WordPress - Tree Navigation

gistfile1.php

		<nav role="navigation">
			<ul>
				<?php foreach($primary_nav_items as $level_one) :
				/* LOOP LEVEL ONE */
				$level_two = get_pages('child_of='.$level_one.'&parent='.$level_one.'&sort_column=menu_order&sort_order=asc&exclude='.$excluded_pages_string.'');
				/* GET ALL LEVEL TWO PAGES */ ?>
				<li<?php if($root_page_id==$level_one): ?> class="current<?= $level_two ? ' open' : '' ?>"<?php endif; ?>>
					<a href="<?= get_permalink($level_one); ?>">
						<?= get_the_title($level_one); ?>
					</a>
					<?php if ($level_two && $root_page_id==$level_one):
					/* TEST FOR LEVEL TWO PAGES */ ?>
					<ul>
						<?php foreach($level_two as $level_two_page):
						/* LOOP LEVEL TWO */
						$level_three = get_pages('child_of='.$level_two_page->ID.'&parent='.$level_two_page->ID.'&sort_column=menu_order&sort_order=asc&exclude='.$excluded_pages_string.'');
						/* GET ALL LEVEL THREE PAGES */
						$level_two_current=0;
						$show_level_three=0;
						/* SET VARS */
						if($level_two_page->ID==$post->ID) {
							$level_two_current=1;
						}
						if($level_three && $level_two_current==1 || $level_two_page->ID==$post->post_parent) {
							$show_level_three=1;
						}
						?>
						<li<?php if($level_two_current==1 || $show_level_three==1): ?> class="current<?= $show_level_three==1 ? ' open' : '' ?>"<?php endif; ?>>
							<a href="<?= get_page_link($level_two_page->ID); ?>">
								<?= $level_two_page->post_title; ?>	
							</a>
							<?php if ($show_level_three==1):
							/* TEST FOR LEVEL THREE PAGES */ ?>
							<ul>
							<?php foreach($level_three as $level_three_page):
							/* LOOP LEVEL THREE */ ?>
								<li<?= $level_three_page->ID==$post->ID ? ' class="current"' : '' ?>>
									<a href="<?= get_page_link($level_three_page->ID); ?>">
										<?= $level_three_page->post_title; ?>	
									</a>
								</li>
							<?php endforeach;
							/* END LOOP LEVEL THREE */ ?>
							</ul>
							<?php endif;
							/* END TEST FOR LEVEL THREE PAGES */ ?>
						</li>
						<?php endforeach;
						/* END LOOP LEVEL TWO */ ?>
					</ul>
					<?php endif;
					/* END TEST FOR LEVEL TWO PAGES */ ?>	
				</li>
				<?php endforeach; 
				/* END LOOP LEVEL ONE */ ?>				
			</ul>
		</nav>