.cObject {
                    special.items = next

                    # If not available -> use parent's sibling
                    stdWrap.ifEmpty.override.cObject < temp.browseMenuItem
                    stdWrap.ifEmpty.override.cObject {
                        special.items = next
                        special.value.data = leveluid:-2

                        # If not available -> use grandparent's sibling
                        stdWrap.ifEmpty.override.cObject < temp.browseMenuItem
                        stdWrap.ifEmpty.override.cObject {
                            special.items = next
                            special.value.data = leveluid:-3
                        }
                    }
                }
            }
}